Area Forecast Discussion
Issued by NWS Phoenix, AZ

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FXUS65 KPSR 050358
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
858 PM MST FRI SEP 4 2015

.SYNOPSIS...
SOMEWHAT DRIER AIR WILL MOVE INTO THE REGION OVER THE
WEEKEND...REDUCING RAINFALL CHANCES SLIGHTLY. WHILE SOME THUNDERSTORM
CHANCES WILL PERSIST DURING THE FIRST HALF OF NEXT WEEK...A
SUBSTANTIALLY WARMER AND DRIER AIRMASS WILL SPREAD INTO THE AREA FOR
THE LATTER HALF OF THE WEEK.

&&

.DISCUSSION...
MOISTURE REMAINS SOMEWHAT LIMITED...BUT STILL SUFFICIENT FOR STORM
ACTIVITY...ACROSS SOUTH-CENTRAL ARIZONA THIS EVENING WITH DRIER
CONDITIONS ACROSS SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA. SHOWERS
AND THUNDERSTORMS LATE THIS AFTERNOON AND EVENING WERE MAINLY
CONFINED ACROSS SOUTHERN AND WESTERN PORTIONS OF MARICOPA COUNTY AND
WERE FAIRLY WEAK IN NATURE. FOR THE REST OF THE EVENING...WILL SEE
THE REMAINING SHOWERS CURRENTLY MOVING THROUGH THE NORTHERN AND
WESTERN PHOENIX METRO AREA MOVE TO THE NORTHEAST AND LIKELY DIMINISH
COMPLETELY WITHIN AN HOUR OR TWO. WITH DYNAMICS ASSOCIATED WITH A
70KT 300MB JET MAX OVER THE FOUR CORNERS REGION IN PLACE TONIGHT
WILL STILL SEE A MINIMAL THREAT OF A FEW SHOWERS AND MAYBE A
THUNDERSTORM WITH BEST CHANCES FROM PHOENIX EASTWARD. HAVE MADE SOME
MINOR TWEAKS TO POPS THROUGH THE REST OF TONIGHT...BUT OVERALL THE
PREVIOUS FORECAST IS STILL IN GOOD SHAPE.

&&

.PREVIOUS DISCUSSION...
FOR THIS WEEKEND...UPPER TROFFING REMAINS SITUATED ALONG THE WEST
COAST AND ARIZONA WILL STAY UNDER A SOUTHWEST FLOW ALOFT.
HOWEVER...LATEST GUIDANCE DOES NOT REALLY DRY OUT THE EASTERN HALF OF
THE STATE...ESPECIALLY IN THE LOWER LEVELS. PWAT VALUES ARE FORECAST
TO REMAIN NEAR OR ABOVE 1.5 INCHES OVER SOUTH CENTRAL ARIZONA THROUGH
SUNDAY...EVEN THOUGH MUCH OF THE MOISTURE FROM KEVIN WILL HAVE
ALREADY LIFTED OUT TO THE NORTHEAST BY SATURDAY EVENING.
AGAIN...DYNAMICS NOT ESPECIALLY IMPRESSIVE EITHER DAY BUT THERE WILL
LIKELY BE WEAK DISTURBANCES MOVING THROUGH THE SOUTHWEST FLOW FROM
TIME TO TIME...INCREASING THE THREAT FOR SHOWERS OR STORMS.
STREAMLINES REMAIN RATHER LAMINAR AND SOUTHWESTERLY...SIMILAR TO WHAT
IS SEEN TODAY. WE FEEL IT IS A BIT OPTIMISTIC TO REMOVE THE THREAT
FOR CONVECTION FROM THE FORECAST THIS WEEKEND...SO WE WILL RAISE POPS
SLIGHTLY AND KEEP SOUTH CENTRAL AZ UNDER AT LEAST A SLIGHT CHANCE FOR
AFTERNOON/EVENING STORMS BOTH SATURDAY AND SUNDAY.

