030  
FXUS65 KPSR 051140  
AFDPSR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE PHOENIX AZ  
440 AM MST TUE MAR 5 2024  
   
UPDATE
 
UPDATED AVIATION DISCUSSION.  
 

 
   
SYNOPSIS
 
 
PLEASANT WEATHER CONDITIONS WILL PERSIST ACROSS THE REGION OVER  
THE NEXT COUPLE OF DAYS, AS TEMPERATURES CLIMB A FEW DEGREES ABOVE  
NORMAL. MORE UNSETTLED WEATHER IS IN STORE FOR THE LATTER PORTIONS  
OF THE WEEK, WITH SOUTH-CENTRAL ARIZONA SEEING RAIN POTENTIAL  
INCREASING FOR THURSDAY AND FRIDAY. DRIER CONDITIONS WILL DEVELOP  
FOR THE WEEKEND, WITH TEMPERATURES ABOVE NORMAL BY SUNDAY.  
 

 
   
DISCUSSION
 
 
GENERALLY WEST FLOW ALOFT ACROSS THE DESERT SOUTHWEST WILL  
PRECLUDE A WARMING TREND, AS THE NEGATIVE HEIGHT ANOMALIES, IN  
ASSOCIATION WITH DEEP LONGWAVE TROUGH ACROSS THE INTERMOUNTAIN  
WEST, HAVE RETREATED FURTHER NORTH. THUS, WARMING TEMPERATURES ARE  
EXPECTED OVER THE NEXT COUPLE OF DAYS ACROSS THE REGION, AS MID-  
LEVEL HEIGHTS BUILD INTO THE 567-570 DAM RANGE.  
 
HIGH CLOUDS WILL PERSIST ACROSS THE REGION, AS A WEAK DISTURBANCE  
PASSES TO THE NORTH TODAY, WITH GRADUAL BUILDING OF CLOUDS FROM  
THE SUB-TROPICAL JET ENHANCING OVER THE NEXT COUPLE OF DAYS TO THE  
SOUTH AND WEST. THESE HIGH CLOUDS WILL PRECEDE THE NEXT WEATHER  
DISTURBANCE SET TO MOVE THROUGH THE REGION ON THURSDAY. ENSEMBLES  
DEPICT A POTENT CLOSED LOW THAT WILL TRACK EASTWARD INTO THE  
DESERT SOUTHWEST THURSDAY INTO FRIDAY. ENSEMBLES NOW ARE IN  
AGREEMENT OF A FIRST ROUND OF RAIN DURING THE DAY THURSDAY, WITH  
RAIN CHANCES CONTINUING TO RISE ACCORDING TO THE LATEST NBM POP'S.  
THE PHOENIX METRO REMAINS RELATIVELY UNCHANGED FROM YESTERDAY'S  
FORECAST OF 20-30% CHANCES, WITH HIGHER CHANCES UP TO 50% IN THE  
HIGHER TERRAIN AREAS. DESPITE THIS INCREASE IN CHANCES, RAIN  
AMOUNTS STILL REMAIN LOW FOR THE LOWER DESERTS, AS NBM  
PROBABILITIES INDICATE AROUND A 10% CHANCE OF TOTAL RAIN AMOUNTS  
EXCEEDING ONE TENTH OF AN INCH. CHANCES FOR EXCEEDING A TENTH OF  
AN INCH ARE HIGHER IN THE HIGHER TERRAIN AREAS, AS LATEST WPC  
QPF'S ARE IN THE TENTH TO A QUARTER INCH RANGE. THERE COULD BE  
SOME LOCALIZED HIGHER AMOUNTS WITH THIS SYSTEM, AS SOUNDING  
ANALYSIS INDICATES SOME GOOD MID-LEVEL LAPSE RATES, WITH ENOUGH  
INSTABILITY TO ENHANCE SHOWER, AND EVEN SOME THUNDER, ACTIVITY ON  
THURSDAY.  
 
