323
FXUS65 KPSR 202100
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
200 PM MST FRI MAR 20 2026
KEY MESSAGES
- RECORD BREAKING LOWER DESERT HIGH TEMPERATURES NEAR OR
EXCEEDING 100 DEGREES WILL BE COMMON THROUGH AT LEAST THE MIDDLE
OF NEXT WEEK, WITH THE HOTTEST DAYS BEING TODAY AND SATURDAY.
- EXTREME HEAT WARNINGS WILL REMAIN IN EFFECT ACROSS THE LOWER
DESERTS THROUGH SUNDAY.
- THE UNPRECEDENTED AFTERNOON HEAT WILL BE DANGEROUS, ESPECIALLY
WITH ANY STRENUOUS OR LONG-DURATION OUTDOOR ACTIVITIES WITHOUT
PROPER HYDRATION AND TAKING BREAKS IN THE SHADE, OR AIR
CONDITIONING.
SHORT TERM /TODAY THROUGH SUNDAY/
CURRENT MIDLEVEL WATER VAPOR IMAGERY AND 500 MB RAP ANALYSIS SHOW
THE CENTER OF THIS STRONG RIDGE POSITIONED OVER SOUTHWEST
ARIZONA, WITH H5 HEIGHTS REACHING UP TO 594 DAM. 500 MB HEIGHTS OF
THIS MAGNITUDE ARE AT THE CLIMATOLOGICAL MAX FOR THIS TIME OF
YEAR AND HAVE BEEN THE MAIN DRIVER FOR THESE RECORD BREAKING
TEMPERATURES OVER THE PAST SEVERAL DAYS. TODAY AND TOMORROW'S
AFTERNOON HIGH TEMPERATURES WILL BE THE HOTTEST THE REGION WILL
EXPERIENCE DURING THIS EARLY MARCH HEAT WAVE. ACROSS THE LOWER
DESERTS AFTERNOON HIGHS WILL BE IN THE 102F-108F RANGE. IF TODAY'S
FORECASTED HIGH TEMPERATURE OF 106F IS REACHED AT PHOENIX SKY
HARBOR, IT WOULD BREAK THE PREVIOUS RECORD OF 96F SET IN 2017, BY
10 DEGREES. ADDITIONALLY, THIS WOULD SURPASS EVEN APRIL'S ALL TIME
HIGH RECORDED TEMPERATURE OF 105F SET ON APRIL 22ND IN 2012 AND
APRIL 29TH IN 1992. THROUGHOUT THE WEEKEND H5 HEIGHTS WILL LOWER
SLIGHTLY TO BETWEEN 582-585 DAM BY SUNDAY AS THE CORE OF THE RIDGE
MIGRATES EASTWARDS. TEMPERATURES WILL LOWER IN RESPONSE TO HOVER
BETWEEN 96F-102F, STILL WELL ABOVE THE SEASONAL NORMALS FOR THIS
TIME OF YEAR. THAT BEING SAID, THE EXTREME HEAT WARNINGS WILL
REMAIN IN EFFECT ACROSS THE LOWER DESERTS THROUGH SUNDAY. ENSURE
TO FOLLOW PROPER HEAT SAFETY PRECAUTIONS SUCH AS STAYING HYDRATED,
TAKING ADEQUATE/FREQUENT BREAKS, AND STAYING INDOORS WITH AC IF
POSSIBLE.
LETS TAKE A BREAK FROM TALKING ABOUT HEAT FOR ONE SECOND. A 700
MB SHORTWAVE TROUGH LOOKS TO DEVELOP BY SATURDAY EVENING. THIS
WILL LEAD TO WINDS AT INCREASING TO AROUND 20-25 MPH, ESPECIALLY
IN PORTIONS OF SOUTHEAST CA, AND PARTICULARLY IN THE SW CORNER OF
IMPERIAL VALLEY.
LONG TERM /MONDAY THROUGH THURSDAY/
OF THE NEXT 7 DAYS, MONDAY IS SHAPING UP TO BE THE "COOLEST" (LOWER
DESERT HIGHS 94F-101F) THANKS TO A COUPLE OF FACTORS. THE RIDGE WILL
NOT REBUILD SUBSTANTIALLY UNTIL TUESDAY OVER THE DESERT SOUTHWEST
AND LOWER LEVEL THERMAL PROFILE WILL REQUIRE STRONGER/SUSTAINED
ANTICYCLONIC SUBSIDENCE TO WARM FURTHER. ANOTHER FACTOR IS THAT
GUIDANCE INDICATES SOMETHING REMINISCENT OF A GULF SURGE
OCCURRING SUNDAY NIGHT AND POSSIBLY AGAIN MONDAY NIGHT, INCREASING
MOISTURE OVER A SHALLOW LAYER NEAR THE SURFACE. DEWPOINT
TEMPERATURES ARE SHOWN INCREASING UPWARDS OF 45F-55F FOR THE YUMA
AREA AND AT TIMES FOR THE ADJACENT VALLEYS (IMPERIAL, LOWER
COLORADO RIVER, LOWER GILA RIVER). DEWPOINTS ARE FORECAST TO
INCREASE AT LEAST INTO THE 30S ELSEWHERE ACROSS THE LOWER DESERTS.
