Weather Service Report


698 
FXUS65 KPSR 311153 AAA
AFDPSR

AREA FORECAST DISCUSSION..UPDATED
NATIONAL WEATHER SERVICE PHOENIX AZ
453 AM MST THU JUL 31 2014

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

&&

.SYNOPSIS...
ANTICIPATE ANTICIPATE ANOTHER HOT DAY TODAY...THOUGH THERE WILL BE 
MORE CLOUDINESS AROUND. A SLIGHT CHANCE OF STORMS RETURNS TO 
PORTIONS OF SOUTH-CENTRAL ARIZONA TODAY. EXPECT AN UPTREND IN 
THUNDERSTORM CHANCES EXPANDING FROM EAST TO WEST FRIDAY THROUGH 
SUNDAY. ACCORDINGLY...TEMPERATURES WILL NOT BE AS HOT. NEXT WEEK...A 
DOWNTREND IS ANTICIPATED AS DRIER AIR FILTERS IN. 


&&

.DISCUSSION...
TODAY...
OVERNIGHT TEMPS RUNNING WARMER AT MOST LOCATIONS IN THE 
FORECAST AREA COMPARED TO 24 HRS AGO. THIS SHOULD HELP KEEP MAX 
TEMPS RATHER WARM TODAY. HOWEVER...AN X FACTOR IN THE MAX TEMPS 
TODAY IS AN MCS CURRENTLY OVER SONORA. ANTICIPATE DEBRIS CLOUDS FROM 
THAT TO SPREAD OVER A GOOD DEAL OF THE FORECAST AREA TODAY. IT 
REMAINS TO BE SEEN JUST HOW THICK THEY WILL BE. ANTICIPATE EASTERN 
HALF OF CWA TO SEE MORE THAN WESTERN HALF. ACCORDINGLY...NUDGED MAX 
TEMPS DOWN IN EASTERN AREAS BY 2-3 DEGREES COMPARED TO YESTERDAY. 
ANOTHER WAY THAT THE MCS COULD AFFECT TEMPERATURES TODAY IS WITH 
LONG LIVED OUTFLOW. 06Z NAM INDICATES A SHALLOW SURGE MOVING INTO 
MOSTLY SOUTHWEST ARIZONA DURING THE DAY. SOME WEAK SHOWER 
DEVELOPMENT NORTH OF THE MEXICO BORDER EARLY THIS MORNING WILL NEED 
TO BE MONITORED AS IT IS POSSIBLE WE COULD SEE SOME ISOLATED 
NUISANCE STUFF IN OUR AREA THIS MORNING. FOR NOW...HAVE HELD OFF ON 
POPS UNTIL THIS AFTERNOON. WOULD NOT BE SURPRISED TO SEE SOME DUST 
OVER PINAL COUNTY TODAY FROM STORMS EMANATING FROM FURTHER 
SOUTH...BUT LINGERING CLOUD COVER THERE COULD INHIBIT STORM 
ACTIVITY. 

