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000
FXUS65 KPSR 212227 AAA
AFDPSR

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PHOENIX AZ
325 PM MST TUE MAY 21 2013

.UPDATE...UPDATED FIRE WEATHER DISCUSSION.

&&

.SYNOPSIS...
A LOW PRESSURE SYSTEM WILL BECOME CENTERED NEAR THE PACIFIC
NORTHWEST. THIS WILL LEAD TO DRY SOUTHWESTERLY FLOW ALOFT AND BREEZY
TO WINDY CONDITIONS AT TIMES THE REST OF THE WEEK AND INTO EARLY
NEXT WEEK. TEMPERATURES WILL BE SEASONABLY WARM.

&&

.DISCUSSION...
REST OF TODAY THROUGH FRIDAY...TEMPS RUNNING 2-4 DEGREES WARMER THAN
24 HOURS AGO. MUCH LIGHTER WINDS THAN YESTERDAY AS WELL. CIRRUS IS
MOVING IN BUT IT ISNT THICK. LOOKING AT THE LARGER SCALE...A REX
PATTERN IS PLACE OVER NORTH AMERICA WITH A NARROW HIGH AMPLITUDE
RIDGE OVER SOUTHERN CALIFORNIA/ARIZONA EXTENDING NORTHEASTWARD INTO
CANADA. IMMEDIATELY DOWNSTREAM IS AN UPPER LOW CENTERED OVER THE
NORTHERN PLAINS AND UPPER MIDWEST AND IMMEDIATELY UPSTREAM OF THE
RIDGE IS A DEEP UPPER LOW CENTERED JUST OFF THE PACIFIC NORTHWEST
COAST. THE RIDGE AXIS IS MOVING INTO ARIZONA THIS AFTERNOON AND WILL
SHIFT TO THE ROCKIES BY WEDNESDAY MORNING. AS THE SOUTHERN END OF
THE TROUGH BEGINS TO MAKE ITS PRESENCE FELT...AFTERNOON TEMPS
WEDNESDAY WILL BE A LITTLE BIT COOLER OVER SOUTHEAST CALIFORNIA
WHILE SOME RESIDUAL WARMING OCCURS OVER SOUTH-CENTRAL ARIZONA. THE
STRONGER SOUTHWESTERLY FLOW ALOFT WILL ALSO TRANSLATE TO STRONGER
SURFACE WINDS. THE UPPER LOW/TROUGH WILL HAVE VARIOUS VORT LOBES
ROTATING THROUGH THE SYSTEM OVER THE NEXT FEW DAYS WHICH WILL LEAD
TO DAY TO DAY FLUCTUATIONS IN WINDS AND TEMPERATURES.  THE POSITION
OF THE LOW WILL KEEP A STRONG RIDGE FROM DEVELOPING WHICH IN TURN
WILL KEEP THINGS FROM GETTING EXCESSIVELY WARM. OVERALL...LOOK FOR
BREEZY TO WINDY CONDITIONS AT TIMES WITH VERY DRY AIR.

SATURDAY THROUGH TUESDAY...OVER THE WEEKEND...THERE CONTINUES TO BE
SOME DIFFERENCE OF OPINION BETWEEN THE GFS AND ECWMF. THE LATTER
DEPICTS SOME NORTHWARD RETREAT OF THE TROUGH WHILE THE FORMER SHOWS
SOME DIGGING. THE GEFS MEAN SUGGESTS THAT THE GFS IS A BIT OVER
DONE. TAKING A BLENDED APPROACH...WEIGHTING TOWARD THE ECMWF BASED
GUIDANCE...TEMPS OVER THE WEEKEND AND EARLY NEXT WEEK DONT CHANGE
MUCH WITH PERHAPS A VERY SUBTLE COOLING TREND. CONDITIONS WILL
REMAIN DRY.


&&

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

HIGH PRESSURE ALOFT WILL DOMINATE OUR WEATHER PATTERN NEXT 24 HOURS
KEEPING WINDS LIGHTER THAN YESTERDAY...THO WE WILL SEE SOME AFTN/EVE
BREEZINESS ESPECIALLY OUT WEST AT KIPL/KBLH. OVERALL WINDS ACROSS
THE CENTRAL DESERTS WILL FAVOR NORMAL DIURNAL TENDENCIES THRU MID
DAY WEDNESDAY...WITH WINDS TO FAVOR THE WEST AFTER 20Z PERSISTING
THRU MIDNIGHT...THEN BECOMING SELY AFTER 2 AM WED. MAY SEE A FEW
AFTN GUSTS TO AROUND 20KTS INCLUDING KPHX. BAND OF BKN CIRRUS TO
MOVE THRU THE AREA THIS AFTERNOON AND EVENING WITH SKIES BECOMING
FEW-SCT250 AFTER MIDNIGHT.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
FRIDAY THROUGH TUESDAY...
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 FLOW ALOFT.
BREEZY CONDITIONS WILL DEVELOP DURING THE AFTERNOON AND EVENING
HOURS EACH DAY OVER THE AREA 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.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

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DISCUSSION...AJ
AVIATION...CB
FIRE WEATHER...CB