000
FXUS62 KKEY 201607
AFDKEY
AREA FORECAST DISCUSSION FOR THE FLORIDA KEYS
NATIONAL WEATHER SERVICE KEY WEST FL
1107 AM EST TUE JAN 20 2009
.DISCUSSION...
A DEEP LONG WAVE TROUGH OVER EASTERN NORTH AMERICA IS BEING
REINFORCED BY ADDITIONAL EQUATORWARD-MOVING SHORT WAVE ENERGY THIS
MORNING. A SURFACE CYCLONE OFFSHORE THE CAROLINAS HAS DEEPENED BELOW
1000MB AND IS ASSISTING IN THE TRANSPORT OF COLD POLAR AIR SOUTHWARD
INTO THE GULF BASIN. WINDS IN THE FLORIDA KEYS SHIFTED FROM WEST TO
NORTHWEST EARLIER THIS MORNING AS A SHEAR LINE THAT RACED OUT AHEAD
OF A PRESSURE TROUGH TRAVERSED THE KEYS. THE APPROACHING TROUGH IS
ASSOCIATED WITH THE LEADING EDGE OF AN AREA OF STRONG COLD THERMAL
ADVECTION...AND SHOULD BE PASSING THROUGH THE KEYS IN THE NEXT FEW
HOURS. AS A CONSEQUENCE...TEMPERATURES WILL BE STEADY FROM 68 TO 70F
FOR ANOTHER HOUR OR TWO BEFORE BEGINNING A SLOW FALL INTO THE MID 60S
BY LATE THIS AFTERNOON. NORTHWEST WINDS WILL SURGE THROUGH THE
AFTERNOON...PEAKING TONIGHT. THE MID-LEVEL OVERCAST WILL THIN BY LATE
THIS AFTERNOON. HOWEVER...LOW-LEVEL STRATOCUMULUS CLOUDS WILL
THICKEN...AND A FEW SPRINKLES WILL BE POSSIBLE THROUGH THIS EVENING.
FORECASTS HAVE ALREADY BEEN UPDATED FOR THE TRANSITION IN WEATHER
EXPECTED THIS AFTERNOON.
&&
.MARINE...
A SMALL CRAFT ADVISORY IS IN EFFECT FOR ALL ZONES. A SHEAR LINE AND
ASSOCIATED LINE OF LIGHT SHOWERS MOVED THROUGH ALL OF THE KEYS THIS
MORNING. WINDS TURNED NORTHWEST IN WAKE OF THIS BOUNDARY. NORTHWEST
BREEZES WILL INCREASE TO NEAR 25KT...WITH GUSTS NEAR 30KT...BY
SUNSET AS A TROUGH ASSOCIATED WITH A DEEPENING GALE CENTER OFFSHORE
THE CAROLINAS MOVES THROUGH THE KEYS. SEAS WILL BUILD IN A NORTHWEST
SWELL...WITH SIGNIFICANT WAVE HEIGHTS EXCEEDING 10FT IN GULF OF
MEXICO WATERS BEYOND 40 NM WEST OF MAINLAND MONROE AND IN THE
VICINITY OF THE DRY TORTUGAS...AS WELL AS AREAS WEST AND SOUTH OF THE
TORTUGAS. ISOLATED SHOWERS WILL END THIS AFTERNOON BEYOND THE REEF...
BUT SPRINKLES ARE POSSIBLE ALL ZONES THROUGH THIS EVENING.
&&
.AVIATION...
FOR THE BALANCE OF TODAY...VFR CEILINGS OF AROUND 3500 FEET WILL
PREDOMINATE AT THE KEYS ISLAND TERMINALS...BUT SPELLS OF MVFR
CEILINGS ARE POSSIBLE THIS AFTERNOON. NORTHWEST WINDS /330 DEGREES/
OF 10 TO 15 KNOTS WILL INCREASE TO NEAR 20 KNOTS EARLY THIS
AFTERNOON...WITH FREQUENT GUSTS OF AROUND 30 KNOTS.
&&
.KEY WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GM...SMALL CRAFT ADVISORY FOR GMZ031-GMZ032-
GMZ033-GMZ052-GMZ053-GMZ054-GMZ072-GMZ073-GMZ074-GMZ075.
&&
$$
PUBLIC/MARINE.........KASPER
AVIATION/NOWCASTS.....APA
DATA COLLECTION.......WAH
VISIT US ON THE WEB AT WWW.WEATHER.GOV/KEYWEST
000
FXUS62 KKEY 200949
AFDKEY
AREA FORECAST DISCUSSION FOR THE FLORIDA KEYS
NATIONAL WEATHER SERVICE KEY WEST FL
449 AM EST TUE JAN 20 2009
...MUCH COLDER TEMPERATURES FOR TONIGHT THROUGH THURSDAY...
.DISCUSSION...
.CURRENTLY...
MOSTLY CLEAR SKIES PREVAIL ACROSS THE FLORIDA KEYS AT PRESENT...
WITH CLOUDINESS AND ISOLATED SHOWERS ASSOCIATED WITH FRONTAL
BOUNDARIES LYING ALONG THE SOUTHERN AND NORTHERN EDGES OF OUR SERVICE
AREA. TEMPERATURES ALONG THE ISLAND CHAIN ARE IN THE UPPER 60S...
AND WINDS ARE FROM THE SOUTHWEST TO WEST AT 10 TO 15 KNOTS WITH
OCCASIONAL STRONGER GUSTS.
SURFACE ANALYSIS DEPICTS A DEVELOPING LOW PRESSURE AREA OFF THE SOUTH
CAROLINA COAST...WITH A STRONG COLD FRONT EXTENDING SOUTHWESTWARD
THROUGH CENTRAL FLORIDA AND INTO THE EASTERN GULF OF MEXICO. ANOTHER
WEAKER FRONT LIES ACROSS THE WESTERN BAHAMAS AND ALONG THE NORTHWEST
COAST OF CUBA. A LARGE ARCTIC HIGH PRESSURE AREA IS CENTERED ACROSS
THE WESTERN HIGH PLAINS...AND IS BUILDING EASTWARD. AT MID AND UPPER
LEVELS...A DEEP TROUGH REMAINS IN PLACE ACROSS THE EASTERN CONUS...
WITH STRONG RIDGING CENTERED OVER THE NORTHERN ROCKIES.
.SHORT TERM (TODAY THROUGH THURSDAY)...
A STRONG COLD FRONT WILL PUSH THROUGH THE KEYS THIS MORNING...
SUPPORTED BY INTENSE MID LEVEL SHORTWAVE ENERGY SWINGING THROUGH THE
BASE OF THE DEEP LONGWAVE TROUGH. LACK OF BOTH AVAILABLE MOISTURE
AND LOW LEVEL CONVERGENCE ALONG THE FRONT WILL GREATLY LIMIT PRECIP.
A NARROW LINE OF SHOWERS ALONG THE FRONT HAS BEEN WEAKENING AS IT
TRACKS SOUTHEASTWARD ALONG THE WEST COAST OF FLORIDA OVERNIGHT.
EXPECT THIS WEAKENING TREND TO CONTINUE AS THIS FEATURE PASSES
THROUGH THE KEYS THIS MORNING. RAINFALL AMOUNTS AT APF AND FMY WERE
ONLY A COUPLE OF HUNDREDTHS OF AN INCH AS THE LINE OF SHOWERS MOVED
THROUGH. WOULD EXPECT SIMILAR VERY LIGHT AMOUNTS AT A FEW SPOTS ALONG
THE KEYS...WITH ZERO OR TRACE AMOUNTS ELSEWHERE. HAVE MAINTAINED
SLIGHT CHANCE POPS FOR TODAY.
IN THE WAKE OF THE FRONTAL PASSAGE...STRONG NORTHWEST WINDS WILL
PREVAIL ACROSS THE KEYS THIS AFTERNOON AND TONIGHT. COLD AIR STRATOCU
HAS BEGUN TO DEVELOP ACROSS THE CENTRAL AND EASTERN GULF...AND WOULD
EXPECT A PERIOD OF CONSIDERABLE CLOUDINESS ACROSS AT LEAST THE MIDDLE
AND LOWER KEYS THIS AFTERNOON AND TONIGHT. A FEW LIGHT SPRINKLES WILL
BE POSSIBLE AS WELL...AND HAVE CARRIED MENTION OF SUCH IN THE
FORECAST FOR THIS AFTERNOON AND EVENING.
THE PRIMARY WEATHER STORY DURING THE REMAINDER OF THE SHORT TERM
PERIOD WILL BE THE COLD TEMPERATURES. WE ARE LIKELY TO SEE OUR LOWEST
TEMPS OF THE SEASON THUS FAR TONIGHT THROUGH WEDNESDAY NIGHT. BY
WEDNESDAY MORNING...READINGS WILL DROP TO BETWEEN 50 AND 55 ACROSS
THE LOWER AND MIDDLE KEYS...AND INTO THE UPPER 40S TO NEAR 50 IN THE
UPPER KEYS. HIGHS WEDNESDAY WILL ONLY CLIMB TO NEAR 60 DEGREES.
WEDNESDAY NIGHT WILL SEE THE COLDEST TEMPS OF THIS EPISODE...WITH
LOWS DROPPING TO AROUND 50 DEGREES IN THE LOWER/MIDDLE KEYS...AND
INTO THE MID TO UPPER 40S IN THE UPPER KEYS. BRISK NORTH WINDS WILL
MAKE IT FEEL EVEN CHILLIER...AND WIND CHILL VALUES MAY DROP TO AROUND
40 DEGREES IN THE FAR UPPER KEYS LATE WEDNESDAY NIGHT INTO EARLY
THURSDAY MORNING.
FIRE WX MAY ALSO BECOME A CONCERN ON WEDNESDAY. MAV MOS FORECASTS
DEWPOINTS TO DROP WELL INTO THE 30S...PRODUCING MINIMUM RELATIVE
HUMIDITIES AROUND 40 PERCENT IN THE UPPER KEYS WEDNESDAY AFTERNOON.
GIVEN THAT THE MAV IS OFTEN TOO HIGH WITH DEWPOINTS IN THESE
SITUATIONS...THERE IS A CHANCE THAT THE RED FLAG CRITERIA OF RH
LESS THAN 35 PERCENT WITH WINDS OF 15 MPH OR GREATER MAY OCCUR. DO
NOT HAVE SUFFICIENT CONFIDENCE IN THE OCCURRENCE OF RED FLAG
CONDITIONS TO ISSUE A FIRE WEATHER WATCH AT THIS TIME...BUT LATER
SHIFTS WILL CONTINUE TO MONITOR.
.LONG TERM (THURSDAY NIGHT THROUGH MONDAY)...
THE EASTERN TROUGH/WESTERN RIDGE PATTERN WILL BREAK DOWN LATE THIS
WEEK INTO THE WEEKEND...WITH ZONAL FLOW DEVELOPING ACROSS THE CONUS.
THIS WILL BRING THE PARADE OF COLD FRONTS TO AN END FOR THE TIME
BEING ACROSS OUR REGION. SURFACE HIGH PRESSURE INITIALLY OVER FLORIDA
WILL SHIFT EASTWARD INTO THE ATLANTIC BY THE WEEKEND. THE NEXT COLD
FRONT IS NOT SHOWN TO MAKE IT TO THE KEYS BY EITHER THE GFS OR ECMWF.
