[top]
000
FXCA62 TJSJ 151951
AFDSJU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
351 PM AST THU JAN 15 2009
.DISCUSSION...
MID-UPPER LVL RIDGE CENTERED OVER THE LOCAL AREA AND EXTENDING NEWD
INTO THE CNTRL ATLC WILL WEAKEN NEXT 24 HRS AS AN UPPER LEVEL LOW
PRES AREA NEAR 53W MOVES WWD INTO THE ERN CARIBBEAN THIS WEEKEND.
MODEL GUIDANCE CONSISTENT IN PAINTING A SIG INCREASE IN MOISTURE
TOMORROW AND CONTINUING INTO EARLY NEXT WEEK. PWAT VALUES PEAK
DURING THE DAY SAT AROUND 2.0 INCHES WITH K INDICES NEAR 35 WHICH
ARE ABNORMALLY HIGH FOR THIS TIME OF THE YEAR. EXPECT MOSTLY CLOUDY
SKIES WITH SCT/NRMS SHOWERS AND POSSIBLE TSTMS THROUGH MUCH OF THE
WEEKEND. THIS TUTT LOW WILL WEAKEN ON SUN WITH WEATHER EARLY NEXT
WEEK BEING MORE INFLUENCED BY LOCAL ISLAND EFFECTS AND REMNANT
MOISTURE. NEXT WEEK...MODELS SHOW AMPLIFICATION OF AN UPPER LVL TROF
OVR THE ERN UNITED STATES ON TUE WITH A CDFNT ENTERING THE WRN AND CNTRL
ATLC BY THU OF NEXT WEEK AND STALLING IT JUST NW OF THE LOCAL
AREA.
&&
.AVIATION...VFR CONDITIONS XPCT IN THE VICINITY OF SHRAS IN THE
ERN COASTAL SECTIONS OF PR/USVI AND ALL SURROUNDING WATERS.
&&
.MARINE...
SCA FOR HAZARDOUS SEAS NOW IN EFFECT THROUGH FRI AFTERNOON FOR
ALL WATERS EAST OF MAINLAND PUERTO RICO XPCT NEARSHORE WATERS.
&&
.PRELIMINARY POINT TEMPS/POPS...
SJU 72 82 72 82 / 40 50 70 50
STT 73 83 73 81 / 40 50 70 50
&&
.SJU WATCHES/WARNINGS/ADVISORIES...
PR...SMALL CRAFT ADVISORY AMZ710...715...725...732 AND 741.
VI...SMALL CRAFT ADVISORY AMZ710...715...722...725 AND 732.
&&
$$
37/64/
000
FXCA62 TJSJ 151416
AFDSJU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
1016 AM AST THU JAN 15 2009
.DISCUSSION...NO CHANGES TO INHERITED SHORT TERM FORECAST ARE
ANTICIPATED AT THIS TIME. 12Z SJU SOUNDING REFLECTS A RELATIVELY
DRY AIRMASS WITH A STRONG INVERSION BETWEEN 800 AND 650
MB...INDICATIVE OF STABILITY IN LOW LEVELS AND WHY THE SKY THIS
MORNING HAS A SOMEWHAT HAZY APPEARANCE. SAL ANALYSIS SHOWS
NORTHEAST CARIBBEAN UNDER LAYER OF SAHARAN AIR AND SOME SAT IMAGES
FROM YESTERDAY SHOW SOME OF THE DUST ACROSS THE EAST TIP OF
HISPANIOLA. FOR THE REMAINDER OF TODAY FORESEE ISOLATED TO
SCATTERED LIGHT SHOWERS AS ELONGATED LINES OF MOISTURE MOVE
WESTWARD ACROSS THE AREA. TONIGHT DEFINITELY AN INCREASE IN
MOISTURE AND THIS WAS REFLECTED IN PREVIOUS FORECASTS. GFS STILL
CLINGING TO PREVIOUS DAYS SOLUTION WITH RETROGRADING TUTT LOW
ESTIMATED FROM VISUAL SAT PIX AROUND 15N53W PROPAGATING WEST TO
JUST EAST OF THE LESSER ANTILLES BY FRIDAY EVENING. BASED ON THIS
SCENARIO AND NAM12 SOLUTION FRIDAY TO SATURDAY PERIOD APPEARS TO
BE ACTIVE WITH SHOWERS AND ISOLATED TO WIDELY SCATTERED
THUNDERSTORMS.
