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000
FXUS65 KPSR 150852
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
150 AM MST WED MAY 15 2013

.SYNOPSIS...
A WEAK WEATHER SYSTEM PASSING MAINLY TO THE NORTH TODAY WILL LEAD TO
SOME SLIGHTLY COOLER HIGH TEMPERATURES AND AN END TO PRECIPITATION
CHANCES OVER SOUTH-CENTRAL ARIZONA. CONDITIONS WILL REMAIN DRY
THROUGH THE WEEKEND. ANTICIPATE SOME MODEST COOLING FRIDAY AND
SATURDAY BEFORE TEMPERATURES START TO WARM AGAIN EARLY NEXT WEEK.

&&

.DISCUSSION...
EARLY THIS MORNING...WESTERLIES HAVE BEGUN TO STRENGTHEN AND EXERT
MORE INFLUENCE ON OUR WEATHER...AND A SHORT WAVE EMBEDDED IN THEM
HAS MOVED INTO SRN NEVADA AT 1 AM. THIS FEATURE IS CLEARLY SEEN IN
THE VAPOR IMAGERY...AND IT HAS HELPED TO EJECT THE LOW...THAT HAD
BEEN SWIRLING TO OUR SOUTH FOR DAYS...OFF TOWARDS THE EAST AND INTO
NEW MEXICO. A STRONGER WESTERLY FLOW ALOFT WILL CONTINUE TO
OVERSPREAD THE AREA...PUSHING THE MID LEVEL CLOUDS/MOISTURE OFF TO
OUR EAST AND ELIMINATE THE THREAT OF HIGH BASED CONVECTION THAT HAD
RESIDED ACROSS PORTIONS OF ZONE 24 THE PAST FEW DAYS. AT 1 AM IR
IMAGERY SHOWED A FEW HIGH CLOUDS OVER OUR AREA BUT OVERALL SKIES
WERE CLEAR.

THE WEAKENING SHORT WAVE NOW MOVING INTO SRN NEVADA WILL CONTINUE TO
PUSH EAST ACROSS UTAH AND NRN AZ TODAY...HELPING BRING SLIGHTLY
COOLER AIR INTO ARIZONA ALONG WITH SOME AFTERNOON BREEZINESS.
STILL...HIGH TEMPS WILL REMAIN NEAR OR ABOVE 100 ACROSS MOST OF THE
DESERTS. DRY WESTERLY FLOW WILL KEEP SUNNY SKIES AND ABOVE NORMAL
HIGH TEMPS IN PLACE TODAY THROUGH THURSDAY.

MODELS...INCLUDING GFS ENSEMBLES...CONTINUE TO ADVERTISE A
PROGRESSIVE AND OPEN WAVE TROF TO PUSH EAST ACROSS THE DESERT
SOUTHWEST FRIDAY THROUGH SATURDAY. TREND OF THE GUIDANCE OVER THE
PAST FEW DAYS HAS BEEN TO MAKE THE TROF A BIT DEEPER...ESPECIALLY
WITH THE GFS. HOWEVER...DIFFERENCES IN THE MODELS ARE MINOR AND
SHOULD NOT IMPACT THE FORECAST MUCH IF AT ALL OTHER THAN TO LOWER
OUR HIGH TEMPS A FEW DEGREES. THIS WILL STILL BE A DRY WEATHER
SYSTEM WITH SKIES FRIDAY TO BE PARTLY CLOUDY...MAINLY HIGH
CLOUDS...THEN BECOMING SUNNY SATURDAY. HIGH TEMPS WILL LOWER TO
BELOW SEASONAL NORMALS AND BY SATURDAY MOST OF THE LOWER DESERTS
WILL FALL INTO THE LOW TO MID 90S...WITH A FEW OF THE COOLER DESERTS
POSSIBLY DROPPING INTO THE UPPER 80S. IT WILL BE BREEZY TO LOCALLY
WINDY FRIDAY AFTERNOON AND EVENING AHEAD OF THE APPROACHING
TROF...ESPECIALLY OVER IMPERIAL COUNTY...BUT SPEEDS SHOULD REMAIN
BELOW WIND ADVISORY THRESHOLDS AND WE DO NOT EXPECT DURATION OF
STRONG WINDS TO BE SUFFICIENT TO WARRANT A FIRE WEATHER WATCH
ISSUANCE. OVERALL WINDS WILL BE ELEVATED FOR MOST OF THE 7 DAY
FORECAST PERIOD BUT FRIDAY WILL LIKELY SEE THE STRONGEST WINDS.

SUNDAY INTO EARLY NEXT WEEK...A DRIER NORTHWEST FLOW ALOFT WILL
SETTLE INTO THE DESERT SOUTHWEST IN THE WAKE OF THE DEPARTING OPEN
WAVE TROF. THIS WILL GIVE US SUNNY DAYS AND CLEAR NIGHTS ALONG WITH
A GRADUAL WARMING TREND. HIGHS SHOULD REACH BACK INTO THE TRIPLE
DIGITS OVER MOST OF THE WARMER DESERTS BY MONDAY.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA...INCLUDING KPHX...KIWA...KSDL...
EXPECT TO SEE CLEARING SKIES OVERNIGHT AND DECREASING WINDS. THE
TYPICAL WIND SWITCH TO A DOWNSLOPE EASTERLY FLOW SHOULD BE DELAYED
TONIGHT DUE TO THE MODEST WESTERLY BACKGROUND FLOW IN PLACE. A LOW
PRESSURE SYSTEM PASSING BY TO THE NORTH WILL AGAIN BRING BREEZY
CONDITIONS DURING THE DAYTIME HOURS WEDNESDAY WITH WINDS GUSTING AT
TIMES TO AROUND 20 KTS DURING THE AFTERNOON.

SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA...INCLUDING KIPL AND KBLH...
GENERALLY CLEAR SKIES THROUGH THE PERIOD WITH WESTERLY WINDS
GRADUALLY DIMINISHING OVERNIGHT. EXPECT TO SEE SOME BREEZY
CONDITIONS AGAIN DURING THE DAYTIME HOURS WEDNESDAY...BUT WIND GUSTS
SHOULD REMAIN BELOW 20 KTS.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
FRIDAY THROUGH TUESDAY...
TEMPERATURES WILL TREND SLIGHTLY COOLER FRIDAY THROUGH THE FIRST
PART OF THE WEEKEND...WITH MID 90 READINGS EXPECTED IN THE LOWER
DESERTS ON SATURDAY. SUNDAY INTO THE EARLY PART OF NEXT WEEK WILL
SEE TEMPERATURES TREND BACK UPWARD THOUGH...WITH HIGHS PUSHING ABOVE
THE CENTURY MARK BOTH MONDAY AND TUESDAY. NO PRECIPITATION IS
EXPECTED THROUGH THE ENTIRE PERIOD. MINIMUM HUMIDITY LEVELS WILL
FALL BELOW 15 PERCENT...WITH MOST LOCATIONS DROPPING INTO THE SINGLE
DIGITS EACH DAY. OVERNIGHT RECOVERY WILL GENERALLY BE FAIR. WINDS
WILL BE PREDOMINATELY OUT OF THE SOUTHWEST WITH AFTERNOON GUSTS
AVERAGING AROUND 10 TO 15 MPH. HIGHER GUSTS OF 20 TO 25 MPH ARE
POSSIBLE FRIDAY AFTERNOON.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

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DISCUSSION...CB
AVIATION...MCLANE/MO
FIRE WEATHER...MCLANE