Area Forecast Discussion
Issued by NWS Phoenix, AZ

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FXUS65 KPSR 291143 AAA
AFDPSR

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PHOENIX AZ
445 AM MST TUE JUL 29 2014

.UPDATE...
UPDATED AVIATION AND FIRE WEATHER SECTIONS.

&&

.SYNOPSIS...
DRIER AIR WILL CONTINUE TO MOVE INTO THE AREA TODAY...RESULTING IN
DECREASED CHANCES OF SHOWERS AND THUNDERSTORMS THROUGH THURSDAY
ALONG WITH INCREASED TEMPERATURES. A RETURN TO A MORE TYPICAL
MONSOON REGIME IS EXPECTED LATE IN THE WEEK INTO THE WEEKEND AS
SHOWERS AND THUNDERSTORMS ARE ONCE AGAIN EXPECTED ACROSS THE REGION.

&&

.DISCUSSION...
VERY QUIET WEATHER ACROSS THE REGION THIS MORNING AS CONVECTION
CONTINUES TO DISSIPATE ACROSS NORTHERN ARIZONA AND SOUTHERN NEVADA.
ACROSS THE LOWER DESERTS OF ARIZONA AND SOUTHEAST
CALIFORNIA...CONVECTION WAS VIRTUALLY NON-EXISTENT DURING THE
AFTERNOON HOURS AS THE SUBSIDENCE ASSOCIATED WITH THE LARGER SCALE
TROUGH OVER NORTHERN BAJA WAS TOO MUCH TO OVERCOME. THUS...SKIES
WERE MOSTLY CLEAR THIS MORNING WITH TEMPS RAPIDLY DROPPING THROUGH
THE MID TO UPPER 80S AS OF 0745Z.

THE FLOW ALOFT HAS SHIFTED AROUND OUT OF THE WEST AND DRYING OF THE
MID LEVELS HAS COMMENCED. PWATS WILL CONTINUE TO DECREASE THROUGH
THE DAY TODAY WITH ONLY A NARROW BAND OF MOISTURE LINGERING OVER THE
MOUNTAINS EAST OF PHOENIX. WITH NO DISCERNIBLE TRIGGERS SEEN IN THE
UPSTREAM WATER VAPOR IMAGERY AND NONE FORECAST FROM ANY OF THE
OPERATIONAL MODELS OR ENSEMBLES...I WILL RETAIN CLIMO-LIKE POPS EAST
OF PHOENIX BUT KEEP THE DESERTS DRY TODAY. ANY CONVECTION THAT
DEVELOPS SHOULD BE SHORT LIVED AND DISORGANIZED. MUCH OF THE SAME
FORECAST FOR WEDNESDAY AND THURSDAY AS DRY AIR WILL REMAIN PARKED
OVER THE AREA COURTESY OF WEST/NORTHWEST WINDS FROM 700MB-300MB.

BOTH THE EUROPEAN AND GFS TRY AND SUGGEST A RETURN TO SOUTHEASTERLY
WINDS ON FRIDAY WITH DEEPER MOISTURE LAGGING BEHIND AND NOT ARRIVING
ACROSS OUR FORECAST AREA UNTIL THE WEEKEND. WILL NEED TO MONITOR AS
THINGS GET CLOSER BUT LOOKING AT THE BIG PICTURE...FRIDAY COULD SEE
DISTANT STORMS TO THE SOUTHEAST ALONG WITH THE POTENTIAL FOR BLOWING
DUST...WHEREAS THE WEEKEND COULD SEE CONVECTION DEVELOP OVERHEAD.
WILL MAINTAIN THE IDEA OF ELEVATED POPS FRIDAY THROUGH THE WEEKEND
BUT THE FINER DETAILS WILL NEED TO BE WORKED OUT AS WE GET FURTHER
INTO THE WEEK. UNFORTUNATELY THERE ARE VARYING SOLUTIONS ON WHAT
HAPPENS FROM MONDAY ONWARD WITH EQUAL CHANCES OF WESTERLY FLOW
RETURNING OR A CONTINUED SOUTHEASTERLY FETCH. GOING WITH CLIMO FOR
NOW.

AS FOR TEMPERATURES...HIGHS WILL REACH THEIR PEAK AROUND THE 110
DEGREE MARK WEDNESDAY/THURSDAY AS A RESULT OF THE DRIER
AIRMASS...THEN DECREASE AND SETTLE CLOSER TO NORMAL /103-105/
THROUGH THE WEEKEND.

&&

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

MOISTURE AND INSTABILITY WILL DECLINE FROM WEST TO EAST UNDER DEEP
WESTERLY FLOW. THIS WILL KEEP STORM ACTIVITY ISOLATED IN NATURE AND
CONFINED TO HIGHER TERRAIN AREAS WELL AWAY FROM PHOENIX AREA TAF
SITES. THERE IS A SLIGHT CHANCE OF OUTFLOWS FROM DISTANT STORMS
CAUSING A WIND SHIFT LATER THIS EVENING BUT PROBABILITY TOO LOW TO
REFLECT IN THE TAFS. ANTICIPATE EVEN LESS STORM ACTIVITY WEDNESDAY.
SURFACE WINDS WILL FAVOR WESTERLY DIRECTIONS.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
THURSDAY THROUGH MONDAY...
DRIER THAN NORMAL CONDITIONS CONTINUE THURSDAY. STORM CHANCES
WILL BE SLIGHT AND WILL BE LIMITED TO THE HIGHER TERRAIN OF EASTERN
ARIZONA. FRIDAY AND OVER THE WEEKEND WEEKEND...AN INCREASE IN
MOISTURE AND ASSOCIATED HUMIDITIES IS ANTICIPATED. THIS WILL LEAD TO
BETTER STORM CHANCES OVER THE HIGHER TERRAIN OF SOUTH-CENTRAL
ARIZONA AND STORM CHANCES...THOUGH SLIGHT...EXPANDING WESTWARD TO
THE LOWER ELEVATIONS. HIGH TEMPERATURES TREND DOWNWARD AS WELL.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

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

DISCUSSION...LEINS
AVIATION...AJ
FIRE WEATHER...AJ






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