250  
FXUS65 KPSR 301740  
AFDPSR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE PHOENIX AZ  
1040 AM MST MON JUN 30 2025  
   
UPDATE...UPDATED AVIATION DISCUSSION  
 
 
   
KEY MESSAGES  
 
- EXTREME HEAT CONDITIONS EXPECTED THROUGH TUESDAY ACROSS THE  
LOWER DESERTS AS HIGH TEMPERATURES TOP OUT BETWEEN 110-117 DEGREES,  
WITH EXTREME HEAT WARNINGS IN EFFECT AS AREAS OF MAJOR HEATRISK  
DEVELOP.  
 
- AN INFLUX OF MONSOONAL MOISTURE WILL LEAD TO INCREASING CHANCES  
OF SHOWERS AND THUNDERSTORMS, MAINLY DURING THE TUESDAY-THURSDAY  
TIME FRAME ACROSS PORTIONS OF AZ, WITH THE BEST CHANCES FOR  
ACTIVITY CONFINED ACROSS THE HIGHER TERRAIN AREAS.  
 
- A DECREASE IN MOISTURE WILL LEAD TO A SIGNIFICANT DECREASE IN  
SHOWER AND THUNDERSTORM ACTIVITY DURING THE JULY 4TH HOLIDAY  
WEEKEND ALONG WITH NEAR NORMAL TEMPERATURES.  
 
 
   
DISCUSSION  
 
LATEST WATER VAPOR SATELLITE IMAGERY AS WELL AS STREAMLINE ANALYSIS  
REVEAL THE SUBTROPICAL HIGH SITUATED NEAR THE AZ/NM BORDER WITH  
AN UPPER-LEVEL LOW SITUATED JUST OFF THE COAST OF SOUTHERN CA.  
WITH THE PRESENCE OF THE SUBTROPICAL HIGH OVER THE AREA WITH 500  
MB HEIGHT FIELDS RANGING BETWEEN 590-593DM, THE MAJOR CONCERN DURING  
THE NEXT COUPLE OF DAYS WILL BE THE EXTREME HEAT CONDITIONS. HIGH  
TEMPERATURES THIS AFTERNOON ARE EXPECTED TO PEAK BETWEEN 112-117  
DEGREES ACROSS THE LOWER DESERTS, LEADING TO WIDESPREAD MAJOR  
HEATRISK. FOR THE PHOENIX AREA, THERE IS A HIGH PROBABILITY, >70%  
CHANCE, OF THE RECORD HIGH OF 115 DEGREES SET BACK IN 2013 AND 1979  
TO BE BROKEN. TEMPERATURES ON TUESDAY WILL BE A DEGREE OR TWO COOLER  
THAN TODAY BUT STILL VERY HOT AS AFTERNOON HIGHS TOP OUT BETWEEN 110-  
114 DEGREES, WITH AREAS OF MAJOR HEATRISK CONTINUING ACROSS THE  
MAJORITY OF THE LOWER DESERTS. AS A RESULT, THE EXTREME HEAT  
WARNINGS WILL CONTINUE IN EFFECT THROUGH TUESDAY EVENING. THEREFORE,  
IT IS VERY ESSENTIAL TO TAKE ALL THE NECESSARY HEAT PRECAUTIONS TO  
AVOID ANY HEAT-RELATED ILLNESSES.  
 
THE COMBINATION OF THE SUBTROPICAL HIGH MIGRATING OVER THE FOUR  
CORNERS REGION AND THE AFOREMENTIONED UPPER-LEVEL LOW JUST OFF  
THE SOUTHERN CA COAST WILL HELP ADVECT A MODEST AMOUNT OF MOISTURE  
THROUGH MIDWEEK ACROSS THE REGION. AS A RESULT OF THE INCREASE IN  
MOISTURE, SHOWER AND THUNDERSTORM ACTIVITY WILL BE INCREASING IN  
COVERAGE EACH DAY THROUGH WEDNESDAY. FOR LATER TODAY, THUNDERSTORM  
ACTIVITY THAT DEVELOPS WILL BE CONFINED MAINLY TO THE EASTERN  
THIRD OF AZ, WITH OUTFLOWS FROM THE ACTIVITY LIKELY TO BE DIRECTED  
WESTWARD INTO THE LOWER ELEVATIONS. THE LATEST HREF, GIVES A  
30-50% CHANCE OF WIND GUSTS EXCEEDING 35 MPH ACROSS AS FAR WEST AS  
FAR EASTERN MARICOPA AND NORTHERN PINAL COUNTIES LATER THIS  
EVENING.  
 
