Area Forecast Discussion
Issued by NWS Phoenix, AZ

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FXUS65 KPSR 281138 AAA
AFDPSR

AREA FORECAST DISCUSSION...UPDATE
NATIONAL WEATHER SERVICE PHOENIX AZ
438 AM MST TUE JUL 28 2015

.UPDATE...
AVIATION SECTION UPDATE.

&&

.SYNOPSIS... AN GRADUAL INCREASE IN SOUTHERLY FLOW...AND MOISTURE
WILL ALLOW THUNDERSTORM CHANCES TO SLOWLY INCREASE THROUGH THURSDAY.
HIGH PRESSURE BUILDING OVER THE REGION WILL THEN REDUCE THUNDERSTORM
CHANCE SOMEWHAT THROUGH THE REMAINDER OF THE WORKWEEK AND THE
UPCOMING WEEKEND...AND INTO EARLY NEXT WEEK.

&&

.DISCUSSION...
TODAY THROUGH THURSDAY... ALTHOUGH THE OVERALL LARGE-SCALE FORECAST
HAS NOT CHANGED MUCH WITH THE LATEST MODEL SUITES...SOME CHANGES IN
THE DETAILS HAVE EMERGED. IT NOW APPEARS THAT THE UPRAMP IN
AVAILABLE MOISTURE OVER THE REGION WILL BE A BIT SLOWER AND LESS
ROBUST THAN WHAT HAD BEEN SEEN ON EARLIER MODEL RUNS...WITH PWATS
ONLY RISING TO AROUND 1.60 INCHES ACROSS SOUTH-CENTRAL ARIZONA BY
WEDNESDAY...INSTEAD OF AROUND 1.80 INCHES...WHICH WAS FORECAST ON
EARLIER GFS MODEL RUNS.  ALSO...ALTHOUGH THE FLOW ALOFT IS STILL
EXPECTED TO BECOME MORE SOUTHERLY OVER TIME...AS THE MAIN UPPER HIGH
CENTER BUILDS WESTWARD FROM THE SOUTHERN PLAINS INTO THE DESERT
SOUTHWEST...IT NOW APPEARS THAT IT WILL TAKE A BIT LONGER FOR DEEP
SOUTHERLY FLOW TO BECOME ESTABLISHED THROUGH THE COLUMN. THUS...IT
NOW APPEARS THAT CONVECTIVE ACTIVITY WILL LIKELY BE A BIT LESS THAN
WHAT WAS EARLIER FORECAST...WITH JUST SOME ISOLATED STORMS MAKING
THEIR WAY INTO SOUTH-CENTRAL ARIZONA TODAY...WITH BETTER CHANCES
STILL FORECAST ON WEDNESDAY AND THURSDAY.

ALTHOUGH SOME BLOWING DUST IS STILL POSSIBLE THIS EVENING AS
OUTFLOWS FROM STORMS OVER SE AZ MOVE INTO THE REGION...THE LATEST
HIGH-RES MODELS ARE NOT SHOWING WINDS MUCH OVER 20 KNOTS.
THUS...DENSE BLOWING DUST IS NOT EXPECTED...WITH MOST OF IT LIKELY
BEING CONFINED TO PINAL AND SOUTHERLY MARICOPA COUNTIES. A BETTER
CHANCE FOR DENSE BLOWING DUST EXISTS ON WEDNESDAY AND THURSDAY AS
THE STORMS ARE MORE LIKELY TO MOVE CLOSER...OR INTO OUR CWA.
ALTHOUGH THE INCREASE IN CLOUDINESS AND CONVECTIVE ACTIVITY WILL
KEEP HIGHS DOWN A BIT ON WEDNESDAY AND THURSDAY...SIGNIFICANT
COOLING IS NOT LIKELY...SINCE WIDESPREAD MORNING CONVECTION/RAINFALL
IS NOT EXPECTED AT THIS TIME.

BEYOND FRIDAY...

ALTHOUGH THERE WILL STILL BE ENOUGH MONSOON MOISTURE TO KEEP UP SOME
ACTIVITY THROUGH THE WEEKEND AND INTO EARLY NEXT WEEK
...THE COMBINATION OF LESS AVAILABLE MOISTURE (PWATS ONLY IN THE 1.3-
1.4 INCH RANGE ACROSS SOUTH-CENTRAL AZ) AND WARMER MID-LEVEL
TEMPERATURES...AS THE MAIN THE UPPER HIGH POSITIONS ITSELF PRETTY
MUCH OVERHEAD DURING THIS ENTIRE PERIOD...WILL LIKELY LIMIT
THUNDERSTORM ACTIVITY...WITH PRETTY MUCH NEAR-CLIMO POPS LOADED INTO
THE GRIDS AT THIS TIME.

&&

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

WESTERLY WINDS ARE JUST FINALLY STARTING TO RELAX ACROSS THE PHOENIX
METRO AREA. EXPECT VERY LIGHT EAST DRAINAGE WINDS THROUGH MID
MORNING...BUT CAN/T RULE OUT THAT THEY DON/T SWING BACK AROUND TO
THE WEST AT TIMES. WEST WINDS SHOULD TAKE HOLD AGAIN AROUND 19Z.
LATER TONIGHT...GOOD CHANCE OF AN OUTFLOW FROM DISTANT THUNDERSTORMS
MOVING NORTH INTO THE PHOENIX AREA. RIGHT NOW DOESN/T APPEAR IT WILL
BE VERY STRONG OR REDUCE VISIBILITY TO A GREAT EXTENT AND IT IS MORE
LIKELY TO OCCUR AFTER THE EVENING PUSH AT KPHX. MORE REFINEMENT
THROUGH THE DAY.

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

FAIRLY LIGHT WINDS WITH LITTLE DIRECTIONAL CHANGE THROUGH THE NEXT 24-
36 HOURS.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
THURSDAY THROUGH MONDAY...
WIDESPREAD MOISTURE WILL ENCOMPASS MUCH OF THE REGION LATE IN THE
WEEK BRINGING CHANCES FOR SHOWERS AND THUNDERSTORMS MAINLY DURING
THE AFTERNOON AND EVENING HOURS WITH BEST CHANCES ACROSS HIGHER
TERRAIN AREAS. A SUBTLE SHIFT IN THE MID LEVEL WIND FLOW SHOULD LEAD
TO SOME DRYING FOR FRIDAY INTO THE WEEKEND ALONG WITH SLIGHTLY LOWER
RAIN CHANCES. TEMPERATURES THROUGH THE PERIOD WILL REMAIN NEAR
NORMALS WHILE MINIMUM AFTERNOON HUMIDITIES WILL GENERALLY FALL INTO
A 20-30 PERCENT RANGE OVER THE DESERTS EACH DAY. WINDS WILL REMAIN
FAIRLY LIGHT EACH DAY ASIDE FROM AFTERNOON BREEZINESS AND POTENTIAL
FOR STRONGER THUNDERSTORM OUTFLOW WINDS.

&&

.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
AVIATION...INIGUEZ
FIRE WEATHER...KUHLMAN



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