Weather Service Report


125 
FXUS65 KPSR 022117
AFDPSR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
215 PM MST THU JUL 2 2015

.SYNOPSIS...
ALTHOUGH HIGH MONSOON HUMIDITY WILL REMAIN OVER THE REGION...THE 
ATMOSPHERE WILL BECOME A LITTLE MORE STABLE TODAY AND FRIDAY...FOR 
REDUCED CHANCES OF AFTERNOON AND EVENING THUNDERSTORMS. THE CHANCE 
OF THUNDERSTORMS HOWEVER WILL INCREASE AGAIN THIS WEEKEND...WITH 
MOST THUNDERSTORM CHANCES NEXT WEEK SHIFTING INTO EASTERN ARIZONA.

&&

.DISCUSSION...
CLEAR TO MOSTLY CLEAR SKIES SPAN THE CWA END-TO-END WITH SOME 
TERRAIN DRIVEN CU SLOWLY POPPING AROUND JTNP AND SOUTHERN GILA 
COUNTY. TEMPERATURES SO FAR HAVE BEEN FAIRLY MILD...FOR EARLY 
JULY...WITH UPPER 90S TO LOW 100S AT SITES AROUND THE FORECAST AREA. 
FAIRLY STRONG WESTERLY SFC WINDS HAVE PERSISTED THROUGHOUT SOUTH-
CENTRAL AZ DURING THE DAY...WITH LIGHTER WINDS NOTED OUT AT WESTERN 
TAF AND OBS SITES. ELEVATED WEST SFC FLOW SHOULD HELP TO ADVECT THE 
EXCESSIVE MOISTURE SFC THAT HAD SETTLED OVER SOUTHEAST CA/SOUTHWEST 
AZ DURING YESTERDAY'S ACTIVITY BACK TOWARDS PHOENIX-GILA BEND-
COOLIDGE. AREA GPS IPW INDICATE A SLOW THINNING OF MOISTURE ACROSS 
IMPERIAL-YUMA AND SOMEWHAT STEADY STATE PWATS OVER PHOENIX. DESPITE 
THE STILL ELEVATED MOISTURE SFC...CONDITIONS HAVE GRADUALLY 
STABILIZED AS UL FLOW AROUND THE TRANSITORY RIDGE ORIENTS MORE SOUTH-
SOUTHEASTERLY WITH NO DISCERNIBLE WAVE FEATURES OR MCVS TO HELP 
REALLY FLAIR UP ANY ACTIVITY UPSTREAM.

THAT BEING SAID...MIDDAY AFTN AMDAR FLIGHTS OVER AZ INDICATE THAT AM 
MODELS UNDERFORECAST UL WINDS OVER THE AREA...WITH SEVERAL TRACKS 
INDICATE 40 TO NEAR 55KT SOUTH-SOUTHEASTERLY WINDS ACROSS MUCH OF 
SOUTHEAST AND CENTRAL AZ. THE ELEVATED UL WINDS ALSO EVIDENT ON 
RECENT AFTN SATELLITE IMAGERY...WITH CONVECTIVE CLOUD TOPS QUICKLY 
BEING SHEARED/ADVECTED TO THE NORTHWEST. UNIDIRECTIONAL SPEED SHEER 
MAY QUICKLY END ANY STORM ACTIVITY WITH ELEVATED WINDS THROUGH THE 
UL LEVELS AND FAIRLY TYPICAL/LIGHT WINDS THROUGH THE LOWER AND SFC 
LEVELS. THE HIGH LEVEL STORM BLOW-OFF THEN HAS THE GREAT POTENTIAL 
TO SHUT DOWN WHAT LITTLE POTENTIAL WE DO HAVE FOR AN ISOLATED STORM 
OR TWO OVER OUR HIGHER TERRAIN. AS A RESULT WE HAVE LOW/NO WEATHER 
MENTIONING  POPS FOR THE PHX METRO AND WESTERN AZ DESERTS 
TONIGHT...WITH SLIGHT CHANCES FOR THE FOOTHILLS/HIGHER TERRAIN OF 
SOUTHERN GILA COUNTY.

FORECAST CONDITIONS FOR TODAY AND TOMORROW HAVE TRANSITIONED BACK 
INTO A TRADITIONAL EARLY SEASON/LOW-GRADE MONSOON FORECAST...WITH 
CONVECTION FAVORING THE HIGHER TERRAIN AND GENERALLY SLIM CHANCES 
FOR STORM SURVIVAL INTO THE LOWER DESERT ELEVATIONS. FOR POINTS 
TOWARDS AND BEYOND THE COLORADO RIVER VALLEY...GENERALLY QUIET 
CONDITIONS ANTICIPATED THIS EVENING WITH OVERNIGHT CLOUD INCREASES 
DUE TO STORM DEBRIS CLOUDS GRADUALLY BEING DRAWN IN FROM THE EAST. 

