000
FXUS65 KVEF 201111
AFDVEF
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
311 AM PST TUE JAN 20 2009
.SYNOPSIS...A RIDGE OF HIGH PRESSURE WILL REMAIN OVER THE
INTERMOUNTAIN WEST THROUGH TODAY BRINGING DRY CONDITIONS WITH ABOVE
NORMAL TEMPERATURES TO THE AREA. HOWEVER A CHANGE WILL BE TAKING
PLACE ON WEDNESDAY AS A PACIFIC STORM BRINGS INCREASING CLOUDS AND
SHOWERS TO THE REGION WEDNESDAY AFTERNOON THROUGH THURSDAY.
&&
.SHORT TERM...HIGH AMPLITUDE RIDGE TO CONTINUE TO OVER THE AREA
THROUGH TODAY AND ALTHOUGH HIGH LEVEL MOISTURE CONTINUES TO BE
TAPPED FROM THE SOUTH...OVERALL DRY CONDITIONS WITH ABOVE NORMAL
TEMPERATURES LOOKED FOR THIS AFTERNOON. RIDGE BEGINS TO BREAK DOWN
TONIGHT AS TROUGH APPROACHING 130W SHIFTS EAST TONIGHT WITH AXIS
ROUGHLY ALONG A LINE FROM 40N/125W TO 20N/132W BY 00Z THURSDAY. THIS
WILL ALLOW FOR INCREASED CLOUDS OVER THE CWA TONIGHT WITH AN
INCREASING CHANCE OF SHOWERS INTO THE SOUTHERN SIERRA BY EARLY
WEDNESDAY BEFORE SPREADING EAST DURING THE DAY. TROUGH WILL LIKELY
TAP INTO MOISTURE PLUME...PREC WATER VALUES NEAR 1.75INCHES...SOUTH
OF 30N BTWN 125-120W AS IT SHIFTS EAST WHICH COULD LOCALLY ENHANCE
PRECIPITATION AMOUNTS OVER THE AREA AS IT SHIFTS INLAND ON THURSDAY.
NAM/GFS/ECMWF COMING INTO LINE WITH THIS SYSTEM WITH OPEN WAVE
MOVING ACROSS THE CWA THURSDAY/THURSDAY NIGHT. HOWEVER DETAILS STILL
BE HARD TO PIN DOWN AS ENERGY FROM THE SYSTEM LIKELY TO SPLIT OVER
CALIFORNIA BEFORE IT MOVES EAST. HOWEVER BEST CHANCES FOR PRECIP
WILL BE THUR/THUR NIGHT AND DUE TO THE SPLIT OF THE SYSTEM...THE
EXTREME NORTH AND SOUTH PORTION OF THE CWA WILL SEE THE BEST CHANCE
OF PRECIPITATION. DO NOT SEE A LOT OF COOLING WITH THIS SYSTEM BUT
WILL SHOW COOLER TEMPS WED/THUR DUE TO CLOUDS/SHOWERS. MEANWHILE
SNOW LEVELS WILL REMAIN FAIRLY HIGH THROUGH THE PERIOD.
.LONG TERM...MODELS STILL HAVING A DIFFICULT TIME SHOWING ANY
CONSISTENCY HEADING INTO NEXT WEEKEND AS THE PATTERN HAS TURNED MORE
ACTIVE. BOTH THE GFS AND ECMWF ARE SHOWING WEAK RIDGING OVER THE
AREA FRIDAY WITH A CLOSED LOW OFF THE CALIFORNIA COAST. BOTH MODELS
KEEP THIS LOW OFF SHORE AND EVENTUALLY DRIVE IT AWAY FROM THE COAST
AS A SHORTWAVE DROPS SOUTH OUT OF WESTERN CANADA. THE GFS CONTINUES
TO BE THE STRONGER MODEL AND EVENTUALLY DEVELOPS A CLOSED LOW OVER
IDAHO AND BRINGS A COLD FRONT THROUGH MUCH OF NEVADA. THE ECMWF IS
ALSO SHOWING THIS SHORTWAVE...BUT KEEPS MOST OF THE ENERGY EAST OF
THE FORECAST AREA. WILL CONTINUE TO PLAY A CONSERVATIVE FORECAST AND
KEEP SLIGHT CHANCE TO CHANCE POPS IN THE GRIDS. TEMPERATURES ARE
ALSO FORECAST TO DROP TO BELOW NORMAL READINGS BY EARLY NEXT
WEEK...BUT THIS IS ALL DEPENDANT ON WHAT THE PATTERN FINALLY DOES.
&&
.AVIATION...FOR MCCARRAN...LIGHT SURFACE WINDS ARE EXPECTED AGAIN
TODAY AROUND THE LAS VEGAS VALLEY. CLOUDS WILL BEGIN TO LOWER LATER
TODAY AS A STORM SYSTEM APPROACHES THE AREA. MAINLY HIGH CLOUDS AOA
20K FEET THIS MORNING...BUT WILL LOWER TO AROUND 14K FEET AFTER 22Z
AND WILL LOWER TO AROUND 10K FEET AFTER 06Z WEDNESDAY. EARLIEST
CHANCE OF PRECIPITATION LOOKS TO OCCUR AFTER 12Z THURSDAY.
FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...WINDS WILL BE LIGHT AND VARIABLE EXCEPT ALONG THE
COLORADO RIVER VALLEY AND IN SOME NORTH/SOUTH CHANNELS OVER THE
EASTERN PART OF THE FORECAST AREA...WHERE NORTH TO NORTHEAST WINDS
OF 10-15KTS WILL PERSIST. MOST OF THE CWA WILL HAVE SCATTERED TO
BROKEN CONDITIONS AS HIGH CLOUDS AOA 20K MOVE ACROSS THE AREA. A
STORM IS EXPECTED TO AFFECT THE ENTIRE CWA STARTING WEDNESDAY NIGHT
WITH LOWERING CLOUDS AND A CHANCE OF SHOWERS BY THURSDAY MORNING.
&&
.VEF WATCHES/WARNINGS/ADVISORIES...
NV...NONE.
AZ...NONE.
CA...NONE.
&&
$$
JENSEN/GORELOW
HTTP://WEATHER.GOV/LASVEGAS
000
FXUS65 KVEF 200423
AFDVEF
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
823 PM PST MON JAN 19 2009
.SYNOPSIS...A RIDGE OF HIGH PRESSURE WILL REMAIN OVER THE
INTERMOUNTAIN WEST THROUGH TUESDAY BRINGING DRY CONDITIONS WITH
ABOVE NORMAL TEMPERATURES TO THE AREA. A PACIFIC STORM WILL BRING
INCREASING CLOUDS AND SHOWERS TO THE REGION LATE WEDNESDAY THROUGH
THURSDAY.
&&
.UPDATE...AS EXPECTED...MOSTLY CLEAR TO PARTLY CLOUDY SKIES AND
LIGHT WINDS ARE BEING OBSERVED AREAWIDE. NO UPDATE NEEDED AT THIS
TIME.
&&
.PREV DISCUSSION...
