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000
FXUS65 KPSR 230420
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
920 PM MST WED MAY 22 2013

.SYNOPSIS...
A LOW PRESSURE CENTER OVER THE PACIFIC NORTHWEST IS EXPECTED TO KEEP
THE REGION UNDER DRY SOUTHWESTERLY FLOW ALOFT...WITH BREEZY TO WINDY
CONDITIONS AT TIMES THE REST OF THIS WEEK AND INTO EARLY NEXT WEEK.
ANTICIPATE SOME MODEST COOLING THURSDAY WITH TEMPERATURES REMAINING
NEAR SEASONAL NORMALS THROUGH THE WEEKEND. SOME MINOR COOLING IS
POSSIBLE NEXT WEEK BUT OTHERWISE...HIGHS ON THE LOWER DESERTS WILL
REMAIN IN THE 90S.

&&

.DISCUSSION...
STRONGER AFTERNOON AND EARLY EVENING WINDS OBSERVED ACROSS THE
SOUTHWEST DESERTS AS UPPER LEVEL RIDGING OVER THE AREA GIVES WAY TO
A LARGE LOW PRESSURE SYSTEM ACROSS THE PAC NW. EVEN BEYOND 8PM
MST/03Z WINDS AT KPHX WERE GUSTING TO NEAR 20KTS. MSL PRESSURE
GRADIENTS WILL RELAX SOMEWHAT OVER THE EVENING DECREASING THE
ELEVATED WINDS AT LEAST ACROSS THE SOUTH CENTRAL ARIZONA DESERTS.
BREEZY TO LOCALLY WINDY CONDITIONS WILL PERSIST ACROSS SOUTHEAST
CALIFORNIA INCLUDING BLYTHE...EL CENTRO AND THE INTERSTATE 8
CORRIDOR WEST OF EL CENTRO OVERNIGHT. GUSTS AT TIME WILL PUSH
30KTS...BUT REMAIN BELOW WIND ADVISORY CRITERIA. SKIES REMAIN MOSTLY
CLEAR...HOWEVER LAST FEW IR SATELLITE FRAMES INDICATE SOME ISOLATED
CLOUD DEVELOPMENT ALONG THE LEEWARD MOUNTAIN SLOPES OF THE SAN DIEGO
COUNTY MOUNTAINS IN CA...THE SKY ISLANDS ACROSS SOUTHEAST AZ AND
EVEN CLOSER TOWARDS THE PHX METRO OVER THE ESTRELLA MTNS. THESE
CLOUD FEATURES COUPLED WITH THE RIPPLED APPEARANCE OVER THE AREA ON
A WATER VAPOR LOOP ARE INDICATIVE OF ELEVATED RIDGETOP AND MID LEVEL
WINDS. DO NOT EXPECT THESE TO CHANGE MUCH IN THE FORM OF SKY
COVERAGE THIS EVENING AND MAY DISSIPATE AS QUICKLY AS THEY FORM.

SLIGHTLY COOLER TEMPERATURES EXPECTED TOMORROW AS COMPARED TO
TODAY/S 103F READINGS BOTH IN PHOENIX AND YUMA. 1000-500MB
THICKNESSES BEGIN TO DECREASE HEADING INTO THE WEEKEND AS TROUGHING
BECOMES MORE ESTABLISHED ACROSS THE INTERMOUNTAIN WEST. NO
SIGNIFICANT UPDATES PLANNED FOR TONIGHT/S FORECAST. PREVIOUS
DISCUSSION BELOW STILL APPLIES FOR THE REMAINDER OF THE FORECAST
PERIOD.

&&

.PREVIOUS DISCUSSION /ISSUED AT 345 PM MST/PDT/...
ANTICIPATE SOMEWHAT LIGHTER WINDS THURSDAY AND AGAIN FRIDAY...MAINLY
SOUTHEAST CALIFORNIA...REMAINING CONSISTENTLY BREEZY IN THE
AFTERNOONS AND EARLY EVENINGS OVER SOUTHWEST AND SOUTH-CENTRAL
ARIZONA. AS FOR TEMPERATURES...RUNNING WARMER TODAY OVER THE ARIZONA
FORECAST ZONES WITH LITTLE CHANGE OR SLIGHTLY COOLER IN SOUTHEAST
CALIFORNIA...EXCEPT JOSHUA TREE NATIONAL PARK WHERE AFTERNOON TEMPS
ARE SEVERAL DEGREES COOLER THAN 24 HOURS AGO. EXPECT MORE NOTICEABLE
DROP IN TEMPERATURES THURSDAY AS THE SOUTHERN END OF THE LARGE UPPER
LOW MAKES ITS PRESENCE FELT. THEN LITTLE CHANGE FRIDAY.

