Area Forecast Discussion
Issued by NWS Phoenix, AZ

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000
FXUS65 KPSR 111640
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
940 AM MST FRI JUL 11 2014

.SYNOPSIS...
MONSOON FLOW WILL BE DISRUPTED SOMEWHAT STARTING TODAY INTO THE
WEEKEND WITH THUNDERSTORM ACTIVITY MAINLY CONFINED ACROSS HIGHER
TERRAIN AREAS. THIS TEMPORARY LULL IN MONSOON ACTIVITY WILL ALLOW
FOR AN INCREASE IN HIGH TEMPERATURES...WARMING WELL INTO THE ABOVE
NORMAL CATEGORY. MOISTURE SHOULD BEGIN TO SURGE BACK TO THE NORTH
AND WEST EARLY NEXT WEEK ALLOWING MORE WIDESPREAD THUNDERSTORM
ACTIVITY WHILE TEMPERATURES FALL BACK TOWARDS THE SEASONAL NORMALS.

&&

.DISCUSSION...
THIS MORNINGS WATER VAPOR SATELLITE IMAGERY SHOWS A LARGE GRADIENT
IN MOISTURE ACROSS THE FORECAST AREA...WITH MUCH DRIER AIR PUNCHING
ACROSS SE CALIFORNIA INTO NORTHWEST ARIZONA. THIS IS REFLECTED IN
THE DIFFERENCE IN PWAT BETWEEN YUMA AND PHOENIX UPPER AIR SOUNDINGS
THIS MORNING...WITH YUMA (K1Y7) MEASURING .73 INCH AND PHOENIX
(KPSR) SHOWING OVER AN INCH MORE AT 1.77 INCH. SOME ENHANCED
CLOUDINESS WAS SEEN ON IR IMAGERY ALONG THE BOUNDARY BETWEEN THE DRY
AND MOIST AIR EXTENDING NORTHWARD FROM MX TO THE COLORADO RIVER. THE
KPHX SOUNDING ALREADY IS SHOWING SOME DRYING BELOW 85H AND BETWEEN
45H AND 40H. MODEL ECMWF AND GFS BUFR SOUNDINGS INDICATE ADDITIONAL
DRYING SHOULD OCCUR THROUGH THE DAY TODAY. DEWPOINTS THIS MORNING
ACROSS THE REGION WERE RUNNING SEVERAL DEGREES LOWER THAN THIS SAME
TIME YESTERDAY..INDICATING PRESENCE OF LESS BOUNDARY LAYER MOISTURE.

GFS...ECMWF...NAM...AND HI RES MESOSCALE MODELS ALL INDICATE MONSOON
ACTIVITY WILL BE MINIMAL TODAY. STORMS THAT DO DEVELOP SHOULD REMAIN
OVER THE RIM AND HIGHER TERRAIN TO OUR EAST AND OVER EXTREME
SOUTHEAST ARIZONA. THAT BEING SAID...WE WILL NEED TO CONTINUE TO
MONITOR OUTFLOW FROM STORMS THAT DO DEVELOP AND CANNOT RULE OUT AN
ISOLATED STORM OR TWO IN THE LOWER DESERTS AND SOME BLOWING
DUST...MAINLY OVER PINAL COUNTY.

FORECAST FOR THE MOST PART WAS ON TRACK. DID ADJUST DEWPOINT GRIDS
AND RAISED MAXIMUM TEMPERATURES TODAY A TAD IN SOME AREAS.

.PREV DISCUSSION...
ISSUED AT 505 AM MST FRI JUL 11 2014

AS OF YESTERDAY AFTERNOON...MUCH DRIER AIR HAS FILTERED INTO
SOUTHEAST CALIFORNIA AND FAR SOUTHWEST ARIZONA DROPPING SURFACE DEW
POINTS INTO THE 30S AND 40S. CURRENT WATER VAPOR IMAGERY SHOWS
THE DRY AIR WORKING ITS WAY NORTH NORTHEASTWARD BEHIND AN
EXITING WEAK SHORTWAVE MOVING INTO SOUTHERN NEVADA. ON THE LARGE
SCALE THIS IS AIDED BY AN EASTWARD SHIFT OF THE SUBTROPICAL HIGH
INTO THE CENTRAL PLAINS. THE EASTERN HALF OF ARIZONA IS STILL FAIRLY
RIPE WITH MOISTURE WITH PWATS STILL ABOVE ONE INCH. A WEAK WAVE
CREEPING NORTHWESTWARD THROUGH NORTHERN MEXICO HELPED TO TRIGGER AN
AREA OF THUNDERSTORMS THAT ARE CURRENTLY ONGOING OVER SOUTHEAST
ARIZONA. THERE HASN/T BEEN MUCH NORTHWARD PROGRESSION OF THE
THUNDERSTORMS SINCE MIDNIGHT AND CURRENT THINKING IS THEY WILL
MOSTLY DIE OUT BEFORE REACHING SOUTHERN GILA COUNTY.

