Area Forecast Discussion
Issued by NWS Phoenix, AZ

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000
FXUS65 KPSR 011140
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
440 AM MST FRI AUG 01 2014

.UPDATE...UPDATED AVIATION AND FIRE WEATHER...

&&

.SYNOPSIS...
SCATTERED LIGHT SHOWERS AND ISOLATED THUNDERSTORMS WILL LINGER
ACROSS SOUTH-CENTRAL ARIZONA THIS MORNING BEFORE TAPERING OFF. STORM
CHANCES RESUME THIS AFTERNOON AND EVENING WITH BEST CHANCES OVER THE
HIGHER TERRAIN AND SOUTHWEST ARIZONA. ACTIVE MONSOON CONDITIONS ARE
ANTICIPATED THIS WEEKEND ACROSS THE REGION AS AN UPPER LOW SLOWLY
MOVES ACROSS ARIZONA AND SOUTHEAST CALIFORNIA. NEXT WEEK...A
DOWNTREND IN THUNDERSTORM CHANCES TAKES PLACE ALONG WITH A WARMING
TREND AS DRIER AIR FILTERS IN FROM THE WEST.

&&

.DISCUSSION...
TODAY...
LONG LIVED OUTFLOW FROM STORMS OVER NORTHERN ARIZONA KICKED OFF
STORMS OVER MARICOPA COUNTY LAST EVENING. THOSE STORMS PRODUCED
OUTFLOW WHICH HAVE INTERACTED WITH OLDER AND LARGER SCALE OUTFLOWS
TO KEEP PESKY ACTIVITY GOING OVER SOUTH-CENTRAL ARIZONA. THERE
APPEARS TO BE AN MCV IN THE MIDST OF THIS WHICH MAY BE HELPING
SHOWERS TO HANG ON. MORE BROADLY WE ARE UNDER A DEFORMATION ZONE
BETWEEN MULTIPLE ANTICYCLONIC CIRCULATIONS. MEANWHILE...A DECAYING
MCS FROM SONORA HAS DRIFTED INTO SOUTHEAST ARIZONA. THIS COULD KEEP
WEAK SHOWERS AND ISOLATED THUNDERSTORMS GOING THROUGH THE MORNING.
EARLIER UPDATES WERE MADE TO THIS EFFECT. NUDGED MAX TEMPS DOWN
SEVERAL DEGREES FROM YESTERDAY. FOR SOUTHWEST ARIZONA AND SOUTHEAST
CALIFORNIA...THERE HAS BEEN MUCH LESS STABILIZING OUTFLOW AIR AND
CLOUDINESS...ESPECIALLY SOUTHEAST CALIFORNIA. OF NOTE...THE HI RES
MODELS HAVE POORLY HANDLED THE CURRENT CONVECTION. MADE SOME UPWARD
ADJUSTMENTS TO POPS FOR THIS AFTERNOON AND EVENING OVER SOUTHWEST
ARIZONA AND SOUTHEAST CALIFORNIA AS THERE WILL BE STEEPER LAPSE
RATES THERE THAN OVER THE LOWER ELEVATIONS OF SOUTH-CENTRAL ARIZONA.
HOWEVER...MODELS ARE MODEST IN THEIR DEPICTION OF CONVECTION...NAM
BEING ONE OF THE MORE ENTHUSIASTIC.

