Weather Service Report


401 
FXUS65 KPSR 020944
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
244 AM MST SUN AUG 2 2015

.SYNOPSIS...
CONSIDERABLE DRYING OCCURS STARTING TODAY AND INTO THE MIDDLE OF
NEXT WEEK WITH STORM CHANCES CONFINED TO THE HIGHER TERRAIN EAST OF
PHOENIX. TEMPERATURES WILL GRADUALLY WARM AND WILL HOVER NEAR NORMAL
OR SLIGHTLY ABOVE THROUGH NEXT WEEK.

&&

.DISCUSSION...
PRETTY QUIET RADAR EARLY THIS MORNING SAVE FOR A SWATH OF SHOWERS AND
ISOLATED THUNDERSTORMS MOVING INTO NAVAJO AND APACHE COUNTIES. FAIRLY
WEEK SOUTH-SOUTHWEST STEERING FLOW THROUGH A MIXED 850-300MB LAYER
OF 10-15 KTS HAS ALLOWED FOR SUFFICIENT RAINFALL AMOUNTS TO
ACCUMULATE ACROSS THE HIGHER ELEVATIONS OF GILA COUNTY THIS EVENING.
MOST OF THE FOCUS OF MONSOON ACTIVITY WAS ACROSS EASTERN PIMA...GILA
AND GRAHAM COUNTIES SATURDAY EVENING. PER CURRENT SATELLITE IMAGERY A
TONGUE OF DRY AIR IS INFILTRATING SOUTH-CENTRAL ARIZONA MOVING THE
DRY AIRMASS IN FROM THE WEST AND KICKING THE MOISTURE OUT THE DOOR TO
THE EAST. AN UPPER LEVEL SHORTWAVE TROUGH IS THE CULPRIT PUSHING IN
FROM THE WEST BRINGING SOUTHERLY FLOW INTO THE DESERT SOUTHWEST ALONG
WITH DRIER AIR /06Z SUNDAY MIXING RATIOS NEARLY 10 G/KG LESS THAN 24
HOURS AGO/. A BROAD REGION OF DIFFLUENCE STILL RESIDES ACROSS WESTERN
ARIZONA THROUGH EAST CENTRAL NEW MEXICO ALONG THE MOGOLLON RIM...AND
AS EXPECTED THIS WOULD BE THE REGION OF FAVORABLE STORM ACTIVITY
TODAY DURING THIS TRANSITION PERIOD. CURRENT MESOSCALE HIGH RES MODEL
THAT IS IN GOOD AGREEMENT APPEARS TO BE THE HRRR FOR TODAY'S
ACTIVITY.

PER LATEST GFS AND ECMWF...AMONG THEIR ENSEMBLE COUNTERPARTS ARE SLOW
TO MOVE A CUT OFF LOW FORMING IN THE EASTERN PACIFIC TO THE EAST OVER
THE NEXT 5-6 DAYS. THIS WILL ALLOW THE RIDGE OF HIGH PRESSURE TO
FLOAT TO THE WEST AND FLATTEN OUT...WITH A WEAK SOUTHWESTERLY
STEERING FLOW SETTLING IN THROUGH MOST OF THE UPCOMING WEEK. AN
OPTIMUM TIME FOR TEMPERATURES TO GRADUALLY RISE EVEN IF SLIGHTLY
ABOVE SEASONAL AVERAGE...THOUGH AT THIS TIME NONE OF THE GUIDANCE
BRINGS TEMPERATURES TO THE 110 DEGREE MARK FOR PHOENIX BUT THERE ARE
A FEW DAYS WITH 110 OR GREATER OUT ALONG THE LOWER COLORADO
RIVER...GENERALLY A WARMER LOCALE. ALL THIS BEING SAID...STORM
CHANCES OVER THE NEXT 5-6 DAYS ARE SUBSTANTIALLY LESS THAN THE
PREVIOUS DAYS ACROSS THE LOWER DESERTS. A SLIGHT CHANCE WILL BE KEPT
FOR HIGHER ELEVATIONS NORTH AND EAST OF PHOENIX DUE TO THE NATURE OF
MOUNTAIN ACTIVITY. THE NEXT FLOW REVERSAL APPEARS TO SHAPE UP BY LATE
WEEK INTO NEXT WEEKEND AS MOISTURE MAKES A RETURN APPEARANCE AND WIND
FLOW RETURNS TO A SOUTH-SOUTHEASTERLY DIRECTION.

&&

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

DRY SOUTHWESTERLY FLOW ALOFT IS EXPECTED TO REDUCE CLOUD COVERAGE 
INTO THE CLR-FEW RANGE AT ALL OF THE TAF SITES BY SUN MORNING...WITH 
BASES REMAINING MAINLY AOA 10K FEET...WITH THUNDERSTORM DEVELOPMENT 
REMAINING WELL OFF TO THE EAST OF THE GREATER PHX AREA ON SUNDAY 
AFTERNOON. WINDS TO MAINLY FOLLOW TYPICAL DIURNAL TRENDS THROUGH THE 
TAF PERIOD.
 
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...

TUESDAY THROUGH SATURDAY...DRIER AND STABLE WESTERLY FLOW ALOFT WILL 
PRODUCE PARTLY CLOUDY SKIES TUESDAY AND WEDNESDAY...WITH LOWER 
MINIMUM RELATIVE HUMIDITY GENERALLY IN THE 10 TO 15 PERCENT RANGE. 
MOISTURE WILL GRADUALLY INCREASE OVER SOUTHWEST AND SOUTH CENTRAL 
ARIZONA THURSDAY THROUGH SATURDAY...INTO THE 15 TO 25 PERCENT 
RANGE...WITH A SLIGHT CHANCE OF AFTERNOON AND EVENING SHOWERS AND 
THUNDERSTORMS IN SOUTHERN GILA COUNTY. AFTERNOON SOUTHWEST WINDS 10 
TO 15 MPH. FAIR RECOVERY AT NIGHT.

&&

.SPOTTER INFORMATION STATEMENT...
SPOTTERS ARE ENCOURAGED TO REPORT CONDITIONS ACCORDING TO STANDARD
OPERATING PROCEDURES.

&&

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

$$

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

DISCUSSION...DEWEY
AVIATION...PERCHA
FIRE WEATHER...VASQUEZ

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