THIS WILL ALLOW FOR MODERATING TEMPERATURES. THURSDAY NIGHT AND
FRIDAY WILL STILL BE BELOW NORMAL WITH LOWS IN THE MID-UPPER 50S AND
HIGHS NEAR 70. A MORE EASTERLY LOW LEVEL TRAJECTORY WILL THEN RETURN
OUR TEMPS TO NEAR NORMAL FOR THE WEEKEND INTO EARLY NEXT WEEK...WITH
LOWS IN THE MID 60S AND HIGHS IN THE MID 70S. LACK OF MOISTURE WITH
PWATS BELOW 1 INCH WILL ALLOW FOR A DRY FORECAST TO CONTINUE THROUGH
SUNDAY NIGHT...FOLLOWED BY TYPICAL DRY SEASON DIME POPS FOR MONDAY.
&&
.MARINE...
WEST WINDS HAVE INCREASED STEADILY ACROSS THE COASTAL WATERS
OVERNIGHT AS LOW PRESSURE STRENGTHENS OFF THE CAROLINA COAST. WINDS
HAVE ALREADY REACHED SCA CRITERIA ACROSS THE ATLANTIC/GULF WATERS...
AND WILL LIKELY EXCEED 20 KNOTS ACROSS FLORIDA BAY EARLY THIS
MORNING. A COLD FRONT WILL MOVE THROUGH THE KEYS THIS MORNING...
TURNING WINDS MORE TO THE NORTHWEST WITH A FURTHER INCREASE IN SPEED.
SMALL CRAFT ADVISORIES WILL REMAIN POSTED FOR ALL KEYS WATERS TODAY.
STRONG NORTHERLY WINDS ARE EXPECTED TONIGHT AS COLD AIR POURS OFF THE
MAINLAND. WINDS WILL THEN BEGIN A GRADUAL DOWNWARD TREND ON WEDNESDAY.
SMALL CRAFT ADVISORIES FOR WINDS WILL PROBABLY BE NEEDED INTO
WEDNESDAY MORNING...THEN SCA FOR SEAS WILL LIKELY BE NECESSARY ACROSS
THE FLORIDA STRAITS WEDNESDAY AFTERNOON...AND POSSIBLY INTO WEDNESDAY
EVENING. MORE TRANQUIL CONDITIONS ARE EXPECTED FOR THURSDAY THROUGH
SATURDAY...AS HIGH PRESSURE SETTLES OVER THE FLORIDA PENINSULA.
GENTLE TO MODERATE NORTHEAST/EAST BREEZES ARE FORECAST DURING THIS
PERIOD.
&&
.AVIATION...
VFR CONDITIONS WILL PREVAIL OVERNIGHT AND TUESDAY AT THE KEYS ISLAND
TERMINALS. AN APPROACHING FRONT IS HEADING SOUTHEAST ACROSS THE
FLORIDA PENINSULA TONIGHT...AND WILL PASS OVER THE ISLAND CHAIN
AROUND 12Z. SURFACE WINDS WILL BE FROM WEST-SOUTHWEST TO WEST NEAR
10 KNOTS AND GUSTY OVERNIGHT...PILOTS...BE AWARE THAT WINDS JUST
ABOVE THE SURFACE ARE CURRENTLY SIGNIFICANTLY STRONGER. LATEST UPPER
AIR SOUNDINGS AND PROFILER DATA INDICATE WEST WINDS OF 20 TO 25
KNOTS ABOVE 1000 FT. WINDS BELOW 1000 FEET WILL INCREASE QUICKLY TO
15 TO 20 KNOTS AND GUSTY AFTER 12Z TO 14Z. WITH THE AFOREMENTIONED
FRONT THERE MAY BE BRIEF MVFR CEILINGS OF SCATTERED TO BROKEN AROUND
FL030 TO FL035...BUT EXPECT VERY LITTLE IF ANY PRECIPITATION WITH
FRONTAL PASSAGE.
&&
.CLIMATE...
WITH THE COLDEST WEATHER OF THE SEASON THUS FAR EXPECTED THIS WEEK...
KEY WEST MAY APPROACH SOME RECORD TEMPERATURES. THE COLDEST HIGH
TEMPERATURE EVER RECORDED FOR JANUARY 21 IS 60 DEGREES...LAST SET IN
1960. THE RECORD LOW TEMPERATURE FOR JANUARY 22 IS 49 DEGREES...SET
IN 1985.
&&
.PRELIMINARY POINT TEMPS/POPS...
KEY WEST 72 56 61 51 / 20 10 - -
MARATHON 72 52 61 49 / 20 10 - -
&&
.KEY WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GM...SMALL CRAFT ADVISORY IN EFFECT FOR GMZ031>033-052>054-072>075.
&&
$$
PUBLIC/MARINE/CLIMATE...JACOBSON
AVIATION/NOWCASTS.......BWC
VISIT US ON THE WEB AT WWW.WEATHER.GOV/KEYWEST
000
FXUS62 KKEY 200238
AFDKEY
AREA FORECAST DISCUSSION FOR THE FLORIDA KEYS
NATIONAL WEATHER SERVICE KEY WEST FL
940 PM EST MON JAN 19 2009
.DISCUSSION...
ACCORDING TO KBYX RADAR...SHOWERS REMAIN OUT OVER THE FLORIDA
STRAITS...ROUGHLY BEYOND 30 NM FROM THE ISLAND CHAIN. OTHERWISE...
SKIES OVER THE KEYS ISLAND CHAIN AND POINTS NORTHWESTWARD ARE MOSTLY
CLEAR. WINDS ALONG THE KEYS ARE WESTERLY...AND HAVE ACTUALLY
SLACKENED OVER THE PAST COUPLE OF HOURS. AT THE CMANS...THE DECREASE
HAS NOT BEEN AS LARGE BUT THE TREND IS STILL NOTICEABLE.
TEMPERATURES ALONG THE ISLAND CHAIN ARE IN THE MID TO UPPER 60S WITH
DEWPOINTS IN THE LOWER 60S.
THE LATE EVENING SOUNDING...CUDJOE PROFILER...AND KBYX VAD WIND
PROFILE INDICATE RATHER STRONG WINDS FROM ROUGHLY 1 KFT UPWARD.
HOWEVER...A TOUGH CALL ON THE UPDATE TONIGHT IN THAT THE AIRMASS
BEING DRAGGED INTO THE IMMEDIATE AREA MAY HAVE A DIFFICULT TIME
MIXING ALONG AND TO THE WEST OF THE ISLAND CHAIN. BUT THE GRADIENT
MAY OVERCOME THIS BY VERY LATE IN THE OVERNIGHT PERIOD. OF
COURSE...THE AIRMASS WILL MIX MORE READILY OUT OVER THE STRAITS. BUT
THE PRESENT OBSERVATIONS ALONG THE ISLAND CHAIN MAKE FOR A TOUGH
UPDATE IN REGARDS TO THE EXPECTED WIND SPEEDS. A TIMELY QUIKSCAT
PASS WOULD MAKE FOR AN EASIER DECISION. NONETHELESS...WILL HAVE TO
MAKE AN UPDATE TO THE ZONES DUE MOSTLY TO THE INITIAL WIND SPEED
DISPARITY. WILL KEEP AN UPWARD TREND IN AN UPCOMING ZONE
UPDATE...BUT BOTH THE INITIAL WIND SPEEDS AND THE EXPECTED SPEEDS BY
LATE TONIGHT WILL HAVE TO BE TRIMMED BACK. AGAIN..BY THE EARLY HOURS
OF THE DAYTIME PERIOD ON TUESDAY...THE GRADIENT WIND WILL BE MORE OF
A DRIVING FACTOR...AND IT WILL BE WINDY. RAIN-WISE...THE CHANCE OF
ANY SIGNIFICANT RETURNS ON RADAR ARE EXPECTED TO BE CONFINED WELL
OUT IN THE STRAITS WHERE BETTER MIXING WILL BE MAINTAINED.
TEMPERATURE-WISE...ALTHOUGH THE WINDS MAY NOT BE AS STRONG AS
PREVIOUSLY ADVERTISED...WE SHOULD ONLY LOSE A COUPLE OF DEGREES FROM
THEIR PRESENT READINGS. MAY TRIM OUR GRIDS BACK BY A FEW DEGREES FOR
THE OVERNIGHT PERIOD.
&&
.MARINE...
AGAIN...A QUIKSCAT PASS WOULD SERVE NICELY ESPECIALLY FOR THE TREND
OVER OUR GULF AND BAY WATERS. AS STATED ABOVE...THE GRADIENT WIND
WILL BE A MORE SUBSTANTIAL FACTOR LATE IN THE OVERNIGHT PERIOD. BUT
INITIALLY AND THROUGH AT LEAST THE VERY EARLY HOURS OF TUESDAY
MORNING...WILL HAVE TO PARE OUR ADVERTISED WINDS BACK BY SEVERAL
KNOTS. BUT I DO NOT PLAN TO DROP OUR SMALL CRAFT ADVISORY SINCE WE
ALREADY HAVE IT ADVERTISED...AND STRENGTHENING WEST WINDS WILL BE
ADVANCING SOUTHWARD LATE TONIGHT AND DURING THE HOURS AROUND SUNRISE
ON TUESDAY.
&&
.AVIATION...
VFR CONDITIONS EXPECTED TONIGHT. SURFACE WINDS WILL START OUT
SOUTHWEST TO WEST AT 10 KNOTS OR LESS OVERNIGHT...THEN INCREASE
QUICKLY TO 15 TO 20 KNOTS AND GUSTY AFTER DAYBREAK. PILOTS...BE
AWARE THAT WINDS JUST ABOVE THE SURFACE ARE SIGNIFICANTLY STRONGER
THEN AT THE SURFACE...WITH LATEST UPPER AIR SOUNDINGS AND PROFILER
DATA INDICATING WEST WINDS OF 20 TO 25 KNOTS AOB 1000 FT.
&&
.KEY WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GM...SMALL CRAFT ADVISORY FOR GMZ031-GMZ032-
GMZ033-GMZ052-GMZ053-GMZ054-GMZ072-GMZ073-GMZ074-GMZ075.
&&
$$
PUBLIC/MARINE.........04
AVIATION/NOWCASTS.....11
DATA COLLECTION.......ROSS
VISIT US ON THE WEB AT WWW.WEATHER.GOV/KEYWEST
000
FXUS62 KKEY 192151
AFDKEY
AREA FORECAST DISCUSSION FOR THE FLORIDA KEYS
NATIONAL WEATHER SERVICE KEY WEST FL
451 PM EST MON JAN 19 2009
.DISCUSSION...
THE BAND OF SHOWERS ASSOCIATED WITH A PRE-FRONTAL WIND SHEAR LINE IS
CURRENTLY TRANSLATING QUICKLY TOWARD THE EAST AND SOUTH. MOST
RAINFALL AMOUNTS IN THE KEYS WERE UNDER A TENTH OF AN INCH. CLOUDS
ARE ALSO BREAKING UP...AND MOSTLY CLEAR SKIES ARE EXPECTED OVER MUCH
OF THE KEYS LATER TONIGHT.
