Area Forecast Discussion
Issued by NWS Phoenix, AZ

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000
FXUS65 KPSR 020530 AAA
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
1030 PM MST SAT AUG 1 2015

.UPDATE...AVIATION DISCUSSION.

&&

.SYNOPSIS...
LINGERING STORM CHANCES THE REST OF TODAY WILL MAINLY AFFECT AREAS
ACROSS HIGHER TERRAIN AREAS OF CENTRAL AND EASTERN ARIZONA WITH A
SLIGHT CHANCE OF A FEW STORMS OVER THE LOWER DESERTS. CONSIDERABLE
DRYING OCCURS STARTING SUNDAY AND INTO THE MIDDLE OF NEXT WEEK WITH
STORM CHANCES CONFINED TO THE HIGHER TERRAIN EAST OF PHOENIX.
TEMPERATURES WILL HOVER NEAR NORMAL OR SLIGHTLY ABOVE THROUGH NEXT
WEEK.

&&

.DISCUSSION... A MUCH QUIETER AFTERNOON/EVENING TODAY THAN WHAT WE
SAW YESTERDAY...ESPECIALLY ACROSS THE LOWER ELEVATIONS OF SOUTH-
CENTRAL AZ. DRY AIR THAT IS BEING PULLED NORTHWARD AHEAD OF AN UPPER
TROF THAT IS APPROACHING THE WEST COAST HAS NOW MOVED INTO SE CA AND
THE WESTERN 1/2 OF ARIZONA. THIS DRY AIR HAS PRETTY MUCH SHUT
CONVECTIVE ACTIVITY DOWN AND PUSHED SFC DEWPOINTS DOWN INTO THE
50S ACROSS THE WESTERN 3/4 OF OUR CWA THIS AFTERNOON.

AHEAD OF THIS DRY SURGE...THUNDERSTORMS HAVE ONCE AGAIN DEVELOPED
THIS AFTERNOON ACROSS SOUTHER GILA COUNTY...WHERE DEWPOINTS ARE
STILL WELL UP IN THE 60S UNDER THE MAIN MONSOON MOISTURE PLUME AND
CONTINUED DIFFLUENCE ALOFT. THIS TS ACTIVITY IS NOW BEGINNING TO
SLOWLY DIMINISH AND SHIFT OFF TO THE NORTH THIS EVENING AS THE
MOISTURE PLUME CONTINUES TO SHIFT OFF SLOWLY TO THE EAST...WITH THE
LATEST HRRR HIGH-RES MODEL RUN INDICATING THAT ANY REMAINING
CONVECTIVE ACTIVITY TO END BY MIDNIGHT TONIGHT. TOMORROW STILL LOOKS
LIKE IT WILL BE THE 1ST IN A SERIES OF VERY QUIET DAYS AS DRY AIR
MAKES ITS WAY ACROSS ALL OF AZ. AS FAR AS THE SHORT-TERM GRIDDED AND
ZONE FORECASTS ARE CONCERNED...HAVE LOWERED POPS FOR THE REST OF
THIS EVENING AND TONIGHT INTO THE SINGLE-DIGIT RANGE ACROSS THE
LOWER DESERTS OF SOUTH-CENTRAL AZ AND HAVE MADE SOME MINOR EDITS TO
THE SHORT-TERM TEMPERATURE/DEWPOINT GRIDS TO BETTER REFLECT CURRENT
TRENDS.

&&

.DISCUSSION...
SO FAR THIS AFTERNOON WE HAVE LITTLE SHOWER OR THUNDERSTORM ACTIVITY
AS THE ATMOSPHERE JUST HAS NOT RECOVERED. SKIES HAVE REMAINED MOSTLY
CLEAR SO SUNSHINE HAS NOT BEEN AN ISSUE...BUT SURFACE TEMPERATURES
ARE STILL SOMEWHAT COOL FOR THIS TIME OF DAY AND GENERALLY 5-8
DEGREES COOLER THAN YESTERDAY. MESOSCALE ANALYSIS DOES SHOW AMPLE
MIXED LAYER CAPE ACROSS SOUTH-CENTRAL AND SOUTHEAST ARIZONA ALONG
WITH BROAD DIFFLUENCE OVER MUCH OF ARIZONA. STILL EXPECTING MORE
THUNDERSTORM DEVELOPMENT THROUGH THE REST OF THIS AFTERNOON...BUT
COVERAGE WILL LIKELY BE LIMITED TO MOSTLY HIGHER TERRAIN AREAS. HAVE
LOWERED POPS OVER THE LOWER DESERTS INTO THE SLIGHT CHANCE CATEGORY
DUE TO THE POOR CONVECTIVE START TO THE AFTERNOON...BUT WE SHOULD
STILL GET A FEW STORMS IN THE DESERTS BY THE END OF THE DAY. THERE IS
SOME POTENTIAL FOR SOME STRONG DOWNDRAFT WINDS WITH ANY STRONGER
STORMS...BUT WITH MORE MOIST AIR IN THE BOUNDARY LAYER...OUTFLOW
INTERACTIONS SHOULD BE LESS ACTIVE THAN YESTERDAY.

WATER VAPOR IMAGERY SHOWS DRY AIR QUICKLY MOVING NORTHWARD THROUGH
THE BAJA AREA INTO NORTHERN MEXICO AND MODELS SHOW THIS DRY AIR
WORKING ACROSS ARIZONA STARTING TONIGHT AND OVERTAKING ALL OF THE
STATE BY SUNDAY NIGHT. LINGERING LOWER LEVEL MOISTURE WILL ALLOW FOR
SOME HIGHER TERRAIN SHOWERS AND THUNDERSTORMS...BUT LITTLE TO NO
CHANCE OF ANY ACTIVITY OVER THE LOWER DESERTS. THIS DRY AIR WILL
BASICALLY END OUR STORM CHANCES FOR A FEW DAYS EARLY THIS
WEEK...WHILE TEMPERATURES START TO WARM UP. HIGHS ACROSS OUR
SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA DESERTS WILL LIKELY BREAK
110 DEGREES SUNDAY THROUGH WEDNESDAY. SOUTH-CENTRAL ARIZONA DESERT
TEMPERATURES WILL PEAK ON MONDAY OR TUESDAY...BUT FALL SHORT OF
HITTING 110 DEGREES.

THE SUBTROPICAL HIGH POSITIONED OVER THE DESERT SOUTHWEST FOR MONDAY
AND TUESDAY IS FORECAST TO SHIFT EASTWARD INTO NEW MEXICO SOMETIME
WEDNESDAY AND THURSDAY AND REDIRECTING OUR FLOW OUT OF THE SOUTHEAST.
THIS WILL BRING A RETURN TO AT LEAST SOME LIMITED MONSOONAL MOISTURE
AND CHANCES FOR SHOWERS AND THUNDERSTORMS OVER MAINLY THE EASTERN
HALF OF ARIZONA.

&&

.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...PERCHA/KUHLMAN
AVIATION...PERCHA
FIRE WEATHER...VASQUEZ


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