Area Forecast Discussion
Issued by NWS Phoenix, AZ

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FXUS65 KPSR 280439
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
935 PM MST MON JUL 27 2015

.SYNOPSIS...
DRY WESTERLY FLOW ALOFT WILL KEEP SHOWERS AND THUNDERSTORM CHANCES
WELL SOUTH OF PHOENIX OVERNIGHT. HOWEVER...INCREASING SOUTHERLY FLOW
ALOFT WILL GRADUALLY INCREASE MOISTURE LEVELS...AS WELL AS THE
THUNDERSTORM CHANCES FROM TUESDAY ONWARD THROUGH THE WEEKEND.

&&

.DISCUSSION...
IR SATELLITE IMAGERY/LIGHTNING SHOWS SOME THUNDERSTORM ACTIVITY THAT
PERSISTS THIS EVENING AROUND NOGALES. WITH THE DRIER SOUTHWESTERLY
FLOW ALOFT...DEBRIS CLOUDS ARE STREAMING OVER SOUTHEAST ARIZONA...
THE EDGE OF THE CLOUD SHIELD BARELY DRIFTING OVER THE GREATER
PHOENIX AREA. ACROSS OUR CWA/SOUTHEAST CALIFORNIA AND SOUTH-CENTRAL
ARIZONA... TEMPERATURES REMAIN WARM -- IN THE UPPER 90S TO NEAR 100
DEGREES. THERE IS ALSO A DEFINITE MOISTURE BOUNDARY THAT CAN BE
DISCERNED IN SURFACE OBSERVATIONS...WITH DEW POINT TEMPERATURES
STILL IN THE 20S AND 30S ACROSS SE CALIFORNIA AND PORTIONS OF THE
LOWER COLORADO RIVER VALLEY...AND EAST OF A LINE FROM YUMA TO
WICKENBURG...DEW POINTS HAVE BEEN SLOWLY CLIMBING BACK INTO THE 50S.

AN UPPER LEVEL LOW DRIFTING WESTWARD OVER NORTHERN MEXICO AND THE
GULF OF CALIFORNIA WILL AID IN THE INCREASE OF MOISTURE NORTHWARD
INTO ARIZONA AND NEW MEXICO OVER THE NEXT 12-18 HOURS. CURRENT MODEL
RUNS STILL SUGGEST A STRENGTHENING OF THE MOISTURE TRANSPORT OVER
THE NEXT FEW DAYS...WITH PRECIPITABLE WATER IN THE GFS MODEL
SOUNDINGS RISING UP CLOSE TO 1.8IN BY THURSDAY...NICELY SATURATED
THROUGHOUT THE MID AND UPPER LEVELS.

EVERYTHING SUGGESTS A QUICK RAMP UP IN MONSOON STORM ACTIVITY OVER
THE NEXT FEW DAYS/THROUGH THURSDAY ACROSS SOUTHWEST AND SOUTH-
CENTRAL ARIZONA...PRESSING AN INFLUENCE INTO SOUTHEAST CA AS WELL.
TUESDAY ACTIVITY IS MORE LIKELY TO REMAIN MOSTLY SOUTH AND SOUTHEAST
OF OUR AREA...BUT THAT OFTEN BRINGS WITH IT A GOOD CHANCE FOR
BLOWING DUST AND MAYBE EVEN DUST STORMS IN THE LATE AFTERNOON AND
EARLY EVENING. THE WRF FOR WEDNESDAY EVEN BRINGS A STRONG OUTFLOW
BOUNDARY THROUGH...GENERATED FROM EXTENSIVE CONVECTION PREDICTED
FROM PIMA COUNTY STORMS. CLEARLY WE WILL HAVE AN ACTIVE MONSOON
PERIOD BEGINNING TUESDAY WITH ACTIVE THUNDERSTORMS AND POTENTIAL FOR
DUST STORMS. AN AREA OF BLOWING DUST WAS ADDED TO OUR GRIDS FOR
TUESDAY AND WEDNESDAY.

BEYOND FRIDAY...WE WILL RETAIN ENOUGH MONSOON MOISTURE TO KEEP UP
SOME ACTIVITY THROUGH THE WEEKEND...BUT LACKING FORCING/TRIGGERING
MECHANISMS...IT DOES NOT APPEAR TO BE AS STRONG AS THE TUESDAY
THROUGH EARLY FRIDAY PERIOD.

&&

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

MOSTLY CLEAR SKIES AND LIGHT WINDS GENERALLY LESS THAN 10KT. STILL
EXPECTING A LATE SHIFT TO EASTERLY FLOW SOMETIME AROUND 12Z TUESDAY.
BY TUESDAY AFTERNOON...EXPECT OCCASIONAL LOCAL WIND GUSTS TO AROUND
15KT...WITH THUNDERSTORMS DEVELOPING WELL SOUTH AND EAST OF THE
TERMINALS AFTER 22Z...AND THE POTENTIAL FOR THUNDERSTORM OUTFLOWS
REACHING INTO THE DESERTS DURING THE EVENING HOURS.

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

A FAIRLY PERSISTENT SOUTH SOUTHWESTERLY WIND EXPECTED INTO TUESDAY
WITH OCCASIONAL AFTERNOON AND EARLY EVENING BREEZINESS AT KBLH.
SKIES WILL REMAIN CLEAR TO MOSTLY CLEAR THROUGH THE PERIOD.

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...MEYERS/WATERS
AVIATION...MEYERS
FIRE WEATHER...KUHLMAN


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