FXUS65 KPSR 142145
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
245 PM MST MON DEC 14 2009
.SYNOPSIS...
CLOUDS WILL CONTINUE TO DRIFT TO THE EAST...WITH PLENTY OF SUNSHINE
ACROSS THE WESTERN DESERTS TODAY. MOSTLY CLEAR SKIES ARE FORECAST ON
TUESDAY AND INTO THE WEEKEND AS HIGH PRESSURE ALOFT DOMINATES THE
REGION. WARMER DAYTIME TEMPERATURES ARE ALSO EXPECTED.
&&
.DISCUSSION...
TRANQUIL WEATHER ACROSS OUR CWA THIS MONDAY AFTERNOON/EVENING.
WEAK UPPER TROUGH CONTINUES TO SLIDE TO THE EAST THIS AFTERNOON. RUC
PUT TROUGH AXIS FROM THE 4 CORNERS TO PHOENIX TO NRN BAJA PENINSULA
AT 20Z. SOME FLAT CUMULUS SEEN ACROSS MARICOPA AND SOUTHERN GILA
COUNTY WITH BOUNDARY LAYER RH STILL RATHER HIGH. IN FACT DEW POINTS
WERE HOLDING IN THE MIDDLE 40S AT THAT TIME...BUT SHOULD BE DROPPING
AFTER DARK. DUE TO CLEARING SKIES AND LGT WINDS...MINIMUMS WILL DIP
INTO THE 30S AND 40S ACROSS THE GREATER PHOENIX AREA...SKY HARBOR
BEING ONE OF THE WARMER SITES. AT THE UPPER LEVELS...80-90 KT WINDS
AT 300 MB WERE MOVING INTO SRN CALIF ON THE BACK SIDE OF THE TROUGH.
12Z GFS/NAM CALL FOR STRONG HEIGHT RISES OVER MOST LOCATIONS THRU
18Z TUESDAY. WITH A STRONGER SFC-BASED INVERSION...AND LIGHT WINDS
WE MAY NOT GET THE FULL WARMING EFFECTS AND OUR HIGH AT PHOENIX IS
LIKELY GOING TO BE A BIT BELOW GUIDANCE. THE BEST WARMING WILL BE ON
WEDNESDAY AND THURSDAY WHEN WE WILL SEE A RETURN TO THE 70S.
WILL ALSO EXPECT SOME HIGH CLOUDS TO SWEEP INLAND AND ACROSS ARIZONA
WEDNESDAY THROUGH THURSDAY.
LATEST ECMWF AND GFS ARE GENERALLY ON THE SAME PAGE WITH REGARD TO
THE NEXT PACIFIC SYSTEM THAT IMPACTS THE PACIFIC NORTHWEST. ABOUT
THE MOST WE WILL GET IS SOME HIGH CLOUDS BY MID WEEK. BUT MODEL
DIFFERENCES GROW LARGER AND LARGER TOWARD THE WEEKEND...WITH THE
MORE PROGRESSIVE GFS SHOWING ANOTHER PACIFIC TROUGH PUSHING INLAND
WHILE THE ECMWF HOLDS ON TO A STRONG RIDGE FROM CALIFORNIA TO CANADA
ON SUNDAY NIGHT. WILL NOT MAKE ANY CHANGES FROM PREVIOUS
SHIFTS...UNTIL MODELS COME INTO BETTER AGREEMENT.
&&
.AVIATION...
SOUTH CENTRAL ARIZONA...INCLUDING KPHX AND KIWA...
SOME HAZE CONTINUES TO LINGER AT BOTH KPHX AND KIWA AS OF 17Z
HOWEVER SURFACE VSBYS REMAIN 10SM OR GREATER. I EXPECT THAT THE HAZE
SHOULD DISSIPATE BY EARLY AFTERNOON ONCE THE INVERSION BREAKS.
OTHERWISE NO CHANGES TO TAFS...WEAK WINDS BECOMING LIGHT WESTERLY BY
20Z...THEN LIGHT EASTERLY LATE THIS EVENING.
SOUTHEAST CALIFORNIA...INCLUDING KIPL AND KBLH...
LIGHT WINDS TODAY AND TONIGHT. CLEAR SKIES THROUGH THE EVENING HOURS
WITH A GRADUAL INCREASE IN HIGH CLOUDS AFTER 04-06Z.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
WEDNESDAY THROUGH SUNDAY...
HIGH PRESSURE ALOFT WILL BE THE DOMINANT WEATHER FEATURE DURING THE
PERIOD...LEADING TO DRY AND WARMER CONDITIONS. MAX TEMPERATURES
SHOULD STAY ABOVE SEASONAL NORMALS...FROM UPPER 60S TO MID 70S OVER
THE WARMER LOWER DESERTS EACH DAY WITH NO SIGNIFICANT DAY TO DAY
TRENDS. ALTHOUGH IT WILL BE DRY...EXPECT MIN RH VALUES TO STAY ABOVE
15 PERCENT EACH DAY...WITH PRETTY GOOD RECOVERY EACH NIGHT. LIGHT
WINDS ARE EXPECTED FOR THE MOST PART...WITH WEAK DIURNAL TENDENCIES.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...NONE.
CA...NONE.
&&
$$
NATIONAL WEATHER SERVICE PHOENIX IS ON THE INTERNET AT
WEATHER.GOV/PHOENIX
DISCUSSION...SIPPLE
AVIATION...LEINS
FIRE WEATHER...CB