THE BEST CHANCES FOR THUNDERSTORM ACTIVITY ACROSS SOUTH-CENTRAL AZ  
WILL MOST LIKELY BE DURING THE TUESDAY-WEDNESDAY TIMEFRAME.  
THUNDERSTORM ACTIVITY ON TUESDAY AFTERNOON/EVENING WILL BE  
CONCENTRATED MAINLY ACROSS PORTIONS OF SOUTHERN GILA COUNTY THROUGH  
THE HIGHER ELEVATIONS OF EASTERN MARICOPA AND NORTHERN PINAL  
COUNTIES. ACROSS THE LOWER DESERTS, STRONG INHIBITION WILL LIKELY  
LIMIT ANY THUNDERSTORM ACTIVITY, HOWEVER, WITH DCAPE VALUES  
APPROACHING 1500 J/KG, THE ENVIRONMENT WILL BE CONDUCIVE FOR  
STRONG, GUSTY OUTFLOW WINDS AND AREAS OF BLOWING DUST. THE BEST  
CHANCES FOR THUNDERSTORM ACTIVITY ACROSS THE LOWER DESERTS OF  
SOUTH-CENTRAL AZ, INCLUDING THE PHOENIX AREA, IS LIKELY WEDNESDAY  
EVENING THROUGH EARLY THURSDAY AS MOISTURE LEVELS PEAK WITH PWATS  
APPROACHING 1.2-1.3", RESULTING IN WEAKER INHIBITION. IN ADDITION,  
UPPER-LEVEL FORCING FROM THE APPROACHING UPPER-LEVEL TROUGH WILL  
ALSO INCREASE. AS OF RIGHT NOW, NBM POPS DURING THIS TIME FRAME  
ACROSS THE LOWER DESERTS RANGE BETWEEN 20-40%.  
 
AS THE UPPER-LEVEL TROUGH TRAVERSES THE DESERT SOUTHWEST ON  
THURSDAY, WESTERLY FLOW ALOFT WILL BEGIN TO SCOUR OUT THE MOISTURE  
FROM WEST TO EAST, LEADING TO A DOWNTREND IN THUNDERSTORM ACTIVITY  
BEGINNING THURSDAY AFTERNOON INTO FRIDAY WITH THE DRIER AIRMASS  
REMAINING IN PLACE THROUGH NEXT WEEKEND. AS A RESULT, IT IS LOOKING  
LIKELY THAT THE ENTIRE JULY 4TH HOLIDAY WEEKEND WILL REMAIN STORM-  
FREE ACROSS THE REGION. WITH THE DECREASING HEIGHTS ALOFT FROM THE  
APPROACHING TROUGH, TEMPERATURES ARE EXPECTED TO TAKE A NOTICEABLE  
DOWNWARD TREND MID TO LATE WEEK. TEMPERATURES ON WEDNESDAY ARE  
EXPECTED TO BE NEAR NORMAL, BEFORE DROPPING A COUPLE OF DAYS BELOW  
NORMAL THURSDAY AND FRIDAY. AS HEIGHTS ALOFT INCREASE ONCE AGAIN  
NEXT WEEKEND, TEMPERATURES WILL BE ON A SLIGHT UPWARD TREND,  
HOWEVER, REMAINING BELOW 110 DEGREES.  
 
 
   
AVIATION  
UPDATED AT 1740Z.  
 