A VERY DEEP AND BROAD REGION OF ENERGETIC CYCLONIC FLOW COVERS
EASTERN NORTH AMERICA OVER MODIFIED COLD AIR OF ARCTIC ORIGIN AT THE
SURFACE. A FEW CYCLONIC VORTICES ARE SWIRLING AT THE SURFACE OVER THE
EASTERN UNITED STATES...WITH AN INTENSIFYING LOW PRESSURE CENTER
LOCATED OVER THE CAROLINAS AT PRESENT. A STRENGTHENING TROUGH AND
COLD FRONT EXTEND SOUTHWESTWARD FROM THIS LOW PRESSURE CENTER ACROSS
THE NORTHERN GULF OF MEXICO...WITH DEEP WESTERLIES PREVAILING OVER
SOUTHERN FLORIDA.
THE KEY WEST DOPPLER VAD AND CUDJOE KEY WIND PROFILERS ARE DETECTING
20-25KT JUST ABOVE THE SURFACE. HOWEVER...THESE SPEEDS HAVE NOT THUS
FAR MATERIALIZED AT THE SURFACE EXCEPT IN GUSTS DURING EARLIER
SHOWERS. HOWEVER...AS LOW PRESSURE DEEPENING PERSISTS NEAR THE
CAROLINAS OVERNIGHT...GRADIENT FLOW WILL INCREASE LOCALLY...AND WEST
WINDS OVER WATER ARE LIKELY TO INCREASE TO 20-25KT BY DAYBREAK...
ESPECIALLY OVER WARMER WATERS ALONG AND SOUTH OF THE REEF WHERE
DECOUPLING IS LESS LIKELY.
THE COLD FRONTAL PASSAGE IS EXPECTED TUESDAY AFTERNOON...PRECEDED BY
A BROKEN BAND OF CLOUDS AND LIGHT SHOWERS...AND BY TUESDAY NIGHT...
NORTHWEST BREEZES WILL BE BLOWING STRONG WITH DROPPING TEMPERATURES.
KEYS RESIDENTS AND VISITORS ARE LIKELY TO AWAKE TO THE COOLEST
TEMPERATURES OF THE SEASON THUS FAR WEDNESDAY MORNING...WITH READINGS
IN THE 40S POSSIBLE IN THE UPPER KEYS...AND KEY WEST TEMPERATURES
DOWN BELOW 55F. TEMPERATURES WILL STRUGGLE TO REACH 60F ON
WEDNESDAY...AND THEN DROP QUICKLY INTO MID 50S WEDNESDAY
EVENING...WITH THURSDAY MORNING TEMPERATURES RANGING FROM MID 40S IN
OCEAN REEF AND NORTH KEY LARGO...TO NEAR 50F IN KEY WEST.
A SLOW MODERATION IN TEMPERATURES AND WIND WILL ENSUE THURSDAY
THROUGH THE WEEKEND...WITH A SLIGHT CHANCE OF SHOWERS POSSIBLE AGAIN
BY EARLY NEXT WEEK IN A MORE EASTERLY FLOW REGIME.
&&
.MARINE...
A SMALL CRAFT ADVISORY HAS BEEN POSTED FOR ALL ZONES. WEST BREEZES
WILL GRADUALLY FRESHEN THIS EVENING...LIKELY REACHING 20-25KT BY
DAYBREAK TUESDAY...WITH HIGHEST WINDS LIKELY OVER THE GULF STREAM. A
STRONG COLD FRONT WILL SWEEP THROUGH THE KEYS TUESDAY AFTERNOON. THE
FRONT MAY BE PRECEDED BY A BROKEN BAND OF CLOUDS AND SHOWERS...BUT
MOISTURE WILL BE LIMITED. WINDS WILL TURN WEST TO NORTHWEST BEHIND
THE FRONT AND SURGE TO NEAR 25KT BY TUESDAY EVENING AS COLD THERMAL
ADVECTION INCREASES. A LONG FETCH OF WESTERLY WINDS WILL RESULT IN
RAPIDLY BUILDING SEAS TONIGHT IN A WESTERLY SWELL. SEAS WILL KEEP
BUILDING ON TUESDAY...EXCEEDING 10 FEET OVER GULF WATERS BEYOND 40
NAUTICAL MILES WEST OF MAINLAND MONROE...AND IN THE VICINITY OF AND
SOUTH OF THE DRY TORTUGAS. NORTH BREEZES WILL BLOW STRONG EARLY
WEDNESDAY MORNING AS COLD AIR FROM THE MAINLAND DRAINS SOUTHWESTWARD.
HOWEVER...A DECREASING TREND IN WIND SHOULD COMMENCE BY WEDNESDAY
MIDDAY...WITH WIND SPEEDS EXCEEDING MODEL GUIDANCE BY 5KT OR SO UNTIL
THURSDAY.
&&
.AVIATION...
FOR THE BALANCE OF THIS AFTERNOON AND TONIGHT...VFR CONDITIONS WILL
PREDOMINATE...WITH PRIMARILY WEST WINDS OF 10 TO 15 KNOTS WITH GUSTS
BETWEEN 15 AND 20 KNOTS AT THE ISLAND TERMINALS.
&&
.KEY WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GM...SMALL CRAFT ADVISORY FOR GMZ031-GMZ032-
GMZ033-GMZ052-GMZ053-GMZ054-GMZ072-GMZ073-GMZ074-GMZ075.
&&
$$
PUBLIC/MARINE.........KASPER
AVIATION/NOWCASTS.....APA
DATA COLLECTION.......ROSS
VISIT US ON THE WEB AT WWW.WEATHER.GOV/KEYWEST
000
FXUS62 KKEY 191601
AFDKEY
AREA FORECAST DISCUSSION FOR THE FLORIDA KEYS
NATIONAL WEATHER SERVICE KEY WEST FL
1101 AM EST MON JAN 19 2009
.DISCUSSION...
A DEEP CYCLONIC FLOW REGIME COVERS MOST OF EASTERN NORTH AMERICA...
EXTENDING SOUTH EVEN TO CUBA. AT THE SURFACE...A WAVY CYCLONIC STREAM
FLOWS AROUND AND THROUGH SEVERAL MIDLATITUDE CYCLONIC VORTICES IN
VARIOUS STAGES OF DEVELOPMENT. A GENERAL SOUTHWEST OR WEST GRADIENT
FLOW PREVAILS ACROSS SOUTHERN FLORIDA AND THE SOUTHEASTERN GULF OF
MEXICO...WITH TWO DISTINCT TROUGHS ANALYZED OVER THE GULF OF MEXICO.
THE FIRST TROUGH IS CURRENTLY LOCATED IMMEDIATELY WEST AND NORTH OF
THE KEYS...AND IS ASSOCIATED WITH A WIND SHIFT AND SURGE. THE SECOND
TROUGH...CURRENTLY ALONG THE NORTHERN GULF COAST...IS ASSOCIATED WITH
A STRONG THERMAL GRADIENT BETWEEN MODIFIED CONTINENTAL POLAR AIR OVER
WARMER GULF WATERS AND COLDER AIR OF ARCTIC ORIGIN TO ITS NORTH. THE
THERMAL GRADIENT WITH THIS SECOND TROUGH IS EXPECTED TO INTENSIFY AS
A GALE CENTER DEEPENS OFF THE EASTERN SEABOARD. A STRONG COLD FRONT
WILL DEVELOP AND MOVE QUICKLY SOUTHWARD...SWEEPING THROUGH THE
FLORIDA KEYS TUESDAY...LIKELY BRINGING THE COLDEST AIR OF THE SEASON
THUS FAR BY WEDNESDAY MORNING.
FORECASTS WILL BE UPDATED FOR TRANSITIONS...BUT BASIC REASONING IS
STILL SOUND FOR THE FIRST PERIOD. IT IS CURRENTLY CLOUDING UP OVER
MOST OF THE KEYS WITH SCATTERED EASTWARD-MOVING SHOWERS ON RADAR.
COVERAGE OF MEASURABLE RAIN WILL BE SPOTTY...BUT THE CURRENTLY
DEPICTED RAIN CHANCES OF 50 PERCENT REFLECT EXPECTED COVERAGE WELL.
&&
.MARINE...
FOR THIS AFTERNOON...A LONG FETCH OF ACCELERATING WESTERLY FLOW IS
RESULTING IN RAPIDLY BUILDING SIGNIFICANT WAVE HEIGHTS OVER WESTERN
MARINE ZONES. WAVE HEIGHTS WILL BE APPROACHING ADVISORY CRITERIA BY
SUNDOWN. IN ADDITION...STRENGTHENING WESTERLY GRADIENT FLOW WILL
RESULT IN A GENERAL UPWARD TREND IN SUSTAINED WIND SPEEDS WHICH COULD
REACH 20KT BY LATE AFTERNOON. WINDS ARE ALREADY GUSTING NEAR 20KT AT
SOME LOCATIONS. SMALL CRAFT SHOULD EXERCISE CAUTION FOR THE REST OF
THE DAY. SMALL CRAFT ADVISORIES ARE A NEAR CERTAINTY FOR TONIGHT.
&&
.AVIATION...
FOR THE REST OF TODAY...VFR CEILINGS OF AROUND 5000 FEET WILL
PREDOMINATE...WITH SOUTHWEST TO WEST SURFACE WINDS AT 10 TO 15 KNOTS
WITH OCCASIONAL GUSTS 20 TO 25 KNOTS NEAR SHOWERS. AN INTERMITTENT
MVFR CEILING/VISIBILITY IS POSSIBLE WITHIN A FAST MOVING SHOWER.
WINDS WILL TURN WEST TO NORTHWEST BY MID AFTERNOON...AND CONTINUE
TONIGHT.
&&
.KEY WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GM...NONE.
&&
$$
PUBLIC/MARINE.........KASPER
AVIATION/NOWCASTS.....APA
DATA COLLECTION.......WAH
VISIT US ON THE WEB AT WWW.WEATHER.GOV/KEYWEST
000
FXUS62 KKEY 190925
AFDKEY
AREA FORECAST DISCUSSION FOR THE FLORIDA KEYS
NATIONAL WEATHER SERVICE KEY WEST FL
425 AM EST MON JAN 19 2009
...MUCH COLDER TEMPERATURES FOR TUESDAY NIGHT THROUGH THURSDAY...
.DISCUSSION...
.CURRENTLY...
MOSTLY CLEAR SKIES AND RATHER COOL TEMPERATURES PREVAIL ALONG THE
FLORIDA KEYS ON THIS JANUARY MORNING. THE CLOSE PROXIMITY OF A
SOUTHWARD MOVING SURFACE RIDGE AXIS HAS ALLOWED FOR LIGHT WESTERLY
FLOW OVERNIGHT...WHICH COMBINED WITH THE CLEAR SKIES HAS PROVIDED
GOOD RADIATIONAL COOLING CONDITIONS. TEMPERATURES ALONG THE ISLAND
CHAIN RANGE FROM THE UPPER 50S TO LOWER 60S...WITH THE COOLER TEMPS
GENERALLY ON THE LARGER ISLANDS OF THE LOWER KEYS. RADAR DETECTS NO
PRECIPITATION WITHIN THE SERVICE AREA.
SURFACE ANALYSIS DEPICTS THE AFOREMENTIONED SURFACE RIDGE...WHICH
IS RETREATING SOUTHWARD AHEAD OF AN APPROACHING COLD FRONT. THIS FRONT
EXTENDS ACROSS NORTH/CENTRAL FLORIDA AT THIS TIME...WESTWARD INTO THE
CENTRAL GULF OF MEXICO. AT MID AND UPPER LEVELS...WE REMAIN LOCKED
IN A STRONGLY POSITIVE PHASE OF THE PACIFIC/NORTH AMERICAN PATTERN...
