187
FXUS65 KPSR 042321
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
420 PM MST SUN OCT 4 2026
UPDATE
UPDATED AVIATION
KEY MESSAGES
- ABOVE NORMAL TEMPERATURES WITH MINIMAL DAY TO DAY CHANGES WILL
EXIST THROUGH THE START OF THE WEEK AS AFTERNOON HIGHS REACH 97 TO
103 DEGREES ACROSS THE LOWER DESERTS.
- BREEZY TO LOCALLY WINDY CONDITIONS CAN BE EXPECTED IN THE MORNINGS
AND EARLY AFTERNOONS ACROSS SOUTH-CENTRAL AND SOUTHWESTERN ARIZONA
THROUGH MONDAY WITH GUSTS REACHING 20 TO 35 MPH.
- TEMPERATURES ACROSS SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA
WARM TO NEAR RECORD LEVELS WEDNESDAY AND THURSDAY.
- DRY WEATHER WITH ZERO RAIN CHANCES WILL PERSIST THROUGH THE WEEK.
SHORT TERM /TODAY THROUGH TUESDAY/
DRY AND WARM CONDITIONS CONTINUE ACROSS THE REGION WITH BROAD HIGH
PRESSURE POSITIONED OVER THE SOUTHWEST CONUS. A STRONG E-W PRESSURE
GRADIENT REMAINS IN PLACE ACROSS SOUTHERN AZ AND HAS RESULTED IN
WIND GUSTS TODAY UP TO 30-40 MPH ACROSS PARTS OF SOUTH-CENTRAL AZ.
SEVERAL DUST CHANNELS DEVELOPED AND WERE VISIBLE ON SATELLITE ACROSS
PINAL COUNTY AROUND MIDDAY. MAGNITUDE OF WIND GUSTS ARE EXPECTED TO
WANE THROUGH THE AFTERNOON AND THIS EVENING. HIGH TEMPERATURES THIS
AFTERNOON WILL BE SIMILAR TO YESTERDAY FOR MOST AREAS AND A COUPLE
DEGREES WARMER ACROSS SOUTH-CENTRAL AZ, TOPPING OUT AROUND 97-102
DEGREES.
WEATHER CONDITIONS HEADING INTO MONDAY WILL ONCE AGAIN BE SIMILAR TO
TODAY WITH BREEZY EASTERLY WINDS, AS THE PRESSURE GRADIENT PERSISTS,
AND ABOVE NORMAL TEMPERATURES WITH AFTERNOON HIGHS AGAIN AROUND 97-
102 DEGREES. EASTERLY WIND GUSTS DURING THE MONDAY ARE FORECAST TO
PEAK AROUND 25-35 MPH IN THE MORNING AND THEN WEAKEN THROUGH THE
REST OF THE DAY AS THE PRESSURE GRADIENT FINALLY RELAXES WITH
LOWERING SURFACE PRESSURE TO THE EAST. BY TUESDAY, A SHORTWAVE
TROUGH, WHICH IS CURRENTLY JUST OFF THE CA COAST, WILL MOVE EASTWARD
INLAND THROUGH NV AND UT AND DISLODGE THE HIGH PRESSURE OVER THE
REGION WHILE ALSO SHIFTING MID-LEVEL FLOW FROM E-SE TO W-NW. DESPITE
THESE CHANGES ALOFT, THERE WILL NOT BE ANY NOTABLE IMMEDIATE CHANGES
AT THE SURFACE. TEMPERATURES TUESDAY WILL REMAIN NEARLY UNCHANGED AT
5-10 DEGREES ABOVE NORMAL WITH HIGHS AROUND 97-103 DEGREES ACROSS
THE LOWER DESERTS. THE SURFACE PRESSURE GRADIENT WILL AT LEAST RELAX
FURTHER INTO TUESDAY. THERE MAY STILL BE SOME MORNING EASTERLY
