Area Forecast Discussion
Issued by NWS Phoenix, AZ

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FXUS65 KPSR 011209
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
510 AM MST SAT AUG 1 2015

.UPDATE...TO AVIATION AND FIRE WEATHER DISCUSSIONS...

&&

.SYNOPSIS...
STORM CHANCES WILL BE LESS TODAY WITH CHANCES LIMITED TO AREAS EAST
OF THE LOWER COLORADO RIVER VALLEY. FURTHER DRYING OCCURS NEXT WEEK
WITH STORM CHANCES CONFINED TO THE HIGHER TERRAIN EAST OF PHOENIX.
TEMPERATURES WILL HOVER NEAR NORMAL THROUGH NEXT WEEK.

&&

.DISCUSSION...
PER LATEST RADAR AND SATELLITE IMAGERY...MOST OF THE SOUTH CENTRAL
DESERTS ARE QUIET ASIDE FROM SOME DEVELOPING STORMS ACROSS SOUTHERN
LA PAZ COUNTY. UNDER THE BULLSEYE OF MAX PRECIPITABLE WATER /1.7 -
1.8 INCH/ AND RIDING A SHORTWAVE INVERTED TROUGH FEATURE MOVING
NORTH THROUGH WESTERN ARIZONA...THERE SEEMS TO BE JUST ENOUGH
INSTABILITY TO GENERATE SOME THUNDERSTORMS EARLY THIS MORNING.
CONCERNING THE MESOSCALE CONVECTIVE MODELS...THE GFS FLAVORS HAVE
INITIALIZED BETTER THAN THE NAM...HINTING AT SOME EARLY AM ACTIVITY
ACROSS WESTERN AZ AND FAR SOUTHEASTERN CA. AS THE UPPER LEVEL FLOW
CONTINUES TO SHIFT MORE TO A SOUTHERLY DIRECTION...MID TO UPPER
LEVEL WINDS SUPPORT A DIFFLUENT ZONE FROM PARKER TO SHOW LOW WHERE
THE RIDGE OF HIGH PRESSURE TO THE EAST MOVES WEST AND AN EMBEDDED
TROUGH FEATURE PUSHES NORTH THROUGH SOUTHERN CALIFORNIA.
TEMPERATURES WARMED A FEW DEGREES HIGHER THAN ANTICIPATED
FRIDAY...TIPPING A HAT TO THE CLEAR SKIES WHICH IN TURN GAVE ENOUGH
DAYTIME HEATING TO GENERATE CONVECTIVE INITIATION EARLY IN THE DAY.

CLEARING SKIES FROM THE SOUTH WILL AGAIN PLAY INTO CONVECTIVE
INITIATION PROVIDING THE ATMOSPHERE IS NOT COMPLETELY MIXED THROUGH
AND OVERWORKED FROM LAST EVENING. LITTLE CHANGE IN ATMOSPHERIC
MOISTURE FROM AREA UPPER AIR SOUNDINGS COMPARING 12Z FRIDAY TO 00Z
SATURDAY. THE BIG FACTOR AGAIN TODAY WILL BE SUFFICIENT DAYTIME
HEATING. UTILIZING THE TROUGH TO THE WEST AND THE REMNANT INVERTED
TROUGH FEATURE SHOULD BE THE DYNAMIC LIFT NEEDED TO DRIVE STORM
DEVELOPMENT. THE HIGHER TERRAIN MOUNTAIN LOCATIONS WILL BE MORE
FAVORABLE FOR ACTIVITY.

LOOKING AHEAD SUNDAY THROUGH WEDNESDAY WILL BE MUCH QUIETER ON THE
STORM FRONT...AS SOUTHWESTERLY FLOW SETTLES IN WITH THE HIGH MOVING
FARTHER WEST. A DRYING AND SUBTLE WARMING TREND WILL TAKE PLACE
ACROSS THE DESERT SOUTHWEST...ALLOWING TEMPERATURES TO REACH JUST
ABOVE SEASONAL AVERAGE. MORE OF A MONSOON PATTERN WILL RETURN LATE
IN THE WEEK WITH A RETURN TO SOUTH-SOUTHEASTERLY FLOW AND BACK ABOVE
THE 90TH PERCENTILE IN TERMS OF PRECIPITABLE WATER READINGS.

