090  
FXUS65 KPSR 151214  
AFDPSR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE PHOENIX AZ  
514 AM MST SUN SEP 15 2019  
   
UPDATE
 
UPDATED AVIATION DISCUSSION.  
 

 
   
SYNOPSIS
 
 
AN UPPER LEVEL DISTURBANCE ACROSS EASTERN ARIZONA WILL SUPPORT  
WIDESPREAD SHOWERS AND A FEW THUNDERSTORMS THROUGH THIS AFTERNOON  
ACROSS THE HIGH TERRAIN WELL EAST OF PHOENIX. THE LOWER DESERTS  
WILL STAY DRY TODAY AS HIGHS REACH NEAR NORMAL READINGS. A LOW  
PRESSURE SYSTEM MOVING INTO THE GREAT BASIN MONDAY INTO TUESDAY  
WILL ALLOW FOR PERIODIC SHOWER CHANCES ACROSS THE HIGHER TERRAIN  
NORTH AND EAST OF PHOENIX. THE LATTER HALF OF THE WEEK SHOULD  
MOSTLY BE DRY AS TEMPERATURES REMAIN NEAR SEASONAL NORMALS.  
 

 
   
DISCUSSION
 
 
A WELL DEFINED MID AND UPPER LEVEL LOW IS CURRENTLY SEEN IN WATER  
VAPOR IMAGERY CENTERED JUST EAST OF PHOENIX, VERY SLOWLY DRIFTING  
NORTH NORTHEAST. EASTERN ARIZONA WILL REMAIN IN A FAVORABLE UPPER  
LEVEL ASCENT REGION FOR MUCH OF TODAY WITH MAINLY SHOWERS  
PERSISTING MAINLY EAST OF A TUCSON TO GLOBE LINE. THE EXTENSIVE  
CLOUDINESS TODAY SHOULD LIMIT INSTABILITY OVERALL, BUT A FEW  
THUNDERSTORMS WILL BECOME POSSIBLE MAINLY ALONG THE MOGOLLON RIM  
THIS AFTERNOON. EASTERN SECTIONS OF GILA COUNTY COULD PICK UP AN  
ADDITIONAL HALF TO ONE INCH OF RAIN THROUGH THIS AFTERNOON, BUT  
HEAVY RAINFALL SHOULD BE LIMITED AND ONLY MINOR LOCALIZED FLOODING  
WILL BE POSSIBLE. FURTHER WEST, NORTHERLY DOWNSLOPING FLOW INTO  
SOUTH-CENTRAL THIS MORNING WILL BECOME MORE WESTERLY WITH DRIER  
AIR CONTINUING TO WORK INTO THE AREA WHILE LIKELY INHIBITING  
CONVECTION ALTOGETHER OVER THE LOWER DESERTS. ASIDE FROM THE  
MOSTLY CLOUDY SKIES AND SHOWERS ACROSS THE HIGHER TERRAIN, THE  
REST OF ARIZONA SHOULD MOSTLY SEE SUNNY SKIES BY LATE MORNING AND  
HIGHS JUST SHY OF NORMAL.  
 
THE COMPACT UPPER LEVEL LOW WILL FINALLY EXIT INTO NEW MEXICO  
THIS EVENING WHILE BROAD CYCLONIC FLOW BECOMES MORE PRONOUNCED TO  
OUR NORTHWEST AHEAD OF APPROACHING PACIFIC TROUGH. THE MAIN  
SHORTWAVE WITH THIS TROUGH IS STILL FORECAST TO TRACK WELL TO OUR  
NORTH, BUT WE WILL AT LEAST SEE SOME WEAK JET SUPPORTED ASCENT ON  
MONDAY. THE COMBINATION OF THE LINGERING MOISTURE, UPPER LEVEL  
DYNAMICS, AND WEAK UPSLOPE SOUTHWESTERLY LOW LEVEL FLOW SHOULD  
SUPPORT SCATTERED SHOWERS AND ISOLATED STORMS OVER AREAS MAINLY  
NORTH AND EAST OF PHOENIX MONDAY AFTERNOON INTO MONDAY NIGHT. WE  
CANNOT RULE OUT A FEW ISOLATED SHOWERS OR STORMS ACROSS THE SOUTH-  
CENTRAL ARIZONA DESERTS AS FORECAST SOUNDINGS INDICATE SUFFICIENT  
INSTABILITY, BUT CHANCES FOR THIS ARE NOT VERY HIGH. BY TUESDAY,  
DRIER WESTERLY FLOW WILL SPREAD ACROSS ALL OF ARIZONA, LIKELY  
LIMITING RAIN CHANCES TO ONLY THE HIGHEST PEAKS IN EASTERN  
ARIZONA. VERY LITTLE CHANGE IN AIRMASS EARLY THIS WEEK WILL KEEP  
TEMPERATURES RIGHT AROUND NORMALS, OR HIGHS IN THE UPPER 90S IN  
PHOENIX TO JUST OVER 100 ACROSS THE WARMER WESTERN DESERTS.  
 