WITH A DEEP POLAR VORTEX CENTERED OVER THE EASTERN GREAT LAKES...AND
STRONG RIDGING OVER THE PACIFIC NORTHWEST. THIS PATTERN IS VERY
FAVORABLE FOR THE DELIVERY OF COLD ARCTIC AIRMASSES DEEP INTO THE
SOUTHEASTERN STATES AND FLORIDA...AND INDEED WE ARE LOOKING AT SOME
RATHER CHILLY WEATHER COMING IN FOR THE MIDDLE OF THIS WEEK.
.SHORT TERM (TODAY THROUGH TUESDAY NIGHT)...
A PAIR OF COLD FRONTS WILL PUSH THROUGH THE KEYS DURING THE SHORT
TERM PERIOD...SUPPORTED BY THE PERSISTENT AND DEEP MID/UPPER LEVEL
TROUGH ACROSS THE EASTERN CONUS. THE FIRST FRONT WILL PROGRESS FROM
CENTRAL FLORIDA THIS MORNING...MOVING THROUGH THE KEYS DURING THE
LATER AFTERNOON AND EARLY EVENING HOURS. MODEL DATA ALONG WITH
SATELLITE/RADAR LOOPS INDICATE DECENT LOW LEVEL MOISTURE CONVERGENCE
AND LIFT AHEAD OF THIS FRONT...AND HAVE GONE WITH HIGH CHANCE POPS
(50 PERCENT) FOR TODAY. IT APPEARS THAT THE BEST MOISTURE CONVERGENCE
WILL BE MOVING THROUGH THE KEYS DURING THE AFTERNOON...WHEN A FEW
BROKEN LINES OF SHOWERS CAN BE EXPECTED.
A NARROW DRY SLOT WILL MOVE THROUGH THE KEYS TONIGHT...WHEN WE WILL
BE IN BETWEEN FRONTAL SYSTEMS. HAVE MAINTAINED JUST SLIGHT CHANCE
POPS. WITH THE SECOND FRONT ALREADY TAKING SHAPE OVER THE EASTERN
GULF BY THAT TIME...WINDS WILL REMAIN FROM THE WEST WHICH WILL PREVENT
ANY SIGNIFICANT COOLING. WE ACTUALLY EXPECT WARMER OVERNIGHT LOWS ON
MONDAY NIGHT COMPARED TO SUNDAY NIGHT...DUE TO BRISK WESTERLY FLOW
OFF THE RELATIVELY MILD OFFSHORE GULF WATERS.
THE SECOND FRONT WILL SWEEP THROUGH THE KEYS ON TUESDAY...AS AN
UNUSUALLY STRONG (FOR SUCH A SOUTHERN LATITUDE) SURFACE LOW MOVES
OFF THE CAROLINA COAST IN RESPONSE TO INTENSE SHORTWAVE ENERGY
DIVING THROUGH THE LONGWAVE TROUGH. THERE WILL NOT BE MUCH OF A
CHANCE FOR LOW LEVEL MOISTURE RETURN AHEAD OF THIS FRONT...BUT THERE
DOES APPEAR TO BE SUFFICIENT MOISTURE/LIFT AND UPPER LEVEL SUPPORT TO
WARRANT LOW CHANCE (30 PERCENT) POPS.
THE COLDEST AIRMASS OF THE SEASON THUS FAR WILL BEGIN POURING INTO
THE KEYS TUESDAY NIGHT...AS STRONG NORTHWEST/NORTH FLOW DEVELOPS
BEHIND THE FRONT. ANY LINGERING SHOWER ACTIVITY SHOULD BE GONE BY
MIDNIGHT. THE MAIN WEATHER STORY THEREAFTER WILL BE MUCH COLDER AND
WINDY CONDITIONS. EXPECT LOWS BY WEDNESDAY MORNING TO REACH 50-55
DEGREES IN THE LOWER/MIDDLE KEYS...AND 45-50 IN THE UPPER KEYS.
NORTHWEST WINDS AROUND 20 MPH WILL MAKE IT FEEL EVEN COLDER.
.LONG TERM (WEDNESDAY THROUGH SUNDAY)...
DRY AND RATHER CHILLY CONDITIONS WILL PERSIST THROUGH THURSDAY...
AS ARCTIC HIGH PRESSURE SETTLES ACROSS FLORIDA. WEDNESDAY APPEARS
LIKELY TO SEE THE COLDEST HIGH TEMPERATURES SO FAR THIS WINTER
SEASON...WITH MAV/MET MOS GUIDANCE SHOWING ONLY AROUND 60 DEGREES
FOR KEY WEST AND MARATHON. CONTINUED NORTHERLY FLOW OFF THE MAINLAND
WILL LIKELY ALLOW FOR THE COLDEST NIGHT OF THE SEASON SO FAR ON
WEDNESDAY NIGHT...WITH LOWS AROUND 50 IN THE LOWER/MIDDLE KEYS...
AND 45-50 IN THE UPPER KEYS. A SLOW WARMING TREND WILL BEGIN
ON THURSDAY...BUT HIGHS WILL STILL BE WELL BELOW NORMAL...REACHING
ONLY THE MID 60S.
THE LONGWAVE PATTERN IS FORECAST TO BREAK DOWN BY THE END OF THIS
WEEK...WITH THE EASTERN TROUGH AND WESTERN RIDGE GIVING WAY TO A
MORE ZONAL FLOW REGIME. THIS SHOULD GIVE US A BREAK BETWEEN COLD
FRONTS...ALLOWING TEMPERATURES TO REBOUND TO NEAR NORMAL LEVELS BY
THE WEEKEND.
&&
.MARINE...
WINDS HAVE BEEN RUNNING WEST TO NORTHWEST OVERNIGHT ACROSS THE
COASTAL WATERS...BUT EXPECT THEM TO BACK TO SOUTHWEST/WEST THIS
MORNING AHEAD OF THE APPROACHING COLD FRONT. WILL POST EXERCISE
CAUTION HEADLINES FOR ALL WATERS AS WIND SPEEDS SHOULD BE INCREASING
TO 15-20 KNOTS AHEAD OF THE FRONT. EXPECT WEST WINDS TO INCREASE
FURTHER TONIGHT AS A SECONDARY COLD FRONT DEVELOPS ACROSS THE EASTERN
GULF. WILL INCLUDE SCA LIKELY OR MAY BE REQUIRED HEADLINES FOR ALL
ZONES. THE SECOND FRONT WILL SWEEP THROUGH THE KEYS ON TUESDAY...
WITH SCA CONDITIONS ALMOST CERTAIN IN NORTHWEST/NORTH FLOW BEHIND THE
FRONT TUESDAY AFTERNOON AND TUESDAY NIGHT. A LARGE NORTHWEST SWELL
WILL MOVE IN FROM THE GULF...AFFECTING THE WATERS WEST OF MAINLAND
MONROE AND SOUTH/WEST OF THE DRY TORTUGAS WITH SEAS AROUND 10 FEET.
WINDS AND SEAS WILL BEGIN TO SUBSIDE ON WEDNESDAY AS HIGH PRESSURE
BUILDS EASTWARD INTO FLORIDA. A RETURN TO MORE TRANQUIL CONDITIONS
SHOULD BE IN STORE FOR THURSDAY/FRIDAY AS THE HIGH SETTLES OVER
CENTRAL FLORIDA.
&&
.AVIATION...
VFR CONDITIONS WILL PREVAIL TODAY. SOUTHWEST TO WEST SURFACE WINDS
AT 10 TO 15 KNOTS AROUND DAYBREAK...WILL BECOME WEST TO NORTHWEST
AND INCREASE FURTHER TO 15 KNOTS AND GUSTY IN THE AFTERNOON. AFTER
1800Z...AS A COLD FRONT APPROACHES THE KEYS FROM SOUTH FLORIDA...EXPECT
SKY COVER TO INCREASE...WITH COVERAGE BECOMING SCATTERED AFTER 1800Z.
AS THE FRONT MOVES CLOSER TO THE KEYS...A BAND OF SHOWERS WILL MOVE
ACROSS THE ISLANDS BETWEEN 18 AND 24Z...WITH THE ACTUAL FRONT MOVING
THROUGH THE KEYS BETWEEN 00 AND 06Z. BRIEF IFR CIGS AND/OR VIS WILL
BE LIKELY WITHIN THESE SHOWERS.
&&
.PRELIMINARY POINT TEMPS/POPS...
KEY WEST 75 68 72 55 / 50 20 30 20
MARATHON 76 67 72 50 / 50 20 30 20
&&
.KEY WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GM...NONE.
&&
$$
PUBLIC/MARINE.........JACOBSON
AVIATION/NOWCASTS.....FUTTERMAN
VISIT US ON THE WEB AT WWW.WEATHER.GOV/KEYWEST
000
FXUS62 KKEY 190243
AFDKEY
AREA FORECAST DISCUSSION FOR THE FLORIDA KEYS
NATIONAL WEATHER SERVICE KEY WEST FL
945 PM EST SUN JAN 18 2009
.DISCUSSION...
LOW AMPLITUDE UPPER WAVE THAT HELPED DEVELOP AN AREA OF SHOWERS
SOUTH OF THE LOWER KEYS THIS AFTERNOON CONTINUES TO PUSH TO THE
EAST. THE LOWER LEVEL CONVERGENT ZONE JUST TO THE SOUTHEAST OF THE
UPPER KEYS IS ALSO WASHING OUT. KBYX SHOWS A GRADUAL BUT STEADY
DECREASE IN THE AREA AND STRENGTH OF THOSE SHOWERS. THERE IS
PROBABLY NO PRECIPITATION ACTUALLY MAKING IT TO THE SURFACE WITH THE
REMAINING ECHOES ON RADAR ON THE EXTREME EAST AND SOUTHEAST PORTIONS
OF OUR MARINE SERVICE AREA. SKIES ARE BECOMING PARTLY CLOUDY ALONG
THE ENTIRE STRETCH OF THE ISLAND CHAIN PER LATE EVENING IR SATELLITE
IMAGES. TEMPERATURES ARE IN THE LOWER 60S WITH DEWPOINTS CLOSE TO 60.
THE SURFACE RIDGE AXIS CONTINUES TO GET ORIENTED FURTHER SOUTH
ACROSS THE WESTERN ATLANTIC AS A COOL FRONT STRETCHES FROM THE
FLORIDA PANHANDLE INTO THE CENTRAL PORTION OF THE GULF OF MEXICO.
THE LATE EVENING LOCAL SOUNDING...CUDJOE PROFILER...AND KBYX VAD
WIND PROFILE SHOW THAT THE LOWER LEVEL WINDS HAVE BECOME ORIENTED
OUT OF THE SOUTHWEST...TOPPED BY STRONGER SOUTHWEST WINDS ABOVE 5
KFT. GUIDANCE SUGGESTS A FRESHENING TREND THROUGH MONDAY MORNING.
BUT WE MAY HAVE A COUPLE OF HOURS OF LIGHTER WINDS BEFORE SUNRISE.
MAYBE EVEN SOME SMALL PATCHES OF FOG ACROSS SOME OF THE LARGER LOWER
KEYS. BUT WILL NOT EXPLICITLY INSERT THIS IN AN UPDATED FORECAST.
