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000
FXUS65 KPSR 190452
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
950 PM MST SAT MAY 18 2013

.SYNOPSIS...
A SERIES OF COOL LOW PRESSURE SYSTEMS WILL CONTINUE TO MOVE INTO THE
WESTERN STATES MAINLY NORTH OF ARIZONA THROUGH MONDAY. NEAR NORMAL
TEMPERATURES...MOSTLY CLEAR SKIES...AND SOMEWHAT BREEZY AFTERNOONS
ARE EXPECTED. A HIGH PRESSURE SYSTEM WILL BUILD BACK INTO THE REGION
NEXT TUESDAY THROUGH FRIDAY...AND EXCEPT FOR SOME HIGH CLOUDS AT
TIMES...AFTERNOON TEMPERATURES ON THE DESERTS WILL WARM BACK INTO
THE 100 TO 103 DEGREE RANGE.

&&

.DISCUSSION...
CONVECTIVE CU ASSOCIATED WITH THE COLD AIR ALOFT AND STEEPER LAPSE
RATES REMAINED CONFINED MAINLY TO NE AZ THIS AFTERNOON. ACROSS THE
LOWER DESERTS...FLOW ALOFT IS NORTHWESTERLY AND
CONVERGENT...YIELDING SUBSIDENCE AND CLEAR SKIES THIS EVENING. NEAR
NORMAL TEMPERATURES ARE EXPECTED OVERNIGHT. MINOR ADJUSTMENTS TO THE
SHORT-TERM TEMPERATURES/DEWPOINTS WERE MADE THIS EVENING.
OTHERWISE...FORECAST REMAINS ON TRACK.

&&

.PREVIOUS DISCUSSION...
WEAK SHORTWAVE TROUGH OVER NORTHERN ARIZONA HAS TAPPED INTO WHAT
LITTLE MOISTURE IS LEFT ACROSS THE AREA...AND HAS MANAGED TO PRODUCE
A FEW SHOWERS ALONG THE UTAH/ARIZONA BORDER. SOME CU HAVE ALSO
DEVELOPED TO THE SOUTH...BUT SKIES REMAIN MOSTLY CLEAR ACROSS THE
LOWER DESERTS. TEMPS ARE GENERALLY IN THE LOWER 90S AS OF
21Z...STILL THINK MID 90S IS FEASIBLE BY THE END OF THIS AFTERNOON.

FORECAST IS RELATIVELY BENIGN FOR THE NEXT SEVERAL DAYS...AS A
SERIES OF WEAK SHORTWAVE TROUGHS WILL MOVE THROUGH THE FOUR CORNERS
REGION SUNDAY THROUGH LATE MONDAY. WITH SUCH LITTLE MOISTURE
FORECAST TO BE IN PLACE...THE ONLY IMPACT ACROSS SOUTHERN
ARIZONA/SOUTHEAST CALIFORNIA WILL BE LOCALLY BREEZY WINDS AND A
SLIGHT INCREASE IN CLOUD COVER. EVEN THE HI-RES LOCAL MODELS ARENT
PRODUCING MUCH MORE THAN SOME MOUNTAIN CU SUNDAY AND MONDAY. POPS
WERE ALREADY AT ZERO THROUGH EARLY NEXT WEEK AND I SEE NO REASON TO
CHANGE THEM BASED ON TODAYS 12Z DATA. ONCE THE FINAL TROUGH MOVES
THROUGH ON MONDAY...WEAK H5 RIDGING WILL ESTABLISH ITSELF ACROSS THE
REGION WITH THE RIDGE AXIS POSITIONING ITSELF OVERHEAD ON WEDNESDAY.

RIDGING IS EXPECTED ACROSS THE AREA THROUGH THE END OF THE
WEEK...ALTHOUGH THE UPPER LEVEL FLOW WILL GRADUALLY TAKE ON A MORE
SOUTHWESTERLY COMPONENT THURSDAY INTO NEXT WEEKEND. A RATHER LARGE
UPPER LOW WILL MOVE INTO THE PACIFIC NORTHWEST LATE NEXT
WEEK...ALTHOUGH THERE ARE MODEL DIFFERENCES HOW QUICKLY IT WILL MOVE
THROUGH THE AREA. REGARDLESS...IT WILL BE TOO FAR NORTH TO HAVE ANY
SIGNIFICANT IMPACT ON OUR WEATHER. EXPECT ABOVE NORMAL TEMPERATURES
TO RETURN TO THE REGION AS EARLY AS MONDAY...LASTING WELL INTO NEXT
WEEKEND.

&&

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

WEAK RIDGING BUILDING INTO THE REGION FROM THE WEST WILL KEEP SKIES
CLEAR...OR MOSTLY CLEAR THROUGH THE TAF PERIOD. WINDS TO REMAIN
MAINLY ON THE LIGHT SIDE THROUGH SUNDAY...EXCEPT FOR SOME WESTERLY
AFTERNOON BREEZES AT THE PHX AREA TERMINALS. NO AVIATION IMPACTS
EXPECTED THROUGH THE PERIOD.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
TUESDAY THROUGH SATURDAY...
HIGH PRESSURE PASSING OVER THE REGION WILL KEEP THE WEATHER
DRY...UNDER MOSTLY CLEAR SKIES...WITH AFTERNOON HIGHS NEAR 100F
ACROSS THE LOWER DESERTS TUESDAY THROUGH THURSDAY. A SLIGHT COOLING
TREND IS THEN EXPECTED ON FRIDAY AND SATURDAY AS A LOW PRESSURE TROF
PUSHES SOUTHWARD INTO THE WESTERN GREAT BASIN. WINDS TO REMAIN ON
THE LIGHT SIDE THROUGH THURSDAY...WITH SOME AFTERNOON WESTERLY
BREEZES TO DEVELOP ON FRIDAY AND SATURDAY. MINIMUM HUMIDITIES TO
REMAIN IN THE 5 TO 10 PERCENT RANGE...WITH FAIR OVERNIGHT RECOVERIES
THROUGH THE FORECAST PERIOD.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

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DISCUSSION...HIRSCH
PREVIOUS DISCUSSION...LEINS
AVIATION...PERCHA
FIRE WEATHER...PERCHA