SATURDAY AND SUNDAY...
MODELS CONTINUE TO SHOW A REGION OF LOW PRESSURE CURRENTLY CENTERED
OVER SOUTHERN BAJA MOVING NORTHWESTWARD WITH WESTERN PORTIONS OF IT
MOVING ACROSS ARIZONA AND SOUTHEAST CALIFORNIA LATER SATURDAY
THROUGH SUNDAY. MODELS ARE IN GOOD AGREEMENT THAT SATURDAY AFTERNOON
INTO SUNDAY AFTERNOON WILL BE ACTIVE AS THIS FEATURE INTERACTS WITH
DEEP MOISTURE. MADE SOME CONSERVATIVE UPWARD ADJUSTMENTS TO REFLECT
THAT SHOWING RELATIVELY HIGH POPS GOING LATE SATURDAY NIGHT AND
SUNDAY MORNING. A CAVEAT IS THAT THERE WILL NOT BE ENOUGH
INSTABILITY AVAILABLE FOR THE WAVE TO TAKE ADVANTAGE OF...DUE TO
EXCESS CLOUD COVER AND COOLING EFFECTS OF OUTFLOW AIR FROM MOUNTAIN
STORMS. GFS AND EC HAVE BEEN SHOWING THE AXIS OF THE WAVE REACHING
THE PSR/VEF-FGZ BORDER BY 18Z SUNDAY. THIS WOULD PUT OUR AREA ON THE
SUBSIDENT SIDE OF THE WAVE SUNDAY AFTERNOON AND FOR SURE SUNDAY
EVENING. THUS MADE SOME ADJUSTMENTS TO REFLECT THAT. TEMPS THIS
WEEKEND WILL BE BELOW NORMAL FOR A CHANGE.

MONDAY THROUGH THURSDAY...
THE FIRST HALF OF THE NEXT WORKWEEK CONTINUES TO LOOK LIKE A
DOWNTREND IN STORM ACTIVITY AS THE INVERTED TROUGH DEPARTS AND DRIER
AIR MOVES INTO THE REGION AND GETS REINFORCED BY A BROADER TROUGH IN
THE WESTERLIES. ACCORDINGLY POPS RETREAT EASTWARD AND TEMPS SLOWLY
CLIMB...DROPPED POPS ALTOGETHER THURSDAY.


&&

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

ISOLATED EARLY MORNING SHOWERS WILL GENERALLY STAY TO THE SOUTH OF
THE AREA TERMINALS WHILE BROKEN TO OVERCAST MID-LEVEL DECKS LIKELY
PERSIST THROUGH THE REST OF THE MORNING. AM EXPECTING STORMS TO
DEVELOP ACROSS HIGHER TERRAIN AREAS FIRST BY MID AFTERNOON AND THEN
MOVE INTO THE LOWER DESERTS BETWEEN 00-03Z. AM FAIRLY CONFIDENT
ISOLATED TO SCATTERED STORMS WILL AFFECT GOOD PORTIONS OF THE
SOUTH-CENTRAL ARIZONA DESERTS SOMETIME THIS EVENING. STORM OUTFLOWS
WILL BRING RAPIDLY CHANGING WIND DIRECTIONS AND THE POTENTIAL FOR
STRONG GUSTS.

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

PERSISTENT SOUTH TO SOUTHEASTERLY WINDS ARE EXPECTED THROUGH MUCH OF
THE PERIOD. THERE WILL BE SLIGHT CHANCE OF SOME ISOLATED STORMS LATE
THIS AFTERNOON THROUGH THIS EVENING MAINLY ACROSS SOUTHWEST ARIZONA
AND THE LOWER COLORADO RIVER VALLEY. THESE STORMS WILL BRING THE
POTENTIAL FOR SHIFTING WIND DIRECTIONS AND STRONG GUSTS...MAINLY AT
KBLH.

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
SUNDAY THROUGH THURSDAY...
INCREASED MOISTURE WILL BE WIDESPREAD THROUGH EARLY NEXT WEEK WITH
ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS EXPECTED SUNDAY
THROUGH TUESDAY WITH A DECENT CHANCE OF A WETTING RAIN EVEN ACROSS
SOME DESERT LOCATIONS. MINIMUM HUMIDITY VALUES WILL BE IN THE 20 TO
30 PERCENT RANGE THROUGH MONDAY AND THEN SLOWLY DECREASE GOING INTO
MID WEEK AS DRIER AIR WORKS IN FROM THE WEST. HIGH TEMPERATURES WILL
START OFF COOLER THEN NORMAL...WARMING UP TO NEAR NORMAL BY TUESDAY
AND THEN ABOVE NORMAL THROUGH THE END OF NEXT WEEK.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...NONE.

CA...NONE.

&&

$$

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

DISCUSSION...AJ
AVIATION...KUHLMAN
FIRE WEATHER...KUHLMAN









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