000
FXUS65 KPSR 141759
AFDPSR

AREA FORECAST DISCUSSION...UPDATED AVIATION SECTION
NATIONAL WEATHER SERVICE PHOENIX AZ
1059 MST TUE MAY 14 2013

.UPDATE...AVIATION SECTION UPDATED.

&&

.SYNOPSIS...
HIGH PRESSURE WILL BEGIN TO EXIT THE REGION TODAY ALTHOUGH
TEMPERATURES WILL STILL REMAIN WELL ABOVE NORMAL. LINGERING MOISTURE
WILL MAINTAIN A SLIGHT CHANCE OF A SHOWER OR THUNDERSTORM OVER THE
HIGHER TERRAIN OF SOUTH-CENTRAL ARIZONA. ON WEDNESDAY...A WEAK
WEATHER SYSTEM PASSING MAINLY TO THE NORTH 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...
WATER VAPOR IMAGERY SHOWS THE UPPER HIGH GETTING PUSHED EASTWARD AND
THE UPPER LOW TO OUR SOUTH IS SLOWLY STARTING TO MOVE EASTWARD.
MEANWHILE...A SHORT WAVE IN THE SOUTHERN BRANCH OF THE WESTERLIES IS
MOVING ACROSS CALIFORNIA. IN BETWEEN THESE FEATURES IS A DEFORMATION
ZONE CENTERED OVER THE MOHAVE DESERT. 12Z SOUNDINGS SHOW AND
INCREASE IN MID LEVEL MOISTURE OVER ARIZONA COMPARED TO YESTERDAY
AND THIS IS ALSO EVIDENT IN THE BATCHES OF CLOUDINESS. BLENDED TPW
IMAGERY ALSO SUPPORTS THIS TREND...ESPECIALLY OVER SOUTHEAST
ARIZONA. THIS WILL LEAD TO BETTER CHANCES OF CONVECTIVE CLOUD
DEVELOPMENT OVER THE HIGHER TERRAIN THAN YESTERDAY. OUR AREA MAY
HAVE SEE MORE CONVECTIVE CLOUD DEVELOPMENT TODAY BUT
OVERALL...MOISTURE AND CAPE ARE MODEST. SO DEVELOPMENT OF DEEP
CONVECTION WILL TEND TO BE ISOLATED AND LACKING IN GOOD PRECIP
POTENTIAL. SHALLOW CONVECTIVE CLOUDS WILL BE MORE NUMEROUS AND THEY
MAY BE ABLE TO PRODUCE SOME VIRGA. THE POTENTIAL FOR STRONG GUSTY
WINDS WILL COME FROM EVAPORATIVE COOLING OF MEAGER PRECIP/VIRGA.
OTHERWISE...MORE DISTINCT SOUTHWESTERLY SURFACE WINDS ARE
ANTICIPATED WHICH WILL TEND TO INHIBIT CONVECTIVELY GENERATED
OUTFLOW FROM PENETRATING VERY FAR INTO THE SOUTH-CENTRAL ARIZONA
DESERTS. SOUTHWEST ARIZONA AND ESPECIALLY SOUTHEAST CALIFORNIA WILL
BE EVEN MORE REMOVED FROM CONVECTIVE WIND POTENTIAL...EXCEPT PERHAPS
NORTHERN LA PAZ COUNTY. OTHERWISE...ANTICIPATE SIMILAR MAX TEMPS
TODAY AS WE HAD YESTERDAY. OTHER THAN SOME MINOR FIRST PERIOD TWEAKS
TO DEW POINTS AND RH GRIDS...NO CHANGES AT THIS TIME.

&&

.PREVIOUS DISCUSSION ISSUED 220 AM...EARLY THIS MORNING...PLOT AND
SATELLITE DATA SHOWED A STRONG UPPER HIGH PERSISTING ACROSS THE
DESERT SOUTHWEST...WITH A 588DM HIGH CENTER OVER SRN NEVADA.
MEANWHILE...A PESKY UPPER LOW CONTINUED TO WOBBLE SLOWLY WESTWARD
SOUTH OF THE ARIZONA/MEXICO BORDER WITH THE CENTER LOCATED OVER
CENTRAL BAJA CA. THESE TWO FEATURES HAVE KEPT EASTERN ARIZONA UNDER
A GENERAL EASTERLY FLOW ALOFT...ALLOWING MID LEVEL MOISTURE TO
REMAIN IN PLACE ACROSS OUR EASTERN ZONES. LATEST 00Z SOUNDINGS FROM
TUS AND FLG SHOWED THE MID LEVEL MOISTURE AND INSTABILITY...LIFTED
INDEX WAS MINUS 2.6 ON THE FLG RAOB. PROGS INDICATE MID LEVEL TEMPS
WILL REMAIN SIMILAR OVER ZONE 24 THIS AFTERNOON COMPARED TO
YESTERDAY...AND GIVEN THE PERSISTENT MID LEVEL MOISTURE AND STRONG
SURFACE HEATING WE CAN EXPECT ANOTHER SLIGHT CHANCE FOR
ELEVATED...DRY AND HIGH BASED THUNDERSTORMS TO FORM THIS AFTERNOON
AND EVENING ACROSS HIGHER TERRAIN EAST OF PHOENIX...WITH THE BEST
THREAT ACTUALLY EAST OF GLOBE. IT DOES APPEAR THE THE LOW TO OUR
SOUTH WILL FINALLY BE NUDGED OFF AND TO THE EAST LATER TODAY AND
TONIGHT...KICKED OUT BY A SHORTWAVE NOW APPROACHING THE NRN CA
COAST. THIS KICKER FEATURE IS CLEARLY SEEN ON THE MORNING VAPOR LOOP.