SATURDAY AND SUNDAY... 
MODELS FORECAST THE 300/250 MB HIGH CENTERS TO MOVE SOUTHWARD INTO 
NORTH CENTRAL MEXICO...SOUTHWEST OF EL PASO THIS WEEKEND. THIS 
PATTERN DEVELOPS A SOUTHERLY FLOW ALOFT WITH A NUMBER OF HARD TO 
TIME MINOR DISTURBANCES MOVING INTO AZ. MID LEVEL TEMPERATURES AT 
500 MB ALSO DECREASE INTO THE MINUS 6 DEG RANGE WHICH IS NORMAL FOR 
THE SEASON. WITH WARMER SURFACE TEMPS AND MORE FAVORABLE SUPPORT 
ALOFT FORECAST THIS WEEKEND...PROBABILITY OF PRECIP WILL BE RAISE A 
BIT ACROSS MUCH OF SOUTHWEST AND SOUTH CENTRAL AZ.
 
MONDAY THROUGH WEDNESDAY...
MODELS FORECAST MID/UPPER LEVEL FLOW TO BECOME MORE WESTERLY THIS 
PERIOD...WITH ONLY ONE PERTURBATION FORECAST TO MOVE INTO AZ ABOUT 
TUESDAY. AS A RESULT...MOST OF THE BOUNDARY LAYER MOISTURE IN AZ 
GETS PUSHED INTO THE EASTERN HALF OF THE STATE. THEREFORE THE 
CONVECTIVE POTENTIAL WILL FAVOR THE MOUNTAINS NORTH THROUGH EAST OF 
PHOENIX. MID LEVEL STEERING CURRENTS ALSO BECOME WESTERLY. THEREFORE 
A ONLY A SLIGHT CHANCE OF LATE AFTERNOON/EVENING STORMS ARE FORECAST 
ON THE SOUTH CENTRAL DESERTS...WITH SLIGHTLY HIGHER PROBABILITIES IN 
OUR MOUNTAINOUS ZONE 24 EAST OF PHOENIX.

THURSDAY AND FRIDAY... 
FLOW ALOFT THIS PERIOD WILL BECOME MORE MONSOONISH AS MID/UPPER 
LEVEL WINDS BECOME MORE SOUTH TO SOUTHEASTERLY. MODELS ALSO FORECAST 
A DEEPER EASTERLY FLOW TO DEVELOP JUST SOUTH OF THE BORDER WITH A 
COUPLE OF HARD TO TIME INVERTED TROFS BRUSHING THE MEXICAN BORDER. 
THEREFORE A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS WILL BE PUT 
BACK INTO THE FORECAST ACROSS A LARGE PORTION OF SOUTHWEST AND SOUTH 
CENTRAL AZ THIS PERIOD.
  
&&

.AVIATION... 
SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...KSDL... 
STORMS SHOULD REMAIN CONFINED TO THE HIGHER TERRAIN WELL NORTH/EAST 
OF PHOENIX TODAY AND TONIGHT. WITH STORMS THAT FAR AWAY...NOT 
CONCERNED ABOUT EASTERLY OUTFLOW WINDS REACHING THE TERMINALS AND 
WINDS WILL FOLLOW TYPICAL DIURNAL TRENDS. ASIDE FROM SOME BLOWOFF 
HIGH CLOUDS FROM DISTANT STORMS...IT SHOULD BE A QUIET FORECAST BY 
MONSOON STANDARDS. 

SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA INCLUDING KIPL AND 
KBLH... 
JUST A FEW HIGH CLOUDS AT BOTH SE CA SITES THIS AFTERNOON/EVENING. 
WINDS WILL FOLLOW TYPICAL DIURNAL TRENDS THROUGH AT LEAST FRIDAY 
AFTERNOON. 
 
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.

&& 

.FIRE WEATHER...
SUNDAY THROUGH THURSDAY... 
TYPICAL MONSOON WEATHER EXPECTED ON SUNDAY...FOLLOWED BY DRYING AND 
A RE-ORIENTING OF HIGHEST STORMS CHANCES WELL NORTH/EAST OF PHOENIX 
MONDAY THROUGH MID WEEK. THIS WILL RESULT IN AFTERNOON HUMIDITIES IN 
THE 10-20 PERCENT RANGE WITH FAIR/GOOD OVERNIGHT RECOVERIES 
EXPECTED. WINDS WILL FAVOR TYPICAL DIURNAL UPSLOPE/DOWNVALLEY TRENDS 
NEXT WEEK OUTSIDE OF THUNDERSTORM INDUCED OUTFLOWS. 

&&
 
.SPOTTER INFORMATION STATEMENT... 
SPOTTERS ARE ENCOURAGED TO REPORT ANY SIGNIFICANT WEATHER CONDITIONS
ACCORDING TO STANDARD OPERATING PROCEDURES.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...NONE.
CA...NONE. 

&&

$$

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DISCUSSION...NOLTE/VASQUEZ
AVIATION...LEINS
FIRE WEATHER...LEINS

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