Area Forecast Discussion
Issued by NWS Phoenix, AZ

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FXUS65 KPSR 171129 AAA
AFDPSR

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PHOENIX AZ
430 AM MST WED SEP 17 2014

.UPDATE...UPDATED AVIATION AND FIRE WEATHER DISCUSSIONS...

&&

.SYNOPSIS...
TROPICAL STORM ODILE...WHICH IS NOW MOVING OVER THE NORTHERN WATERS
OF THE GULF OF CALIFORNIA...IS STILL EXPECTED TO MOVE NORTHEASTWARD
INTO...AND ACROSS SOUTHEAST ARIZONA LATE TONIGHT AND ON THURSDAY.
THERE IS A HIGH LIKELIHOOD OF HEAVY RAIN...AND FLOODING ACROSS
SOUTHEAST AND EAST-CENTRAL ARIZONA AS THE REMAINS OF ODILE MOVE
ACROSS THE REGION. AFTER THE REMNANTS OF ODILE MOVES OUT OF THE
REGION SOMETIME THURSDAY...SOME MOISTURE...ALONG WITH A CHANCE OF
SHOWERS AND THUNDERSTORMS WILL LINGER INTO THE WEEKEND. DRIER AIR
WILL GRADUALLY RETURN BY LATE IN THE WEEKEND INTO EARLY NEXT WEEK.

&&

.DISCUSSION...
TODAY THROUGH THURSDAY...
MODEL CONSENSUS CONTINUES TO IMPROVE AS FAR AS THE FORECAST FOR
TROPICAL STORM ODILE...WHICH IS NOW LOCATED ABOUT 85 MI SOUTH OF
PUERTO PENASCO...AND THE TIMING...EXTENT...AND AMOUNT OF RAINFALL
THAT IT WILL PRODUCE AS AT MOVES NORTHEASTWARD ACROSS SOUTHEAST AZ
LATER TODAY AND ON THURSDAY. THE LARGE-SCALE GLOBAL MODEL SUITES
(EURO/GFS) AND THE HI-RES MODELS ARE NOW IN GOOD AGREEMENT...TAKING
THE REMAINS OF ODILE NORTHEASTWARD ACROSS AZ TONIGHT AND EARLY THU.
THE EURO/GFS MODELS TRACK THE CENTER OF ODILE/S LOW-LEVEL
CIRCULATION RIGHT OVER THE TUCSON METRO AREA AROUND MIDNIGHT
TONIGHT...THEN INTO THE WHITE MOUNTAINS BY MIDDAY ON THURSDAY. THE
WRF4KM HI-RES MODEL...AND THE OFFICIAL NHC FORECAST...ON THE OTHER
HAND...BOTH MOVE THE CENTER OF ODILE/S CIRCULATION INTO
SOUTH-CENTRAL PINAL COUNTY BY EARLY THURSDAY MORNING...THEN INTO THE
WHITE MOUNTAINS ON THURSDAY AFTERNOON.

EITHER SOLN SHOULD KEEP THE HEAVIEST RAINFALL...IN THE 3-6 INCH
RANGE...TO THE SOUTH OF OUR CWA...OVER SE AZ...UNDER DEEP UPSLOPE
SOUTHERLY FLOW...WITH LOW-LEVEL DOWNSLOPE EASTERLY TO NORTHEASTERLY
FLOW TO THE NORTH OF THE CIRCULATION CENTER KEEPING RAINFALL AMOUNTS
DOWN ACROSS THE PHOENIX AREA...WITH EVEN LESS RAINFALL EXPECTED
ACROSS SW AZ AND SE CA. STILL...SOME AREAS ACROSS NORTHWEST PINAL
COUNTY AND SOUTHERN GILA COUNTY COULD SEE RAINFALL AMOUNTS IN THE
1.50-3.00 INCH RANGE...WITH THE GREATER PHOENIX AREA SEEING
STORM-TOTAL RAINFALLS IN THE 0.75-1.00 INCH RANGE...WHICH COULD
STILL RESULT IN LOCALIZED FLOODING. THE FLASH FLOOD WATCH REMAINS IN
EFFECT STARTING LATE THIS MORNING...LASTING THROUGH MIDDAY THURSDAY.

ACROSS SW AZ AND SE CA...ALTHOUGH OVERALL RAINFALL AMOUNTS WILL
LIKELY BE BELOW...OR WELL BELOW 0.75 INCH...LOCALIZED HEAVIER
SHOWERS COULD PRODUCE HEAVIER AMOUNTS THIS AFTERNOON...WHERE BREAKS
IN THE CLOUD COVER COULD ALLOW HEAVIER SHOWER/TS DEVELOPMENT. BY
LATE THURSDAY AFTERNOON...AS THE REMAINS OF ODILE MOVE OFF TO THE
EAST...AND AN APPROACHING UPPER TROF BEGINS TO SHIFT THE FLOW ALOFT
TO A WESTERLY ONE...CHANCES FOR RAINFALL ARE EXPECTED TO BEGIN TO
DIMINISH FROM WEST TO EAST...WITH THIS DRYING TREND CONTINUING INTO
THURSDAY NIGHT.