200 PM PST MON JAN 19 2009
.SHORT TERM...THE HIGH AMPLITUDE RIDGE EVIDENT ON SATELLITE IMAGERY
WILL REMAIN THE DOMINANT FEATURE THROUGH TUESDAY...RESULTING IN
CONTINUED DRY CONDITIONS AND ABOVE NORMAL TEMPERATURES. TO OUR
SOUTH...WV IMAGERY INDICATES A LARGE POOL OF MOISTURE...WITH GOES
SOUNDERS INDICATING PW VALUES OF 2 INCHES AROUND 20N/120W. THIS
FEATURE MAY VERY WELL COME INTO PLAY LATE WEDNESDAY/THURSDAY AS A
LOW PRESSURE SYSTEM APPROACHING FROM THE WEST DEEPENS AND TAPS INTO
THIS MOISTURE. THE SREF AND NAM BOTH INDICATE PW VALUES AT LEAST 4
STANDARD DEVIATIONS ABOVE NORMAL WEDNESDAY NIGHT THROUGH THURSDAY
ACROSS THE SOUTHERN HALF OF THE FORECAST AREA....AND MODEL
SOUNDING WHICH ARE NEARLY SATURATED FROM THE SURFACE TO 25-30KFT.
THERE IS STILL MUCH TO BE DESIRED IN THE WAY OF MODEL CONSENSUS AT
THIS TIME...BUT THE SREF/NAM/UKMET ALL INDICATE A FORECAST TRACK
WHICH COULD RESULT IN SIGNIFICANT PRECIP. SNOW LEVELS WILL REMAIN
ABOVE 8000FT...WITH ONLY MINOR HEIGHT FALLS. HAVE BUMPED UP POP AND
QPF CONSIDERABLY BEGINNING WEDNESDAY NIGHT....AND DECREASED DAYTIME
HIGHS ON WEDNESDAY WITH SIGNIFICANT CLOUD COVER EXPECTED. MINOR
FLOODING WILL BE A POSSIBILITY LATE WEDNESDAY/THURSDAY IF THE
WEATHER EVOLVES AS EXPECTED.
.LONG TERM...MODELS COMING TOGETHER CONCERNING THE SHORTWAVE ON
THURSDAY...WITH THE ECMWF/NAM12/SREF CONVERGING ON A SIMILAR
SOLUTION. ALL MODELS SHOWING A DECENT TROPICAL FETCH BEING ENTRAINED
INTO THE SHORTWAVE SYSTEM AND BRINGING A SIGNIFICANT AMOUNT OF
MOISTURE INTO THE FORECAST AREA. MOST CURRENT ECMWF RUN REMAINING
CONSISTENT WITH THE TRACKING AND PLACEMENT OF THE SHORTWAVE...SO
BUMPED UP POPS ACROSS THE FORECAST AREA FOR THURSDAY MORNING.
LITTLE CHANGES WERE MADE TO THE REMAINDER OF THE FORECAST...OTHER
THAN INCREASING POPS AND QPF FOR THURSDAY. RIDGING BUILDS IN AFTER
THE SHORTWAVE MAKES ITS WAY OUT OF THE SOUTHWEST...WHILE ANOTHER
SYSTEM LINES UP DIRECTLY BEHIND. CONFIDENCE IS MUCH LOWER WITH THIS
SECOND SYSTEM...SINCE THE MODEL SOLUTIONS ARE NOT VERY CLOSE TO EACH
OTHER. FROM SATURDAY THROUGH THE BEGINNING OF NEXT WEEK IT IS
UNCERTAIN AS TO WHAT THE NEXT WAVE WILL DECIDE TO DO...BUT IT LOOKS
LIKE UNSETTLED WEATHER WILL BE ON THE HORIZON.
.AVIATION...FOR MCCARRAN...LIGHT WINDS FOR THE REST OF THE PERIOD
WITH SCATTERED AND BROKEN HIGH CLOUDS AOA 20K. A STORM IS STILL
MAKING ITS WAY ACROSS THE PACIFIC INTO THE AREA AND WILL START TO
IMPACT THE AIRPORT BEGINNING WEDNESDAY EVENING...RESULTING IN
SHOWERS AND CIGS AOB 5KFT.
FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...WINDS WILL BE LIGHT AND VARIABLE EXCEPT ALONG THE
COLORADO RIVER VALLEY AND IN SOME NORTH/SOUTH CHANNELS OVER THE
EASTERN PART OF THE FORECAST AREA...WHERE NORTH TO NORTHEAST WINDS
OF 10-15KTS WILL PERSIST. MOST OF THE CWA WILL HAVE SCATTERED TO
BROKEN CONDITIONS AS HIGH CLOUDS AOA 20K MOVE ACROSS THE AREA. A
STORM IS EXPECTED TO AFFECT THE ENTIRE CWA STARTING WEDNESDAY NIGHT.
&&
.VEF WATCHES/WARNINGS/ADVISORIES...
NV...NONE.
AZ...NONE.
CA...NONE.
&&
$$
MORGAN/KENNEDY/LINDAMAN
HTTP://WEATHER.GOV/LASVEGAS
000
FXUS65 KVEF 192152
AFDVEF
AREA FORECAST DISCUSSION UPDATE
NATIONAL WEATHER SERVICE LAS VEGAS NV
200 PM PST MON JAN 19 2009
.SYNOPSIS...A RIDGE OF HIGH PRESSURE WILL REMAIN OVER THE
INTERMOUNTAIN WEST THROUGH TUESDAY BRINGING DRY CONDITIONS WITH
ABOVE NORMAL TEMPERATURES TO THE AREA. A PACIFIC STORM WILL BRING
INCREASING CLOUDS AND SHOWERS TO THE REGION LATE WEDNESDAY THROUGH
THURSDAY.
&&
.SHORT TERM...THE HIGH AMPLITUDE RIDGE EVIDENT ON SATELLITE IMAGERY
WILL REMAIN THE DOMINANT FEATURE THROUGH TUESDAY...RESULTING IN
CONTINUED DRY CONDITIONS AND ABOVE NORMAL TEMPERATURES. TO OUR
SOUTH...WV IMAGERY INDICATES A LARGE POOL OF MOISTURE...WITH GOES
SOUNDERS INDICATING PW VALUES OF 2 INCHES AROUND 20N/120W. THIS
FEATURE MAY VERY WELL COME INTO PLAY LATE WEDNESDAY/THURSDAY AS A
LOW PRESSURE SYSTEM APPROACHING FROM THE WEST DEEPENS AND TAPS INTO
THIS MOISTURE. THE SREF AND NAM BOTH INDICATE PW VALUES AT LEAST 4
STANDARD DEVIATIONS ABOVE NORMAL WEDNESDAY NIGHT THROUGH THURSDAY
ACROSS THE SOUTHERN HALF OF THE FORECAST AREA....AND MODEL
SOUNDING WHICH ARE NEARLY SATURATED FROM THE SURFACE TO 25-30KFT.
