217
FXUS65 KPSR 210510
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
1010 PM MST FRI MAR 20 2026
UPDATE
UPDATED AVIATION
KEY MESSAGES
- RECORD BREAKING LOWER DESERT HIGH TEMPERATURES NEAR 100 DEGREES
WILL BE COMMON THROUGH AT LEAST THE MIDDLE OF NEXT WEEK WITH THE
HOTTEST DAY BEING SATURDAY.
- EXTREME HEAT WARNINGS 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 0510Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT; AND
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
NO MAJOR WEATHER ISSUES WILL EXIST THROUGH SATURDAY NIGHT WITH AN
INCREASE IN HIGH CIRRUS DECKS LATE IN THE PERIOD. CONFIDENCE IS GOOD
THAT TRENDS IN WIND SPEEDS AND TIMING OF DIRECTIONAL SHIFTS WILL BE
NEARLY IDENTICAL TO THE PAST 24 HOURS - ESPECIALLY ACROSS THE
PHOENIX METRO. IN SE CALIFORNIA, WIND SPEEDS SHOULD INCREASE
SATURDAY AFTERNOON WITH MODERATE CONFIDENCE OF GUSTS NEAR 20KT,
PRIMARILY AT KIPL AFTER SUNSET.
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
---- ------- ---- ---------
3/21 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...18
FIRE WEATHER...RYAN/WHITTOCK
CLIMATE...WHITTOCK/18
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