Red Flag Warning 32, NWS Phoenix, AZ

AREA FORECAST DISCUSSION...CORRECTION
NATIONAL WEATHER SERVICE PHOENIX AZ
550 AM MST SAT APR 19 2008

SOUTH-CENTRAL AND SOUTHWEST ARIZONA...AND SOUTHEAST CALIFORNIA
FORECAST DISCUSSION

.UPDATE...UPDATED FIRE WX SECTION.

&&

.SYNOPSIS...
THE SOUTHERN END OF A PACIFIC LOW PRESSURE SYSTEM WILL BRING BREEZY
TO WINDY CONDITIONS TODAY...AND LOCALLY BREEZY AND COOLER WEATHER
SUNDAY. SOME SLIGHT ADDITIONAL COOLING IS ANTICIPATED MONDAY BEFORE
WARMING TUESDAY. THE REST OF NEXT WEEK WILL SEE LITTLE CHANGE IN
TEMPERATURES WITH PERHAPS A GRADUAL WARMING. OTHERWISE...CLEAR
NIGHTS AND SUNNY DAYS CAN BE EXPECTED THIS WEEKEND AND NEXT WEEK.

&&

.DISCUSSION...
THE LOW PRESSURE SYSTEM CENTERED OVER THE PACIFIC NORTHWEST COAST
WILL SAG SOUTHWARD ENOUGH TO CREATE BREEZY TO WINDY CONDITIONS THIS
AFTERNOON AND EVENING...MOST NOTABLY IN SOUTHEAST CALIFORNIA. AS THE
SYSTEM SLOWLY SHIFTS INLAND...IT WILL LEAD TO COOLER TEMPERATURES
...BEGINNING IN SOUTHEAST CALIFORNIA THIS AFTERNOON. SOUTHWEST AND
SOUTH-CENTRAL ARIZONA WILL SEE LITTLE TEMPERATURE CHANGE TODAY. IN
FACT THERE MAY A BIT OF WARMING OVER FRIDAYS READINGS. THE COOLING
WILL BE FELT MORE ON SUNDAY WITH SOME SLIGHT ADDITIONAL COOLING
MONDAY.

AS THE LOW TO OUR NORTH WEAKENS AND SHIFTS NORTHEASTWARD...WARMER
TEMPERATURES ARE ANTICIPATED TUESDAY. MODELS DIVERGE IN SOLUTIONS
DURING THE LATTER HALF OF NEXT WEEK. WHILE THEY AGREE ON THE IDEA OF
A REX PATTERN OVER THE NORTHEAST PACIFIC...THEY DISAGREE ON THE
BEHAVIOR OF THE UNDERCUTTING FLOW ACROSS THE CONUS. THE 00Z
OPERATIONAL GFS DEVELOPS A RIDGE OVER THE WESTERN STATES WHILE THE
GFS ENSEMBLE MEAN AND THE OPERATIONAL ECMWF HANG ON TO TROUGHING
WITH A GRADUAL INCREASE IN HEIGHTS. KEPT THE PREVIOUS FORECAST TREND
OF SHOWING LITTLE CHANGE IN TEMPERATURES SINCE THE OPERATIONAL GFS
AND ASSOCIATED MEX GUIDANCE APPEAR TO BE ANOMALOUS AT THIS TIME.
THUS LOOKING FOR TEMPS TO BE NEAR OR ONLY SLIGHTLY ABOVE NORMAL
DURING THE LATTER HALF OF NEXT WEEK.

&&

.AVIATION...
BIGGEST CONCERN TODAY WILL BE THE BREEZY/WINDY CONDITIONS AT ALL TAF
SITES. SOUTHWESTERLY FLOW (AHEAD OF A LOW PRESSURE SYSTEM CENTERED
WELL NORTH OF THE REGION) WILL GENERALLY TOP OUT IN THE 15 TO 20 KT
RANGE THIS AFTERNOON. HOWEVER...LATEST MODELS SUGGEST GUSTS TO 30 KT
WILL BE POSSIBLE FOR A BRIEF PERIOD DURING THE 22Z SAT TO 02Z SUN
WINDOW...MAINLY AT KPHX. WINDS WILL SUBSIDE DURING THE LATE EVENING
ACROSS THE PHOENIX METRO AREA...BUT WILL REMAIN SOMEWHAT ELEVATED
ACROSS SE CA.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
TOUGH CALL WITH REGARD TO THE FIRE WEATHER WATCH/RED FLAG WARNING.
ULTIMATELY DECIDED TO CANCEL THE FIRE WEATHER WATCH...AS IT LOOKS
LIKE WE WILL NOT MEET CRITERIA ACROSS THE AREA.

CA ZONES (WEST OF THE RIVER)...EARLIER MODEL RUNS WERE CONSISTENTLY
DEPICTING AN AREA OF 30 KT TRANPORT WINDS. HOWEVER...MOST RECENT
RUNS HAVE TRENDED DOWNWARD. THERE IS ALSO SOME DOUBT AS TO HOW DRY
IT WILL GET ACROSS THE HIGHER ELEVATIONS (WHERE THE STRONGEST WINDS
ARE EXPECTED)...AS PACIFIC MOISTURE WORKS ITS WAY EASTWARD. IT IS
LIKELY THAT CRITICAL THRESHOLDS WILL BE REACHED FOR A FEW
HOURS...THOUGH SEVERAL SEEM UNLIKELY.

AZ AND CO RIVER ZONES...HIGH-RES MODELS HAVE KEYED IN ON A LOW-LEVEL
JET DEVELOPING THIS AFTERNOON ALONG A TRAJECTORY FROM GILA BEND TO
PHOENIX. THESE AREAS STAND A BETTER CHANCE OF REACHING RED FLAG
CRITERIA LATE THIS AFTERNOON...THOUGH SUSTAINED WINDS OF 25 MPH WITH
WIND GUSTS TO 35 MPH ARE ONLY EXPECTED FOR AN HOUR OR TWO.

SUNDAY THROUGH FRIDAY...
SIGNIFICANTLY LESS WIND WITH CONTINUED DRY CONDITIONS EXPECTED NEXT
WEEK.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

NATIONAL WEATHER SERVICE PHOENIX IS ON THE INTERNET AT
WEATHER.GOV/PHOENIX

SHORT/LONG TERM...AJ
AVIATION...HIRSCH
FIRE WEATHER...HIRSCH