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, KDVT:  
LITTLE TO NO AVIATION IMPACTS ARE EXPECTED THROUGH TUESDAY  
AFTERNOON. TYPICAL DIURNAL WIND PATTERNS WITH SOME WESTERLY  
BREEZINESS ARE EXPECTED THROUGH THIS EVENING. STARTING AROUND  
MIDNIGHT TONIGHT, EXPECT EASTERLY WINDS AT AROUND 10 KTS WITH SOME  
GUSTINESS AT TIMES THROUGH TUESDAY MORNING. WINDS ARE THEN  
EXPECTED TO SHIFT OF THE SOUTH TUESDAY AFTERNOON WITH INCREASED  
PERIODS OF GUSTS UP TO 20 KTS. SKIES WILL REMAIN CLEAR TO MOSTLY  
CLEAR WITH SOME FEW TO SCT DECKS AROUND 15-18K FEET.  
 
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:  
NO AVIATION IMPACTS ARE ARE EXPECTED THROUGH THE PERIOD. WEST  
WINDS WILL CONTINUE TO PREVAIL AT KIPL, WHILE KBLH WILL GENERALLY  
SEE SOUTH SOUTHWEST WINDS THIS AFTERNOON SHIFTING WESTERLY LATER  
THIS EVENING AND THEN WILL BE OUT OF THE NORTH AFTER MIDNIGHT  
TONIGHT. SKIES WILL REMAIN CLEAR TO MOSTLY CLEAR WITH SOME FEW  
DECKS AROUND 15-18K FEET.  
 
 
   
FIRE WEATHER  
 
VERY HOT CONDITIONS WILL PERSIST THROUGH TUESDAY AS TEMPERATURES  
ACROSS THE LOWER DESERTS EXCEED 110 DEGREES. MINRHS WILL REMAIN  
BETWEEN 5-15% TODAY WITH THE OVERALL WIND PATTERN FOLLOWING THE  
FAMILIAR DIURNAL TENDENCIES WITH SOME AFTERNOON UPSLOPE GUSTINESS.  
LOW-LEVEL MOISTURE WILL INCREASE TUESDAY-WEDNESDAY, WITH MINRH  
VALUES CLIMBING TO 20-25% ACROSS THE EASTERN DISTRICTS. THE  
MOISTURE INCREASE WILL ALSO LEAD TO INCREASING CHANCES FOR SHOWER  
AND THUNDERSTORM ACTIVITY ACROSS THE HIGHER TERRAIN AREAS OF  
SOUTH-CENTRAL AZ STARTING ON TUESDAY WITH GUSTY OUTFLOW WINDS  
AFFECTING THE LOWER DESERTS. THERE WILL BE SOME INITIAL CONCERNS  
FOR DRY LIGHTNING ACTIVITY BEFORE A FURTHER INCREASE IN MOISTURE  
LEVELS LEADS TO A BETTER POTENTIAL FOR WETTING RAINS BY MIDWEEK.  
STORM CHANCES DIMINISH BY THE END OF THE WEEK THROUGH NEXT WEEKEND  
AS DRIER FILTERS INTO THE REGION ALONG WITH A DECREASE IN MINRH  
VALUES.  
 
 
   
PSR WATCHES/WARNINGS/ADVISORIES  
 
AZ...EXTREME HEAT WARNING UNTIL 8 PM MST TUESDAY FOR AZZ530>536-538-  
539-553-554-559.  
 
EXTREME HEAT WARNING UNTIL 8 PM MST TUESDAY FOR AZZ537-540-  
542>544-546-548-550-551.  
 
EXTREME HEAT WARNING UNTIL 8 PM MST THIS EVENING FOR AZZ541-545-  
547-549-552-555-556-560>562.  
 
CA...EXTREME HEAT WARNING UNTIL 8 PM PDT TUESDAY FOR CAZ562-565>567-  
569-570.  
 
 
 
 
 
DISCUSSION...LOJERO  
AVIATION...KUHLMAN/95  
FIRE WEATHER...LOJERO  
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