IT WILL BE HARDER TO REALIZE WIDESPREAD TEMPERATURES IN EXCESS OF
100F ESPECIALLY ON MONDAY THANKS TO THESE FACTORS.
DURING THE MIDDLE OF NEXT WEEK, ENSEMBLES CONTINUE TO ADVERTISE
ANOTHER SIGNIFICANT YET MORE TRANSIENT RIDGING FEATURE BUILDING
UNDER AN ANTICYCLONICALLY CURVED JET STREAK. THOUGH THE RIDGING WILL
BE LOWER AMPLITUDE COMPARED TO THE CURRENT RIDGE, AND ANTICYCLONIC
SUBSIDENCE WILL BE SHORTER LIVED (LIKELY PEAKING IN ITS INFLUENCE
SOMETIME TUESDAY-WEDNESDAY), H5 HEIGHTS ARE FORECAST TO RISE INTO
A 588-591 DAM RANGE - ONCE AGAIN ABOVE CFSR CLIMATOLOGICAL
MAXIMUM VALUES OVER A BROAD AREA. THIS WILL ALLOW A GRADUAL
WARMING INTO THE MIDDLE OF THE UPCOMING WORKWEEK, WITH COVERAGE OF
100F+ TEMPERATURES INCREASING. IN SUMMARY, CONFIDENCE CONTINUES
TO GROW IN A LONGER DURATION HEATWAVE, WITH HIGHS REMAINING
BETWEEN 15F-25F ABOVE DAILY NORMALS AND BREAKING DAILY RECORDS
WELL INTO NEXT WEEK.
AVIATION
UPDATED AT 1730Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT; AND
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
NO AVIATION WEATHER CONCERNS ARE EXPECTED THROUGH THE FORECAST
PERIOD. WINDS WILL CONTINUE TO FOLLOW FAMILIAR DIURNAL TRENDS SEEN
OVER THE PAST 24 HOURS WITH SPEEDS REMAINING AOB 8 KTS. EXTENDED
PERIODS OF CALM AND VRB CONDITIONS WILL BE COMMON, ESPECIALLY AT
THE SE CALIFORNIA TERMINALS. CLEAR SKIES WILL DOMINATE THE REGION
THROUGH SATURDAY.
FIRE WEATHER
HISTORIC MARCH HEAT AND VERY DRY CONDITIONS WILL CONTINUE THROUGH
THE WEEKEND. AFTERNOON HIGHS AROUND 25 DEGREES ABOVE DAILY NORMALS
WILL BE COMMON TODAY AND SATURDAY, FALLING TO AROUND 20 DEGREES
ABOVE NORMAL BY SUNDAY. AFTERNOON MINRHS BETWEEN 5-10% WILL
PERSIST THROUGH SUNDAY, INCREASING SLIGHTLY INTO A 10-20% RANGE
FOR PORTIONS OF THE WESTERN DESERTS EARLY NEXT WEEK. OVERNIGHT
RECOVERIES WILL BE POOR, AROUND 15-35% THROUGH SATURDAY NIGHT.
HOWEVER, MAXRH'S IMPROVE TO 40-60% SUNDAY NIGHT AND MONDAY NIGHT
PRIMARILY FOR VALLEY LOCATIONS IN THE WESTERN DESERTS LIKE THE
YUMA AREA, LOWER COLORADO RIVER VALLEY, IMPERIAL VALLEY, AND LOWER
GILA RIVER VALLEY. WINDS WILL BE LIGHT TODAY, MOSTLY BELOW 15
MPH, BUT LATE AFTERNOON AND EARLY EVENING BREEZINESS WILL INCREASE
THIS WEEKEND, WITH GUSTS LOCALLY TO 20-25 MPH.
CLIMATE
DAILY RECORD HIGHS THROUGH THE MIDDLE OF NEXT WEEK:
DATE PHOENIX YUMA EL CENTRO
---- ------- ---- ---------
3/20 96 IN 2017 99 IN 2004 98 IN 2004
3/21 97 IN 2004 102 IN 2004 100 IN 2004
3/22 94 IN 1990 98 IN 2004 96 IN 2004
3/23 93 IN 1990 96 IN 1990 93 IN 1990
3/24 96 IN 2025 97 IN 2025 96 IN 2025
3/25 99 IN 2025 99 IN 1896 99 IN 2025
3/26 100 IN 1988 99 IN 1988 98 IN 1988
PSR WATCHES/WARNINGS/ADVISORIES
AZ...EXTREME HEAT WARNING UNTIL 8 PM MST SUNDAY FOR AZZ530>555-559-
561.
CA...EXTREME HEAT WARNING UNTIL 8 PM PDT SUNDAY FOR CAZ561>570.
SHORT TERM...RYAN
LONG TERM...WHITTOCK
AVIATION...SALERNO
FIRE WEATHER...RYAN/WHITTOCK
CLIMATE...WHITTOCK/18
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