WILL ISSUANCE AN UPDATED ZONE IN A SHORT WHILE TO REMOVE SOME
TRANSITIONAL SKY WORDING FROM THIS AFTERNOON...AND INITIATE THE
LIGHT WINDS MORE DEFINITELY FROM THE SOUTHWEST.
&&
.MARINE...
THE LATE EVENING MARINE UPDATE WILL HAVE THE SAME WIND ADJUSTMENTS
AS MENTIONED ABOVE. OTHERWISE...WE ARE NOT EXPECTED THE ONSET OF
FRESHER WESTERLY BREEZES UNTIL MONDAY...FOLLOWED BY STRONGER
NORTHWEST WINDS ON THE BACK SIDE OF ANOTHER FRONT TUESDAY AND
TUESDAY NIGHT.
&&
.AVIATION...
VFR CONDITIONS WILL PREVAIL THROUGH THE OVERNIGHT PERIOD. SURFACE
WINDS WILL BE LIGHT AND MOSTLY OUT OF THE SOUTHWEST THROUGH MUCH OF
THE NIGHT. THEN SHOULD PICK UP OUT OF THE SOUTHWEST TO WEST AT 10 TO
15 KNOTS AROUND DAYBREAK...AND INCREASE FURTHER TO 15 KNOTS AND
GUSTY IN THE AFTERNOON. THERE IS A CHANCE FOR SOME GROUND FOG IN THE
EARLY MORNING HOURS DUE TO A LOW DEW POINT DEPRESSION...CLEAR
SKIES...AND LIGHT WINDS. THIS SHOULD DISSIPATE QUICKLY AFTER
SUNRISE. SKY COVER WILL INCREASE THROUGH THE DAY AT LOW VFR HEIGHTS
AHEAD OF AN APPROACHING COLD FRONT.
&&
.KEY WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GM...NONE.
&&
$$
PUBLIC/MARINE.........04
AVIATION/NOWCASTS.....11
DATA COLLECTION.......ROSS
VISIT US ON THE WEB AT WWW.WEATHER.GOV/KEYWEST
000
FXUS62 KKEY 182110
AFDKEY
AREA FORECAST DISCUSSION FOR THE FLORIDA KEYS
NATIONAL WEATHER SERVICE KEY WEST FL
410 PM EST SUN JAN 18 2009
.DISCUSSION...
AN AREA OF SHOWERS DEVELOPED OVER THE LOWER STRAITS OF FLORIDA SOUTH
OF THE DRY TORTUGAS EARLIER THIS MORNING AT THE INTERSECTION OF TWO
SYNOPTIC-SCALE ASCENT FIELDS ASSOCIATED WITH A MIGRATORY SHORT-WAVE
TROUGH IN THE MIDTROPOSPHERIC WESTERLIES NORTH OF THE KEYS AND A
ZONE OF WEAK WARM THERMAL ADVECTION IN THE LOWER TROPOSPHERE...
RESPECTIVELY. THE VERTICAL MOTION FIELDS INTERSECTED IN SPACE AND
TIME WHILE COUPLING VERTICALLY...IT APPEARS. THE AREA OF RAIN AND
SHOWERS HAS GRADUALLY SHIFTED EASTWARD DURING THE DAY...WITH A FEW
SPRINKLES BRUSHING THE ISLANDS WITH NON-MEASURABLE SPRINKLES. CLOUD
COVER HAS BEEN PLENTIFUL...BUT IS BEGINNING TO THIN.
THE PRIMARY WEATHER STORY FOR THIS PACKAGE WILL BE THE INCREASING
LIKELIHOOD OF A STRONG COLD FRONT -- THE STRONGEST OF THE SEASON? --
PUSHING THROUGH MID WEEK. A DEEP CYCLONIC FLOW REGIME HAS DEVELOPED
OVER MOST OF THE EAST WITH ARCTIC...OR MODIFIED ARCTIC AIR...IN PLACE
ACROSS MUCH OF THE NORTHEASTERN QUARTER OF THE UNITED STATES. A
STRONG SHORT WAVE TROUGH WILL DIG EQUATORWARD MONDAY AND TUESDAY WITH
AN ASSOCIATED LOW PRESSURE SYSTEM....TROUGH...AND COLD FRONT MOVING
SOUTHEASTWARD ACROSS THE SOUTHEASTERN UNITED STATES...GULF
BASIN...AND FLORIDA PENINSULA ON TUESDAY. THE FRONT SHOULD PUSH
THROUGH TUESDAY NIGHT BRINGING LOTS OF COLD AIR ADVECTION...DRIER
AIR...AND GUSTY WINDS. SHOWERS WILL BE MOST PROBABLE MONDAY THROUGH
TUESDAY...WITH NEAR NIL RAIN CHANCES WEDNESDAY AND BEYOND. A SLOW
MODERATION IN TEMPERATURE AND WIND IS LIKELY TO ENSUE MID TO LATE
WEEK.
&&
.MARINE...
VARIABLE BREEZES THIS EVENING WILL TURN SOUTHWESTERLY OVERNIGHT AND
FRESHEN. THEN...SOUTHWEST TO WEST BREEZES WILL FRESHEN FURTHER ON
MONDAY...WITH 15-20KT SUSTAINED WIND LIKELY BY SUNDOWN. A STRONG COLD
FRONT WILL DEVELOP OVER THE GULF OF MEXICO AND PUSH SOUTHWARD...
SWEEPING THROUGH THE FLORIDA KEYS TUESDAY NIGHT. A SMALL CRAFT
ADVISORY WILL LIKELY GO UP BY EARLY TUESDAY AND STAY UP THROUGH
WEDNESDAY.
&&
.AVIATION...
VFR CONDITIONS WILL PREVAIL THIS EVENING AT THE KEY WEST AND
MARATHON TERMINALS. BKN-OVC CIGS FL050-070 WILL BE LIKELY AFTER 12Z
(7AM) MONDAY WITH RAIN ON THE WAY.
&&
.KEY WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GM...NONE.
&&
$$
PUBLIC/MARINE.........KASPER
AVIATION/NOWCASTS.....DFM
DATA COLLECTION.......ROSS
VISIT US ON THE WEB AT WWW.WEATHER.GOV/KEYWEST
000
FXUS62 KKEY 181603
AFDKEY
AREA FORECAST DISCUSSION FOR THE FLORIDA KEYS
NATIONAL WEATHER SERVICE KEY WEST FL
1103 AM EST SUN JAN 18 2009
.DISCUSSION...
FORECASTS WERE UPDATED TO INCREASE SKY COVER...REDUCE HIGH
TEMPERATURES...ADJUST WIND TRANSITIONS...AND SPLIT ZONE GROUPINGS FOR
DIFFERENCES IN SKY COVER. WE KEPT RAIN CHANCES OVER THE KEYS NEAR
ZERO FOR THE REST OF THE AFTERNOON. HOWEVER...WE WILL HAVE TO WATCH
RADAR TRENDS CLOSELY AS SOME SHOWERS ARE ALREADY GETTING CLOSE TO THE
REEFS IN THE MEAN SOUTHWESTERLY LOWER-TROPOSPHERIC FLOW PATTERN.
&&
.MARINE...
NORTHEAST BREEZES ARE GRADUALLY SLACKENING...AND SEAS ARE UNDERGOING
A SLOW SUBSIDING TREND...AS A RIDGE OF HIGH PRESSURE MOVES TOWARD THE
AREA FROM CENTRAL FLORIDA. BREEZES WILL TURN VARIABLE NEAR 10 KNOTS
LATE THIS AFTERNOON...BEFORE SHIFTING TO SOUTH/SOUTHWEST AND
FRESHENING TONIGHT. ISOLATED SHOWERS OF LIGHT TO MODERATE RAIN WILL
MOVE SLOWLY NORTHEASTWARD THIS AFTERNOON...WITH SOME POCKETS OF RAIN
REACHING THE REEFS.
&&
.AVIATION...
VFR CONDITIONS WILL PREVAIL TODAY AT THE KEY WEST AND MARATHON
TERMINALS. BKN-OVC CIGS FL070-090 WILL BE PRESENT THROUGH 18Z-21Z
(1PM - 4PM).
&&
.KEY WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GM...NONE.
&&
$$
PUBLIC/MARINE.........KASPER
AVIATION/NOWCASTS.....DFM
DATA COLLECTION.......WAH
VISIT US ON THE WEB AT WWW.WEATHER.GOV/KEYWEST
000
FXUS62 KKEY 180806 RRA
AFDKEY
AREA FORECAST DISCUSSION FOR THE FLORIDA KEYS
NATIONAL WEATHER SERVICE KEY WEST FL
300 AM EST SUN JAN 18 2009
.DISCUSSION...IN THE MIDDLE AND UPPER LEVELS...700-200 MB...LATEST
AVAILABLE SATELLITE IMAGERY OVERLAID WITH STREAMLINE ANALYSIS AS OF
200 AM...DEPICT AN EXPANSIVE AND DEEP COLD CORE TROUGH THAT
ENCOMPASSES ABOUT THE EASTERN TWO THIRDS OF THE CONUS...WITH AN
IDENTIFIABLE AXIS THAT EXTENDS FROM THE UP OF MICHIGAN DOWN TO THE
YUCATAN PENINSULA. THE FLORIDA KEYS ARE BENEATH A DEEPLY CYCLONIC
BUT VERY DRY MID AND UPPER ATMOSPHERE ON THE LOWER RIGHT FLANK OF
THIS MASSIVE TROUGH. JUST SOME SLIGHT MOISTURE IN THE SOUTHWEST MID
TO UPPER LEVEL FLOW WITHIN THE 500-400 MB LAYER IS BEING TRANSPORTED
IN THE FORM OF CIRRUS OVERHEAD.
IN THE LOWER AND MIDDLE LEVELS...SURFACE TO 700 MB...LATEST
AVAILABLE SATELLITE IMAGERY OVERLAID WITH SURFACE OBSERVATIONS AND
ANALYSIS AS OF 200 AM DETAIL A NEAR 1040 ANTICYCLONE CENTERED OVER
THE GREAT BASIN IN THE WESTERN UNITED STATES. EAST OF THAT...A COLD
FRONT EXTENDS SOUTHWEST FROM LOW PRESSURE OVER MICHIGAN. WELL TO THE
SOUTH OF THAT...A NEAR 1030 MB RIDGE IS POSITIONED ACROSS NORTH
FLORIDA AND THE NORTHERN GULF OF MEXICO. THE FLORIDA KEYS STILL
REMAIN BENEATH A FRESH NORTHEAST SURFACE TO 5000 FOOT FLOW...SOUTH
OF THIS RIDGE OF HIGH PRESSURE.
.CURRENTLY...AS OF 200 AM...TEMPERATURES AT THIS HOUR REMAIN IN THE
LOWER TO MIDDLE 60S WITH DEWPOINTS IN THE MIDDLE TO UPPER 50S. C-MAN
STATIONS ALONG THE FLORIDA REEF AND SOUTHERN FLORIDA BAY ARE
REGISTERING NORTHEAST WINDS BETWEEN 11 AND 18 KNOTS WITH GUSTS
BETWEEN 16 AND 20 KNOTS. KEY WEST RADAR STILL DETECTS ISOLATED
SHOWERS WITHIN A CONVERGENCE ZONE ACROSS THE WESTERN FLORIDA
STRAITS. ISLAND SENSORS ARE RECORDING NORTHEAST WINDS NEAR 10 MPH.
