Area Forecast Discussion
Issued by NWS Phoenix, AZ

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000
FXUS65 KPSR 242039
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
138 PM MST SUN MAY 24 2015

.SYNOPSIS...
A SERIES OF WEAK WEATHER SYSTEMS MOVING THROUGH ARIZONA WILL KEEP
TEMPERATURES BELOW NORMAL THROUGH THE REMAINDER OF THE MEMORIAL DAY
WEEKEND. ANY ORGANIZED SHOWER ACTIVITY AND MEASURABLE PRECIPITATION
WILL REMAIN NORTH AND EAST OF PHOENIX TODAY AND MEMORIAL DAY. A
GRADUAL WARMING AND DRYING TREND WILL BEGIN IN THE EARLY WEEK...WITH
TEMPERATURES RETURNING TO THE UPPER 90S AND EVEN EXCEEDING THE 100
DEGREE MARK BY THE COMING WEEKEND.

&&

.DISCUSSION...

LATEST UPPER VORT MAX/COMPACT SHORTWAVE OFF THE LARGER PARENT LOW
OVER NORTHWEST CO AND SOUTHERN WY CONTINUES TO CARVE ITS WAY ACROSS
OUR FORECAST AREA THIS AFTERNOON. MAIN CIRC CENTER WAS MOVING ALONG
THE INTL BORDER HEADING INTO SOUTHEAST AZ THIS AFTERNOON AND
GENERATING A WELL-DEFINED MID AND HIGH LEVEL CLOUD SHIELD OVER SOUTH-
CENTRAL AZ. LATEST SATELLITE IMAGERY ALREADY SHOWS THE THICKER
CLOUDS HEADING EAST INTO SOUTHERN GILA COUNTY AND PATCHES OF BLUE
SKY ARE NOW VISIBLE ON PHOENIX-AREA WEBCAMS. DRIER AND SLIGHTLY
SUBSIDENT FLOW ON THE BACKSIDE OF THE VORT MAX HAS KEPT SKIES MOSTLY
CLEAR OVER THE LOWER CO RIVER VALLEY AND SOUTHEAST CA...SAVE FOR A
LIMITED FEW TERRAIN DRIVEN CU. AREA TEMPERATURES ARE RUNNING A FEW
DEGREES WARMER THAN THIS TIME YESTERDAY EVEN IN SPOTS UNDERNEATH THE
THICK...BUT PASSING...CLOUD COVER. SUBTLE ANTICYCLONIC AND STABLE
FLOW WILL FOLLOW THE VORT MAX AS IT CLEARS INTO SOUTHEAST AZ
TONIGHT...LEAVING SKIES MOSTLY CLEAR AND OVERNIGHT TEMPS ON THE
MILD SIDE.

ADDITIONAL UPSTREAM SHORTWAVES/DISTURBANCES WILL BRUSH PAST OR
THROUGH THE REGION FOR THE COMING WEEK...BUT DO LITTLE BY WAY OF
USHERING IN ANY COOLER AIRMASS TEMPERATURES OR REDUCTION IN ML AND
UL THICKNESSES. THE MEAN FLOW WILL BECOME MORE ZONAL AND ULTIMATELY
SOUTHWESTERLY WHILE THE PERSISTENT NEGATIVE HEIGHT ANOMALY OVER THE
WEST MIGRATES EASTWARD AND DISSOLVES. HEIGHTS ACROSS THE REGION WILL
RISE STEADILY THROUGH THE WEEK...HERALDING A RETURN TO WARMER AND
DRIER CONDITIONS. GFS/ECMWF INDICATE THAT A WEAK PACIFIC TROUGH WILL
MOVE THROUGH THE DESERT SOUTHWEST WEDNESDAY...BUT THIS SYSTEM WILL
DO LITTLE TO TEMPER THE BUILDING HEAT. FORECAST IS WEIGHTED HEAVILY
TOWARDS THE OPERATIONAL AND ENSEMBLE-BASED ECMWF...WHICH ARE
EXHIBITING VERY LOW SPREAD AND ARE OFTEN TOP PERFORMERS IN THESE
TYPES OF SCENARIOS. WHAT THIS EQUATES TO IS LOWER DESERT HIGHS
RISING THROUGH THE 90S THROUGH MIDWEEK. HIGH TEMPERATURES MAY EXCEED
THE 100 DEGREE MARK AS EARLY AS FRIDAY IN PHOENIX BUT WILL REMAIN
WELL BELOW RECORDS.

&&

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

NO AVIATION IMPACTS EXPECTED THROUGH MONDAY. SCT-BKN MID-HIGH LEVEL
CLOUD LAYERS ASSOCIATED WITH WEAK WEATHER DISTURBANCE PASSING OVER
PHX AREA TERMINALS TO GIVE WAY TO MAINLY CLEAR SKIES FROM LATER THIS
EVENING INTO MONDAY AS DRIER AIR FILTERS IN FROM THE WEST. MAINLY
CLEAR SKIES TO PREVAIL AT BOTH KIPL AND KBLH THROUGH THE TAF PERIOD.
WEAK PRESSURE GRADIENTS TO KEEP WINDS MAINLY AOB 10KTS THROUGH THE
PERIOD...MAINLY FOLLOWING TYPICAL DIURNAL PATTERNS.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
WEDNESDAY THROUGH SUNDAY...
DRIER AND WARMER CONDITIONS TO MAKE THEIR WAY INTO THE REGION
THROUGH THE PERIOD AS HIGH PRESSURE GRADUALLY STRENGTHENS OVER THE
DESERT SOUTHWEST...WITH HIGH TEMPERATURES RISING TO NEAR...OR JUST
ABOVE 100 DEGREES AT MANY LOWER DESERT LOCATIONS FROM FRIDAY ONWARD
INTO NEXT WEEKEND. ALTHOUGH HUMIDITIES ARE EXPECTED TO FALL INTO THE
HIGH SINGLE-DIGIT TO MID-TEEN RANGE EACH AFTERNOON...THE COMBINATION
OF LIGHT WINDS AND FAIR-GOOD OVERNIGHT RECOVERIES WILL KEEP FIRE
DANGER LEVELS AT RELATIVELY LOW LEVELS THROUGH THE FORECAST PERIOD.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...NONE.
CA...NONE.
&&

$$

VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX

DISCUSSION...NOLTE/HIRSCH
AVIATION...PERCHA
FIRE WEATHER...PERCHA



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