&&

.AVIATION...
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL...
AMPLE AREA OF DEBRIS CLOUDS LINGER ACROSS SOUTH-CENTRAL AZ...AND IN
PARTICULAR AT TIME OF THIS WRITING ALONG THE NORTHERN MARICOPA
COUNTY LINE. SOME SHOWERS HAVE POPPED-UP ACROSS PORTIONS OF THE
NORTH VALLEY...SO AM VCSH WERE INCLUDED IN THE KPHX AND KSDL TAFS.
SFC FLOW THIS AM MAINTAINING SOME WEAK WESTERLY
INFLUENCE...OTHERWISE WINDS WILL BE VRB UNTIL MIDDAY WHEN STRONGER
WEST FLOW AT THE SFC AND ALOFT TRANSITIONS INTO THE AREA. COULD SEE
ANOTHER ROUND OF POP-UP STORMS OVER PARTS OF THE DESERTS THIS
AFTERNOON...WITH INITIATION PROGGED ATTM AROUND 01/22Z TO 02/00Z.
SOUTHERLY AM CLOUD/STORM MOTION WILL TRANSITION TO WESTERLY BY THE
AFTERNOON...SENDING ANY PTNL STORMS THAT MAY FORM ACROSS W/SW
MARICOPA COUNTY TOWARDS THE PHX METRO. COVERAGE SHOULD BE MORE
LIMITED THAT WHAT WAS OBSERVED ON FRIDAY...BUT WITH STILL PLENTY OF
MOISTURE IN PLACE DURING THE DAY...CANNOT RULE OUT SOME VC DEVELOPMENT
THIS AFTN.


SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA INCLUDING KIPL AND
KBLH...
PASSING FEW-SCT MID AND HIGH LEVEL CLOUDS WILL CONTINUE TO STREAM
MOSTLY TO THE NORTH BEFORE SKIES CLEAR ALMOST COMPLETELY BY THE LATE
AFTN/EVENING HOURS. DRYING WEST TO SOUTHWEST FLOW ALOFT SHOULD KEEP
ANY STORM CHANCES EAST IN AZ THROUGHOUT THE DAY. WINDS OVERALL TO
FAVOR SOUTHERLY HEADINGS FOR KBLH AND WESTERLY FOR KIPL.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
MONDAY THROUGH FRIDAY...
SOUTHWEST TO WEST FLOW THROUGH THE BULK OF THE ATMOSPHERIC
COLUMN...SFC TO UPPER LEVELS...WILL SWEEP THE MONSOON MOISTURE
SURFACE INTO FAR EASTERN AZ. STORM CHANCES WILL BE RELEGATED TO THE
HIGHER TERRAIN WITH MOSTLY QUIET CONDITIONS EXPECTED OVER THE LOWER
DESERT ELEVATIONS. MINIMUM RH VALUES WILL BEGIN TO SETTLE INTO THE
TEENS WHILE STILL MAKING MOSTLY MODEST TO FAIR OVERNIGHT RECOVERIES.
THE SLIGHTLY DRIER AIRMASS AND BUILDING UPPER RIDGE HEIGHTS WILL
LEND THEMSELVES TOWARD WARMER SFC CONDITIONS...AT OR ABOVE SEASONAL
NORMALS. WINDS WILL FOLLOW FAMILIAR WARM SEASON PATTERNS. BY MIDWEEK
A SUBTLE RETURN OF GULF MOISTURE MAY BOOST AREA HUMIDITIES AND BRING
SOME STORM CHANCES OUT OF THE MOUNTAINS AND BACK INTO THE LOWER AZ
DESERT LOCALES. DAYTIME HUMIDITIES WILL RETURN TO READINGS IN THE
UPPER TEENS TO LOW TWENTIES.

&&

.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...DEWEY
AVIATION...NOLTE
FIRE WEATHER...NOLTE


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