&&
.AVIATION...MOSTLY VFR CONDITIONS ARE EXPECTED ACROSS THE LOCAL TAF
SITES DURING THE REMAINDER OF TODAY. BRIEF PERIODS OF MVFR
CONDITIONS ARE POSSIBLE ACROSS LOCAL TAF SITES DUE TO CEILING IN
ISOLATED TO WIDELY SCATTERED SHOWERS. AFT 06Z FRIDAY INCREASING
LOW LEVEL MOISTURE UNDER ENE LOW LEVEL WINDS WILL INDUCED
SCATTERED LOCALLY NUMEROUS SHOWERS MOST TAF SITES EXCEPT WEST AND
SOUTH PUERTO RICO WITH OCCASIONAL MVFR.
&&
.PREV DISCUSSION... /ISSUED 422 AM AST THU JAN 15 2009/
DISCUSSION...THE SURFACE HIGH PRESSURE ACROSS THE NORTHCENTRAL
ATLANTIC THIS MORNING...WILL WEAKEN ACROSS THE REGION DURING THE
NEXT 24 HOURS LOOSING RAPIDLY ITS INFLUENCE OVER THE FA. THIS
FEATURE WILL MAINTAIN A MODERATE TRADE WIND FLOW ACROSS THE LOCAL
ISLANDS AND COASTAL WATERS TODAY. DURING THE OVERNIGHT HOURS...THE
NWS DOPPLER RADAR DETECTED ISOLATED TO SCATTERED SHOWERS ACROSS
EASTERN THIRD OF PUERTO RICO AND ACROSS THE SURROUNDING COASTAL
WATERS. HOWEVER...THE TOTAL RAINFALL AMOUNTS WERE GENERALLY MINIMAL.
A GENERALLY DRY AIR MASS WILL CONTINUE ACROSS THE REGION TODAY AND
TONIGHT LIMITING THE SHOWERS ACTIVITY ACROSS THE LOCAL ISLANDS.
AN UPPER LEVER LOW (TUTT) WAS LOCATED EAST OF THE LESSER ANTILLES
ALONG 50W EARLY THIS MORNING. BASED ON LATEST SATELLITE IMAGERY...
THE ASSOCIATED CLOUD PATTERN IS EXHIBITING A WELL DEFINED CYCLONIC
CIRCULATION. THE GFS MODEL SUGGESTS THAT THIS SYSTEM WILL MOVE WEST
NORTHWESTWARD UNDER THE TRADE WIND FLOW ACROSS THE REGION...
AFFECTING THE U.S. VIRGIN ISLANDS AND PUERTO RICO FRIDAY THROUGH
SATURDAY. THIS UPPER TROUGH WILL ALSO INDUCE A SURFACE TROUGH JUST
OVER THE FA BY EARLY SATURDAY. THESE FEATURES WILL BRING A
SIGNIFICANT INCREASE IN DEEP TROPICAL MOISTURE ACROSS THE
NORTHEASTERN CARIBBEAN...PROMOTING THE DEVELOPMENT OF SCATTERED
SHOWERS AND THUNDERSTORMS ACROSS THE REGION. MOST OF THE COMPUTER
MODELS SUGGEST THAT THIS WET WEATHER PATTERN WILL LAST AT LEAST
THROUGH THE FIRST PART OF THE UPCOMING WEEK. WE NEED TO STAY TUNE
WITH THE EVOLUTION OF THESE FEATURES.
AVIATION...MOSTLY VFR CONDITIONS ARE EXPECTED ACROSS THE LOCAL TAF
SITES DURING THE MORNING HOURS. HOWEVER...BRIEF PERIODS OF MVFR
CONDITIONS ARE POSSIBLE ACROSS TKPK...TNCM...TIST...AND TISX FROM
1512/1522 AS AN AREA OF MOISTURE MOVE ACROSS THESE AREAS FROM THE
EAST. WINDS WILL BE GENERALLY FROM THE EAST AT 10-15KT.
MARINE...MODERATE TO FRESH TRADE WIND FLOW WILL CONTINUE TO
GENERATE HAZARDOUS MARINE CONDITIONS ACROSS THE REGIONAL WATERS
THROUGH AT LEAST FRIDAY. WINDS UP TO 21 KNOTS AND SEAS UP TO 8 FEET
ARE EXPECTED TO CONTINUE ACROSS THE COASTAL WATERS DURING THE
PERIOD.
&&
.PRELIMINARY POINT TEMPS/POPS...
SJU 83 72 82 72 / 40 50 50 50
STT 84 73 83 73 / 40 50 50 50
&&
.SJU WATCHES/WARNINGS/ADVISORIES...
PR...NONE.
VI...NONE.