.FORECASTS...IN THE MID AND UPPER LEVELS...700-200 MB...TODAY
THROUGH WEDNESDAY...00Z RUNS OF ALL LARGE SCALE MODELS ARE
MAINTAINING THE PNA (PACIFIC NORTH AMERICAN) PATTERN THROUGH
MIDWEEK. SEVERAL IMPULSES MOVING SOUTHWARD WITHIN THE FLOW WILL
CONTINUE TO CARVE OUT THE LARGE TROUGH OVER THE EASTERN TWO THIRDS
OF THE CONUS. LITTLE IN THE WAY OF MIDDLE AND UPPER TRIGGERS WILL BE
IN PLACE TO INCREASE OVERALL LARGE SCALE RAIN CHANCES THROUGH THIS
TIME. AS A RESULT...COOL AND DRY CYCLONIC FLOW PATTERN WILL PERSIST
OVER THE FLORIDA KEYS THRU THIS TIME.
EXTENDED...WED NIGHT THRU SATURDAY...THE 00Z ECMWF AND GFS ARE
STEADY WITH INDICATIONS OF THE DEMISE OF THE LARGE TROUGH OVER THE
SOUTHEAST INCLUDING THE FLORIDA KEYS...WITH 500 MB RISING HEIGHTS
EXPECTED THURSDAY THRU SATURDAY AS THE BASE OF THE TROUGH LIFTS
NORTHWARD. A WEAK SOUTHERN STREAM OF THE JETSTREAM WILL ONCE AGAIN
MOVE ACROSS THE GULF OF MEXICO...AND OVER THE FLORIDA KEYS.
IN THE LOWER AND MIDDLE LEVELS...TODAY AND TONIGHT...MODELS CONTINUE
TO INDICATE THAT A QUICK RECOVERY IN TEMPERATURE AND SLACKENING
WINDS IS IN ORDER FOR TODAY...AS THE RIDGE OF HIGH PRESSURE OVER
NORTH FLORIDA WILL SAG SOUTHWARD...REACHING SOUTH FLORIDA BY
TONIGHT. THE NEXT COLD FRONT NOW APPROACHING THE SOUTHEAST STATES IS
POISED TO MOVE RAPIDLY SOUTHWARD LATER ON MARTIN LUTHER KING JR
DAY...REACHING THE KEYS BY LATE AFTERNOON OR DURING THE EVENING
HOURS. IT DOES APPEAR THAT LOW LEVEL CONVERGENCE WILL ALSO BE
ACCOMPANIED BY SOME INCREASE IN WEAK LOW LEVEL ASCENT AHEAD OF THE
FRONT. GIVEN THE GUIDANCE CONSISTENCY IN SUGGESTING MIDDLE OF THE
ROAD TO GOOD CHANCE POPS FOR THIS PERIOD (MONDAY)...HAVE ELECTED TO
RAISE POPS INTO THE LOWER CHANCE CATEGORY. SO WOULD EXPECT A BAND OF
SHOWERS TO DEVELOP AND THEN MOVE ACROSS THE KEYS LATER IN THE
AFTERNOON ON MONDAY AHEAD OF THE FRONT.
FOR MONDAY NIGHT THROUGH TUESDAY NIGHT...LAST TWO MODEL RUNS FOR
BEHIND THE FROPA HAVE BEEN MORE INTERESTING...WITH THE
NAM...GFS...AND UKMET ALL DEVELOPING WEAK AREAS OF LOWER PRESSURE
SOMEWHERE OVER THE NORTHERN AND/OR EASTERN GULF OF MEXICO ON MONDAY
NIGHT...THEN MOVING THEM NORTHEAST DURING TUESDAY. THESE MODELS ARE
ALSO NOW SHOWING THAT THE DEVELOPING SYSTEM WILL SLIDE ANOTHER COLD
FRONT SOUTHEAST ACROSS THE KEYS BY TUESDAY AFTERNOON AND EVENING.
GIVEN THIS DEVELOPMENT OVER THE GULF...WOULD ALSO NOW EXPECT
STRONGER WINDS BEHIND THE FIRST FRONT FOR THE PERIOD BETWEEN MONDAY
NIGHT THROUGH TUESDAY NIGHT. SO NOW NEED TO INSERT SLIGHT CHANCE
POPS FOR TUESDAY...GIVEN THIS HINT AT WEAK SYSTEM DEVELOPMENT OVER
THE NORTHEAST GULF. AND THEN ON TUESDAY NIGHT...THE NEAR 1030 MB
RIDGE OVER THE SOUTHERN PLAINS WILL SLIDE EASTWARD...REACHING THE
NORTH CENTRAL GULF COAST...SO WINDS WILL FINALLY BECOME MORE
NORTHERLY AND ONCE AGAIN...COOLER TEMPERATURES AND VERY DRY AIR WILL
MOVE BACK INTO THE ISLANDS.
EXTENDED...WEDNESDAY THRU SATURDAY...WITH THE 1000-850 MB COOL
THICKNESS ADVECTION PATTERN...COOLER TEMPERATURES LOOK TO BE ON TAP
FOR WEDNESDAY THROUGH THURSDAY NIGHT. HIGH TEMPERATURES MAY REMAIN
IN THE 60S WITH OVERNIGHT LOW TEMPERATURES IN THE 50S.
THEREAFTER...THERE ARE INDICATIONS THAT A WESTERN ATLANTIC RIDGE OF
HIGH PRESSURE WILL ALLOW FOR VEERING WINDS AND MODERATION OF
TEMPERATURES FOR FRIDAY AND SATURDAY. SO...WILL SHOW TREND OF
MODERATING TEMPERATURES IN THE GRIDS AND FORECASTS.
&&
.MARINE...TODAY AND TONIGHT...HAVE NOT RECEIVED ANY SHIP REPORTS FOR
COMBINED SEAS OF 6 FEET OR MORE OUTSIDE OF THE GULF STREAM. WILL
PROBABLY REPLACE THE SCA FOR HAZARDOUS SEAS WITH AN EXERCISE CAUTION
HEADLINE FOR THE STRAITS FOR THE MORNING HOURS TO BE ON THE SAFE
SIDE. BY THE AFTERNOON HOURS...EXPECT WINDS TO DIMINISH TO BETWEEN
10 AND 15 KNOTS...AS WELL AS CLOCK AROUND TO SOUTHEAST TONIGHT AND
BECOME SOUTH BY TOMORROW MORNING.
MONDAY AND MONDAY NIGHT...THE NEXT FRONT WILL APPROACH THE KEYS BY
MONDAY AFTERNOON AND EVENING. SCATTERED SHOWERS ASSOCIATED WITH LOW
LEVEL CONVERGENCE...WILL MOVE ACROSS THE WATERS DURING THE LATE
MORNING OR AFTERNOON ON MONDAY. SOUTH TO SOUTHWEST WINDS WILL
INCREASE TO BETWEEN 15 AND 20 KNOTS IN THE AFTERNOON...WITH MUCH
HIGHER GUSTS IN THESE SHOWERS. EXPECT EXERCISE CAUTIONARY HEADLINES
WILL NEED TO IN PLACE ACROSS ALL WATERS BY MONDAY
AFTERNOON...POSSIBLY CONTINUING MONDAY NIGHT. SMALL CRAFT ADVISORY
CONDITIONS MAY BE MET ACROSS ALL WATERS...BUT WILL BE LEFT OUT FOR
NOW DUE TO UNCERTAINTY.
TUESDAY AND TUESDAY NIGHT...BOTH THE 00Z GFS AND UKMET ARE INSISTENT
THAT DEVELOPMENT OF LOWER PRESSURE IN THE SOUTHEAST GULF OF MEXICO
SHOULD RESULT IN SMALL CRAFT ADVISORY CONDITIONS ACROSS ALL
WATERS....GIVEN THE UNCERTAINTY WITH THE EXACT POSITION AND TIMING
OF THE DEVELOPMENT OF LOWER PRESSURE...WILL BE CONSERVATIVE WITH THE
WINDS AND SEAS FORECAST ATTM.
WEDNESDAY AND WEDNESDAY NIGHT...NORTH WINDS BETWEEN 15 AND 20 KNOTS
WILL LIKELY RESULT IN EXERCISE CAUTION CONDITIONS...BUT SMALL CRAFT
ADVISORY CONDITIONS ARE A GOOD POSSIBILITY ACROSS THE ATLANTIC
WATERS AS WINDS WILL GRADUALLY VEER.
&&
.AVIATION...VFR CONDITIONS WILL PREVAIL AT THE KEY WEST AND MARATHON
ISLAND TERMINALS TODAY. A BROKEN MID LEVEL CLOUD DECK NEAR FL080
WILL BE IN THE AREA THIS MORNING...THEN SHOULD DEPART THIS
AFTERNOON. ISOLATED SHOWERS WILL BE PRESENT OVER THE FLORIDA
STRAITS...BUT SHOULD REMAIN BEYOND 10 MILES SOUTH OF THE TERMINALS.
SURFACE WINDS WILL CONTINUE FROM THE NORTHEAST AROUND 10 KNOTS
THROUGH THE MORNING...THEN BECOME VARIABLE AT 5 TO 10 KNOTS THIS
AFTERNOON AS HIGH PRESSURE DROPS SOUTHWARD OVER THE REGION...AHEAD
OF A COLD FRONT MOVING THROUGH NORTH AND CENTRAL FLORIDA.
&&
.CLIMATE...
ON THIS DATE IN KEYS WEATHER HISTORY IN 1981...THE DAILY RECORD LOW
TEMPERATURE OF 48F WAS RECORDED.
&&
.TEMPS AND POPS...
KEY WEST 70 61 75 64 / 05 05 30 20
MARATHON 71 61 74 63 / 05 05 30 20
&&
.KEY WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GM...NONE.
&&
$$
PUBLIC/MARINE/GRIDS.........FUTTERMAN
AVIATION/NOWCASTS...........JACOBSON
VISIT US ON THE WEB AT WWW.WEATHER.GOV/KEYWEST
000
FXUS62 KKEY 180756
AFDKEY
AREA FORECAST DISCUSSION FOR THE FLORIDA KEYS
NATIONAL WEATHER SERVICE KEY WEST FL
300 AM EST SUN JAN 18 2009
.DISCUSSION...IN THE MIDDLE AND UPPER LEVELS...700-200 MB...LATEST
AVAILABLE SATELLITE IMAGERY OVERLAID WITH STREAMLINE ANALYSIS AS OF
200 AM...DEPICT AN EXPANSIVE AND DEEP COLD CORE TROUGH THAT
ENCOMPASSES ABOUT THE EASTERN TWO THIRDS OF THE CONUS...WITH AN
IDENTIFIABLE AXIS THAT EXTENDS FROM THE UP OF MICHIGAN DOWN TO THE
YUCATAN PENINSULA. THE FLORIDA KEYS ARE BENEATH A DEEPLY CYCLONIC
BUT VERY DRY MID AND UPPER ATMOSPHERE ON THE LOWER RIGHT FLANK OF
THIS MASSIVE TROUGH. JUST SOME SLIGHT MOISTURE IN THE SOUTHWEST MID
TO UPPER LEVEL FLOW WITHIN THE 500-400 MB LAYER IS BEING TRANSPORTED
IN THE FORM OF CIRRUS OVERHEAD.