BREEZES, BUT OVERALL WINDS WILL BE MUCH LIGHTER TUESDAY ACROSS THE
REGION. SKIES WILL REMAIN MOSTLY CLEAR THROUGH THE START OF THE
WORKWEEK WITH NO RAIN EXPECTED
LONG TERM /WEDNESDAY THROUGH SATURDAY/
BY WEDNESDAY, A QUASI-OMEGA BLOCK IS SHOWN TO DEVELOP WITH AN
ANTICYCLONE DEVELOPING NEAR/OVER THE SOCAL COAST. FORECAST
CONFIDENCE IS GOOD THAT THIS PATTERN WILL HOLD THROUGH THE END OF
THE WORKWEEK. THIS WILL RESULT IN TEMPERATURES REMAINING FAIRLY
STEADY ACROSS SOUTH-CENTRAL AZ WITH AFTERNOON HIGHS IN THE 95-100
DEGREE RANGE ACROSS THE LOWER DESERTS AND RANGING FROM THE MID 80S
TO LOWER 90S ACROSS THE HIGHER TERRAIN AREAS. MEANWHILE TEMPERATURES
ARE EXPECTED TO HEAT UP ACROSS SOUTHEAST CA AND SOUTHWEST AZ WITH A
STRENGTHENING OF THE NEARBY ANTICYCLONE. LATEST NBM FORECAST
CONTINUES TO SHOW AFTERNOON HIGHS REACHING THE 100-106 DEGREE RANGE
ACROSS THE LOWER DESERTS IN SE CA AND SW AZ FOR BOTH WEDNESDAY AND
THURSDAY. THESE TEMPERATURES WILL BE OVER 10 DEGREES ABOVE NORMAL
AND NEAR DAILY RECORDS IN BOTH EL CENTRO, CA AND YUMA, AZ BOTH DAYS.
THESE TEMPERATURES ALSO WILL LIKELY LEAD TO MAJOR HEATRISK FOR THIS
TIME OF YEAR, WITH PROBABILITY OF MAJOR HEATRISK AT 50-70%. AS A
RESULT, AN EXTREME HEAT WATCH HAS BEEN ISSUED FOR THE YUMA AREA AND
IMPERIAL VALLEY FOR WEDNESDAY AND THURSDAY. WITH HIGH PRESSURE IN
PLACE DRY CONDITIONS ARE EXPECTED TO PERSIST WITH NO CHANCES FOR
RAIN, EXCEPT FOR NEAR THE WHITE MTNS WEDNESDAY WITH A WEAK SHORTWAVE
MOVING THROUGH THE FOUR CORNERS.
THE HIGH PRESSURE TO THE WEST IS THEN EXPECTED TO START TO WEAKEN BY
THE END OF THE WORKWEEK AND INTO THE WEEKEND WITH A TROUGH MOVING
INTO WESTERN CONUS THIS UPCOMING WEEKEND. HOWEVER, FORECAST
CONFIDENCE DECREASES CONSIDERABLY BY THE END OF THE WEEKEND AND
START OF THE FOLLOWING WEEK AS THE ENSEMBLE SPREAD IS LARGE WITH THE
TIMING OF THE HIGH WEAKENING AND MOVING OUT OF THE REGION AND THE
TROUGH MOVING IN. THE ENSEMBLES ALSO DISAGREE ON THE STRENGTH OF THE
TROUGH FOR THIS UPCOMING WEEKEND. EITHER WAY TEMPERATURES ARE
EXPECTED TO GRADUALLY DECREASE BACK TOWARD NORMAL BY THIS UPCOMING
WEEKEND. ADDITIONALLY, DRY CONDITIONS LOOK TO CONTINUE THROUGH AT
LEAST SATURDAY, BUT THIS COULD CHANGE DEPENDING ON THE EVOLUTION OF
TROUGHING DURING THE WEEKEND. RIGHT NOW BETTER CHANCES FOR RAIN LOOK
TO ARRIVE BY THE BEGINNING OF NEXT WEEK, WITH THE BEST CHANCES
ACROSS THE HIGHER TERRAIN IN EASTERN AZ. STAY TUNED FOR UPDATES.