&&
$$
37/93/
000
FXCA62 TJSJ 150822
AFDSJU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
422 AM AST THU JAN 15 2009
.DISCUSSION...THE SURFACE HIGH PRESSURE ACROSS THE NORTHCENTRAL
ATLANTIC THIS MORNING...WILL WEAKEN ACROSS THE REGION DURING THE
NEXT 24 HOURS LOOSING RAPIDLY ITS INFLUENCE OVER THE FA. THIS
FEATURE WILL MAINTAIN A MODERATE TRADE WIND FLOW ACROSS THE LOCAL
ISLANDS AND COASTAL WATERS TODAY. DURING THE OVERNIGHT HOURS...THE
NWS DOPPLER RADAR DETECTED ISOLATED TO SCATTERED SHOWERS ACROSS
EASTERN THIRD OF PUERTO RICO AND ACROSS THE SURROUNDING COASTAL
WATERS. HOWEVER...THE TOTAL RAINFALL AMOUNTS WERE GENERALLY MINIMAL.
A GENERALLY DRY AIR MASS WILL CONTINUE ACROSS THE REGION TODAY AND
TONIGHT LIMITING THE SHOWERS ACTIVITY ACROSS THE LOCAL ISLANDS.
AN UPPER LEVER LOW (TUTT) WAS LOCATED EAST OF THE LESSER ANTILLES
ALONG 50W EARLY THIS MORNING. BASED ON LATEST SATELLITE IMAGERY...
THE ASSOCIATED CLOUD PATTERN IS EXHIBITING A WELL DEFINED CYCLONIC
CIRCULATION. THE GFS MODEL SUGGESTS THAT THIS SYSTEM WILL MOVE WEST
NORTHWESTWARD UNDER THE TRADE WIND FLOW ACROSS THE REGION...
AFFECTING THE U.S. VIRGIN ISLANDS AND PUERTO RICO FRIDAY THROUGH
SATURDAY. THIS UPPER TROUGH WILL ALSO INDUCE A SURFACE TROUGH JUST
OVER THE FA BY EARLY SATURDAY. THESE FEATURES WILL BRING A
SIGNIFICANT INCREASE IN DEEP TROPICAL MOISTURE ACROSS THE
NORTHEASTERN CARIBBEAN...PROMOTING THE DEVELOPMENT OF SCATTERED
SHOWERS AND THUNDERSTORMS ACROSS THE REGION. MOST OF THE COMPUTER
MODELS SUGGEST THAT THIS WET WEATHER PATTERN WILL LAST AT LEAST
THROUGH THE FIRST PART OF THE UPCOMING WEEK. WE NEED TO STAY TUNE
WITH THE EVOLUTION OF THESE FEATURES.
&&
.AVIATION...MOSTLY VFR CONDITIONS ARE EXPECTED ACROSS THE LOCAL TAF
SITES DURING THE MORNING HOURS. HOWEVER...BRIEF PERIODS OF MVFR
CONDITIONS ARE POSSIBLE ACROSS TKPK...TNCM...TIST...AND TISX FROM
1512/1522 AS AN AREA OF MOISTURE MOVE ACROSS THESE AREAS FROM THE
EAST. WINDS WILL BE GENERALLY FROM THE EAST AT 10-15KT.
&&
.MARINE...MODERATE TO FRESH TRADE WIND FLOW WILL CONTINUE TO
GENERATE HAZARDOUS MARINE CONDITIONS ACROSS THE REGIONAL WATERS
THROUGH AT LEAST FRIDAY. WINDS UP TO 21 KNOTS AND SEAS UP TO 8 FEET
ARE EXPECTED TO CONTINUE ACROSS THE COASTAL WATERS DURING THE
PERIOD.
&&
.PRELIMINARY POINT TEMPS/POPS...
SJU 83 72 82 72 / 40 50 50 50
STT 84 73 83 73 / 40 50 50 50
&&
.SJU WATCHES/WARNINGS/ADVISORIES...
PR...SMALL CRAFT ADVISORY AMZ710...715...725...732 AND 741.
VI...SMALL CRAFT ADVISORY AMZ710...715...722...725 AND 732.
&&
$$
71/72/
000
FXCA62 TJSJ 141947
AFDSJU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
347 PM AST WED JAN 14 2009
.DISCUSSION...