IN THE LOWER AND MIDDLE LEVELS...SURFACE TO 700 MB...LATEST
AVAILABLE SATELLITE IMAGERY OVERLAID WITH SURFACE OBSERVATIONS AND
ANALYSIS AS OF 200 AM DETAIL A NEAR 1040 ANTICYCLONE CENTERED OVER
THE GREAT BASIN IN THE WESTERN UNITED STATES. EAST OF THAT...A COLD
FRONT EXTENDS SOUTHWEST FROM LOW PRESSURE OVER MICHIGAN. WELL TO THE
SOUTH OF THAT...A NEAR 1030 MB RIDGE IS POSITIONED ACROSS NORTH
FLORIDA AND THE NORTHERN GULF OF MEXICO. THE FLORIDA KEYS STILL
REMAIN BENEATH A FRESH NORTHEAST SURFACE TO 5000 FOOT FLOW...SOUTH
OF THIS RIDGE OF HIGH PRESSURE.
.CURRENTLY...AS OF 200 AM...TEMPERATURES AT THIS HOUR REMAIN IN THE
LOWER TO MIDDLE 60S WITH DEWPOINTS IN THE MIDDLE TO UPPER 50S. C-MAN
STATIONS ALONG THE FLORIDA REEF AND SOUTHERN FLORIDA BAY ARE
REGISTERING NORTHEAST WINDS BETWEEN 11 AND 18 KNOTS WITH GUSTS
BETWEEN 16 AND 20 KNOTS. KEY WEST RADAR STILL DETECTS ISOLATED
SHOWERS WITHIN A CONVERGENCE ZONE ACROSS THE WESTERN FLORIDA
STRAITS. ISLAND SENSORS ARE RECORDING NORTHEAST WINDS NEAR 10 MPH.
.FORECASTS...IN THE MID AND UPPER LEVELS...700-200 MB...TODAY
THROUGH WEDNESDAY...00Z RUNS OF ALL LARGE SCALE MODELS ARE
MAINTAINING THE PNA (PACIFIC NORTH AMERICAN) PATTERN THROUGH
MIDWEEK. SEVERAL IMPULSES MOVING SOUTHWARD WITHIN THE FLOW WILL
CONTINUE TO CARVE OUT THE LARGE TROUGH OVER THE EASTERN TWO THIRDS
OF THE CONUS. LITTLE IN THE WAY OF MIDDLE AND UPPER TRIGGERS WILL BE
IN PLACE TO INCREASE OVERALL LARGE SCALE RAIN CHANCES THROUGH THIS
TIME. AS A RESULT...COOL AND DRY CYCLONIC FLOW PATTERN WILL PERSIST
OVER THE FLORIDA KEYS THRU THIS TIME.
EXTENDED...WED NIGHT THRU SATURDAY...THE 00Z ECMWF AND GFS ARE
STEADY WITH INDICATIONS OF THE DEMISE OF THE LARGE TROUGH OVER THE
SOUTHEAST INCLUDING THE FLORIDA KEYS...WITH 500 MB RISING HEIGHTS
EXPECTED THURSDAY THRU SATURDAY AS THE BASE OF THE TROUGH LIFTS
NORTHWARD. A WEAK SOUTHERN STREAM OF THE JETSTREAM WILL ONCE AGAIN
MOVE ACROSS THE GULF OF MEXICO...AND OVER THE FLORIDA KEYS.
IN THE LOWER AND MIDDLE LEVELS...TODAY AND TONIGHT...MODELS CONTINUE
TO INDICATE THAT A QUICK RECOVERY IN TEMPERATURE AND SLACKENING
WINDS IS IN ORDER FOR TODAY...AS THE RIDGE OF HIGH PRESSURE OVER
NORTH FLORIDA WILL SAG SOUTHWARD...REACHING SOUTH FLORIDA BY
TONIGHT. THE NEXT COLD FRONT NOW APPROACHING THE SOUTHEAST STATES IS
POISED TO MOVE RAPIDLY SOUTHWARD LATER ON MARTIN LUTHER KING JR
DAY...REACHING THE KEYS BY LATE AFTERNOON OR DURING THE EVENING
HOURS. IT DOES APPEAR THAT LOW LEVEL CONVERGENCE WILL ALSO BE
ACCOMPANIED BY SOME INCREASE IN WEAK LOW LEVEL ASCENT AHEAD OF THE
FRONT. GIVEN THE GUIDANCE CONSISTENCY IN SUGGESTING MIDDLE OF THE
ROAD TO GOOD CHANCE POPS FOR THIS PERIOD (MONDAY)...HAVE ELECTED TO
RAISE POPS INTO THE LOWER CHANCE CATEGORY. SO WOULD EXPECT A BAND OF
SHOWERS TO DEVELOP AND THEN MOVE ACROSS THE KEYS LATER IN THE
AFTERNOON ON MONDAY AHEAD OF THE FRONT.
FOR MONDAY NIGHT THROUGH TUESDAY NIGHT...LAST TWO MODEL RUNS FOR
BEHIND THE FROPA HAVE BEEN MORE INTERESTING...WITH THE
NAM...GFS...AND UKMET ALL DEVELOPING WEAK AREAS OF LOWER PRESSURE
SOMEWHERE OVER THE NORTHERN AND/OR EASTERN GULF OF MEXICO ON MONDAY
NIGHT...THEN MOVING THEM NORTHEAST DURING TUESDAY. THESE MODELS ARE
ALSO NOW SHOWING THAT THE DEVELOPING SYSTEM WILL SLIDE ANOTHER COLD
FRONT SOUTHEAST ACROSS THE KEYS BY TUESDAY AFTERNOON AND EVENING.
GIVEN THIS DEVELOPMENT OVER THE GULF...WOULD ALSO NOW EXPECT
STRONGER WINDS BEHIND THE FIRST FRONT FOR THE PERIOD BETWEEN MONDAY
NIGHT THROUGH TUESDAY NIGHT. SO NOW NEED TO INSERT SLIGHT CHANCE
POPS FOR TUESDAY...GIVEN THIS HINT AT WEAK SYSTEM DEVELOPMENT OVER
THE NORTHEAST GULF. AND THEN ON TUESDAY NIGHT...THE NEAR 1030 MB
RIDGE OVER THE SOUTHERN PLAINS WILL SLIDE EASTWARD...REACHING THE
NORTH CENTRAL GULF COAST...SO WINDS WILL FINALLY BECOME MORE
NORTHERLY AND ONCE AGAIN...COOLER TEMPERATURES AND VERY DRY AIR WILL
MOVE BACK INTO THE ISLANDS.
EXTENDED...WEDNESDAY THRU SATURDAY...WITH THE 1000-850 MB COOL
THICKNESS ADVECTION PATTERN...COOLER TEMPERATURES LOOK TO BE ON TAP
FOR WEDNESDAY THROUGH THURSDAY NIGHT. HIGH TEMPERATURES MAY REMAIN
IN THE 60S WITH OVERNIGHT LOW TEMPERATURES IN THE 50S.
THEREAFTER...THERE ARE INDICATIONS THAT A WESTERN ATLANTIC RIDGE OF
HIGH PRESSURE WILL ALLOW FOR VEERING WINDS AND MODERATION OF
TEMPERATURES FOR FRIDAY AND SATURDAY. SO...WILL SHOW TREND OF
MODERATING TEMPERATURES IN THE GRIDS AND FORECASTS.
&&
.MARINE...TODAY AND TONIGHT...HAVE NOT RECEIVED ANY SHIP REPORTS FOR
COMBINED SEAS OF 6 FEET OR MORE OUTSIDE OF THE GULF STREAM. WILL
PROBABLY REPLACE THE SCA FOR HAZARDOUS SEAS WITH AN EXERCISE CAUTION
HEADLINE FOR THE STRAITS FOR THE MORNING HOURS TO BE ON THE SAFE
SIDE. BY THE AFTERNOON HOURS...EXPECT WINDS TO DIMINISH TO BETWEEN
10 AND 15 KNOTS...AS WELL AS CLOCK AROUND TO SOUTHEAST TONIGHT AND
BECOME SOUTH BY TOMORROW MORNING.
MONDAY AND MONDAY NIGHT...THE NEXT FRONT WILL APPROACH THE KEYS BY
MONDAY AFTERNOON AND EVENING. SCATTERED SHOWERS ASSOCIATED WITH LOW
LEVEL CONVERGENCE...WILL MOVE ACROSS THE WATERS DURING THE LATE
MORNING OR AFTERNOON ON MONDAY. SOUTH TO SOUTHWEST WINDS WILL
INCREASE TO BETWEEN 15 AND 20 KNOTS IN THE AFTERNOON...WITH MUCH
HIGHER GUSTS IN THESE SHOWERS. EXPECT EXERCISE CAUTIONARY HEADLINES
WILL NEED TO IN PLACE ACROSS ALL WATERS BY MONDAY
AFTERNOON...POSSIBLY CONTINUING MONDAY NIGHT. SMALL CRAFT ADVISORY
CONDITIONS MAY BE MET ACROSS ALL WATERS...BUT WILL BE LEFT OUT FOR
NOW DUE TO UNCERTAINTY.
TUESDAY AND TUESDAY NIGHT...BOTH THE 00Z GFS AND UKMET ARE INSISTENT
THAT DEVELOPMENT OF LOWER PRESSURE IN THE SOUTHEAST GULF OF MEXICO
SHOULD RESULT IN SMALL CRAFT ADVISORY CONDITIONS ACROSS ALL
WATERS....GIVEN THE UNCERTAINTY WITH THE EXACT POSITION AND TIMING
OF THE DEVELOPMENT OF LOWER PRESSURE...WILL BE CONSERVATIVE WITH THE
WINDS AND SEAS FORECAST ATTM.
WEDNESDAY AND WEDNESDAY NIGHT...NORTH WINDS BETWEEN 15 AND 20 KNOTS
WILL LIKELY RESULT IN EXERCISE CAUTION CONDITIONS...BUT SMALL CRAFT
ADVISORY CONDITIONS ARE A GOOD POSSIBILITY ACROSS THE ATLANTIC
WATERS AS WINDS WILL GRADUALLY VEER.
&&
.AVIATION...VFR CONDITIONS WILL PREVAIL AT THE KEY WEST AND MARATHON
ISLAND TERMINALS TODAY. A BROKEN MID LEVEL CLOUD DECK NEAR FL080
WILL BE IN THE AREA THIS MORNING...THEN SHOULD DEPART THIS
AFTERNOON. ISOLATED SHOWERS WILL BE PRESENT OVER THE FLORIDA
STRAITS...BUT SHOULD REMAIN BEYOND 10 MILES SOUTH OF THE TERMINALS.
SURFACE WINDS WILL CONTINUE FROM THE NORTHEAST AROUND 10 KNOTS
THROUGH THE MORNING...THEN BECOME VARIABLE AT 5 TO 10 KNOTS THIS
AFTERNOON AS HIGH PRESSURE DROPS SOUTHWARD OVER THE REGION...AHEAD
OF A COLD FRONT MOVING THROUGH NORTH AND CENTRAL FLORIDA.
&&
.CLIMATE...
ON THIS DATE IN KEYS WEATHER HISTORY IN 1981...THE DAILY RECORD LOW
TEMPERATURE OF 48F WAS RECORDED.