THERE IS STILL MUCH TO BE DESIRED IN THE WAY OF MODEL CONSENSUS AT
THIS TIME...BUT THE SREF/NAM/UKMET ALL INDICATE A FORECAST TRACK
WHICH COULD RESULT IN SIGNIFICANT PRECIP. SNOW LEVELS WILL REMAIN
ABOVE 8000FT...WITH ONLY MINOR HEIGHT FALLS. HAVE BUMPED UP POP AND
QPF CONSIDERABLY BEGINNING WEDNESDAY NIGHT....AND DECREASED DAYTIME
HIGHS ON WEDNESDAY WITH SIGNIFICANT CLOUD COVER EXPECTED. MINOR
FLOODING WILL BE A POSSIBILITY LATE WEDNESDAY/THURSDAY IF THE
WEATHER EVOLVES AS EXPECTED.
.LONG TERM...MODELS COMING TOGETHER CONCERNING THE SHORTWAVE ON
THURSDAY...WITH THE ECMWF/NAM12/SREF CONVERGING ON A SIMILAR
SOLUTION. ALL MODELS SHOWING A DECENT TROPICAL FETCH BEING ENTRAINED
INTO THE SHORTWAVE SYSTEM AND BRINGING A SIGNIFICANT AMOUNT OF
MOISTURE INTO THE FORECAST AREA. MOST CURRENT ECMWF RUN REMAINING
CONSISTENT WITH THE TRACKING AND PLACEMENT OF THE SHORTWAVE...SO
BUMPED UP POPS ACROSS THE FORECAST AREA FOR THURSDAY MORNING.
LITTLE CHANGES WERE MADE TO THE REMAINDER OF THE FORECAST...OTHER
THAN INCREASING POPS AND QPF FOR THURSDAY. RIDGING BUILDS IN AFTER
THE SHORTWAVE MAKES ITS WAY OUT OF THE SOUTHWEST...WHILE ANOTHER
SYSTEM LINES UP DIRECTLY BEHIND. CONFIDENCE IS MUCH LOWER WITH THIS
SECOND SYSTEM...SINCE THE MODEL SOLUTIONS ARE NOT VERY CLOSE TO EACH
OTHER. FROM SATURDAY THROUGH THE BEGINNING OF NEXT WEEK IT IS
UNCERTAIN AS TO WHAT THE NEXT WAVE WILL DECIDE TO DO...BUT IT LOOKS
LIKE UNSETTLED WEATHER WILL BE ON THE HORIZON.
&&
.AVIATION...FOR MCCARRAN...LIGHT WINDS FOR THE REST OF THE PERIOD
WITH SCATTERED AND BROKEN HIGH CLOUDS AOA 20K. A STORM IS STILL
MAKING ITS WAY ACROSS THE PACIFIC INTO THE AREA AND WILL START TO
IMPACT THE AIRPORT BEGINNING WEDNESDAY EVENING...RESULTING IN
SHOWERS AND CIGS AOB 5KFT.
FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...WINDS WILL BE LIGHT AND VARIABLE EXCEPT ALONG THE
COLORADO RIVER VALLEY AND IN SOME NORTH/SOUTH CHANNELS OVER THE
EASTERN PART OF THE FORECAST AREA...WHERE NORTH TO NORTHEAST WINDS
OF 10-15KTS WILL PERSIST. MOST OF THE CWA WILL HAVE SCATTERED TO
BROKEN CONDITIONS AS HIGH CLOUDS AOA 20K MOVE ACROSS THE AREA. A
STORM IS EXPECTED TO AFFECT THE ENTIRE CWA STARTING WEDNESDAY NIGHT.
&&
.VEF WATCHES/WARNINGS/ADVISORIES...
NV...NONE
AZ...NONE
CA...NONE
&&
$$
KENNEDY/LINDAMAN
HTTP://WEATHER.GOV/LASVEGAS
000
FXUS65 KVEF 191805
AFDVEF
AREA FORECAST DISCUSSION UPDATE
NATIONAL WEATHER SERVICE LAS VEGAS NV
1000 AM PST MON JAN 19 2009
.SYNOPSIS...A RIDGE OF HIGH PRESSURE WILL REMAIN OVER THE
INTERMOUNTAIN WEST THROUGH TUESDAY BRINGING DRY CONDITIONS WITH
ABOVE NORMAL TEMPERATURES TO THE AREA. A PACIFIC STORM WILL BRING
INCREASING CLOUDS AND SHOWERS TO THE REGION LATE WEDNESDAY THROUGH
THURSDAY.
&&
.UPDATE...TODAYS FORECAST RIGHT ON TRACK...SO NO UPDATE WILL BE
ISSUED THIS MORNING. WILL LIKELY MAKE A SUBSTANTIAL INCREASE TO THE
POP AND QPF FORECAST FOR WEDNESDAY AFTERNOON/THURSDAY ACROSS THE
ENTIRE FORECAST AREA. THE NAM/UKMET/SREF/ECMWF ALL INDICATE THE NEXT
SYSTEM TAPPING INTO A SIGNIFICANT POOL OF MOISTURE TO OUR
SOUTH...WITH PRECIPITABLE WATER ANOMALIES AROUND 4 STANDARD
DEVIATIONS ABOVE NORMAL ACROSS THE SOUTHERN PORTION OF THE FORECAST
AREA.
&&
.PREV DISCUSSION...FROM 328 AM PST...HIGH AMPLITUDE RIDGE OVER THE
WESTERN STATES REMAINS THE DOMINANT FEATURE THROUGH TUESDAY AND WITH
THE EXCEPTION OF VARIABLE HIGH CLOUDS BEING DRAWN UP FROM THE
SOUTH...DRY CONDITIONS WITH ABOVE NORMAL TEMPERATURES WILL CONTINUE
ACROSS THE CWA THROUGH TUESDAY. RIDGE TO BEGIN BREAKING DOWN LATE
TUESDAY INTO WEDNESDAY AS PACIFIC TROUGH APPROACHES THE WEST COAST.
DIFFERENCES CONTINUE BETWEEN THE 00Z MODELS ON THE
INTENSITY/POSITION OF THIS TROUGH INTO 12Z THURSDAY WITH NAM SHOWING
FAIRLY STRONG CLOSED LOW FORMING BY 12Z WEDNESDAY OFF THE CENTRAL
CALIFORNIA COAST WHILE GFS/ECMWF LEANING TOWARDS AN OPEN WAVE. GFS
THEN STRONGER WITH THIS SYSTEM INTO 12Z THURSDAY THAN ECMWF. HOWEVER
06Z NAM/GFS SHOWING A WEAKER/FURTHER SOUTH TRAJECTORY THAN THE 00Z
RUN. THUS THESE CONTINUED INCONSISTENCIES ARE LEADING TOWARDS A
FAIRLY LOW CONFIDENCE IN THE FORECAST FROM MID WEDNESDAY THROUGH 12Z
THURSDAY. FOR NOW...WILL CONTINUE AFTERNOON TREND OF INCREASING
CLOUDS OVER THE CWA ON WEDNESDAY...LEADING TO INCREASING POPS OVER
THE SOUTHERN SIERRA BY WEDNESDAY AFTERNOON THEN SPREADING POPS EAST
WEDNESDAY NIGHT. HIGHEST POPS WILL BE OVER THE SOUTHERN PORTION OF
THE CWA WEDNESDAY NIGHT DUE TO THE POTENTIAL SOUTHERN TRAJECTORY.