MID-UPPER LEVEL RIDGE OF HIGH PRES EXTENDING FROM THE SRN CARIBBEAN
NORTHEAST INTO THE CENTRAL ATLC WILL WEAKEN DURING THE NEXT 24 HRS
WHILE TUTT LOW JUST EAST OT 50W ATTM WILL BEGIN TO APPROACH THE ERN
CARIBBEAN BY FRIDAY. THIS TUTT LOW WILL ALSO INDUCE LOW-LVL
TROFFINESS ACROSS THE REGION ON SAT. 12Z GFS SHOWS A SIG INCREASE IN
MOISTURE BEGINNING THU NIGHT AND CONTINUING THROUGH SAT. PWATS
VALUES PEAK AROUND 2.0 INCHES ON 12Z SAT. EXPECT FRI AFTERNOON AND
SAT TO BE THE MOST ACTIVE TIME PERIOD FOR CONVECTION BASED ON PWAT
FIELDS AND BEST LIFT ASSOCIATED WITH THE TUTT LOW. WOULDN`T BE BY
SUN...TUTT LOW AND ITS SFC REFLECTION WILL MOVE WEST OF PR INTO THE
DOMINICAN REPUBLIC WITH WEATHER BEING MORE INFLUENCED BY LOCAL
ISLAND EFFECTS AND REMNANT MOISTURE. THIS PATTERN LOOKS TO PERSIST
INTO THE MIDDLE OF NEXT WEEK. A WEAK CDFNT IS FCST TO STALL ACROSS
THE NCRNTL ATLC AND EXTEND SW JUST SOUTHEAST OF THE TURKS AND
CAICOS.
&&
.AVIATION...MOSTLY VFR CONDITIONS ARE EXPECTED ACROSS THE LOCAL TAF
SITES DURING THE REMAINDER OF THIS AFTERNOON AND TONIGHT EXCEPT IN
THE VICINITY OF TJMZ AND TJBQ WHERE MVFR DUE TO CEILINGS NEAR
SHOWERS COULD BE EXPECTED UNTIL 02Z.
&&
.MARINE...
SCA FOR HAZARDOUS SEAS EXTENDED THROUGH THU NIGHT FOR SEAS
GREATER THAN 7 FT FOR ALL OFFSHORE WATERS AND PASSAGES. WINDS
GENERALLY 15 TO 20 KTS.
&&
.PRELIMINARY POINT TEMPS/POPS...
SJU 72 83 72 82 / 20 40 50 50
STT 73 84 73 83 / 20 40 40 50
&&
.SJU WATCHES/WARNINGS/ADVISORIES...
PR...SMALL CRAFT ADVISORY AMZ710...715...725...732 AND 741.
VI...SMALL CRAFT ADVISORY AMZ710...715...722...725 AND 732.
&&
$$
37/64/
000
FXCA62 TJSJ 141410
AFDSJU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
1010 AM AST WED JAN 14 2009
.DISCUSSION...PATCHES OF LOW LEVEL CLOUDS AND SCATTERED SHOWERS
CURRENTLY MOVING WEST NORTHWEST ACROSS THE EASTERN ONE THIRD OF
PUERTO RICO AT AROUND 20 KTS. RAINFALL ACCUMULATIONS THROUGH MID
MORNING HAVE BEEN MOSTLY LIGHT EXCEPT FOR A FEW POCKETS ALONG THE
EAST SOUTHEAST BETWEEN LAS PIEDRAS NAGUABO AND HUMACAO WHERE
AMOUNTS RANGING FROM ONE QUARTER TO HALF AND INCH ARE POSSIBLE
BASED ON DOPPLER ESTIMATES. AS INDICATED BY PREVIOUS DISCUSSION...
THESE CLOUDS AND SHOWERS SHOULD MOVE INTO THE WEST HALF OF PUERTO
RICO THROUGH THIS AFTERNOON WITH DRIER CONDITIONS BEGINNING ACROSS
THE VIRGIN ISLANDS BY EARLY AFTERNOON AND ACROSS EASTERN PUERTO RICO
BY MID AFTERNOON. LATER TONIGHT ANOTHER BUT WEAKER BOUNDARY OF
LIGHT SHOWERS EAST SOUTHEAST OF SAINT MARTEEEN COULD BRING
ISOLATED LIGHT SHOWERS TO THE USVI AND NORTH AND EAST PR. AS THE
UPPER LEVEL HIGH CENTERED OVER PUERTO RICO WEAKEN THROUGH FRIDAY
WE WILL SEE INCREASING CHANCES FOR SHOWERS AND THUNDERSTORMS
FRIDAY THROUGH SUNDAY AS INDUCED LOW LEVEL TROUGH TO THE EAST
APPROACHES AND MOVES WESTWARD.
MARINE...MODERATE TO FRESH TRADE WIND FLOW WILL CONTINUE TO
GENERATE HAZARDOUS MARINE CONDITIONS ACROSS THE REGIONAL WATERS
THROUGH AT LEAST THURSDAY AFTERNOON. WINDS UP TO 20 KNOTS AND
SEAS UP TO 8 FEET ARE EXPECTED TO CONTINUE ACROSS THE COASTAL
WATERS.
