496 FXUS65 KPSR 221156 AFDPSR AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PHOENIX AZ 455 AM MST TUE APR 22 2014 ...UPDATED AVIATION AND FIRE WEATHER... .SYNOPSIS... BREEZY TO WINDY CONDITIONS WILL DEVELOP OVER MUCH OF THE AREA THIS AFTERNOON INTO WEDNESDAY AS A DRY WEATHER SYSTEM PASSES TO THE NORTH. TEMPERATURES WILL FALL IN RESPONSE TO THIS WEATHER SYSTEM... AND LOWER TO AROUND SEASONAL NORMALS BY WEDNESDAY. A SLIGHT WARMING TREND WILL OCCUR THURSDAY INTO FRIDAY AS HIGHER PRESSURE ALOFT RETURNS TO THE AREA...BEFORE ANOTHER VIGOROUS PACIFIC UPPER LEVEL LOW PRESSURE SYSTEM BRINGS SIGNIFICANT WIND AND COOLING TO THE AREA OVER THE WEEKEND. && .DISCUSSION... WATER VAPOR IMAGERY REVEALS OUR NEXT WEATHER SYSTEM CURRENTLY MOVING INLAND ALONG THE WEST COAST...THE CENTER OF THE 533DM LOW SPINNING IN THE PACIFIC WEST OF BRITISH COLUMBIA...THE SOUTHERN EXTENT OF THE TROUGH IMPACTING CENTRAL AND NORTHERN CALIFORNIA. FURTHER SOUTH AND AHEAD OF THE TROUGH...BANDS OF HIGH CLOUDS ARE STREAMING ACROSS SOUTHEAST CALIFORNIA INTO NEVADA AND WESTERN ARIZONA THIS MORNING. MID AND LOWER LEVEL PRESSURE GRADIENTS CONTINUE TO TIGHTEN...AND THE LOW LEVEL WIND FIELDS ARE BEGINNING TO RESPOND THROUGH PORTIONS OF THE SIERRA NEVADA IN CALIFORNIA WITH SOME GUSTS UP TO 30 MPH NOTED IN SURFACE OBSERVATIONS. THE INFLUENCE OF THE TROUGH WILL BE FELT ACROSS OUR CWA LATER THIS AFTERNOON AND EVENING...WITH STRONG GUSTY WINDS OF 20-25 MPH AND LOCAL GUSTS TO 35 MPH COMMON ACROSS SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA. SOME LOCATIONS IN AND AROUND THE IMPERIAL VALLEY/EL CENTRO CA...JOSHUA TREE NATIONAL PARK...AND OTHER HIGHER TERRAIN AREAS IN LA PAZ COUNTY AZ MAY EXPERIENCE STRONGER WIND GUSTS ALONG WITH AREAS OF BLOWING DUST/SAND. RIGHT NOW...FORECAST WIND SPEEDS ARE NOT MEETING WIND ADVISORY CRITERIA...BUT IT WILL BE SOMETHING TO MONITOR. GIVEN THE DRY NATURE OF THE TROUGH AND FRONTAL PASSAGE...THE WINDS WILL ONLY CONTRIBUTE TO DANGEROUS FIRE WEATHER CONDITIONS. AS SUCH...A RED FLAG WARNING IS IN EFFECT FROM 2 TO 8 PM TODAY FOR SOUTHWEST ARIZONA INCLUDING THE LOWER COLORADO RIVER VALLEY. THE SYSTEM WILL ALSO BRING 8-10 DEGREES OF COOLING...LOWERING DAYTIME TEMPERATURES BACK INTO THE MID TO UPPER 80S OVER THE LOWER DESERTS. SHORTWAVE RIDGING COMMENCES THURSDAY...WITH 500MB HEIGHTS REBOUNDING TO NEAR 576DM OVER SOUTHERN CALIFORNIA AND SOUTH-CENTRAL ARIZONA BY FRIDAY. HOWEVER...ANOTHER POTENT UPPER LEVEL TROUGH WILL MOVE INTO THE REGION LATE FRIDAY AND ONCE AGAIN BRING ANOTHER ROUND OF COOLER TEMPERATURES AND INCREASED WINDS THIS WEEKEND. THE GFS/ECMWF ARE NOW IN MUCH BETTER AGREEMENT WITH THIS NEXT SYSTEM...EVEN THOUGH THERE ARE STILL SOME TIMING DIFFERENCES. BOTH PLACE A 542-556DM UPPER LEVEL