DUE TO THE INCREASED CLOUD COVER ON WEDNESDAY...TEMPS SHOULD COOL
SLIGHTLY...BUT OVERALL HEIGHT/THICKNESS VALUES CHANGE LITTLE AS
TROUGH IS STILL OFF THE COAST.
.LONG TERM...STILL SOME DIFFERENCES IN THE MODELS WITH REGARDS TO
THURSDAYS SHORTWAVE. GFS HAS BEEN THE MOST CONSISTENT MODEL IN
BRINGING AN UPPER LOW INTO SOUTHERN CALIFORNIA WHILE THE ECMWF WAS
KEEPING THIS FEATURE WELL TO THE SOUTH. NEWEST RUN SHOWS LITTLE
CHANGE IN THE GFS SOLUTION WHILE THE ECMWF NOW SHOWS THE UPPER LOW
MUCH FARTHER NORTH. HOWEVER...BOTH MODELS ARE SHOWING A BETTER
MOISTURE TAP AND HAVE INCREASED QPF VALUES OF THE CWA. EVEN THE NAM
HAS GOTTEN INTO THE PICTURE AND SHOWING DECENT MOISTURE OVER THE
AREA THURSDAY NIGHT. ALTHOUGH ITS LOOKING BETTER FOR THE AREA TO SEE
PRECIPITATION...AMOUNTS ARE EXPECTED TO REMAIN FAIRLY LIGHT. AFTER
FRIDAY...THE MODELS SHOW SIGNIFICANT DIFFERENCES WITH THE GFS
SHOWING A STRONG COLD SYSTEM DIVING SOUTH ALONG THE WEST COAST WHILE
THE ECMWF KEEPS THE AREA UNDER A NORTHWEST FLOW. THERE ARE SEVERAL
ENSEMBLE MEMBERS THAT DO SUPPORT THE OPERATIONAL GFS SOLUTION...SO
NEXT WEEKEND COULD BE QUITE INTERESTING WITH REGARDS TO ADDITIONAL
PRECIPITATION AND MUCH COOLER TEMPERATURES. FOR NOW...INCREASED POPS
ON THURSDAY NIGHT AND MADE LITTLE CHANGES TO THE WEEKEND FORECAST.
&&
.AVIATION...FOR MCCARRAN...ONCE AGAIN GENERALLY LIGHT WINDS THROUGH
TODAY. THE REGION WILL SEE AN INCREASE IN CIRRUS CLOUDS WHICH WILL
REMAIN AOA 20K. A STORM IS EXPECTED TO BRING IMPACTS TO THE AIRPORT
AS EARLY AS WEDNESDAY.
FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...WINDS WILL BE LIGHT AND VARIABLE EXCEPT ALONG THE
COLORADO RIVER VALLEY AND IN SOME NORTH/SOUTH CHANNELS OVER THE
EASTERN CWA WHERE NORTH TO NORTHEAST WINDS OF 10-15KTS ARE EXPECTED
TO CONTINUE ONCE AGAIN. SOUTHERN AREAS OF THE CWA WILL SEE A BR
&&
.VEF WATCHES/WARNINGS/ADVISORIES...
NV...NONE
AZ...NONE
CA...NONE
&&
$$
JENSEN/GORELOW
HTTP://WEATHER.GOV/LASVEGAS
000
FXUS65 KVEF 191127
AFDVEF
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
328 AM PST MON JAN 19 2009
.SYNOPSIS...A RIDGE OF HIGH PRESSURE WILL REMAIN OVER THE
INTERMOUNTAIN WEST THROUGH TUESDAY BRINGING DRY CONDITIONS WITH
ABOVE NORMAL TEMPERATURES TO THE AREA. A PACIFIC STORM WILL BRING
INCREASING CLOUDS AND A CHANCE OF SHOWERS TO THE REGION LATE
WEDNESDAY THROUGH THURSDAY.
&&
.SHORT TERM...HIGH AMPLITUDE RIDGE OVER THE WESTERN STATES REMAINS
THE DOMINANT FEATURE THROUGH TUESDAY AND WITH THE EXCEPTION OF
VARIABLE HIGH CLOUDS BEING DRAWN UP FROM THE SOUTH...DRY CONDITIONS
WITH ABOVE NORMAL TEMPERATURES WILL CONTINUE ACROSS THE CWA THROUGH
TUESDAY. RIDGE TO BEGIN BREAKING DOWN LATE TUESDAY INTO WEDNESDAY AS
PACIFIC TROUGH APPROACHES THE WEST COAST. DIFFERENCES CONTINUE
BETWEEN THE 00Z MODELS ON THE INTENSITY/POSITION OF THIS TROUGH INTO
12Z THURSDAY WITH NAM SHOWING FAIRLY STRONG CLOSED LOW FORMING BY
12Z WEDNESDAY OFF THE CENTRAL CALIFORNIA COAST WHILE GFS/ECMWF
LEANING TOWARDS AN OPEN WAVE. GFS THEN STRONGER WITH THIS SYSTEM
INTO 12Z THURSDAY THAN ECMWF. HOWEVER 06Z NAM/GFS SHOWING A
WEAKER/FURTHER SOUTH TRAJECTORY THAN THE 00Z RUN. THUS THESE
CONTINUED INCONSISTENCIES ARE LEADING TOWARDS A FAIRLY LOW
CONFIDENCE IN THE FORECAST FROM MID WEDNESDAY THROUGH 12Z THURSDAY.
FOR NOW...WILL CONTINUE AFTERNOON TREND OF INCREASING CLOUDS OVER
THE CWA ON WEDNESDAY...LEADING TO INCREASING POPS OVER THE SOUTHERN
SIERRA BY WEDNESDAY AFTERNOON THEN SPREADING POPS EAST WEDNESDAY
NIGHT. HIGHEST POPS WILL BE OVER THE SOUTHERN PORTION OF THE CWA
WEDNESDAY NIGHT DUE TO THE POTENTIAL SOUTHERN TRAJECTORY. DUE TO
THE INCREASED CLOUD COVER ON WEDNESDAY...TEMPS SHOULD COOL
SLIGHTLY...BUT OVERALL HEIGHT/THICKNESS VALUES CHANGE LITTLE AS
TROUGH IS STILL OFF THE COAST.
.LONG TERM...STILL SOME DIFFERENCES IN THE MODELS WITH REGARDS TO
THURSDAYS SHORTWAVE. GFS HAS BEEN THE MOST CONSISTENT MODEL IN
BRINGING AN UPPER LOW INTO SOUTHERN CALIFORNIA WHILE THE ECMWF WAS
KEEPING THIS FEATURE WELL TO THE SOUTH. NEWEST RUN SHOWS LITTLE
CHANGE IN THE GFS SOLUTION WHILE THE ECMWF NOW SHOWS THE UPPER LOW
MUCH FARTHER NORTH. HOWEVER...BOTH MODELS ARE SHOWING A BETTER
MOISTURE TAP AND HAVE INCREASED QPF VALUES OF THE CWA. EVEN THE NAM
HAS GOTTEN INTO THE PICTURE AND SHOWING DECENT MOISTURE OVER THE
AREA THURSDAY NIGHT. ALTHOUGH ITS LOOKING BETTER FOR THE AREA TO SEE
PRECIPITATION...AMOUNTS ARE EXPECTED TO REMAIN FAIRLY LIGHT. AFTER
FRIDAY...THE MODELS SHOW SIGNIFICANT DIFFERENCES WITH THE GFS
SHOWING A STRONG COLD SYSTEM DIVING SOUTH ALONG THE WEST COAST WHILE
THE ECMWF KEEPS THE AREA UNDER A NORTHWEST FLOW. THERE ARE SEVERAL
ENSEMBLE MEMBERS THAT DO SUPPORT THE OPERATIONAL GFS SOLUTION...SO
NEXT WEEKEND COULD BE QUITE INTERESTING WITH REGARDS TO ADDITIONAL
PRECIPITATION AND MUCH COOLER TEMPERATURES. FOR NOW...INCREASED POPS
ON THURSDAY NIGHT AND MADE LITTLE CHANGES TO THE WEEKEND FORECAST.
