Area Forecast Discussion
Issued by NWS Phoenix, AZ

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000
FXUS65 KPSR 021553
AFDPSR

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

.SYNOPSIS...
CONSIDERABLE DRYING WILL OCCUR 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...
WHAT A STARK CONTRAST COMPARED TO THE LAST COUPLE OF DAYS. EVEN
THOUGH YESTERDAY ENDED BEING SOMEWHAT QUIET OVER MOST OF THE
AREA...TODAY WILL BE EVEN MORE QUIET. LITTLE MOISTURE IS LEFT FROM
PHOENIX WESTWARD AND WATER VAPOR IMAGERY CONTINUES TO SHOW EVEN DRIER
AIR WORKING IN FROM THE SOUTH. SOME LINGERING LOW LEVEL MOISTURE
SHOULD ALLOW FOR SOME SPORADIC AFTERNOON CU ACROSS THE DESERTS...BUT
DRIER AIR MIXING DOWN WILL QUICKLY DROP SURFACE DEW POINTS FROM THE
CURRENT MID 50S TO LOWER 60S DOWN CLOSER TO 50 DEGREES BY LATE
AFTERNOON. SLIGHT CHANCES OF SHOWERS AND MAYBE A FEW THUNDERSTORMS
WILL BE POSSIBLE OVER HIGHER TERRAIN AREAS EAST OF PHOENIX...BUT AM
NOT ANTICIPATING MUCH ACTIVITY TODAY. TEMPERATURES WILL AGAIN TOP OUT
NEAR 110 DEGREES OR SLIGHTLY WARMER OVER THE DESERTS OF SOUTHEAST
CALIFORNIA AND SOUTHWEST ARIZONA...WHILE HIGHS SHOULD PEAK OUT IN A
104-108 RANGE OVER THE SOUTH-CENTRAL ARIZONA DESERTS. THE CURRENT
FORECAST LOOKS TO BE ON TRACK AND NO SIGNIFICANT CHANGES ARE NEEDED.

&&

.PREVIOUS 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...

DRIER AND MORE STABLE AIR WILL TRANSITION INTO THE AREA FROM THE
WEST-SOUTHWEST...SHUNTING THE BEST CHANCES FOR ANY STORMS TODAY INTO
THE MOUNTAINS NORTH-EAST-SOUTHEAST OF THE PHX AREA. SKY COVERAGE TO
RANGE FROM SKC TO SCT WITH ANY DAYTIME CU GNLY AOA 10KFT. WINDS WILL
FOLLOW TYPICAL SUMMERTIME PATTERNS...WITH SLIGHTLY ENHANCED WESTERLY
AFTN AND EVENING FLOW FOR KIPL AND THE PHX AREA TERMINALS.

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. MOISTURE WILL BEGIN TO THIN TOWARDS THE END OF THE
WEEK...WITH DAILY STORM CHANCES PERSISTING FOR THE HIGHER TERRAIN
AND DAYTIME HUMIDITIES STILL RANGING FROM 10 TO 20 PERCENT IN THE
LOWER DESERTS AND 30 TO 35 PERCENT FOR THE HIGHER TERRAIN.

&&

.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...KUHLMAN
PREVIOUS DISCUSSION...DEWEY
AVIATION...NOLTE
FIRE WEATHER...NOLTE/VASQUEZ



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