&&
.TEMPS AND POPS...
KEY WEST 68 61 71 / 05 -- --
MARATHON 69 61 71 / 05 -- --
&&
.KEY WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GM...NONE.
&&
$$
PUBLIC/MARINE/GRIDS.........FUTTERMAN
AVIATION/NOWCASTS...........JACOBSON
VISIT US ON THE WEB AT WWW.WEATHER.GOV/KEYWEST
000
FXUS62 KKEY 180332
AFDKEY
AREA FORECAST DISCUSSION FOR THE FLORIDA KEYS
NATIONAL WEATHER SERVICE KEY WEST FL
1030 PM EST SAT JAN 17 2009
.DISCUSSION...
CURRENTLY - A BROAD MID AND UPPER LEVEL TROUGH BLANKETS THE EASTERN
STATES AND DOWN ACROSS THE GULF OF MEXICO AND FLORIDA. A LOWER
TROPOSPHERIC RIDGE IS HOLDING ACROSS THE FLORIDA REGION...WITH THE
PARENT HIGH LONG GONE TO THE NORTHEAST. STRONG WINDS OF LAST NIGHT
THROUGH THIS AFTERNOON FINALLY SETTLED DOWN THIS AFTERNOON ACROSS
THE KEYS AREA...AND NORTHEAST WINDS HAVE BEEN RUNNING AROUND 10
KNOTS ACROSS THE GULF AND BAY SIDE...AND CLOSER TO 15 KNOTS ACROSS
THE STRAITS. THE LATEST 00Z QUIKSCAT PASS REVEALED 15 TO 20 KNOT
WINDS REMAIN ACROSS THE STRAITS BEYOND THE REEF. A FEW CLUSTERS OF
SHOWERS HAVE BEEN DETECTED OVER THE PAST SEVERAL HOURS...BUT REMAIN
WITHIN CLOUDLINES DRAPED ACROSS THE OUTER STRAITS. CLOSER IN...ONLY
A FEW PATCHES OF LIGHT RAIN HAVE AFFECTED PORTIONS OF THE UPPER
KEYS. AFTER DAY TIME HIGHS IN THE UPPER 60S TO AROUND
70...TEMPERATURES ARE NOW DOWN IN THE MID 60S...WITH DEW POINTS IN
THE MID 50S.
SHORT TERM UPDATE (OVERNIGHT) - THE REMNANT HIGH OVER FLORIDA WILL
CONTINUE TO WEAKEN AS IT IS SHOVED FURTHER SOUTHEASTWARD BY THE NEXT
LOW DEVELOPING OVER THE GREAT LAKES. THIS WILL BRING THE RIDGE AXIS
CLOSER TO THE KEYS. EXPECT WINDS TO CONTINUE THEIR GENERAL DOWNWARD
TREND OVER THE NEXT 12 TO 24 HOURS...ALTHOUGH A WEAK NOCTURNAL SURGE
IS EXPECTED TONIGHT...BRINGING WINDS UP NEAR 15 MPH FOR A FEW
HOURS. OVERNIGHT LOWS SHOULD BE ABLE TO GET DOWN TO AROUND 60...DUE
TO A COMBINATION OF SOME DECOUPLING OVER THE INTERIOR AND PROTECTED
AREAS...AND NEARSHORE WATER TEMPERATURES FINALLY DOWN IN THE MID
60S. LITTLE IN THE WAY OF PRECIPITATION IS EXPECTED. WHAT WE DO GET
WILL MOSTLY REMAIN OVER THE OUTER STRAITS...PERHAPS CLIPPING THE
UPPER KEYS WITH A ROUND OR TWO OF SPRINKLES...NOTHING CHANGE WORTHY.
THE ONGOING FORECAST IS ON TRACK AND NO UPDATE IS REQUIRED.
&&
.MARINE...THE PRESSURE GRADIENT ACROSS THE KEYS CONTINUES TO
RELAX...AS A WEAKENING RIDGE OVER NORTH FLORIDA SHIFTS TO THE
SOUTHEAST. THE SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS WILL REMAIN
IN EFFECT TO GIVE THE SEAS MORE TIME TO RELAX...AS THE LATEST
QUIKSCAT PASS INDICATED WINDS WERE A BIT HIGHER ACROSS THE OUTER
STRAITS THAN GUIDANCE WOULD HAVE SUGGESTED. THIS IS IN LINE WITH THE
ONGOING FORECAST REASONING...WHICH HELD THE ADVISORY UP UNTIL
MORNING. OUTSIDE OF SMALL TWEAKS...NO MAJOR CHANGES PLANNED.
&&
.AVIATION...
VFR CONDITIONS WILL CONTINUE THROUGH TOMORROW. SURFACE WINDS WILL BE
OUT OF THE NORTHEAST AT AROUND 10 KNOTS.
&&
.KEY WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GM...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 5 AM EST SUNDAY
FOR GMZ052-GMZ053-GMZ054-GMZ072-GMZ073-GMZ074-GMZ075. &&
$$
11/MR/DR
VISIT US ON THE WEB AT WWW.WEATHER.GOV/KEYWEST
000
FXUS62 KKEY 172048
AFDKEY
AREA FORECAST DISCUSSION FOR THE FLORIDA KEYS
NATIONAL WEATHER SERVICE KEY WEST FL
348 PM EST SAT JAN 17 2009
.DISCUSSION...
.CURRENTLY...
IT WAS SUNNY ON MOST OF THE ISLANDS TODAY WITH THE EXCEPTION BEING
KEY LARGO WHERE SOME CLOUDS MOVED IN FROM THE SEA. WITH NORTHEAST
WINDS 15 TO 20 MPH...OUR TEMPERATURES STRUGGLED TO GET OUT OF THE 60S
EVEN WITH THE SUNSHINE.
OUR RADAR DETECTED A NARROW LINE OF SHOWERS IN THE STRAITS...CLOSE
INSHORE NEAR KEY LARGO AND TRENDING TOWARD CUBA OFF THE LOWER KEYS.
&&
.ANALYSIS AND FORECASTS...
THE CLOUDS ON KEY LARGO ARE PART OF THE RAIN SYSTEM OUT OVER THE
STRAITS. AS SEEN ON SATELLITE AND RADAR...WHEN THE CLOUD ELEMENTS
GET OVER THE ISLANDS THE ECHOES DISSIPATE. THE NARROW LINE REPRESENTS
THE CONVERGENCE ZONE BETWEEN THE ENVIRONMENTAL FLOW AND AIR THAT WAS
DIVERTED BY THE PENINSULA. ONLY THE GULF STREAM PROVIDES ENOUGH
INSTABILITY TO CAUSE THE GROWTH OF SHOWERS...SO WHEN THEY LEAVE THE
FRIENDLY CONFINES AND ENCOUNTER KEY LARGO THEY RUN OUT OF GAS.
WELL...OUR LARGE-SCALE SETUP HAS NOT CHANGED MUCH SINCE YESTERDAY.
SOME VERY COLD AIR IS PRESENT THROUGHOUT THE EASTERN HALF OF THE
COUNTRY AND THIS SHOWS UP ON OUR WEATHER MAPS AS A LARGE HIGH
PRESSURE CELL WHICH EXTENDS FROM MAINE TO THE GULF OF MEXICO AND
BEYOND. ACCORDING TO OUR GUIDANCE (GFS) OVER THE NEXT 24 HOURS THIS
FEATURE WILL DISPLACE SOUTH TOWARD FLORIDA AND WEAKEN...DUE TO THE
APPROACH OF A NEW SHORT WAVE TROF ALOFT UP NEAR THE GREAT LAKES. THUS
WE EXPECT OUR LOCAL WINDS TO DECREASE MARKEDLY ON SUNDAY.
HOWEVER THE NEW SYSTEM WILL DRIVE A SECONDARY COLD FRONT INTO FLORIDA
LATE IN THE DAY ON MONDAY. THUS OUR WINDS WILL GO QUICKLY ROUND THE
COMPASS SUNDAY NIGHT INTO TUESDAY MORNING WHILE THE FRONT GOES
THROUGH. RAINFALL IS LIKELY TO BE MINIMAL...AND BEHIND THE FRONT WILL
BE ANOTHER SPELL OF COOLER-THAN-NORMAL TEMPERATURES ACCOMPANIED BY
FRESH TO STRONG BREEZES. THIS IS TURNING INTO AN ACTIVE WINTER.
&&
.MARINE...
WE OBSERVED A DECREASE IN WIND SPEEDS THIS AFTERNOON -- WE WERE
WAITING AND THEY FINALLY SHOWED UP. THIS ENABLED US TO DROP THE
SMALL CRAFT ADVISORIES FOR THE BAY AND OUR GULF-SIDE WATERS FOR THE
COMING NIGHT. WE RETAINED AN ADVISORY FOR THE ATLANTIC SIDE FOR
RESIDUAL SEAS THROUGH NEXT MORNING. (DEPENDING ON CIRCUMSTANCES THIS
MAY BE DROPPED THIS EVENING.) IN ANY CASE MUCH BETTER CONDITIONS FOR
RECREATIONAL BOATING WILL PREVAIL ON SUNDAY COMPARED TO TODAY.
&&
.AVIATION...
VFR CONDITIONS WILL CONTINUE THROUGH TOMORROW.
&&
.CLIMATE...
ON THIS DATE IN KEYS WEATHER HISTORY...IN 1983...THE LOW TEMPERATURE
SET THE DAILY RECORD OF 53 DEGREES. THIS WAS ONLY 6 DEGREES COLDER
THAN THIS MORNINGS LOW OF 59. THE AVERAGE LOW FOR TODAY IS 65.
&&
.TEMPS AND POPS...
KEY WEST 61 71 64 74 / 05 05 05 20
MARATHON 61 71 64 74 / 05 05 05 20
&&
.KEY WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GM...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 5 AM EST SUNDAY FOR
GMZ052-GMZ053-GMZ054-GMZ072-GMZ073-GMZ074-GMZ075.
&&
$$
PUBLIC/MARINE/MORALE..........DFM
AVIATION/CLIMATE/NOWCASTS.....STRAHAN
DATA COLLECTION/SHEET METAL...ROSS
VISIT US ON THE WEB AT WWW.WEATHER.GOV/KEYWEST
000
FXUS62 KKEY 171752
AFDKEY
AREA FORECAST DISCUSSION FOR THE FLORIDA KEYS
NATIONAL WEATHER SERVICE KEY WEST FL
1252 PM EST SAT JAN 17 2009
.UPDATE...
BASED ON RECENT OBSERVATIONS WE HAVE TAKEN DOWN THE SMALL CRAFT
ADVISORY FOR THE BAY AND GULF-SIDE WATERS. THE SCA WILL CONTINUE
THROUGH 700 PM ON THE ATLANTIC SIDE.
&&
.KEY WATCHES/WARNINGS/ADVISORIES...
FL...NONE.
GM...SMALL CRAFT ADVISORY UNTIL 700 PM EST ATLANTIC SIDE.
GMZ052-GMZ053-GMZ054-GMZ072-GMZ073-GMZ074-GMZ075.
&&
$$
PUBLIC/MARINE.........DFM
AVIATION/NOWCASTS.....STRAHAN
DATA COLLECTION.......FUENTES
VISIT US ON THE WEB AT WWW.WEATHER.GOV/KEYWEST
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