&&
.AVIATION...ISOLATED MVFR CONDITIONS ARE EXPECTED ACROSS WEST AND
NORTHWEST PUERTO RICO THROUGH 22Z AS AREA OF SCATTERED TO BROKEN
CLOUDS BETWEEEN 25 AND 35 HUNDRED FEET MOVE WEST NORTHWEST. ACROSS
EASTERN PR...USVI AND NEAR TNCM AND TKPK MOSTLY VFR CONDITIONS.
MODERATELY STRONG EAST SOUTHEAT WINDS EXPECTED BETWEEN 5 TO 10
THSD FT.
&&
.PREV DISCUSSION... /ISSUED 416 AM AST WED JAN 14 2009/
DISCUSSION...THE STRONG SURFACE HIGH PRESSURE ACROSS THE
NORTHWESTERN ATLANTIC THIS MORNING...WILL SHIFT SLOWLY EASTWARD
DURING THE NEXT FEW DAYS...LOOSING ITS INFLUENCE OVER THE FA. IN
THE MEANTIME...THIS FEATURE WILL MAINTAIN A FRESH TO MODERATE
TRADE WIND FLOW ACROSS THE LOCAL ISLANDS AND COASTAL WATERS.
THE NWS DOPPLER RADAR DETECTED ONLY LIGHT ISOLATED SHOWERS
OVERNIGHT ACROSS EASTERN AND NORTHERN SECTIONS OF PUERTO RICO AND
ACROSS THE SURROUNDING COASTAL WATERS. HOWEVER...DUE TO THE RAPID
MOVEMENT OF THE SHOWERS THE TOTAL RAINFALL AMOUNTS WERE MINIMAL.
LATEST SATELLITE IMAGES INDICATED THAT A BAND OF LOW LEVEL
MOISTURE WILL REACH THE LOCAL ISLANDS EARLY THIS MORNING...
SLIGHTLY INCREASING THE CHANCES OF SHOWERS ACROSS THE EASTERN
SECTIONS OF PUERTO RICO AS WELL ACROSS THE U.S. VIRGIN ISLANDS.
HOWEVER...AS THE DAY PROGRESSES...DRY AND STABLE AIR WILL MOVE
ACROSS THE REGION FROM THE EAST LIMITING THE SHOWERS ACTIVITY
ACROSS THE FA FOR THE REST OF THE DAY. THE LATEST RUN OF THE GFS
MODEL GUIDANCE AS WELL AS MIMIC TPW COMPOSITE INDICATED THAT THIS
RELATIVELY DRY AIR MASS WILL PERSIST ACROSS THE FA UNTIL EARLY
THURSDAY.
A MID TO UPPER LEVEL TROUGH WITH AXIS EXTENDING FROM THE TROPICAL
ATLANTIC EAST OF THE LESSER ANTILLES...NORTHEASTWARD ACROSS THE
CENTRAL TROPICAL ATLANTIC THIS MORNING...WILL DEVELOP INTO A MID
TO UPPER LOW...JUST TO THE EAST OF THE LESSER ANTILLES BY THIS
AFTERNOON. THE MID TO UPPER LOW WILL ALSO INDUCE AN INVERTED
TROUGH AT THE SURFACE. THE MID TO UPPER LOW AND THE SURFACE TROUGH
WILL THEN TRACK SLOWLY NORTHWESTWARD APPROACHING TO THE NORTHERN
LEEWARD ISLANDS LATE THURSDAY AND FRIDAY BRINGING A SIGNIFICANT
INCREASE IN DEEP TROPICAL MOISTURE ACROSS THE NORTHEASTERN
CARIBBEAN AND PROMOTING THE DEVELOPMENT OF SCATTERED SHOWERS AND
POSSIBLE THUNDERSTORMS ACROSS THE REGION. BY THE UPCOMING WEEKEND
THE REMNANTS OF A FRONTAL BOUNDARY WILL ALSO APPROACH TO THE
REGION FROM THE NORTHWEST INCREASING THE INSTABILITY. MOST OF THE
COMPUTER MODELS SUGGEST THAT THIS WET WEATHER PATTERN WILL LAST AT
LEAST THROUGH THE FIRST PART OF THE UPCOMING WEEK. WE NEED TO STAY
TUNE WITH THE EVOLUTION OF THESE FEATURES DURING THE NEXT SHIFTS.
MARINE...MODERATE TO FRESH TRADE WIND FLOW WILL CONTINUE TO
GENERATE HAZARDOUS MARINE CONDITIONS ACROSS THE REGIONAL WATERS
THROUGH AT LEAST THURSDAY AFTERNOON. WINDS UP TO 20 KNOTS AND
SEAS UP TO 8 FEET ARE EXPECTED TO CONTINUE ACROSS THE COASTAL
WATERS DURING THE PERIOD.