AVIATION
UPDATED AT 2320Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
UNDER CLEAR SKIES, THE PRIMARY WEATHER ISSUE THROUGH MONDAY EVENING
WILL FREQUENTLY GUSTY EAST WINDS. CONFIDENCE IS MODERATE THAT SOME
MEASURE OF GUSTINESS WILL PERSIST THROUGH THE EVENING AS DECOUPLING
MAY NEVER FULLY BE ACCOMPLISHED OVERNIGHT. AS A RESULT, LLWS
CONDITIONS MAY ONLY BE REACHED AT THE MOST SHELTERED AERODROMES WITH
STEADY WIND SPEEDS AND OCCASIONAL GUSTS THROUGH THE NIGHT ELSEWHERE.
CONFIDENCE IS VERY GOOD THAT EASTERLY GUSTS 20-25KT WILL REDEVELOP
MONDAY MID MORNING BEFORE RELAXING MID AFTERNOON. WHILE SOME DUST
MAY LOCALLY BE LOFTED WITH THESE WIND GUSTS, THE LIMITED TEMPORAL
AND AREAL EXPANSE SHOULD PRECLUDE SURFACE OR SLANTWISE VISIBILITY
ISSUES.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
NO WEATHER ISSUES WILL EXIST THROUGH MONDAY EVENING UNDER CLEAR
SKIES. CONFIDENCE IS GOOD THAT WIND DIRECTIONS WILL OSCILLATE
BETWEEN A DAYTIME E/NE AND OVERNIGHT N/NW WITH SPEEDS OCCASIONALLY
REACHING 10-12KT.
FIRE WEATHER
EXPECT EASTERLY WINDS TO REMAIN ELEVATED AROUND 8-15 MPH WITH EARLY
MORNING AND AFTERNOON GUSTS UP TO 20-35 MPH, AND LOCALLY HIGHER
GUSTS OF 35-40 MPH, TODAY MAINLY ACROSS SW AZ AND THE EASTERN
DISTRICT. WINDS WILL BE A TOUCH WEAKER MONDAY AND THEN WINDS WILL
RETURN TO THEIR MORE TYPICAL LIGHT DIURNAL TENDENCIES ON TUESDAY
WITH ONLY MINOR AFTERNOON UPSLOPE GUSTINESS. THESE LIGHTER WINDS MAY
ONLY LAST A COUPLE DAYS BEFORE GUSTY EASTERLY GRADIENT WINDS DEVELOP
AGAIN BY FRIDAY. DRY CONDITIONS WITH ABOVE NORMAL TEMPERATURES WILL
CONTINUE THROUGH THE UPCOMING WEEK. A SLIGHT INCREASE IN
TEMPERATURES, INTO THE 101-106 DEGREE RANGE IS ANTICIPATED ACROSS
SOUTHEAST CA AND SOUTHWEST AZ WEDNESDAY AND THURSDAY. MINRHS WILL
MOSTLY RANGE FROM 15-25% ACROSS THE WESTERN DISTRICTS TO 20-35%
ACROSS EASTERN DISTRICTS WITH FAIR TO GOOD OVERNIGHT RECOVERY (35-
60%) AREA-WIDE. NO WETTING RAIN EXPECTED THROUGH THE NEXT 7 DAYS.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...EXTREME HEAT WATCH FROM WEDNESDAY MORNING THROUGH THURSDAY
EVENING FOR AZZ532.
CA...EXTREME HEAT WATCH FROM WEDNESDAY MORNING THROUGH THURSDAY
EVENING FOR CAZ566-567.
SHORT TERM...BENEDICT
LONG TERM...BENEDICT/BERISLAVICH
AVIATION...18
FIRE WEATHER...BENEDICT/BERISLAVICH
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