508  
FXUS65 KPSR 280911  
AFDPSR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE PHOENIX AZ  
211 AM MST MON JUL 28 2025  
   
KEY MESSAGES  
 
- WIDESPREAD MODERATE HEATRISK WITH LOWER DESERT HIGH TEMPERATURES  
AROUND 110 DEGREES WILL BE COMMON EACH DAY THIS WEEK.  
 
- A RETURN TO A MORE TYPICAL MONSOON PATTERN WILL ALLOW SHOWER AND  
THUNDERSTORM ACTIVITY TO INCREASE FOR EASTERN PORTIONS OF  
ARIZONA TODAY INTO TUESDAY AND THEN INTO SOUTH-CENTRAL ARIZONA  
WEDNESDAY INTO THURSDAY.  
 
 
   
SHORT TERM /TODAY THROUGH TUESDAY/  
 
TODAY INTO TUESDAY WILL BE A TRANSITION PERIOD FOR MUCH OF THE  
REGION AS THE UPPER LEVEL TROUGH TO OUR NORTHWEST SHIFTS FARTHER  
AWAY WHILE THE SUBTROPICAL RIDGE CURRENTLY CENTERED OVER THE  
LOWER MS RIVER VALLEY CONTINUES TO NUDGE BACK INTO OUR REGION. THE  
DRY AIR MASS WHICH HAS BEEN PRESENT OVER OUR REGION SINCE THE  
MIDDLE OF LAST WEEK WILL ALSO BEGIN TO MODIFY. THIS WILL BE AIDED  
BY A WEAK INVERTED TROUGH WHICH IS NOW MOVING INTO SONORA AND IS  
FORECAST TO REACH FAR SOUTHEAST ARIZONA LATER TODAY INTO TONIGHT.  
 
MOISTURE WILL IMPROVE MODESTLY ACROSS SOUTHEAST ARIZONA TO AS FAR  
NORTH AS THE WHITE MTNS BY THIS AFTERNOON PROVIDING FOR SOME  
SCATTERED SHOWERS AND A FEW THUNDERSTORMS. AS THE INVERTED TROUGH  
MOVES INTO SOUTHEAST ARIZONA BY TONIGHT, SOUTHEASTERLY FLOW INTO  
THE AREA WILL CONTINUE TO BRING BETTER MOISTURE INTO TUESDAY.  
SHOWER AND STORM COVERAGE ON TUESDAY MAY BE SLIGHTLY BETTER THAN  
TODAY, BUT OVERALL IT IS EXPECTED TO BE CONFINED TO HIGHER TERRAIN  
AREAS OF EASTERN ARIZONA.  
 
TEMPERATURES TODAY AND TUESDAY ARE FORECAST TO HEAT UP EVEN MORE  
WITH THE LOWER DESERTS SEEING HIGHS BETWEEN 108-112 DEGREES (3-6  
DEGREES ABOVE NORMAL), BUT OVERNIGHT LOWS ARE STILL EXPECTED TO  
MOSTLY FALL WITHIN THE NORMAL RANGE.  
 
 
   
LONG TERM /WEDNESDAY THROUGH SATURDAY/  
 
GUIDANCE IS STARTING TO AGREE MORE WITH WHAT MAY HAPPEN FOR THE  
LATTER HALF OF THE WEEK. BOTH THE GEFS AND THE EPS MOSTLY AGREE ON  
THE INVERTED TROUGH SLOWLY PROGRESSING INTO FAR SOUTH-CENTRAL  
ARIZONA ON WEDNESDAY WITH WEAK MOISTURE ADVECTING INTO THE AREA.  
THIS SHOULD BRING SHOWER AND THUNDERSTORM CHANCES AS FAR WEST AS  
MARICOPA COUNTY ON WEDNESDAY, BUT WITH LOW LEVEL MIXING RATIOS  
ONLY LIKELY REACHING 8-9 G/KG STORM COVERAGE ON WEDNESDAY SHOULD  
BE FAIRLY LIMITED OVER THE LOWER DESERTS. FORECAST SOUNDINGS FOR  
WEDNESDAY DO SHOW IMPROVING MUCAPE TO AROUND 500 J/KG INTO THE  
LOWER DESERTS, WHILE DCAPES WILL BE QUITE HIGH AT AROUND 1500  
J/KG. THIS SHOULD AT LEAST POSE A VERY LOCALIZED THREAT FOR  
STRONG WINDS ACROSS THE AREA.  
 
THE INVERTED TROUGH IS LIKELY TO WASH OUT OVER SOUTH-CENTRAL  
ARIZONA BY THURSDAY, BUT MOISTURE SHOULD CONTINUE TO INCREASE AND  
REACH ITS PEAK DURING THE DAYTIME HOURS THURSDAY. FORECAST PWATS  
ON THURSDAY ARE SEEN REACHING BETWEEN 1.2-1.4" WITH MORE ADEQUATE  
LOW LEVEL MIXING RATIOS OF 10-11 G/KG. THIS SHOULD BOOST MUCAPES  
CLOSER TO 1000 J/KG AND ALLOW FOR BETTER CHANCES FOR LOWER DESERT  
THUNDERSTORM ACTIVITY THURSDAY AFTERNOON AND EVENING. HOWEVER, AN  
OVERALL WEAK SOUTH TO SOUTHWEST STEERING FLOW AND LITTLE TO NO  
UPPER LEVEL SUPPORT IS LIKELY TO PRECLUDE ANY ORGANIZED STORM  
CLUSTERS FROM OCCURRING. POTENTIAL STORM THREATS THURSDAY WILL  
AGAIN LEAN TOWARD STRONG GUSTY WINDS/BLOWING DUST, BUT WITH THE  
IMPROVED MOISTURE THERE MAY ALSO BE A VERY LOCALIZED HEAVY  
RAINFALL/FLOOD THREAT. NBM POPS ALSO REACH THEIR PEAK ON THURSDAY  
AT 20-30% ACROSS THE SOUTH-CENTRAL ARIZONA LOWER DESERTS.  
 
