Area Forecast Discussion
Issued by NWS Phoenix, AZ

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000
FXUS65 KPSR 250319
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
819 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 ON 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...
QUIET CONDITIONS PREVAIL ACROSS THE AREA THIS EVENING. THE WEAK
SHORTWAVE TROUGH THAT MOVED THROUGH THE REGION THIS AFTERNOON HAS
SHIFTED EAST...MEANWHILE THE CONVECTION THAT DEVELOPED ALONG THE RIM
HAS STARTED TO DISSIPATE WITH THE LOSS OF DAYTIME HEATING. WHILE SOME
CLOUDS ARE NOTED ON SATELLITE MAINLY ACROSS NEVADA AND NORTHWEST
ARIZONA...SKIES REMAIN MOSTLY CLEAR ACROSS THE LOWER DESERTS AS OF
03Z.

SUBSIDENCE BEHIND THE DEPARTING SHORTWAVE TROUGH SHOULD RESULT IN
MOSTLY CLEAR SKIES AND LIGHT WINDS FOR THE REST OF THE EVENING AND
OVERNIGHT HOURS. INHERITED FORECAST LOOKS VERY REPRESENTATIVE AND I
AM ONLY MAKING MINOR ADJUSTMENTS TO TEMPS AND SKY COVER BASED ON
OBSERVATIONAL TRENDS AND INCOMING SHORT-RANGE 00Z MODEL DATA.
MEANWHILE...THE FORECAST FOR MEMORIAL DAY STILL LOOKS ON TRACK WITH
HIGHS IN THE LOWER 90S.

&&

.PREVIOUS DISCUSSION...
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...

ASIDE FROM SOME FEW/SCT HIGH CLOUDS...WEATHER IMPACTS SHOULD BE
MINIMAL ACROSS THE REGION THROUGH MONDAY EVENING. LIGHT DIURNALLY
DRIVEN WINDS ARE EXPECTED AT ALL SITES.

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


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