&&
.AVIATION...FOR MCCARRAN...ONCE AGAIN GENERALLY LIGHT WINDS THROUGH
TODAY. THE REGION WILL SEE AN INCREASE IN CIRRUS CLOUDS WHICH WILL
REMAIN AOA 20K. A STORM IS EXPECTED TO BRING IMPACTS TO THE AIRPORT
AS EARLY AS WEDNESDAY.
FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...WINDS WILL BE LIGHT AND VARIABLE EXCEPT ALONG THE
COLORADO RIVER VALLEY AND IN SOME NORTH/SOUTH CHANNELS OVER THE
EASTERN CWA WHERE NORTH TO NORTHEAST WINDS OF 10-15KTS ARE EXPECTED
TO CONTINUE ONCE AGAIN. SOUTHERN AREAS OF THE CWA WILL SEE A BR
&&
.VEF WATCHES/WARNINGS/ADVISORIES...
NV...NONE
AZ...NONE
CA...NONE
&&
$$
JENSEN/GORELOW
HTTP://WEATHER.GOV/LASVEGAS
000
FXUS65 KVEF 190437
AFDVEF
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
837 PM PST SUN JAN 18 2009
.SYNOPSIS...A RIDGE OF HIGH PRESSURE WILL REMAIN OVER THE
INTERMOUNTAIN WEST THROUGH TUESDAY BRINGING DRY CONDITIONS WITH
ABOVE NORMAL TEMPERATURES TO THE AREA. A PACIFIC STORM WILL BRING
INCREASING CLOUDS AND A CHANCE OF SHOWERS TO THE REGION LATE
WEDNESDAY THROUGH THURSDAY.
&&
.UPDATE...CIRRUS OVER THE SOUTHERN PORTION OF THE CWFA IS THICKER
AND MORE PERSISTENT THAN EXPECTED. UPDATED SKY GRIDS FOR TONIGHT AND
SENT UPDATED PRODUCTS. NO CHANGES BEYOND THE FIRST PERIOD.
&&
.PREV DISCUSSION...
305 PM PST SUN JAN 18 2009
.SHORT TERM...THE UPPER RIDGE OF HIGH PRESSURE WHICH HAS BROUGHT THE
AREA DRY AND WARM WEATHER WILL SHIFT SLIGHTLY TO THE
EAST...REMAINING OVER THE INTERMOUNTAIN REGION THROUGH TUESDAY. THIS
WILL ALLOW SOME HIGH CLOUDS TO MOVE IN FROM THE SOUTH OVER THE NEXT
COUPLE OF DAYS BUT THE DRY AND WARM WEATHER WILL CONTINUE. 12Z
MODELS ARE NOW IN FAIR AGREEMENT WITH THE INCOMING UPPER TROUGH
TOWARD THE END OF THE SHORT TERM PERIOD. THE TROUGH WILL APPROACH
THE SOUTHERN CALIFORNIA COAST ON WEDNESDAY SPREADING A SLIGHT CHANCE
OF SHOWERS INTO THE WESTERN PORTION OF THE FORECAST AREA. KEPT
SLIGHT CHANCE TO CHANCE POPS OVER THE ENTIRE FORECAST AREA FOR
WEDNESDAY NIGHT AS THE TROUGH AXIS REACHES THE COAST AND APPEARS TO
BE TAPPING INTO SOME HIGHER PRECIPITABLE WATER VALUES AS IT DOES SO.
ALTHOUGH THE TROUGH AXIS WILL STILL BE TO OUR WEST ON
WEDNESDAY...TEMPERATURES SHOULD COOL A LITTLE DUE TO CLOUD COVER.
.LONG TERM...NEW MODEL DATA FROM THE ECMWF IS NOW FORECASTING THE
DEVELOPMENT OF A TROPICAL MOISTURE TAP INTO THE SYSTEM PASSING
THROUGH THE AREA ON THURSDAY. A SPECIAL DISCUSSION FROM NESDIS TODAY
NOTED DEEP MOISTURE AND HIGH PWATS CURRENTLY HOLDING TOGETHER JUST
AHEAD OF THE TROUGH AS IT MOVES ACROSS THE EASTERN PACIFIC AND YET
ANOTHER DEEP POOL OF MOISTURE RESIDING SOUTH OF THE AREA AND MOVING
NORTH. THE LATEST SSM/I SATELLITE IMAGERY SHOWS DEEP MOISTURE IN
BOTH OF THESE AREAS WITH GREATER THAN 1.5 INCH PWATS. IN ADDITION...
THE LATEST 18Z GFS ALSO SHOWS THE TROPICAL TAP BUT BRINGS IT IN
FASTER. IF THE ABOVE SCENARIO WERE TO PLAY OUT...IT COULD GREATLY
ENHANCE QPF OVER THE FORECAST AREA THURSDAY. IN RESPONSE...INCREASED
POPS IN THE GRIDS ESPECIALLY ACROSS THE SOUTH BUT ADJUSTMENTS TO
TIMING WILL BE NECESSARY AS THE STORM APPROACHES. BOTH MODELS ARE
SUPPORTED BY THE MAJORITY OF GEFS MEMBERS WITH SHORTWAVE RIDGING AND
DRYING CONDITIONS OVER THE AREA FRIDAY FOLLOWED BY ANOTHER POTENTIAL
STORM SOMETIME OVER THE WEEKEND. ALTHOUGH THE INITIAL SYSTEM IS
RELATIVELY WARM AND TEMPERATURES ARE FORECAST TO REMAIN ABOVE NORMAL
THROUGH SATURDAY... THIS WILL BE DETERMINED BY THE EXTENT OF CLOUD
COVER AND SHOWER ACTIVITY.
.AVIATION...FOR MCCARRAN...NO SIGNIFICANT WEATHER EXPECTED THROUGH
TUESDAY. HIGH CLOUDS WILL MOVE IN FROM THE SOUTH OVERNIGHT AND
THICKEN INTO MONDAY BUT REMAIN AOA 20KFT. WINDS WILL GENERALLY BE
LIGHT AND VARIABLE THROUGH TUESDAY. A STORM IS EXPECTED TO BRING
IMPACTS TO THE AIRPORT AS EARLY AS WEDNESDAY.
FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...A GENERAL INCREASE IN HIGH CLOUDINESS OVERNIGHT AND
MONDAY AS MOISTURE MOVES INTO THE REGION FROM THE SOUTH BUT NO
SIGNIFICANT WEATHER EXPECTED THROUGH TUESDAY. IN GENERAL...WINDS
WILL BE LIGHT AND VARIABLE EXCEPT ALONG THE COLORADO RIVER VALLEY
AND IN SOME NORTH/SOUTH CHANNELS OVER THE EASTERN CWA WHERE NORTH TO
NORTHEAST WINDS OF 10-15KTS ARE EXPECTED TO CONTINUE.
&&
.VEF WATCHES/WARNINGS/ADVISORIES...
NV...NONE
AZ...NONE
CA...NONE
&&
$$
MORGAN/HARRISON/SALMEN
HTTP://WEATHER.GOV/LASVEGAS
000
FXUS65 KVEF 182305
AFDVEF
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
305 PM PST SUN JAN 18 2009
.SYNOPSIS...A RIDGE OF HIGH PRESSURE WILL REMAIN OVER THE
INTERMOUNTAIN WEST THROUGH TUESDAY BRINGING DRY CONDITIONS WITH
ABOVE NORMAL TEMPERATURES TO THE AREA. A PACIFIC STORM WILL BRING
INCREASING CLOUDS AND A CHANCE OF SHOWERS TO THE REGION LATE
WEDNESDAY THROUGH THURSDAY.
&&
.SHORT TERM...THE UPPER RIDGE OF HIGH PRESSURE WHICH HAS BROUGHT THE
AREA DRY AND WARM WEATHER WILL SHIFT SLIGHTLY TO THE
EAST...REMAINING OVER THE INTERMOUNTAIN REGION THROUGH TUESDAY. THIS
WILL ALLOW SOME HIGH CLOUDS TO MOVE IN FROM THE SOUTH OVER THE NEXT
COUPLE OF DAYS BUT THE DRY AND WARM WEATHER WILL CONTINUE. 12Z
MODELS ARE NOW IN FAIR AGREEMENT WITH THE INCOMING UPPER TROUGH
TOWARD THE END OF THE SHORT TERM PERIOD. THE TROUGH WILL APPROACH
THE SOUTHERN CALIFORNIA COAST ON WEDNESDAY SPREADING A SLIGHT CHANCE
OF SHOWERS INTO THE WESTERN PORTION OF THE FORECAST AREA. KEPT
SLIGHT CHANCE TO CHANCE POPS OVER THE ENTIRE FORECAST AREA FOR
WEDNESDAY NIGHT AS THE TROUGH AXIS REACHES THE COAST AND APPEARS TO
BE TAPPING INTO SOME HIGHER PRECIPITABLE WATER VALUES AS IT DOES SO.
ALTHOUGH THE TROUGH AXIS WILL STILL BE TO OUR WEST ON
WEDNESDAY...TEMPERATURES SHOULD COOL A LITTLE DUE TO CLOUD COVER.
.LONG TERM...NEW MODEL DATA FROM THE ECMWF IS NOW FORECASTING THE
DEVELOPMENT OF A TROPICAL MOISTURE TAP INTO THE SYSTEM PASSING
THROUGH THE AREA ON THURSDAY. A SPECIAL DISCUSSION FROM NESDIS TODAY
NOTED DEEP MOISTURE AND HIGH PWATS CURRENTLY HOLDING TOGETHER JUST
AHEAD OF THE TROUGH AS IT MOVES ACROSS THE EASTERN PACIFIC AND YET
ANOTHER DEEP POOL OF MOISTURE RESIDING SOUTH OF THE AREA AND MOVING
NORTH. THE LATEST SSM/I SATELLITE IMAGERY SHOWS DEEP MOISTURE IN
BOTH OF THESE AREAS WITH GREATER THAN 1.5 INCH PWATS. IN ADDITION...
THE LATEST 18Z GFS ALSO SHOWS THE TROPICAL TAP BUT BRINGS IT IN
FASTER. IF THE ABOVE SCENARIO WERE TO PLAY OUT...IT COULD GREATLY
ENHANCE QPF OVER THE FORECAST AREA THURSDAY. IN RESPONSE...INCREASED
POPS IN THE GRIDS ESPECIALLY ACROSS THE SOUTH BUT ADJUSTMENTS TO
TIMING WILL BE NECESSARY AS THE STORM APPROACHES. BOTH MODELS ARE
SUPPORTED BY THE MAJORITY OF GEFS MEMBERS WITH SHORTWAVE RIDGING AND
DRYING CONDITIONS OVER THE AREA FRIDAY FOLLOWED BY ANOTHER POTENTIAL
STORM SOMETIME OVER THE WEEKEND. ALTHOUGH THE INITIAL SYSTEM IS
RELATIVELY WARM AND TEMPERATURES ARE FORECAST TO REMAIN ABOVE NORMAL
THROUGH SATURDAY... THIS WILL BE DETERMINED BY THE EXTENT OF CLOUD
COVER AND SHOWER ACTIVITY.
&&
.AVIATION...FOR MCCARRAN...NO SIGNIFICANT WEATHER EXPECTED THROUGH
TUESDAY. HIGH CLOUDS WILL MOVE IN FROM THE SOUTH OVERNIGHT AND
THICKEN INTO MONDAY BUT REMAIN AOA 20KFT. WINDS WILL GENERALLY BE
LIGHT AND VARIABLE THROUGH TUESDAY. A STORM IS EXPECTED TO BRING
IMPACTS TO THE AIRPORT AS EARLY AS WEDNESDAY.
FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...A GENERAL INCREASE IN HIGH CLOUDINESS OVERNIGHT AND
MONDAY AS MOISTURE MOVES INTO THE REGION FROM THE SOUTH BUT NO
SIGNIFICANT WEATHER EXPECTED THROUGH TUESDAY. IN GENERAL...WINDS
WILL BE LIGHT AND VARIABLE EXCEPT ALONG THE COLORADO RIVER VALLEY
AND IN SOME NORTH/SOUTH CHANNELS OVER THE EASTERN CWA WHERE NORTH TO
NORTHEAST WINDS OF 10-15KTS ARE EXPECTED TO CONTINUE.
&&
.VEF WATCHES/WARNINGS/ADVISORIES...
NV...NONE
AZ...NONE
CA...NONE
&&
$$
HARRISON/SALMEN
HTTP://WEATHER.GOV/LASVEGAS
000
FXUS65 KVEF 181730
AFDVEF
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
930 AM PST SUN JAN 17 2009
.SYNOPSIS...HIGH PRESSURE WILL CONTINUE TO BRING DRY CONDITIONS WITH
ABOVE NORMAL TEMPERATURES TO THE AREA THROUGH THE FIRST OF THE WEEK.
HOWEVER A PACIFIC STORM WILL BRING INCREASING CLOUDS AND A SLIGHT
CHANCE OF SHOWERS TO THE REGION WEDNESDAY AND THURSDAY.
&&
.UPDATE...ANOTHER SUNNY AND WARM DAY WITH JUST SOME LOCALIZED
NORTHERLY WINDS...MAINLY DOWN THE COLORADO RIVER. FORECAST IN GOOD
SHAPE AND NO UPDATES ANTICIPATED THIS MORNING.