WITH LITTLE CHANGE IN THICKNESS VALUES EXPECTED TODAY...AND UNDER
PLENTIFUL SUNSHINE...HIGH TEMPS WILL CHANGE LITTLE FROM YESTERDAY
AND WILL REMAIN WELL ABOVE SEASONAL NORMALS AND IN THE TRIPLE DIGITS
OVER MOST OF THE LOWER DESERT. THE PREVIOUSLY MENTIONED LOW
APPROACHING THE CA COAST WILL SCOOT EAST ACROSS THE AREA WEDNESDAY
BRINGING A DRIER WESTERLY FLOW ALOFT INTO THE AREA AND CAUSING HIGH
TEMPS TO FALL SEVERAL DEGREES OVER MUCH OF OUR WESTERN DESERT. IN
ADDITION...IT WILL KICK UP SOME AFTERNOON BREEZINESS AS INCREASED
MID LEVEL WINDS ARE MIXED TO THE SURFACE.

FOR THE REST OF THE FORECAST PERIOD...THURSDAY THROUGH MONDAY...THE
WESTERLIES WILL DROP FURTHER TO THE SOUTH AND IMPACT OUR
AREA...BRINGING INCREASED WIND DURING THE AFTERNOON AND EVENING
HOURS...AND DROPPING OUR HIGH TEMPERATURES BACK TO NEAR SEASONAL
NORMALS BY SATURDAY. OVERALL DRY WESTERLY FLOW ALOFT WILL DOMINATE
OUR WEATHER PATTERN EACH DAY AND MOSTLY SUNNY DAYS AND CLEAR NIGHTS
WILL BE THE GENERAL RULE. GUIDANCE...INCLUDING GFS ENSEMBLE
MEMBERS...REMAINS CONSISTENT IN CALLING FOR A PROGRESSIVE OPEN WAVE
TROF TO PUSH EAST ACROSS THE AREA FRIDAY INTO SATURDAY. ALTHOUGH IT
APPEARS THAT THE TROF WILL BE SLIGHTLY DEEPER THAN PREVIOUSLY
THOUGHT...THE TROF AXIS SHOULD REMAIN JUST NORTH OF OUR AREA AND WE
WILL REMAIN ON THE DRY SOUTHERN PERIPHERY. SUNDAY INTO NEXT
MONDAY...A DRIER MORE NORTHWEST FLOW WILL FOLLOW AS THE TROF EXITS
INTO THE CENTRAL CONUS...AND WE CAN EXPECT A WARMING TREND WITH
DESERT HIGH TEMPS REACHING BACK INTO THE TRIPLE DIGITS OVER THE
WARMEST LOCALES BY NEXT MONDAY.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA...INCLUDING KPHX...KIWA...KSDL...
SCT HI CLOUDS WILL DRIFT ACROSS THE REGION THROUGHOUT THE AFTERNOON
AND EVENING WITH BASES FROM 15 TO 20 KFT. MODELS INDICATE WINDS WILL
BECOME SOUTHWEST THIS AFTERNOON...WITH SOMEWHAT STRONGER SPEEDS THAN
THE PAST SEVERAL DAYS. SPEEDS OF 10 TO 15 KTS CAN BE EXPECTED...WITH
OCCASIONAL GUSTS UP TO AROUND 20 KTS POSSIBLE.

SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA...INCLUDING KIPL AND KBLH...
ONLY SOME HIGH CIRRUS WILL AFFECT SOUTHEAST CALIFORNIA...WITH THE
PRIMARY AVIATION IMPACT BEING GUSTY SFC WINDS. SPEEDS SHOULD
INCREASE MARKEDLY EARLY/MID AFTERNOON WITH FREQUENT HIGHER GUSTS
ABOVE 20KT FROM THE S/SW. GUSTINESS MAY CONTINUE THROUGH THE EVENING
HOURS BEFORE BETTER DECOUPLING OCCURS.


AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
THURSDAY THROUGH MONDAY...
CONFIDENCE IS HIGH THAT ABNORMALLY WARM TEMPERATURES WILL PERSIST
THROUGH EARLY NEXT WEEK WITH LOWER ELEVATION HIGHS RANGING FROM THE
MID 90S TO JUST ABOVE 100F. NO PRECIPITATION IS EXPECTED THROUGH THE
ENTIRE PERIOD. MINIMUM HUMIDITY LEVELS WILL FALL BELOW 15
PERCENT...WITH MOST LOCATIONS INTO THE SINGLE DIGITS EACH DAY.
OVERNIGHT RECOVERY WILL GENERALLY BE FAIR. AFTERNOON WIND SPEEDS
SHOULD COMMONLY REACH 15-20 MPH THROUGH FRIDAY...RELAXING
SOMEWHAT DURING THE WEEKEND. FREQUENT HIGHER GUSTS CAN ALSO BE
EXPECTED...THOUGH REMAINING BELOW CRITICAL THRESHOLDS.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

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DISCUSSION...AJ
PREVIOUS DISCUSSION...CB
AVIATION...MCLANE/MO
FIRE WEATHER...VLM/MO