LOW/OPEN WAVE OVER NEVADA BY SATURDAY MORNING. THE OPERATIONAL GEM MORE ALIGNED WITH THE GFS AND ECMWF... BUT MAINTAINING A CLOSED LOW SOLUTION. AT THIS TIME...UNLESS THE SYSTEM DIGS EVEN DEEPER WEST OF CALIFORNIA...ANY SOLUTION WILL REMAIN CONSIDERABLY DRY WITH PRECIPITATION CHANCES SLIGHT/SLIM FOR OUR FORECAST AREA. WITH LOWER HEIGHTS AND A TIGHTENED GRADIENT OF 555-564DM SPLAYED ACROSS SOUTHEAST CALIFORNIA AND SOUTH-CENTRAL ARIZONA...THE FORECAST WILL CONTINUE TO DROP DAYTIME TEMPERATURES BACK INTO THE LOW 80S...ALONG WITH BREEZY TO WINDY CONDITIONS AGAIN SATURDAY AND SUNDAY. && .AVIATION... SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL... WINDS WILL BE THE MAIN AVIATION CONCERN THROUGH WEDNESDAY MORNING...WITH INCREASING SPEEDS AND FREQUENT GUSTS DEVELOPING THIS AFTERNOON THROUGH EARLY EVENING. THE LARGEST PROBLEM MAY BE A PROLONGED SEVERAL HOUR PERIOD OF A SOUTHERLY CROSS COMPONENT LATE MORNING/EARLY AFTERNOON. ANY GUSTS ASSOCIATED WITH A DUE SOUTH WIND SHOULD REMAIN AOB 20KT...BEFORE THE DIRECTION VEERS TOWARDS A MORE SWLY/WLY DIRECTION LATER IN THE AFTERNOON. GUSTS SHOULD SUBSIDE LATER THIS EVENING...HOWEVER FORECAST CONFIDENCE IN TIMING THE LOSS OF GUSTINESS IS LOW. SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH... STRONG SFC WINDS WILL BE THE LARGEST AVIATION CONCERN ACROSS SE CALIFORNIA THIS AFTERNOON AND EVENING. A WLY COMPONENT AT KIPL AND SLY WIND AT KBLH WILL BOTH BEGIN GUSTING ABOVE 20KT BY LATE MORNING. EVENTUALLY WINDS AT BOTH AIRFIELDS WILL BECOMING SWLY BY LATE AFTERNOON WITH FREQUENT GUSTS TO AROUND 30KT DEVELOPING. NOCTURNAL DECOUPLING SHOULD ALLOW GUSTS TO SUBSIDE LATER THIS EVENING...HOWEVER THE FORECAST CONFIDENCE IN TIMING WHEN WIND SPEEDS BEGIN TO DECREASE IS LOW. AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS. && .FIRE WEATHER... THURSDAY THROUGH MONDAY... WEAK HIGH PRESSURE AND RELATIVELY LIGHT WINDS THURSDAY WILL BE REPLACED BY A STRONG PACIFIC WEATHER SYSTEM MOVING NORTH OF THE DISTRICT FRIDAY AND SATURDAY. THIS SYSTEM WILL ALLOW WINDS TO INCREASE IN A SIMILAR FASHION TO TODAY...YIELDING AN ELEVATED FIRE DANGER WITH HUMIDITY LEVELS FALLING INTO THE LOWER TEENS AND WIND GUSTS APPROACHING 30 MPH. MORE TRANQUIL WEATHER CONDITIONS ARE LIKELY NEXT WEEK WITH A WARMING TREND...ALBEIT WITH MINIMUM HUMIDITY LEVELS FALLING BACK INTO THE SINGLE DIGITS AND ONLY FAIR OVERNIGHT RECOVERY. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...RED FLAG WARNING TUESDAY AFTERNOON AND EVENING FOR FIRE ZONES AZZ131 AND AZZ132...2 PM UNTIL 8 PM. CA...RED FLAG WARNING TUESDAY AFTERNOON AND EVENING FOR FIRE ZONE CAZ231...2 PM UNTIL 8 PM. && $$ VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX DISCUSSION...MEYERS AVIATION...MO FIRE WEATHER...MO