052
FXUS65 KPSR 301018
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
318 AM MST MON JUN 30 2025
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 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 0539Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, KDVT:
WESTERLY WINDS WILL PREVAIL THROUGH THE MIDDLE OF THE NIGHT AND
THEN A LATE AND RELATIVELY BRIEF PERIOD OF EASTERLIES ARE EXPECTED
TOMORROW MORNING, MAINLY BETWEEN 12-18Z AT KPHX. WESTERLY WINDS
REDEVELOP BY TOMORROW AFTERNOON WITH GUST REACHING AROUND 20 KTS.
FEW MID LEVEL CLOUDS, ABOVE 13K FT AGL CAN BE EXPECTED AT TIMES
THROUGH THE TAF PERIOD. THERE IS POTENTIAL FOR AN OUTFLOW BOUNDARY
TO MOVE TOWARD THE VALLEY FROM THE EAST TOMORROW EVENING, BUT ODDS
AND CONFIDENCE ARE TOO LOW TO INCLUDE A REFLECTION OF ONE IN THE
TAFS. A STRONG EASTERLY GRADIENT WIND WILL DEVELOP AROUND 7Z
TOMORROW NIGHT AND PUSH EASTERLY WINDS UP TO 10-15 KTS.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
WESTERLY WINDS ARE FAVORED AT KIPL THROUGH MOST OF THE TAF PERIOD,
WITH OCCASIONAL PERIODS OF LIGHT VARIABILITY. SPEEDS WILL MOSTLY
REMAIN AT OR BELOW 10 KTS, WITH SLIGHTLY HIGHERS SPEEDS AND SOME
20 KT GUSTS ANTICIPATED FOR TOMORROW EVENING. DIURNAL WIND TRENDS
ARE EXPECTED AT KBLH, WITH PERIODS OF LIGHT VARIABILITY, BUT WIND
DIRECTIONS WILL MOSTLY FAVOR A S-SW COMPONENT THROUGH THE PERIOD
WITH SPEEDS MOSTLY AT OR BELOW 10 KTS. SKIES WILL REMAIN MOSTLY
CLEAR WITH FEW MID LEVEL CUMULUS AT TIMES IN THE AFTERNOON AND
EVENING.
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 FROM 10 AM THIS MORNING TO 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 FROM 10 AM THIS MORNING TO 8 PM MST THIS
EVENING FOR AZZ541-545-547-549-552-555-556-560>562.
CA...EXTREME HEAT WARNING FROM 10 AM THIS MORNING TO 8 PM PDT TUESDAY
FOR CAZ562-565>567-569-570.
DISCUSSION...LOJERO
AVIATION...BENEDICT
FIRE WEATHER...LOJERO
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