AVIATION...MOSTLY VFR CONDITIONS ARE EXPECTED ACROSS THE LOCAL TAF
SITES DURING THE OVERNIGHT HOURS INTO EARLY WEDNESDAY AS A FEW
ISOLATED TO SCATTERED SHOWERS MOVE ACROSS THE AREA. RELATIVELY DRIER
AIR MOVES IN BEHIND THIS PATCH OF MOISTURE LATER IN THE
DAY...KEEPING FLYING CONDITIONS FAVORABLE.
&&
.PRELIMINARY POINT TEMPS/POPS...
SJU 84 72 83 72 / 30 20 40 50
STT 84 73 84 73 / 40 20 40 40
&&
.SJU WATCHES/WARNINGS/ADVISORIES...
PR...NONE.
VI...NONE.
&&
$$
37/93/
000
FXCA62 TJSJ 140816
AFDSJU
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
416 AM AST WED JAN 14 2009
.DISCUSSION...THE STRONG SURFACE HIGH PRESSURE ACROSS THE
NORTHWESTERN ATLANTIC THIS MORNING...WILL SHIFT SLOWLY EASTWARD
DURING THE NEXT FEW DAYS...LOOSING ITS INFLUENCE OVER THE FA. IN
THE MEANTIME...THIS FEATURE WILL MAINTAIN A FRESH TO MODERATE
TRADE WIND FLOW ACROSS THE LOCAL ISLANDS AND COASTAL WATERS.
THE NWS DOPPLER RADAR DETECTED ONLY LIGHT ISOLATED SHOWERS
OVERNIGHT ACROSS EASTERN AND NORTHERN SECTIONS OF PUERTO RICO AND
ACROSS THE SURROUNDING COASTAL WATERS. HOWEVER...DUE TO THE RAPID
MOVEMENT OF THE SHOWERS THE TOTAL RAINFALL AMOUNTS WERE MINIMAL.
LATEST SATELLITE IMAGES INDICATED THAT A BAND OF LOW LEVEL
MOISTURE WILL REACH THE LOCAL ISLANDS EARLY THIS MORNING...
SLIGHTLY INCREASING THE CHANCES OF SHOWERS ACROSS THE EASTERN
SECTIONS OF PUERTO RICO AS WELL ACROSS THE U.S. VIRGIN ISLANDS.
HOWEVER...AS THE DAY PROGRESSES...DRY AND STABLE AIR WILL MOVE
ACROSS THE REGION FROM THE EAST LIMITING THE SHOWERS ACTIVITY
ACROSS THE FA FOR THE REST OF THE DAY. THE LATEST RUN OF THE GFS
MODEL GUIDANCE AS WELL AS MIMIC TPW COMPOSITE INDICATED THAT THIS
RELATIVELY DRY AIR MASS WILL PERSIST ACROSS THE FA UNTIL EARLY
THURSDAY.
A MID TO UPPER LEVEL TROUGH WITH AXIS EXTENDING FROM THE TROPICAL
ATLANTIC EAST OF THE LESSER ANTILLES...NORTHEASTWARD ACROSS THE
CENTRAL TROPICAL ATLANTIC THIS MORNING...WILL DEVELOP INTO A MID
TO UPPER LOW...JUST TO THE EAST OF THE LESSER ANTILLES BY THIS
AFTERNOON. THE MID TO UPPER LOW WILL ALSO INDUCE AN INVERTED
TROUGH AT THE SURFACE. THE MID TO UPPER LOW AND THE SURFACE TROUGH
WILL THEN TRACK SLOWLY NORTHWESTWARD APPROACHING TO THE NORTHERN
LEEWARD ISLANDS LATE THURSDAY AND FRIDAY BRINGING A SIGNIFICANT
INCREASE IN DEEP TROPICAL MOISTURE ACROSS THE NORTHEASTERN
CARIBBEAN AND PROMOTING THE DEVELOPMENT OF SCATTERED SHOWERS AND
POSSIBLE THUNDERSTORMS ACROSS THE REGION. BY THE UPCOMING WEEKEND
THE REMNANTS OF A FRONTAL BOUNDARY WILL ALSO APPROACH TO THE
REGION FROM THE NORTHWEST INCREASING THE INSTABILITY. MOST OF THE
COMPUTER MODELS SUGGEST THAT THIS WET WEATHER PATTERN WILL LAST AT
LEAST THROUGH THE FIRST PART OF THE UPCOMING WEEK. WE NEED TO STAY
TUNE WITH THE EVOLUTION OF THESE FEATURES DURING THE NEXT SHIFTS.