FORECAST CONFIDENCE IS SLIGHTLY LOWER FOR THE REST OF THE WEEK AS  
MODELS SOMEWHAT DIFFER IN AVAILABLE MOISTURE FOR ANOTHER PACIFIC  
TROUGH LIKELY PASSING BY TO OUR NORTH ON THURSDAY. AT THIS POINT,  
THE OPERATIONAL GFS IS AN OUTLIER COMPARED TO THE REST OF ITS  
ENSEMBLE MEMBERS AND THE EUROPEAN MODEL SUITE AS IT BRINGS TOO  
MUCH MOISTURE BACK INTO EASTERN ARIZONA LATE WEDNESDAY INTO  
THURSDAY. LATEST MODEL RUNS SHOW THE TROUGH DIGGING FARTHER SOUTH  
INTO CENTRAL CALIFORNIA THEN PREVIOUS TROUGHS, SO WE CANNOT RULE  
OUT THE POSSIBILITY OF SUFFICIENT MOISTURE BEING DRAWN NORTHWARD  
TO AT LEAST SUPPORT LIMITED RAIN CHANCES OVER THE HIGHER TERRAIN.  
THE CONTINUED BROAD TROUGHING OVER THE WESTERN U.S. DURING THE  
LATTER HALF OF THE WEEK SHOULD KEEP TEMPERATURES NEAR SEASONAL  
NORMALS.  
 

 
   
AVIATION
 
UPDATED AT 1205Z.  
 
SOUTH-CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:  
 
EXPECT SOME LINGERING ISOLATED SPRINKLES IN THE EAST VALLEY EARLY  
IN THE PERIOD ON SUNDAY MORNING WITH MOSTLY LIGHT TO OCCASIONALLY  
MODERATE EASTERLY WINDS. SKIES THIS MORNING WILL BE PARTLY CLOUDY  
WITH MID TO HIGH LEVEL CLOUD CIGS NEAR 14-21KFT AND FEW LOW  
CLOUDS AT 7-8KFT. WINDS WILL TREND WESTERLY BY MID AFTERNOON WITH  
DECREASING CLOUDINESS AS ISOLATED AFTERNOON THUNDERSTORMS DEVELOP  
AND REMAIN OVER THE HIGH TERRAIN TO THE DISTANT EAST AND NORTH OF  
PHOENIX. THERE IS A FAIR CHANCE OF LIGHT TO MODERATE  
NORTHEASTERLY OUTFLOW FROM HIGH COUNTRY CONVECTION REACHING THE  
TERMINALS AROUND 02-03Z THIS EVENING WITH WIND SPEEDS NEAR 7-12KT  
AS SOME HIGH CLOUD CIGS MOVE BACK INTO THE AREA.  
 
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:  
 
LOOK FOR LIGHT TO MODERATE WINDS FAVORING THE SOUTHEAST AT KIPL  
TODAY TO SWITCH OVER TO THE WEST EARLY THIS EVENING. AT KBLH  
MOSTLY MODERATE WINDS WILL FAVOR THE SOUTH TO SOUTHWEST BY MID  
MORNING. SKIES WILL BE CLEAR TO MOSTLY CLEAR THIS MORNING WITH  
INCREASING HIGH CLOUD CIGS AND FEW MID CLOUDS MOVING IN FROM THE  
WEST DURING THE COURSE OF THE AFTERNOON AND INTO THIS EVENING.  
 
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.  
 

 
   
FIRE WEATHER
 
 
TUESDAY THROUGH SATURDAY:  
A SERIES OF LOW PRESSURE SYSTEMS WILL MOVE THROUGH GREAT BASIN NEXT  
WEEK GRADUALLY PUSHING MOISTURE AND STORM CHANCES FROM THE  
DISTRICTS. RESIDUAL LINGERING MOISTURE MAY SUPPORT SOME UPSLOPE  
SHOWERS DURING THE MIDDLE OF THE WEEK, HOWEVER MUCH DRIER AIR WILL  
ENCOMPASS THE REGION BY THE END OF THE WEEK. THESE STORM SYSTEMS  
WILL ALLOW TEMPERATURES TO HOVER AROUND THE SEASONAL AVERAGE WHILE  
THE DRIER AIRMASS WILL PULL AFTERNOON HUMIDITY LEVELS INTO A 10-25%  
RANGE. A FEW PERIODS OF BREEZY CONDITIONS WILL BE POSSIBLE WITH THE  
PASSAGE OF THESE WEATHER DISTURBANCES.  
 

 
   
SPOTTER INFORMATION STATEMENT
 
 
SPOTTERS SHOULD FOLLOW STANDARD REPORTING PROCEDURES.  
 

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

 
 

 
 
DISCUSSION...KUHLMAN  
AVIATION...SAWTELLE  
FIRE WEATHER...MO  
 
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