&&
.PREV DISCUSSION...308 AM PST SUN JAN 17...SHORT TERM...THE STRONG
RIDGE WHICH HAD BEEN OFF THE WEST COAST FOR THE PAST WEEK HAS
SHIFTED EAST WITH THE AXIS GENERALLY BEING OVER THE ROCKIES TODAY
THROUGH 12Z TUESDAY. THIS WILL CONTINUE TO BRING MOSTLY CLEAR SKIES
WITH ABOVE NORMAL TEMPERATURES TO THE AREA THROUGH MONDAY. BY
TUESDAY HOWEVER THE RIDGE BEGINS TO WEAKEN AS MODELS DEVELOP A
TROUGH OFF THE WEST COAST BY 00Z WED AND THEN SLOWLY SHIFT IT ONTO
THE CALIFORNIA COAST BY 12Z WEDNESDAY. DIFFERENCES BETWEEN THE
ECMWF/NAM/GFS WITH TREATMENT OF THIS SYSTEM...BUT MAIN IMPACTS WILL
BE DURING THE LONG TERM. THUS FOR TUESDAY AND TUESDAY NIGHT WILL
SHOW AN INCREASING TREND FOR CLOUDS...BUT KEEP DRY CONDITIONS OVER
THE AREA WITH TUESDAY TEMPERATURES REMAINING ABOVE NORMAL. WINDS TO
CONTINUE TO BE LIGHT AND VARIABLE WITH THE EXCEPTION OF LOCALLY
GUSTY AFTERNOON WINDS REMAINING ALONG THE COLORADO RIVER VALLEY.
.LONG TERM...STILL SOME INCONSISTENCIES IN THE MODELS BEGINNING WITH
THE INITIAL SHORTWAVE EXPECTED ON WEDNESDAY. THE GFS HAS REMAINED
THE STRONGEST AND FASTEST AS IT BRINGS A WEAK CLOSED LOW ACROSS FAR
SOUTHERN CALIFORNIA AND SPREADS PRECIPITATION OVER MUCH OF THE CWA
DURING THE DAY WEDNESDAY AND EXITS TO THE EAST THURSDAY MORNING. THE
ECMWF IS ALSO SHOWING THE SAME CLOSED LOW...BUT BRINGS IT ONSHORE
ABOUT 300 MILES FURTHER SOUTH AND ABOUT 12 HOURS SLOWER. EITHER
SOLUTION WOULD HAVE BIG IMPACTS ON POPS ACROSS THE AREA AND STILL
FEEL THAT THE BEST WAY TO HANDLE IT WOULD BE TO KEEP THE CURRENT
SLIGHT CHANCE TO CHANCE POPS OVER THE AREA AND CONTINUE TO WAIT FOR
BETTER CONSISTENCY. THINGS GET REALLY TRICKY FOR THE WEEKEND AS THE
MODELS SHOW RATHER BIG DISCREPANCIES. THE GFS DROPS A COLD TROUGH
INTO THE WEST COAST AND SPREADS QPF OVER MUCH OF THE AREA FRIDAY
NIGHT AND SATURDAY. THE ECMWF KEEPS A RELATIVELY DRY NORTHWEST FLOW
OVER THE AREA WITH A CUTOFF LOW WELL OFF SHORE. THE MOST CONSISTENT
MODEL HAS BEEN THE ECMWF...BUT WITH LARGE DIFFERENCES BETWEEN THE
MODELS WILL CONTINUE TO GO WITH A CAUTIOUS APPROACH AND KEEP SLIGHT
CHANCE POPS OVER THE AREA THROUGH THE WEEKEND.
&&
.AVIATION...FOR MCCARRAN...NO SIGNIFICANT WEATHER EXPECTED THROUGH
MONDAY WITH CLEAR SKIES AND WINDS THAT ARE GENERALLY LIGHT AND
VARIABLE.
FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...NO SIGNIFICANT WEATHER IS EXPECTED THROUGH MONDAY. SOME
HIGH CLOUDINESS TO CONTINUE OVER PORTIONS OF THE AREA BUT OTHERWISE
SKIES REMAIN CLEAR. IN GENERAL...WINDS WILL BE LIGHT AND VARIABLE
EXCEPT ALONG THE COLORADO RIVER VALLEY WHERE NORTH WINDS OF 10-20KTS
ARE EXPECTED TO CONTINUE.
&&
.VEF WATCHES/WARNINGS/ADVISORIES...
NV...NONE
AZ...NONE
CA...NONE
&&
$$
HARRISON/JENSEN/GORELOW
HTTP://WEATHER.GOV/LASVEGAS
000
FXUS65 KVEF 181108
AFDVEF
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
308 AM PST SUN JAN 17 2009
.SYNOPSIS...HIGH PRESSURE WILL CONTINUE TO BRING DRY CONDITIONS WITH
ABOVE NORMAL TEMPERATURES TO THE AREA THROUGH THE FIRST OF THE WEEK.
HOWEVER A PACIFIC STORM WILL BRING INCREASING CLOUDS AND A SLIGHT
CHANCE OF SHOWERS TO THE REGION WEDNESDAY AND THURSDAY.
&&
.SHORT TERM...THE STRONG RIDGE WHICH HAD BEEN OFF THE WEST COAST FOR
THE PAST WEEK HAS SHIFTED EAST WITH THE AXIS GENERALLY BEING OVER
THE ROCKIES TODAY THROUGH 12Z TUESDAY. THIS WILL CONTINUE TO BRING
MOSTLY CLEAR SKIES WITH ABOVE NORMAL TEMPERATURES TO THE AREA
THROUGH MONDAY. BY TUESDAY HOWEVER THE RIDGE BEGINS TO WEAKEN AS
MODELS DEVELOP A TROUGH OFF THE WEST COAST BY 00Z WED AND THEN
SLOWLY SHIFT IT ONTO THE CALIFORNIA COAST BY 12Z WEDNESDAY.
DIFFERENCES BETWEEN THE ECMWF/NAM/GFS WITH TREATMENT OF THIS
SYSTEM...BUT MAIN IMPACTS WILL BE DURING THE LONG TERM. THUS FOR
TUESDAY AND TUESDAY NIGHT WILL SHOW AN INCREASING TREND FOR
CLOUDS...BUT KEEP DRY CONDITIONS OVER THE AREA WITH TUESDAY
TEMPERATURES REMAINING ABOVE NORMAL. WINDS TO CONTINUE TO BE LIGHT
AND VARIABLE WITH THE EXCEPTION OF LOCALLY GUSTY AFTERNOON WINDS
REMAINING ALONG THE COLORADO RIVER VALLEY.