.MARINE...MODERATE TO FRESH TRADE WIND FLOW WILL CONTINUE TO
GENERATE HAZARDOUS MARINE CONDITIONS ACROSS THE REGIONAL WATERS
THROUGH AT LEAST THURSDAY AFTERNOON. WINDS UP TO 20 KNOTS AND
SEAS UP TO 8 FEET ARE EXPECTED TO CONTINUE ACROSS THE COASTAL
WATERS DURING THE PERIOD.
.AVIATION...MOSTLY VFR CONDITIONS ARE EXPECTED ACROSS THE LOCAL TAF
SITES DURING THE OVERNIGHT HOURS INTO EARLY WEDNESDAY AS A FEW
ISOLATED TO SCATTERED SHOWERS MOVE ACROSS THE AREA. RELATIVELY DRIER
AIR MOVES IN BEHIND THIS PATCH OF MOISTURE LATER IN THE
DAY...KEEPING FLYING CONDITIONS FAVORABLE.
&&
.PRELIMINARY POINT TEMPS/POPS...
SJU 84 72 83 72 / 30 20 40 50
STT 84 73 84 73 / 40 20 40 40
&&
.SJU WATCHES/WARNINGS/ADVISORIES...
PR...SMALL CRAFT ADVISORY AMZ710...715...725...732 AND 741.
VI...SMALL CRAFT ADVISORY AMZ710...715...722...725 AND 732. &&
$$
15/72/
000
FXCA62 TJSJ 140249 AAA
AFDSJU
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE SAN JUAN PR
1049 PM AST TUE JAN 13 2009
.UPDATE...THE BAND OF MOISTURE EXPECTED TO MOVE THROUGH THE LOCAL
AREA AFTER 12Z TOMORROW...SOMEWHAT EARLIER IN THE U.S. VIRGIN
ISLANDS...IS NOW MOVING INTO THE LEEWARD ISLANDS BRINGING LOWER
CEILINGS AND SCATTERED LIGHT SHOWERS. ALTHOUGH THE BEST OF THE
CLOUDS AND SHOWERS WILL PASS NORTH OF THE AREA...THE TAIL HANGING
DOWN SHOULD STILL BRING A GOOD CHANCE OF SHOWERS TO THE VIRGIN
ISLANDS AND THE EAST AND NORTHEAST OF PUERTO RICO WEDNESDAY MORNING.
DRYING BEGINS ALMOST IMMEDIATELY AFTERWARD. ALTHOUGH WEAK MOISTURE
MOVES THROUGH OVERNIGHT WEDNESDAY NIGHT...MUCH BETTER MOISTURE IS
FORECAST TO ARRIVE AFTER NOON ON THURSDAY BY BOTH THE GFS AND NAM.
THE 00Z RUN OF THE NAM IS PARTIALLY IN NOW AND THIS BANK OF
MOISTURE MOVES INTO EASTERN PUERTO RICO BETWEEN 21Z THURSDAY AND
00Z FRIDAY WITH SIMILAR INTENSITY AND FORCE AS THE PREVIOUS 18Z
RUN. SINCE THE MODELS HAVE BEEN FORECASTING THIS INCLEMENT WEATHER
SINCE THE WEEKEND...WILL TAKE THIS AS A GOOD OPPORTUNITY TO BEGIN
INTRODUCING HIGHER POPS INTO THE FORECAST AS UNCERTAINTY
DECREASES. AND...SPEAKING OF THE WEEKEND...AS THE PREVIOUS
DISCUSSION WRITER SAID...MODELS ARE KEEPING MOIST AIR AND SHOWERS
IN THE FORECAST AT LEAST THROUGH SUNDAY AND THE 18Z RUN KEEPS AIR
MOIST AND FLOW SOUTHEASTERLY THROUGH WEDNESDAY OF NEXT WEEK ONCE
THE MOISTURE ARRIVES SOMETIME THIS THURSDAY.