CONVECTIVE POTENTIAL FOR EARLY NEXT WEEK MAY BE SOMEWHAT MORE MUTED
THAN RECENT DAYS AS DEEP LAYER WINDS VEER SOMEWHAT MORE WESTERLY AS
TROUGHING TRANSLATES INTO THE GREAT BASIN AND NRN ROCKIES.
STILL...BOUNDARY LAYER MOISTURE WILL BE DIFFICULT TO COMPLETELY
SCOUR OUT AND SOME MODEST INFUSION OF MIDLEVEL MOISTURE PEELING OFF
THE REMNANTS OF KEVIN MAY BE POSSIBLE. HOWEVER...THERE REMAINS SOME
DISCONNECT WITH THE MORE QUALITY TROPICAL MOISTURE TO THE
SOUTH...AND THE BEST WV TRANSPORT MAY BE DEFLECTED AROUND THE
FORECAST AREA. IN ADDITION...WITH MID LATITUDE TROUGHING LIFTING TO
THE NORTH AND HEIGHTS ALOFT RISING AHEAD OF THE REMNANT TROPICAL
SYSTEM...MODELS DEPICT SUBSTANTIAL MIDLEVEL WARMING AND INCREASED
CONVECTIVE INHIBITION. KEPT SOME MODEST NEAR CLIMATOLOGY POPS
THROUGH TUESDAY...HOWEVER MEASURABLE RAINFALL AT LOWER DESERT
ELEVATIONS MAY BE DIFFICULT TO COME BY.

SOME MINOR UNCERTAINTY STILL EXISTS FOR THE LATTER HALF OF NEXT WEEK
AS SUBTLE DIFFERENCES IN THE SUBTROPICAL RIDGE POSITION WILL DICTATE
IF AND HOW QUICKLY MOISTURE IS COMPLETELY SCOURED SOUTH OF THE
FORECAST AREA. MESOSCALE PROCESSES AND OUTFLOW FROM SONORAN MCS/S
MAY ALLOW FOR GULF SURGES AND BOUNDARY LAYER MOISTURE
ADVECTION...BUT DEFINITIVELY FORECASTING AND TIMING SUCH EVENTS
WOULD PROVE FRUITLESS AT THIS TIME. REGARDLESS...H5 HEIGHT RISES AOA
590DM WILL RESULT IN TEMPERATURES PEAKING BACK ABOVE NORMAL UNDER
GRADUALLY MORE COMPRESSIONAL SUBSIDENT FLOW.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL...
SCT-BKN MID CLOUDS AOA 10KFT CAN BE EXPECTED THROUGH THE REST OF
TONIGHT WITH A FEW LINGERING SHOWERS POSSIBLE ACROSS THE NORTH AND
WEST PART OF PHOENIX INTO LATE EVENING. WINDS WILL GRADUALLY SHIFT TO
AN EASTERLY DIRECTION AFTER MIDNIGHT AND REMAIN EITHER EASTERLY OR
SOUTHEASTERLY THROUGH SATURDAY AFTERNOON. ANOTHER CHANCE OF SCATTERED
SHOWERS AND THUNDERSTORMS WILL BE PRESENT LATE SATURDAY AFTERNOON AND
EVENING.

SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH...
SKIES GENERALLY CLEAR WITH A FEW MID-HIGH CLOUDS DURING PERIOD.
WINDS WILL REMAIN LESS THAN 12 KTS AT KIPL AND SOMEWHAT VARIABLE
WHILE A PERSISTENT SOUTHERLY WIND AT KBLH WILL BE GUSTY DURING THE
DAYTIME HOURS.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
MONDAY THROUGH FRIDAY...
STORM CHANCES WILL CONTINUE OVER SOUTH-CENTRAL ARIZONA BEFORE
TRENDING DOWN SIGNIFICANTLY WEDNESDAY. HUMIDITIES WILL ALSO BEGIN TO
TREND DOWN FROM WEST TO EAST ACROSS THE ENTIRE FORECAST AREA NEXT
WEEK...BEGINNING AS EARLY AS MONDAY. A GRADUAL WARMING TREND WILL
ENSUE DURING THE PERIOD CLIMBING TO SEVERAL DEGREES ABOVE NORMAL BY
NEXT THURSDAY.

&&

.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...KUHLMAN
PREVIOUS DISCUSSION...CB/MO
AVIATION...KUHLMAN
FIRE WEATHER...MEYERS


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