FXUS65 KPSR 150930
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
230 AM MST TUE DEC 15 2009

.SYNOPSIS...
WITH EXCEPTION OF AN INCREASE IN HIGH CLOUDS WEDNESDAY...EXPECT 
GENERALLY CLEAR SKIES AND WARMER TEMPERATURES THROUGH THE WEEKEND AS 
HIGH PRESSURE ALOFT IS THE MAIN WEATHER FEATURE OVER THE SOUTHWEST 
STATES. CLOUDS WILL AGAIN INCREASE EARLY NEXT WEEK AS THE WEATHER 
PATTERN SHIFTS AND MAY BECOME MORE ACTIVE.

&&

.DISCUSSION...
RIDGE AXIS STARTING TO SHIFT TO OVER OUR CWA THIS MORNING PER WV 
IMAGERY. A LOT OF MID/HIGH CLOUDS BETWEEN THE RIDGE AXIS AND THE 
NEXT TROUGH. EXPECTING THOSE CLOUDS TO FILTER INTO THE CWA 
TODAY...REACHING PEAK COVERAGE TOMORROW AS THE LOW AMPLITUDE TROUGH 
WEAKENS WITH THE REMAINING ENERGY MOVING TOWARD CO.

H5 RIDGE CONTINUES TO BUILD LATER IN THE WEEK AS TWO LARGE LOWS 
CONTINUE TO SPIN...ONE OVER NEW ENGLAND AND ANOTHER NEAR ALASKA. 
TEMPERATURES WILL UNDERGO A WARMING TREND WITH THIS PATTERN...THOUGH 
THE WARMING WILL BE SOMEWHAT MUTED BY THE CLOUDS COMING IN AND ALSO 
THE SHALLOW MIX LAYER WHICH IS TYPICAL FOR DECEMBER. THERE WILL 
LIKELY BE AT LEAST ONE SHORT WAVE...MAYBE THURSDAY OR FRIDAY...THAT 
MOVES DOWN THE FRONT SIDE OF THE RIDGE WHICH WILL PUT A HALT TO THE 
WARMING AND BRING JUST A FEW DEGREES OF COOLING. BUT OVERALL THE 
RIDGE LOOKS TO REMAIN IN PLACE THROUGH THE WEEKEND.

FOR EARLY NEXT WEEK...MODELS BEGIN TO WILDLY DIVERGE AS THE STABLE 
WAVE PATTERN BECOMES MORE AMPLIFIED AND STARTS TO BREAK DOWN. GFS IS 
ADVERTISING A POSSIBLE LOW/TROUGH MOVING TOWARD THE SOUTHWEST EARLY 
NEXT WEEK WHILE THE PAST TWO ECMWF RUNS PREFER TO HOLD THE RIDGE. 
NAEFS H5 MEAN HEIGHT FIELD GIVES MORE SUPPORT TO THE GFS THAN THE 
ECMWF THEREFORE SOME SLIGHT RAIN CHANCES WERE ADDED TO THE TAIL END 
OF THE FORECAST.

&&

.AVIATION...
SOUTH CENTRAL ARIZONA...INCLUDING KPHX AND KIWA...
MOSTLY CLEAR SKIES AND LIGHT WIND EXPECTED THROUGH AT LEAST 23Z TUE.

SOUTHEAST CALIFORNIA...INCLUDING KIPL AND KBLH...
MOSTLY CLEAR SKIES AND LIGHT WIND EXPECTED THROUGH AT LEAST 23Z TUE.

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...INIGUEZ
AVIATION...VASQUEZ  
FIRE WEATHER...CB