HEADING INTO FRIDAY, A COUPLE LOBES OF VORTICITY MAXIMUMS LINGER  
ACROSS ARIZONA, THUS PROVIDING SOME ENHANCEMENTS IN LIFT,  
RESULTING IN RAIN CHANCES TO LINGER ON FRIDAY. MOST ACTIVITY IS  
EXPECTED TO REMAIN IN THE HIGH TERRAIN AREAS, WITH MINIMAL  
ACCUMULATIONS EXPECTED. ENSEMBLE CLUSTERS SHOW THIS TROUGHING  
FEATURE LINGERING INTO SATURDAY, BUT WARMING TEMPERATURES WILL  
COMMENCE AS A HIGHLY AMPLIFIED RIDGE WILL BE IN PLACE ACROSS  
WESTERN CONUS. THIS RIDGING FEATURE IS EXPECTED TO BE SHORT LIVED  
ACROSS THE REGION, AS THE NEXT TROUGHING FEATURE MOVES INTO THE  
PACIFIC NORTHWEST EARLY NEXT WEEK. WHILE THERE IS NO THREAT FOR  
RAIN, UNCERTAINTY GROWS DURING THE BEGINNING OF NEXT WEEK ON THE  
DEPTH OF THE TROUGH, WHICH INEVITABLY WILL AFFECT TEMPERATURE  
TRENDS. NBM TEMPERATURES INDICATE WARMING TEMPERATURES THROUGH  
SUNDAY (HIGHS WELL INTO THE 80S ACROSS THE LOWER DESERTS), WITH  
PRONOUNCED SPREAD IN THE INTERQUARTILE RANGES GROWING STARTING  
MONDAY. THUS, THE UNCERTAINTY WILL BE ON IF AND HOW MUCH  
TEMPERATURES COOL GOING THROUGH EARLY NEXT WEEK AT THIS POINT.  
 

 
   
AVIATION
 
UPDATED AT 1135Z.  
 
SOUTH-CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT;  
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:  
NO AVIATION WEATHER IMPACTS EXPECTED THROUGH WEDNESDAY. LIGHT,  
DIURNAL WINDS WILL GENERALLY PREDOMINATE WITH OCCASIONAL PERIODS  
OF LIGHT AND VARIABLE WINDS. OTHERWISE, ABUNDANT HIGH CLOUDS WILL  
PERSIST ACROSS THE DESERT SOUTHWEST.  
 

 
   
FIRE WEATHER
 
 
TEMPERATURES WILL TREND WARMER THROUGH THE MIDDLE OF THE WEEK  
AHEAD OF COOLING TEMPERATURES BACK TO BELOW NORMAL THROUGH THE END  
OF THE WEEK. DAYTIME MINIMUM RELATIVE HUMIDITY VALUES WILL HOVER  
IN THE 15-25% RANGE OVER THE NEXT COUPLE OF DAYS BEFORE MOISTENING  
AGAIN DUE TO A WEATHER DISTURBANCE BRINGING INCREASING RAIN  
CHANCES THURSDAY AND FRIDAY, AT LEAST ACROSS THE EASTERN  
DISTRICTS. BEST CHANCES FOR WETTING RAINS WILL BE THURSDAY, WHERE  
CHANCES ARE IN THE 10-20% (25-40%) RANGE FOR THE LOWER DESERTS  
(HIGHER TERRAIN) OF SOUTHCENTRAL ARIZONA. LESS CHANCES FOR WETTING  
RAINS ON FRIDAY, AS THE MAIN DISTURBANCE EXITS EAST OF THE  
REGION GOING INTO THE WEEKEND. DRYING CONDITIONS ARE ANTICIPATED  
FOR THE WEEKEND.  
 

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

 
 

 
 
DISCUSSION...YOUNG  
AVIATION...HIRSCH  
FIRE WEATHER...YOUNG  
 
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