PHXAFDPSR (01/09/09 1410)


FXUS65 KPSR 092211
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
310 PM MST FRI JAN 9 2009

.UPDATE...UPDATED AVIATION DISCUSSION.

&&

.SYNOPSIS...
A DRY LOW PRESSURE SYSTEM WILL PUSH THROUGH THE AREA TONIGHT INTO
SATURDAY. WINDY CONDITIONS WILL PERSIST THIS EVENING ALONG THE LOWER
COLORADO RIVER VALLEY INTO SOUTHEAST CALIFORNIA...WITH BREEZY
CONDITIONS EXPECTED JUST ABOUT EVERYWHERE ON SATURDAY. HIGH PRESSURE
WILL THEN BUILD OFF THE WEST COAST NEXT WEEK. TEMPERATURES WILL SHOW
VERY LITTLE CHANGE THE NEXT SEVERAL DAYS...WITH AFTERNOON READINGS
NEAR OR SLIGHTLY ABOVE NORMAL.

&&

.SHORT TERM...
POSITIVELY-TILTED SHORTWAVE TROUGH IS CONTINUING ITS MARCH ACROSS 
THE SOUTHWEST STATES TODAY...WITH LATEST IR/WV SATELLITE IMAGES 
REVEALING ITS CURRENT POSITION IN SOUTHERN UTAH. NOT MUCH MOISTURE 
IS ASSOCIATED WITH THIS SYSTEM...SO WE WILL REMAIN DRY. THE BIGGEST 
ISSUE WITH THIS SYSTEM WILL BE THE GUSTY WINDS. ALREADY...SURFACE 
OBSERVATIONS HAVE INDICATED WIND GUSTS OVER 35 MPH AT 
BLYTHE/KBLH...WITH WINDY CONDITIONS LIKELY TO PERSIST THROUGH LATE 
THIS EVENING ALONG THE LOWER COLORADO RIVER VALLEY. A WIND ADVISORY 
REMAINS IN EFFECT FOR THIS AREA UNTIL 8 PM MST/7 PM PST. WINDS 
SHOULD BECOME LESS GUSTY AND DECREASE IN INTENSITY OVERNIGHT.

AS SURFACE TROUGH AND ASSOCIATED COOL FRONT PROGRESS TOWARDS THE 
SOUTHEAST...SURFACE PRESSURE RISES WILL OCCUR FROM THE FOUR CORNERS 
INTO THE GREAT BASIN...LEADING TO A TIGHT GRADIENT. STRONG NORTHEAST 
WINDS WILL DEVELOP ABOVE THE SURFACE...WITH NAM12 SHOWING 925 HPA 
WINDS OF 30 TO 40 KTS ACROSS MOST OF THE AREA OVERNIGHT. THE
QUESTION IS HOW PROMINENT WILL MIXING BE. IF STRONGER WINDS CAN MIX
DOWN TO THE SURFACE...THEN MINIMUM TEMPERATURES WILL LIKELY BE
ELEVATED ACROSS THE DESERTS OF SOUTH-CENTRAL ARIZONA. MINIMUM
TEMPERATURE FORECASTS FOR THE AREA TAKES THIS INTO ACCOUNT...AND ARE
A COUPLE DEGREES ABOVE GUIDANCE. BREEZY NORTHEAST WINDS WILL PERSIST
THROUGH MID-DAY SATURDAY.

BY SUNDAY...PACIFIC RIDGE OFF THE CALIFORNIA COAST BEGINS TO 
STRENGTHEN TO AN IMPRESSIVE 592 DM...BEFORE IT BEGINS SLOWLY 
MIGRATING TO THE EAST. THIS MEANS CONTINUED DRY AND ABOVE NORMAL 
TEMPERATURES THROUGH NEXT WEEK.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX AND KIWA...
ATYPICAL NORTHERLY WINDS ARE EXPECTED TO DEVELOP AFTER 03 UTC...AND 
WILL VARY BETWEEN NNW AND NNE THROUGH THE EARLY MORNING HOURS. 
PHOENIX TRACON IS REPORTING SLANTWISE VISIBILITY ISSUES THIS 
AFTERNOON...AND DON'T EXPECT IMPROVEMENT UNTIL AFTER SUNSET.  

SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA INCLUDING KBLH AND 
KIPL...
STRONG NORTHERLY WINDS WILL CONTINUE DOWN THE LOWER COLORADO 
RIVER VALLEY THROUGH EARLY EVENING...DECEASING SOMEWHAT AFTER 
SUNSET. LESS WIND IS EXPECTED SATURDAY.
 
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
SUNDAY THROUGH THURSDAY...
CONSIDERABLY LESS WIND CAN BE EXPECTED NEXT WEEK AS A RIDGE OF HIGH 
PRESSURE KEEPS CONDITIONS DRY AND TEMPERATURES ABOVE NORMAL. WINDS 
WILL FAVOR NORTH AND NORTHEAST DIRECTIONS. 

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...WIND ADVISORY UNTIL 8 PM MST THIS EVENING FOR AZZ020.

CA...WIND ADVISORY UNTIL 7 PM PST THIS EVENING FOR CAZ031.

&&



NATIONAL WEATHER SERVICE PHOENIX IS ON THE INTERNET AT

WEATHER.GOV/PHOENIX

DISCUSSION...ROGERS
AVIATION...WANEK
FIRE WEATHER...AJ