Area Forecast Discussion
Issued by NWS Phoenix, AZ

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000
FXUS65 KPSR 292238
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
338 PM MST WED JUL 29 2015

.SYNOPSIS...SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED OVER
SOUTHERN ARIZONA AND SOUTHEAST CALIFORNIA TONIGHT...INCLUDING THE
LOWER DESERTS. LOCALIZED HEAVY RAIN AND STRONG WINDS CAN BE
EXPECTED...ESPECIALLY OVER HIGHER TERRAIN. HIGH PRESSURE BUILDING
OVER THE REGION WILL THEN GRADUALLY REDUCE RAIN CHANCES FROM THURSDAY
ONWARD INTO THE UPCOMING WEEKEND...AND INTO EARLY NEXT WEEK...BUT AT
LEAST SLIGHT CHANCES WILL REMAIN OVER SOUTH-CENTRAL ARIZONA.
TEMPERATURES WILL TAKE A SLIGHT DIP BELOW NORMAL THURSDAY DUE TO
WIDESPREAD CLOUD COVERAGE...BEFORE SLOWING WARMING BACK UP FROM
FRIDAY INTO EARLY NEXT WEEK AS THE ATMOSPHERE SLOWLY DRIES OUT.

&&

.DISCUSSION...
REST OF TODAY THROUGH THURSDAY...
STORM ACTIVITY BUILDING OVER GILA...SOUTHERN YAVAPAI...AND SOUTHEAST
ARIZONA ARE ANTICIPATED TO PRODUCE OUTFLOWS WHICH WILL LEAD TO NEW
STORM DEVELOPMENT OVER THE LOWER DESERTS. RELATIVELY HIGH POPS FOR
THIS EVENING ARE PREDICATED ON THAT. OF NOTE...MODEL CAPE NOT VERY
IMPRESSIVE FOR PHOENIX AREA AND LATEST HRRR UNIMPRESSIVE WITH
PRECIP/REFLECTIVITIES THERE AS WELL. MODEL CAPE IS BETTER OVER
SOUTHEAST CALIFORNIA...LESS SO SOUTHWEST ARIZONA. OF NOTE...HRRR
CONTINUES TO SHOW A GOOD DEAL OF ACTIVITY OVER LA PAZ COUNTY...DUE TO
INFLUENCE FROM SOUTHERN YAVAPAI STORMS. THE SHORT WAVE MOVING ACROSS
THE NORTHERN GULF OF CALIFORNIA AND SOUTHERN PORTIONS OF ARIZONA AND
CALIFORNIA HAS BEEN SLOW IN AIDING STORM PRODUCTION WHICH SUGGESTS
THAT DYNAMICAL FORCING HAS NOT BEEN OVERLY STRONG. THE MCV OVER
SOUTHERN ARIZONA HAS NOT BEEN PARTICULARLY PRODUCTIVE EITHER.
HOWEVER...WITH CLOUD COVER THINNING OUT AND A FEW HOURS OF DAYLIGHT
LEFT...THE WINDOW OF OPPORTUNITY HAS NOT CLOSED YET. THE STRONGER
STORMS WILL BE CAPABLE OF LOCALIZED FLOODING AS WELL AS STRONG
ERRATIC WINDS.

THURSDAY MAY START OFF LOOKING LIKE TODAY WITH A LOT OF DEBRIS CLOUDS
AND SPOTTY SHOWERS AROUND AS MODELS INDICATE AN MCV ORIGINATING FROM
SONORA MOVING THROUGH VERY LATE TONIGHT AND THURSDAY MORNING. LATEST
SREF ACTUALLY DEPICTS MORE CAPE THURSDAY THAN TODAY. IF WE ARE ACTIVE
TONIGHT...THAT WONT BE THE CASE. CONVERSELY...IF WE STAY RELATIVELY
QUIET THEN THAT COULD VERY WELL BE THE CASE. AS USUAL THIS TIME OF
YEAR...A LOT OF UNCERTAINTY REMAINS.

FRIDAY AND BEYOND...ALTHOUGH THERE WILL STILL BE ENOUGH MONSOON
MOISTURE TO KEEP UP SOME ACTIVITY DURING THIS PERIOD...A GRADUAL
DOWNTREND IN CONVECTIVE ACTIVITY AND A SLOW WARMING TREND APPEARS TO
BE IN THE CARDS AS THE MAIN UPPER HIGH CENTER GRADUALLY BUILDS
OVERHEAD AND THE ATMOSPHERE SLOWLY DRIES OUT...WITH PWATS FALLING
INTO THE 1.30 TO 1.50 RANGE BY EARLY NEXT WEEK.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL...

STORMS OVER GILA AND SOUTHERN YAVAPAI COUNTIES...AS WELL AS SOUTHEAST
ARIZONA...ARE EXPECTED TO PRODUCE OUTFLOW WINDS WHICH WILL EVENTUALLY
GENERATE NEW STORMS OVER THE VALLEY FLOOR...MAINLY AFTER 00Z. ENOUGH
UNCERTAINTY REMAINS THAT VICINITY THUNDERSTORM PHRASING WAS USED IN
THE TAFS AS OPPOSED TO TEMPO OR PREVAILING TSRA. ENOUGH MOISTURE IS
AVAILABLE IN THE ATMOSPHERE THAT STORMS WILL BE CAPABLE OF PRODUCING
LOCALLY REDUCED VISIBILITY IN HEAVY RAIN. IF STRONG STORMS MANAGE TO
FORM OVER PINAL COUNTY...THEN LARGE AREAS OF DUST ARE POSSIBLE BUT
PROBABLY ANY BLOWING DUST WILL TEND TO BE PATCHY. LINGERING DEBRIS
CLOUDS AND SHOWERS ARE QUITE POSSIBLE THROUGH THE OVERNIGHT HOURS.

SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH...

SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP BY 01Z WITH MOST OF
THE ACTIVITY FINISHED BY 07Z. HOWEVER...LINGERING DEBRIS SHOWERS AND
CLOUDS POSSIBLE OVERNIGHT. ENOUGH UNCERTAINTY REMAINS AT ANY GIVEN
TAF SITE THAT VICINITY THUNDERSTORM PHRASING WAS USED AS OPPOSED TO
TEMPO OR PREVAILING TSRA. ENOUGH MOISTURE IS AVAILABLE IN THE
ATMOSPHERE THAT STORMS WILL BE CAPABLE OF PRODUCING LOCALLY REDUCED
VISIBILITY IN HEAVY RAIN ALONG WITH STRONG WINDS. IF STRONG ENOUGH STORMS
MANAGE TO FORM...THEN LARGE AREAS OF DUST ARE POSSIBLE BUT PROBABLY
ANY BLOWING DUST WILL TEND TO BE PATCHY.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...SATURDAY THROUGH WEDNESDAY...ATMOSPHERIC MOISTURE
WILL DECLINE FROM WEST TO EAST OVER THE WEEKEND. THIS WILL CONFINE
STORM CHANCES TO SOUTH-CENTRAL ARIZONA...MAINLY THE HIGHER
TERRAIN...THROUGH THE FIRST HALF OF NEXT WEEK. HUMIDITIES WILL BE A
BIT LOWER AS WELL WITH MAX TEMPERATURES A BIT ABOVE NORMAL. WINDS
WILL FOLLOW FAMILIAR WARM SEASON PATTERNS.

&&

.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...AJ/PERCHA
AVIATION...AJ
FIRE WEATHER...AJ



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