FRIDAY THROUGH SUNDAY...
LATEST MODELS DEPICT AN OVERALL UPTREND IN MOISTURE AND QPF FROM 
EAST TO WEST FRIDAY AND SATURDAY AND CONTINUING SUNDAY. THE BASIC 
SCENARIO IS THE ANTICYCLONE...CURRENTLY CENTERED NEAR THE MEXICO 
BORDER...BREAKING UP INTO TWO MAIN ANTICYCLONIC CIRCULATIONS WITH A 
DEFORMATION ZONE IN BETWEEN. MEANWHILE AN UPPER LOW...CURRENTLY 
CENTERED NOT FAR WEST OF SOUTHERN BAJA...WILL SLOWLY MOVE 
NORTHWESTWARD AND A VORT LOBE ON THE EASTERN PERIPHERY WILL MOVE UP 
THROUGH WESTERN SONORA. THE GFS AND EC INDICATE THIS FEATURE HELPING 
TO REIGNITE SONORA CONVECTION LATER TONIGHT. EVENTUALLY...AN 
INVERTED TROUGH MOVES NORTHWESTWARD FROM SOUTHEAST ARIZONA INTO THE 
MOHAVE DESERT OVER THE WEEKEND. THERE MAY EVEN BE SOME SHORT WAVE 
ENERGY FROM THE WESTERLIES WHICH BREAKS OFF FROM NEW MEXICO THAT 
COMES INTO PLAY. A BACKDOOR FRONT ALREADY OVER NEW MEXICO MAY ALSO 
BE AN AID IN THE UPWARD MOISTURE TREND. OF NOTE...THERE ARE 
SIGNIFICANT DIFFERENCES IN THE DETAILS BETWEEN THE MODELS. IN 
GENERAL...THE EC IS SLOWER THAN THE GFS WITH THE PASSAGE OF THE 
INVERTED TROUGH. FORECASTS REFLECT THE WESTWARD ADVANCE OF STORM 
CHANCES...OVERSPREADING THE ENTIRE FORECAST AREA BY SATURDAY. WITH 
MORE CLOUDINESS AND OUTFLOW AIR AROUND...TEMPERATURES TREND DOWNWARD.

MONDAY THROUGH WEDNESDAY...
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...AT FIRST FROM WESTERLY FLOW THEN 
NORTHERLY. ACCORDINGLY...POPS RETREAT EASTWARD AND TEMPS SLOWLY 
CLIMB. 


&&

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

STARTING TO SEE SOME THICKER CLOUDS AND ISOLATED SHOWERS MOVING INTO 
SOUTHEAST ARIZONA ON THE LEADING EDGE OF A DECAYING MCS. NOT 
ANTICIPATING ANY PRECIP AT ANY OF THE TERMINALS BUT CLOUDS WILL 
CERTAINLY THICKEN UP THIS MORNING...POSSIBLY LINGERING ALL THE WAY 
INTO THE AFTERNOON. BKN150-BKN250 WILL BE COMMON AT ALL PHOENIX 
SITES AND TO A LESSER EXTENT AT IPL/BLH AS WELL. OTHERWISE NO MAJOR 
WEATHER IMPACTS EXPECTED. WINDS WILL FAVOR TYPICAL DIURNAL TRENDS. 

AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&&

.FIRE WEATHER...
SATURDAY THROUGH WEDNESDAY...
MOISTURE WILL RETURN TO THE AREA BY THE WEEKEND WITH SHOWERS AND 
THUNDERSTORMS EXPECTED. DAY TO DAY TIMING AND PLACEMENT OF STORMS IS 
HARD TO PIN DOWN BUT IT LOOKS LIKE A DECENT CHANCE OF A WETTING RAIN 
EVEN ACROSS SOME DESERT LOCATIONS. HUMIDITY VALUES WILL STEADILY 
INCREASE WITH MINIMUM VALUES BETWEEN 20 AND 30 PERCENT EXPECTED 
ACROSS THE DESERTS SATURDAY INTO THE EARLY PART OF NEXT WEEK. 
CORRESPONDINGLY...HIGH TEMPERATURES WILL FALL OFF...DROPPING FROM 
AROUND SEASONAL NORMALS FRIDAY TO WELL BELOW NORMAL VALUES ON 
SUNDAY. SLIGHT WARMING WILL RETURN BY NEXT TUESDAY AS HUMIDITY 
VALUES LOWER SOMEWHAT. STRONG WINDS ARE NOT EXPECTED DURING THE FIVE 
DAY PERIOD...AND THEY SHOULD TYPICALLY FAVOR SOUTH TO SOUTHWEST 
DIRECTIONS DURING THE AFTERNOON AND EVENING HOURS.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...

AZ...EXCESSIVE HEAT WARNING TODAY UNTIL 8 PM MST AZZ020>023-025>028.

CA...EXCESSIVE HEAT WARNING TODAY UNTIL 8 PM PDT CAZ031>033.

&&

$$

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

DISCUSSION...AJ
AVIATION...LEINS
FIRE WEATHER...LEINS



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