FRIDAY THROUGH TUESDAY...
ALTHOUGH WESTERLY FLOW ALOFT WILL PUSH SOMEWHAT DRIER AIR EASTWARD
INTO THE REGION FROM FRIDAY ONWARD INTO THE UPCOMING WEEKEND...WITH
PWATS ACROSS THE PHX AREA RUNNING IN THE 1.40-1.60 INCH
RANGE...DIFLUENCE AHEAD OF AN UPPER TROF THAT WILL BE APPROACHING
FROM THE WEST IS EXPECTED TO KEEP AT LEAST LOW-END CHANCES FOR
SHOWERS/TS GOING ACROSS SOUTH-CENTRAL AND SW AZ THROUGH THIS
WEEKEND...WITH THE BEST CHANCES FOR MEASURABLE RAINFALL ACROSS THE
HIGHER TERRAIN OF SOUTHERN GILA COUNTY. AT THIS POINT...IT APPEARS
THAT SATURDAY AFTERNOON/EVENING WILL BE THE MOST ACTIVE DAY...AS A
WEAK SHORTWAVE ROTATES NORTHWARD ACROSS THE REGION AHEAD OF THE MAIN
UPPER TROF. AS FAR AS THE IMPACT FROM TROPICAL STORM POLO IS
CONCERNED...THE LATEST NHC FORECAST TRACKS IT WELL TO THE SOUTH AND
WEST OF CABO SAN LUCAS AS HIGH PRESSURE RIDGING ALOFT BUILDS
WESTWARD TO THE NORTH OF THE STORM CENTER...KEEPING ITS IMPACTS WELL
TO OUR SOUTH AND WEST.

FURTHER DRYING IS EXPECTED EARLY NEXT WEEK AS THE AFOREMENTIONED
UPPER LOW LIFTS OUT TO OUR NORTH AND EAST AND HIGH PRESSURE ALOFT
BUILDS IN FROM THE WEST...WHICH SHOULD PRETTY MUCH END THE THREAT
FOR CONVECTIVE ACTIVITY OVER OUR CWA...WITH THE EXCEPTION OF SOME
ISOLATED STORMS OVER THE EASTERNMOST PORTION OF SOUTH GILA COUNTY.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL...
SHOWERS ARE MOVING TOWARD THE PHOENIX AREA BUT HAVE REALLY GOTTEN
SHEARED OUT THIS MORNING. NONETHELESS I STILL THINK A FEW HOURS OF
LIGHT RAIN IS WARRANTED IN THE PHOENIX TAFS ALONG WITH CIGS AROUND
10KFT. COULD BE LOWER /AROUND 5KFT/ FOR A BRIEF TIME WITHIN THE
HEAVIEST SHOWERS BASED ON OBS AT KCGZ BUT THIS HAS BEEN THE
EXCEPTION NOT THE RULE SO FAR THIS MORNING. MEANWHILE THE MODELS ARE
TRYING TO INDICATE A MID MORNING BREAK BEFORE ADDITIONAL CONVECTION
THIS AFTERNOON. TIMING AND PLACEMENT OF STORMS LATER TODAY IS VERY
DIFFICULT TO PIN DOWN AND CONFIDENCE MUCH BEYOND 19Z IS LIMITED.
CONFIDENCE THAT STORMS WILL FORM IS HIGH BUT WHERE/WHEN IS UP FOR
DEBATE.

SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH...
LOOKING LIKE BOTH SE CA SITES ARE ALREADY STARTING TO DRY OUT ONCE
AND FOR ALL. BOTH LOCATIONS HAVE BEEN DRY SINCE MIDNIGHT AND ITS
ENTIRELY CONCEIVABLE THAT THEY ARE DONE WITH THE RAIN FOR THIS
EVENT. I RETAINED A FEW HOURS OF CLOUD COVER THROUGH MID AFTERNOON
IN THE EVENT STORMS MANAGE TO FORM IN AZ AND DRIFT INTO SE CA...BUT
THE BIGGER IMPACTS WILL BE DISPLACED WELL INTO ARIZONA.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
FRIDAY THROUGH TUESDAY...
MOISTURE WILL REMAIN ELEVATED THROUGH SATURDAY BEFORE DRIER AIR
MOVES IN FROM THE WEST THIS WEEKEND. THIS WILL RE-ORGANIZE STORM
CHANCES TO THE MOUNTAINS EAST OF PHOENIX AS OPPOSED TO THE DESERTS.
STORM CHANCES WILL DIMINISH FURTHER THROUGH THE WEEKEND INTO NEXT
WEEK.  EVEN WITH THIS DRIER AIR...HUMIDITIES WILL ONLY DROP INTO THE
20-30 PERCENT RANGE WITH GOOD OVERNIGHT RECOVERIES EXPECTED. WINDS
TO REMAIN MAINLY ON THE LIGHT SIDE...EXCEPT AROUND THUNDERSTORMS.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...FLASH FLOOD WATCH FROM THIS MORNING THROUGH THURSDAY
     AFTERNOON AZZ021>024-027-028.

CA...NONE.

&&

$$

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

DISCUSSION...PERCHA
AVIATION...LEINS
FIRE WEATHER...LEINS




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