AREA FORECAST DISCUSSION

 
 FXUS65 KPSR 050456
 AFDPSR
 
 AREA FORECAST DISCUSSION
 NATIONAL WEATHER SERVICE PHOENIX AZ
 955 PM MST WED MAR 4 2009
 
 .SYNOPSIS...
 HIGH CLOUDS WILL CONTINUE TO STREAM OVER THE AREA THROUGH FRIDAY... 
 AHEAD OF A LARGE PACIFIC LOW PRESSURE SYSTEM EXPECTED TO MOVE INTO 
 THE WESTERN STATES. WINDS WILL INCREASE ON FRIDAY...PARTICULARLY IN 
 SOUTHEAST CALIFORNIA AHEAD OF A DRY COLD FRONT. PARTIAL CLEARING 
 ALONG WITH LOWER TEMPERATURES ARE EXPECTED FOR THE WEEKEND...WITH
 LITTLE CHANGE IN TEMPERATURES INTO EARLY NEXT WEEK.
 
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 .DISCUSSION...
 ASIDE FROM SOME GUSTY WEST WINDS OUT IN CA PORTION OF CWA...WX CONDS 
 HAVE BEEN RATHER QUIET AROUND THE DESERT SW THIS EVENING. BAND OF 
 HIGH CLOUDS STILL NOTED ON IR SATELLITE LOOPS THIS EVENING HAS 
 THINNED SOME PAST FEW HRS...BUT MODEL RH PROGS INSIST THIS BAND WILL 
 REMAIN DRAPED ACROSS ERN CWA THRU TOMORROW. MEANWHILE...PAC NW 
 TROUGH WILL DROP SWD ALONG THE CA COAST BEFORE SWINGING INLAND TO 
 OUR N ON FRIDAY. THIS WILL BE A RATHER INNOCUOUS SYSTEM FOR US...
 WITH DEEP MOISTURE AND MOST FAVORABLE DYNAMICS EXPECTED TO REMAIN 
 WELL TO OUR N. WINDS WILL INCREASE ONCE AGAIN BY FRIDAY...MAINLY OUT 
 IN WRN CWA...LESS WIND TOMORROW. ALL IN ALL...CURRENT FORECAST GRIDS 
 HAVE THE ABOVE SITUATION WELL IN HAND...NO UPDATES ASIDE FROM MINOR 
 FIRST PERIOD TWEAKS. 
 
 PREVIOUS DISCUSSION...
 LATEST SATL IMAGERY SHOWS A THINNING BAND OF MAINLY HIGH CLOUDS 
 STREAMING ACROSS SOUTHEAST CALIFORNIA AND WESTERN AZ BY MIDDAY. RUC 
 AND NAM SHOWED EXCELLENT RH TRENDS WITH THE PLUME EXTENDING FROM THE 
 SUBTROPICS INTO THE SOUTHERN ROCKIES. SFC DEW POINTS HAVE ALSO DRIED 
 OUT IN THE LATE MORNING...AND FURTHER DRYING LIKELY INTO FRIDAY.
 MAX TEMPS INTO THE LOWER 80S STILL LOOK GOOD FOR THE PHOENIX AREA.
 
 AS MENTIONED EARLIER...MODELS IN GOOD AGREEMENT IN FILLING THE WEST 
 COAST LOW ON THURSDAY INTO FRIDAY BEFORE BEING KICKED ALONG BY 
 ANOTHER SHORT WAVE FROM CANADA. THE ASSOCIATED FRONT WILL BE 
 WEAKENING AS IT SWINGS INLAND. HOWEVER...EXPECT A SHARP INCREASE IN 
 WINDS ON FRIDAY...ESPECIALLY IN OUR WESTERN ZONES. ONLY IN THE FAR 
 EASTERN AND NORTHERN PORTIONS OF AZ IS THERE SUFFICIENT MOISTURE TO 
 SUPPORT ANY SLIGHT CHANCES OF PRECIP ON FRIDAY NIGHT INTO SATURDAY.
 PREVIOUS FORECASTS LOWERED THE CHANCE OF RAIN...AND A FURTHER 
 DECREASE IN THE CHANCES FOR THIS WEEKEND IS WARRANTED. ALSO...HIGH 
 TEMPERATURES WILL DROP INTO THE LOWER 70S ON THE DESERTS BY SATURDAY 
 AS THIS SYSTEM RACES THROUGH.  
 