MARINE UPDATE...THE BUOY NORTH OF THE AREA IS STILL SHOWING SEAS
OF AROUND 7 FEET AND UPSTREAM WINDS SUGGEST THAT THIS WILL
CONTINUE FOR SOME TIME. THE WAVE WATCH MODEL DIMINISHED SEAS TO 2
METERS BY 00Z WEDNESDAY...AND SEAS ARE GENERALLY HIGHER THAN THEY
WERE 48 HOURS AGO IN THE ATLANTIC. SEAS WILL VERY SLOWLY INCREASE
ANOTHER 1 OR 2 FEET BETWEEN NOW AND SATURDAY. IN THE CARIBBEAN
SEAS ARE EXPECTED TO DECREASE SLIGHTLY THROUGH MOST OF THE DAY
WEDNESDAY AND THEN INCREASE SOMEWHAT THROUGH THURSDAY. SEAS IN THE
CARIBBEAN ARE FORECAST TO IMPROVE AFTER THURSDAY IN SPITE OF THE
TROUGH PASSAGE EXPECTED...MAINLY DUE TO WEAKER GRADIENTS. SUDDEN
SQUALLS MAY BRIEFLY MAKE SEAS SOMEWHAT HAZARDOUS THEN HOWEVER.
&&
.AVIATION UPDATE...MOSTLY VFR CONDITIONS WILL PREVAIL ACROSS THE LOCAL TAF
SITES DURING THE NEXT 24 HOURS WITH NO SIGNIFICANT WEATHER FLYING
HAZARDS EXPECTED. A SLIGHT INCREASE OF MOISTURE IS EXPECTED TO OCCUR
THROUGH THE OVERNIGHT AND WEDNESDAY MORNING HOURS AND COULD RESULT
IN ISOLATED TO SCATTERED SHOWER ACTIVITY ACROSS PUERTO RICO.
MOUNTAIN OBSCURATIONS SHOULD BE EXPECTED AFTER 10Z WEDNESDAY.
&&
.PREV DISCUSSION... /ISSUED 238 PM AST TUE JAN 13 2009/
DISCUSSION...STRONG SURFACE HIGH PRESSURE OVER THE WESTERN ATLANTIC
WILL SHIFT EAST DURING THE NEXT DAY OR SO...PRODUCING A FRESH
TRADE WIND FLOW ACROSS THE LOCAL AREA. AT MID LEVEL... STRONG
SUBSIDENCE BETWEEN 700-500MB WILL BE IN PLACE UNTIL THURSDAY...
LIMITING THE DEVELOPMENT OF CLOUDS ACROSS THE LOCAL AREA.
HOWEVER...FOR LATE THURSDAY INTO EARLY FRIDAY...A SIGNIFICANT
INCREASE IN MOISTURE WILL OCCUR. THIS INCREASE IN MOISTURE WILL BE
ASSOCIATED WITH A TUTT LOCATED OVER THE TROPICAL ATLANTIC WHICH
WILL ALLOW LOW PRESSURE TO BUILD INTO THE LOW TO MID LEVELS. MOST
OF THE COMPUTER MODELS SUGGEST THAT THIS EVENT WILL LAST AT LEAST
THROUGH THE WEEKEND. GFS COMPUTER MODEL HAS BEEN VERY CONSISTENT
BRINGING THIS FEATURE ON FRIDAY...THEREFORE THE POPS FOR DAY 4 AND
5 WILL BE ADJUST ACCORDINGLY. ALTHOUGH BEFORE THIS FEATURE
APPROACH THE LOCAL AREA FROM THE EAST...WE EXPECT MAINLY DRY
CONDITIONS ACROSS THE LOCAL AREA...SCATTERED PASSING SHOWERS WILL
BE POSSIBLE UNTIL THURSDAY...MAINLY OVER THE COASTAL
WATERS...DURING THE MORNING HOURS...AND THE EASTERN HALF OF PUERTO
RICO DURING THE OVERNIGHT HOURS.
AVIATION...VFR CONDITIONS WILL PREVAIL NEXT 24 HOURS. WINDS ARE
FAIRLY STRONG IN THE 15 TO 25 KNOT RANGE AT ALL SITES...AND WILL
REMAIN GUSTY THROUGH THIS EVENING.
MARINE....MODERATE TO FRESH TRADE WIND FLOW AND MODERATE LONG PERIOD
NORTH SWELLS WILL CONTINUE TO GENERATE HAZARDOUS MARINE CONDITIONS
ACROSS THE REGIONAL WATERS THROUGH AT LEAST THURSDAY. WINDS UP TO
20 KNOTS AND SEAS UP TO 8 FEET ARE EXPECTED TO CONTINUE ACROSS THE
COASTAL WATERS DURING THE PERIOD.
&&
.PRELIMINARY POINT TEMPS/POPS...
SJU 71 84 72 83 / 30 30 20 40
STT 72 84 73 84 / 40 40 20 40
&&
.SJU WATCHES/WARNINGS/ADVISORIES...
PR...SMALL CRAFT ADVISORY AMZ710...715...725...732 AND 741.
VI...SMALL CRAFT ADVISORY AMZ710...715...722...725 AND 732. &&
$$
10/12/
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