MODELS INDICATE THE DRY AIR WILL NOT MAKE MUCH MORE HEADWAY
EASTWARD...GENERALLY STALLING SOMEWHERE ACROSS CENTRAL ARIZONA.
HOWEVER...WE DO THINK THIS WILL MAINLY KEEP THUNDERSTORM CHANCES FOR
TODAY OVER HIGHER TERRAIN AREAS NORTH AND EAST OF PHOENIX. A WEAK
SOUTHWESTERLY STEERING FLOW SHOULD KEEP ANY STORMS THAT DO FIRE OVER
THE HIGH TERRAIN FROM MOVING INTO THE LOWER DESERTS. SIMILAR
CONDITIONS WILL EXIST FOR SATURDAY...THOUGH MONSOON ACTIVITY WILL BE
EVEN MORE SUPPRESSED AND GENERALLY CONFINED TO SOUTHEAST ARIZONA AS
THE DRY AIR INFILTRATES ALL BUT SOUTHEAST AND EAST CENTRAL ARIZONA.
HIGH TEMPERATURES WILL GET A BOOST DUE TO THE DRIER CONDITIONS WITH
HIGHS REACHING AROUND NORMAL FOR TODAY AND LIKELY PEAKING OUT AROUND
110 IN THE HOTTEST SPOTS ON SATURDAY.

BY SUNDAY...THE SUBTROPICAL HIGH CENTER REORIENTS ITSELF OVER THE
GREAT BASIN AS A DEEP UPPER LOW DIVES INTO THE GREAT
LAKES...AMPLIFYING THE UPPER RIDGING OVER THE WESTERN UNITED STATES
AND CANADA. THIS WILL SHIFT WINDS BACK AROUND TO AN EASTERLY
DIRECTION AND ALLOW FOR A RESURGENCE OF MOISTURE TO BEGIN. THE
FORECAST FOR SUNDAY IS A BIT TRICKY AT THIS POINT SINCE IT DEPENDS
ON THE TIMING OF THE MOISTURE SURGE. THINKING IS IT WILL BE A MUCH
MORE ACTIVE MONSOON DAY ACROSS THE HIGHER TERRAIN IN EASTERN ARIZONA
AND WITH AN EASTERLY STEERING FLOW SOME OF THESE STORMS MAY SURVIVE
INTO THE LOWER DESERTS. IF THE MOISTURE HASN/T FILTERED INTO THE
LOWER DESERTS BY SUNDAY AFTERNOON...THUNDERSTORM OUTFLOWS INTO THE
LOWER DESERTS WILL BE MUCH MORE LIKELY THAN ACTUAL THUNDERSTORMS.
FORECAST SOUNDINGS FOR SUNDAY DO SHOW A FAVORABLE STRUCTURE FOR
GUSTY WINDS...SO CAN/T RULE OUT THE POSSIBILITY FOR A FEW STRONG TO
SEVERE WIND GUSTS FROM PHOENIX EASTWARD.

THE FULL FORCE OF THE MONSOON MOISTURE WILL OVERSPREAD THE REST OF
ARIZONA BY MONDAY AND LIKELY LAST THROUGH MUCH OF NEXT WEEK. AS PER
THE PREVIOUS COUPLE FORECAST PACKAGES...MONDAY POPS ARE THE HIGHEST
DURING THE PERIOD DUE TO A HINT OF AN INVERTED TROUGH MOVING THROUGH
SOUTHERN ARIZONA. A GENERAL SLIGHT CHANCE OVER THE LOWER DESERTS AND
CHANCE POPS OVER THE HIGHER TERRAIN IS FORECAST AFTER MONDAY.
TEMPERATURES WILL TREND DOWNWARD STARTING MONDAY AND LIKELY END UP
BEING A COUPLE DEGREES BELOW NORMAL ACROSS ARIZONA AREAS TO AROUND
NORMAL FOR SOUTHEAST CALIFORNIA.
+
&&

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

UNUSUALLY TRANQUIL CONDITIONS WILL PREVAIL ACROSS THE REGION THROUGH
SATURDAY MORNING...WITH VARYING AMOUNTS OF SCT-BKN CLOUD COVER AND
BASE HEIGHTS RANGING FROM 12K-25K FT. OUTSIDE OF THE PREFERRED LATE
NIGHT/MORNING TIME FRAMES OF LIGHT AND VARIABLE/DRAINAGE
WINDS...DIRECTIONS SHOULD KEEP MOSTLY A SOUTHWESTERLY HEADING.
SPEEDS SHOULD STAY BELOW 12KT...THOUGH A FEW BRIEF GUSTS UP TO 20KT
MAY BE POSSIBLE LATE IN THE AFTERNOON.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
SUNDAY THROUGH THURSDAY...
A SURGE OF RENEWED MONSOON MOISTURE WILL AFFECT THE DISTRICT
BEGINNING SUNDAY NIGHT EVENTUALLY LEADING TO SIGNIFICANTLY INCREASED
CHANCES OF SHOWERS AND THUNDERSTORMS...HIGHER HUMIDITIES...AND
SLIGHTLY LOWER AFTERNOON HIGH TEMPERATURES. THE BEST OPPORTUNITY FOR
WETTING RAIN WILL OCCUR ON MONDAY AND TUESDAY...WITH CHANCES
GENERALLY TAPERING DOWN LATER IN THE WEEK. WINDS WILL REMAIN RATHER
LIGHT WITH ONLY OCCASIONAL AFTERNOON GUSTS...HOWEVER SUBSTANTIALLY
STRONGER GUSTS WILL ACCOMPANY ANY AFTERNOON AND EVENING
THUNDERSTORMS. MINIMUM HUMIDITY LEVELS WILL GENERALLY ONLY FALL INTO
A 20 TO 30 PERCENT RANGE...WITH GOOD TO EXCELLENT OVERNIGHT
RECOVERY.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

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

DISCUSSION...MCLANE/KUHLMAN
AVIATION....MO
FIRE WEATHER...MO








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