 FOR SUNDAY AND MONDAY A KICKER SYSTEM CROSSES INTO THE NORTHERN 
 ROCKIES...KEEPING A DRY WEST/NORTHWEST FLOW ALOFT ACROSS AZ/SRN 
 CALIFORNIA. THERE ARE SOME TIMING DIFFERENCES WITH THE FOLLOWING 
 SYSTEMS...BUT NOTHING SIGNIFICANT EXPECTED THIS FAR SOUTH.  THAT 
 REMAIN WELL NORTH OF ARIZONA INTO THE MIDDLE OF NEXT WEEK...BUT 
 NOTHING TO JUSTIFY ANY MENTION OF R TWO SYSTEMS THAT TRACK ACROSS 
 THE ...AND HOW STRONG BUT BOTH AGREE ON DRY PATTERN WITH GFS 
 ENSEMBLE TEMPS RUNNING NEAR OR A BIT BELOW NORMAL FOR EARLY MARCH.
 
 &&
 
 .AVIATION...
 ALL AREA AIRFIELDS WILL SEE PERIODS OF HIGH CLOUDS THRU 00Z FRI...
 WITH THICKEST CLOUDS OVER KPHX/KIWA. WINDS WILL BE GUSTY FROM THE 
 WEST THRU MUCH OF TONIGHT OUT IN WRN AREAS SUCH AS KIPL/KBLH...WITH 
 SOME GUSTS TO NEAR 25 KTS UNTIL AROUND 12Z. OTHERWISE...LESS WIND 
 EXPECTED THURSDAY AFTERNOON. SURFACE WINDS AT KPHX/KIWA WILL BEHAVE 
 IN A MORE NORMAL FASHION...ELY TONIGHT TURNING TO LIGHT WLY THU PM. 
 
 AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
 
 &&
 
 .FIRE WEATHER...
 FRIDAY THROUGH TUESDAY...
 AS A PACIFIC LOW PRESSURE SYSTEM CONTINUES TO MOVE SOUTHWARD ALONG 
 THE WESTERN CONUS MODEL GUIDANCE AGREES THAT THE BRUNT OF THE ENERGY 
 WILL PASS THROUGH NORTHERN AZ OVER THE WEEKEND. THIS MEANS COOLER 
 TEMPERATURES WITH MAXIMUM TEMPERATURES GENERALLY IN THE LOW TO MID 
 70S AND GRADUALLY INCREASING HUMIDITIES FROM WEST TO EAST THROUGH 
 MONDAY. BY MONDAY MINIMUM RH VALUES ARE FORECAST TO BE IN THE LOW TO 
 MID 20S ACROSS THE LOWER DESERTS. PERIODS OF BREEZY TO LOCALLY WINDY 
 CONDITIONS ARE POSSIBLE DURING THE AFTERNOON HOURS...PARTICULARLY 
 FRIDAY AND MONDAY. IT APPEARS THERE WILL BE ONLY A SLIGHT CHANCE OF 
 PRECIPITATION FRIDAY NIGHT AND SATURDAY MORNING FROM PHOENIX 
 EASTWARD. TUESDAY...MAXIMUM TEMPERATURES WILL HOLD IN THE LOWER 70S 
 AND HUMIDITIES WILL BEGIN TO DECREASE. ALSO...WINDS WILL BEGIN TO 
 DECREASE EXCEPT OVER THE COLORADO RIVER VALLEY WHERE NORTHERLY FLOW 
 WILL COMMENCE AND COULD BE GUSTY AT TIMES.
 
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 .PSR WATCHES/WARNINGS/ADVISORIES...
 
 AZ...NONE.
 
 CA...NONE.
 
 &&
 
 $$
 
 NATIONAL WEATHER SERVICE PHOENIX IS ON THE INTERNET AT
 
 WEATHER.GOV/PHOENIX
 
 DISCUSSION...ESTLE/SIPPLE
 AVIATION...ESTLE
 FIRE WEATHER...PADDOCK
 
 
 

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