.LONG TERM...STILL SOME INCONSISTENCIES IN THE MODELS BEGINNING WITH
THE INITIAL SHORTWAVE EXPECTED ON WEDNESDAY. THE GFS HAS REMAINED
THE STRONGEST AND FASTEST AS IT BRINGS A WEAK CLOSED LOW ACROSS FAR
SOUTHERN CALIFORNIA AND SPREADS PRECIPITATION OVER MUCH OF THE CWA
DURING THE DAY WEDNESDAY AND EXITS TO THE EAST THURSDAY MORNING. THE
ECMWF IS ALSO SHOWING THE SAME CLOSED LOW...BUT BRINGS IT ONSHORE
ABOUT 300 MILES FURTHER SOUTH AND ABOUT 12 HOURS SLOWER. EITHER
SOLUTION WOULD HAVE BIG IMPACTS ON POPS ACROSS THE AREA AND STILL
FEEL THAT THE BEST WAY TO HANDLE IT WOULD BE TO KEEP THE CURRENT
SLIGHT CHANCE TO CHANCE POPS OVER THE AREA AND CONTINUE TO WAIT FOR
BETTER CONSISTENCY. THINGS GET REALLY TRICKY FOR THE WEEKEND AS THE
MODELS SHOW RATHER BIG DISCREPANCIES. THE GFS DROPS A COLD TROUGH
INTO THE WEST COAST AND SPREADS QPF OVER MUCH OF THE AREA FRIDAY
NIGHT AND SATURDAY. THE ECMWF KEEPS A RELATIVELY DRY NORTHWEST FLOW
OVER THE AREA WITH A CUTOFF LOW WELL OFF SHORE. THE MOST CONSISTENT
MODEL HAS BEEN THE ECMWF...BUT WITH LARGE DIFFERENCES BETWEEN THE
MODELS WILL CONTINUE TO GO WITH A CAUTIOUS APPROACH AND KEEP SLIGHT
CHANCE POPS OVER THE AREA THROUGH THE WEEKEND.
&&
.AVIATION...FOR MCCARRAN...NO SIGNIFICANT WEATHER EXPECTED THROUGH
MONDAY WITH CLEAR SKIES AND WINDS THAT ARE GENERALLY LIGHT AND
VARIABLE.
FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...NO SIGNIFICANT WEATHER IS EXPECTED THROUGH MONDAY. SOME
HIGH CLOUDINESS TO CONTINUE OVER PORTIONS OF THE AREA BUT OTHERWISE
SKIES REMAIN CLEAR. IN GENERAL...WINDS WILL BE LIGHT AND VARIABLE
EXCEPT ALONG THE COLORADO RIVER VALLEY WHERE NORTH WINDS OF 10-20KTS
ARE EXPECTED TO CONTINUE.
&&
&&
.VEF WATCHES/WARNINGS/ADVISORIES...
NV...NONE
AZ...NONE
CA...NONE
&&
$$
JENSEN/GORELOW
HTTP://WEATHER.GOV/LASVEGAS
000
FXUS65 KVEF 172306
AFDVEF
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LAS VEGAS NV
306 PM PST SAT JAN 17 2009
.SYNOPSIS...THE PERSISTENT HIGH PRESSURE OVER THE AREA WILL CONTINUE
A FEW MORE DAYS BRINGING SUNNY SKIES AND ABOVE NORMAL TEMPERATURES.
CHANGE IS COMING THAT WILL START TO SHOW UP LATE TUESDAY WITH
INCREASING CLOUDS AND A SLIGHT CHANCE WEDNESDAY OF PRECIPITATION IN
ADVANCE OF A PACIFIC STORM SYSTEM.
&&
.SHORT TERM...THE LONG PERSISTENT RIDGE HAS BEEN MOVING INLAND PER
MODEL GUIDANCE AND WILL SET UP BRIEFLY OVER THE NORTHERN STATES AND
SOUTHERN CANADA. NO SIGNIFICANT CHANGE THROUGH TUESDAY EXPECTED.
ONLY TWEAKED FORECAST A LITTLE DURING THAT TIME. CHANGE DOES BEGIN
TO SHOW AS MODELS HAVE THE NEXT PACIFIC SYSTEM APPROACHING THE CWA.
DIFFERENCES IN DEPTH AND TIMING BETWEEN MODELS ARE PRESENT AND WENT
WITH THE MORE CONSISTENT ECMWF. INCREASED CLOUD COVER BEGINNING ON
TUESDAY AS APPROACH TROUGH PUSHES RIDGE EAST AND TAPS SOME MOISTURE
IN THE SOUTHWEST FLOW OVER THE AREA. BELIEVE ONSET OF ANY
PRECIPITATION WILL BE AFTER THE SHORT TERM FORECAST WHICH ENDS
WEDNESDAY MORNING.
.LONG TERM...MODELS CONTINUE TO FORECAST AN ACTIVE WEATHER PATTERN
IN THE EXTENDED PERIOD. THIS WILL ALLOW FOR VARIABLE AMOUNTS OF
CLOUD COVER...COOLER TEMPERATURES AND A CHANCE OF SHOWERS. THE 12Z
ECMWF WAS BLENDED INTO THE INHERITED FORECASTED BASED ON GOOD
OVERALL RUN TO RUN CONSISTENCY. THE 12Z GFS/GEM WERE DISREGARDED
WITH THEIR EVER CHANGING SOLUTIONS. THE NEW 18Z GFS LOOKS FAIRLY
SIMILAR TO THE 12Z ECMWF IN TRACK BUT ABOUT 6-12 FASTER ON TIMING.
IT IS ALSO SOMEWHAT WETTER THAN THE EC...SO A SLIGHT CHANCE TO A
CHANCE OF SHOWERS LOOKS REASONABLE FOR MUCH OF THE AREA WEDNESDAY
AND WEDNESDAY NIGHT. THE WEATHER DURING THE THURSDAY TO SATURDAY
TIME FRAME REMAINS UNCERTAIN BUT BASED ON THE LATEST DATA...THERE
COULD BE A BREAK BETWEEN SYSTEMS BEGINNING LATER THURSDAY AND
CONTINUING THROUGH SATURDAY. PRESSURE GRADIENTS REMAIN WEAK AND
WINDS ARE NOT A CONCERN AT THIS TIME. TEMPERATURES ARE LIKELY TO
EXPERIENCE A DOWNWARD TREND DUE TO THE GENERAL TROUGH PATTERN WHICH
SHOULD MAINTAIN SOME CLOUD COVER OVER THE AREA FOR MUCH OF THE TIME.
&&
.AVIATION...FOR MCCARRAN...NO SIGNIFICANT WEATHER EXPECTED THROUGH
MONDAY WITH CLEAR SKIES AND WINDS THAT ARE GENERALLY LIGHT AND
VARIABLE.
FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST
CALIFORNIA...NO SIGNIFICANT WEATHER IS EXPECTED THROUGH MONDAY. SOME
HIGH CLOUDINESS TO CONTINUE OVER THE FAR NORTHERN CWA THROUGH THE
REST OF THE AFTERNOON AND OVERNIGHT BUT OTHERWISE SKIES REMAIN
CLEAR. IN GENERAL...WINDS WILL BE LIGHT AND VARIABLE EXCEPT ALONG
THE COLORADO RIVER VALLEY WHERE NORTH WINDS OF 10-20KTS ARE EXPECTED
TO CONTINUE.
&&
.VEF WATCHES/WARNINGS/ADVISORIES...
NV...NONE
AZ...NONE
CA...NONE
&&
$$
JACQUES/SALMEN
HTTP://WEATHER.GOV/LASVEGAS
| 