SATURDAY AND SUNDAY...THE UPPER TROUGH AXIS REMAINS IN PLACE THOUGH
THE UPPER LOW IS NOT AS DEEP. EXPECT LITTLE CHANGE IN TEMPERATURES
WITH READINGS CLOSE TO NORMAL FOR THIS TIME OF YEAR...PERHAPS
SLIGHTLY BELOW NORMAL IN SOUTHEAST CALIFORNIA. MODERATE AFTERNOON
AND EVENING BREEZINESS WILL CONTINUE.

MONDAY THROUGH WEDNESDAY...SOME MINOR COOLING IS POSSIBLE EARLY
NEXT WEEK AS BOTH THE GFS AND ECMWF ROTATE A SHORTWAVE AROUND THE
PARENT LOW EASTWARD INTO SOUTHERN CA AND AZ...WITH UPDATED GRIDDED
TEMPERATURE FORECASTS SHOWING A BLEND BETWEEN THE WARMER/SLOWER
ECMWF AND THE COOLER/FASTER GFS. BUT OVERALL...HIGHS ON THE LOWER
DESERTS REMAIN IN THE 90S.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA...INCLUDING KPHX...KIWA...KSDL...
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA...INCLUDING KIPL AND KBLH...

DRY SOUTHWEST FLOW ALOFT WILL KEEP GENERALLY CLEAR SKIES IN PLACE
THROUGH MID DAY THURSDAY. HOWEVER...STRONG GUSTY WINDS ARE EXPECTED
THIS EVENING...ESPECIALLY OUT WEST...FAVORING SOUTHWEST TO WEST AT
ALL AIRFIELDS. PEAK GUSTS AT KIPL/KBLH MAY EXCEED 30KT AT
TIMES...WITH GUSTS ACROSS CENTRAL AZ OVER 22KT LIKELY. EXPECT WINDS
TO TAPER OFF AND RETURN TO THE SOUTHEAST AFTER MIDNIGHT OVER THE
CENTRAL AZ DESERTS...HOWEVER WINDS WILL LIKELY REMAIN SW OR WEST AT
KIPL AND KBLH ALL NIGHT. LESS WIND EXPECTED THURSDAY...BUT THERE
WILL BE BREEZY CONDITIONS AT MOST AIRFIELDS AFTER ABOUT 20Z. SKIES
WILL REMAIN MOSTLY CLEAR...SAVE FOR SOME ISOLATED CLOUDS JUST
DOWNWIND OF AREA RIDGETOPS.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
SATURDAY THROUGH WEDNESDAY...
A LARGE AND NEARLY STATIONARY PACIFIC LOW PRESSURE SYSTEM WILL
REMAIN IN PLACE ALONG THE WEST COAST THROUGH THE PERIOD...KEEPING
ARIZONA AND SOUTHEAST CALIFORNIA UNDER A DRY SOUTHWEST TO WEST FLOW
ALOFT. BREEZY TO WINDY CONDITIONS WILL DEVELOP DURING THE AFTERNOON
AND EVENING HOURS EACH DAY...WITH PEAK WIND GUSTS IN EXCESS OF 25
MPH POSSIBLE. SINGLE DIGIT MINIMUM HUMIDITIES WILL CONTINUE.
OVERNIGHT RECOVERY WILL BE POOR OVER SOUTH-CENTRAL ARIZONA AND POOR
TO FAIR OVER SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA. HIGH
TEMPERATURES WILL REMAIN NEAR OR A BIT BELOW SEASONAL NORMALS EACH
DAY.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

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DISCUSSION...NOLTE
PREVIOUS DISCUSSION...AJ/PERCHA
AVIATION...CB/NOLTE
FIRE WEATHER...CB