STARTING THURSDAY NIGHT, THE FLOW PATTERN IS EXPECTED TO SHIFT  
OUR WINDS MORE OUT OF THE WEST SOUTHWEST AS GUIDANCE SHOWS THE  
SUBTROPICAL RIDGE CENTER MOVING SOMEWHERE ACROSS SOUTHWEST NEW  
MEXICO, SOUTHEAST ARIZONA, OR OVER SONORA. ASSUMING THIS OCCURS,  
IT WOULD BRING A QUICK DRYING TREND ON FRIDAY WITH LOWER DESERT  
RAIN CHANCES DROPPING TO AROUND 10% AND TO 20-30% OVER THE EASTERN  
ARIZONA HIGH TERRAIN. THIS PATTERN IS THEN LIKELY TO HOLD THROUGH  
THE WEEKEND, ENDING RAIN CHANCES ACROSS THE LOWER DESERTS  
COMPLETELY AND ONLY ALLOWING VERY LIMITED CHANCES OVER HIGHER  
TERRAIN AREAS.  
 
 
   
AVIATION  
UPDATED AT 0500Z.  
 
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:  
SOME MINOR UNCERTAINTY IN TIMING OF WIND SHIFTS WILL BE THE MAIN  
WEATHER CHALLENGE THROUGH MONDAY NIGHT UNDER PERIODS OF OCCASIONAL  
MID/HIGH CLOUD DECKS. CONFIDENCE IS GOOD THAT WINDS WILL SHIFT TO  
AN EASTERLY COMPONENT OVERNIGHT, THOUGH EXACT TIMING IS SOMEWHAT  
UNCERTAIN. WINDS SHOULD HAVE LIMITED GUSTINESS MONDAY AFTERNOON  
AFTER THE W/SW WIND SHIFT WHILE THUNDERSTORMS REMAIN RELEGATED TO  
FAR EASTERN ARIZONA. HOWEVER, CONFIDENCE IS MODERATE THAT DISTANT  
OUTFLOWS WILL BE MAINTAINED INTO THE PHOENIX AIRSPACE SUCH THAT AN  
EARLIER THAN USUAL, AND POSSIBLY ABRUPT WIND SHIFT WILL SWEEP ACROSS  
AERODROMES MONDAY MID-EVENING.  
 
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:  
NO WEATHER CONCERNS WILL EXIST THROUGH MONDAY NIGHT UNDER CLEAR  
SKIES. CONFIDENCE IS VERY GOOD THAT WIND BEHAVIOR WILL BE SIMILAR  
TO THE PAST 24 HOURS INCLUDING A PREFERENCE TOWARDS DIRECTIONS  
OSCILLATING BETWEEN WEST AND NORTH AT KIPL AND SOUTH TO SOUTHWEST  
AT KBLH. ANY GUSTINESS SHOULD BE MINIMAL WITH NEARLY CALM  
OR WEAK DRAINAGE CONDITIONS LIKELY DURING THE POST-SUNRISE MORNING  
HOURS.  
 
 
   
FIRE WEATHER  
 
CHANCES FOR SCATTERED SHOWERS AND A FEW THUNDERSTORMS WILL RETURN  
TO THE HIGH TERRAIN EAST OF PHOENIX BEGINNING THIS AFTERNOON,  
WITH HIGHER CHANCES AND COVERAGE POSSIBLY EXTENDING INTO THE LOWER  
DESERTS BY WEDNESDAY. THE NEXT COUPLE OF DAYS WILL ALSO POSE AT  
LEAST A MINOR RISK OF DRY LIGHTNING ACROSS GILA COUNTY. AFTERNOON  
MINRHS FOR THE LOWER DESERTS WILL REMAIN BETWEEN 5-10% TODAY,  
BEFORE INCREASING INTO THE TEENS BY WEDNESDAY. OUTSIDE OF THE  
INFLUENCE OF THUNDERSTORMS, WINDS WILL GENERALLY FOLLOW DIURNAL  
TENDENCIES WITH TYPICAL AFTERNOON UPSLOPE GUSTINESS. TEMPERATURES  
WILL MOSTLY RUN 3-6 DEGREES ABOVE NORMAL OVER THE NEXT SEVERAL  
DAYS. MOISTURE AND RAIN CHANCES ARE THEN LIKELY TO SPREAD  
WESTWARD INTO SOUTH-CENTRAL ARIZONA BY WEDNESDAY OR AT THE LATEST  
ON THURSDAY WITH A MODEST INCREASE IN HUMIDITIES.  
 
 
   
PSR WATCHES/WARNINGS/ADVISORIES  
 
AZ...NONE.  
CA...NONE.  
 
 
 
 
SHORT TERM...KUHLMAN  
LONG TERM...KUHLMAN  
AVIATION...18  
FIRE WEATHER...KUHLMAN  
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