652
FXUS65 KPSR 190455
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
955 PM MST WED MAR 18 2026
UPDATE...UPDATED 06Z AVIATION DISCUSSION
KEY MESSAGES
- A HISTORIC MARCH HEATWAVE WILL PRODUCE RECORD SHATTERING LOWER
DESERT HIGH TEMPERATURES EXCEEDING 100 DEGREES THROUGH AT LEAST
THE WEEKEND.
- AN EXTREME HEAT WARNING IS IN EFFECT ACROSS SOUTHEAST CALIFORNIA
AND WILL GO INTO EFFECT THURSDAY ACROSS THE ARIZONA DESERTS, AND
WILL CONTINUE THROUGH THIS 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 THURSDAY/
THE HOTTEST TEMPERATURES THE SOUTHWESTERN U.S. HAS EVER
EXPERIENCED IN MARCH WILL ARRIVE BY THURSDAY AS A RECORD STRENGTH
HIGH PRESSURE CENTER SLOWLY SHIFTS FROM SOUTHERN CALIFORNIA INTO
ARIZONA ON THURSDAY. H5 HEIGHTS ARE CURRENTLY AROUND 592DM AND
WILL RISE TO AROUND 596-597DM TOMORROW. RECORD H5 HEIGHTS FOR THE
MONTH OF MARCH FOR THE DESERT SOUTHWEST ARE BETWEEN 591-593DM,
MEANING THIS RIDGE WILL SMASH THE ALL-TIME MARCH RECORD. THIS HIGH
PRESSURE SYSTEM IS SOMETHING LIKE WE WOULD TYPICALLY GET DURING
SUMMERTIME HEAT EVENTS. CLIMATOLOGICAL RECORD HIGH H5, H7, AND H8
TEMPERATURES HAVE ALREADY SPREAD ACROSS ALL OF CALIFORNIA AND THE
BULK OF THE DESERT SOUTHWEST. FULL MIXING OF THE RECORD HEAT
ALOFT INTO THE BOUNDARY LAYER WILL TAKE ANOTHER DAY OR SO, KEEPING
SURFACE TEMPERATURES FROM REACHING THEIR PEAK UNTIL FRIDAY.
THE HEAT OVER THE NEXT SEVERAL DAYS WILL BE UNPRECEDENTED FOR
THIS TIME OF YEAR, BUT CONSIDERING HOW MUCH ABOVE CLIMATOLOGICAL
RECORDS THIS RIDGE WILL BE, THERE ARE A COUPLE OF POSITIVE THINGS.
THE DAYLENGTH IS STILL AT LEAST TWO HOURS SHY OF WHAT WE GET FROM
LATE MAY-JULY AND THE DRY AIR WILL HELP WITH OVERNIGHT
TEMPERATURES. A WIDE DIURNAL TEMPERATURE RANGE WILL ALLOW FOR SOME
RELIEF FROM THE HEAT DURING THE OVERNIGHT HOURS WITH LOW
TEMPERATURES MOSTLY STAYING IN THE 60S TO LOW 70S, HOWEVER STILL
NEAR 15 DEGREES ABOVE NORMAL.
TEMPERATURES EARLY THIS AFTERNOON HAVE ALREADY CLIMBED INTO THE
UPPER 90S TO LOW 100S ACROSS THE LOWER DESERTS AND ALL THREE OF
OUR CLIMATE SITES (PHOENIX, YUMA, AND EL CENTRO) HAVE ALREADY
SET NEW DAILY RECORDS, SURPASSING THE PREVIOUS RECORDS BY 4-6
DEGREES (SEE CLIMATE SECTION BELOW FOR THE PREVIOUS RECORDS).
WITH SOME MORE DAYTIME HEATING STILL LEFT FOR TODAY THOSE
TEMPERATURES ARE EXPECTED TO CLIMB ANOTHER COUPLE DEGREES. IF
PHOENIX REACHES 100 DEGREES THIS AFTERNOON IT WILL BE THE EARLIEST
100 DEGREE DAY IN PHOENIX, WHICH THE CURRENT EARLIEST 100 DEGREE
DAY IS MARCH 26, 1988. ADDITIONALLY, IF PHOENIX REACHES 101
DEGREES IT WILL BREAK THE ALL TIME RECORD HIGH TEMPERATURE FOR THE
MONTH OF MARCH, WHICH STANDS AT 100 DEGREES ON MARCH 26, 1988.
ADDITIONALLY, OUR OTHER TWO CLIMATE SITES ARE EXPECTED TO NEAR OR
SURPASS THEIR MONTHLY MARCH RECORD HIGH TEMPERATURES. YUMA'S
CURRENT MARCH RECORD IS 102 DEGREES, SET ON MARCH 21, 2004, AND
EL CENTRO'S CURRENT MARCH RECORD IS 101 DEGREES, SET ON MARCH 17,
2007 AND MARCH 30, 1934. BY TOMORROW AFTERNOON HIGH TEMPERATURES
ARE FORECASTED TO BE IN THE 102-106 DEGREE RANGE ACROSS THE LOWER
DESERTS AND IN THE MID TO UPPER 90S ACROSS THE HIGHER TERRAIN. IF
ANY OF THE THREE CLIMATE SITES DON'T BREAK THEIR MONTHLY MARCH
RECORD TODAY THEY SHOULD TOMORROW.
IT GOES WITHOUT SAYING, THIS WILL BE AN IMPACTFUL HEATWAVE.
EXTREME HEAT WARNINGS ARE ALREADY IN EFFECT ACROSS SOUTHEAST
CALIFORNIA AND WILL GO INTO EFFECT ACROSS THE REST OF THE AREA
STARTING TOMORROW MORNING.
LONG TERM /FRIDAY THROUGH TUESDAY/
THE HOTTEST DAYS THIS WEEK STILL LOOK TO BE ON FRIDAY AND SATURDAY
WITH HIGHS MOSTLY BETWEEN 103-107 DEGREES, ROUGHLY 25 DEGREES
ABOVE NORMAL AND 7-10 DEGREES ABOVE DAILY RECORDS. GUIDANCE HAS
BARELY DEVIATED OVER THE PAST COUPLE OF DAYS WITH THE RIDGE
STARTING TO WEAKEN EVER SO SLOWLY STARTING FRIDAY AND MORE SO
SATURDAY INTO SUNDAY. H5 HEIGHTS ARE FORECAST TO DROP BACK TO
BETWEEN 585-588DM BY LATER SATURDAY BEFORE SETTLING INTO A
582-585DM RANGE STARTING SUNDAY, STILL WELL ABOVE THE 90TH
PERCENTILE OF CLIMATOLOGY. THE WEAKER RIDGE SHOULD ALLOW FOR
DAYTIME HIGHS TO DROP TO BETWEEN 99-102 DEGREES BY SUNDAY.
ONE NOTICEABLE CHANGE WITH THE GUIDANCE IS A HIGHER LIKELIHOOD OF
HOLDING ONTO HIGHER HEIGHTS WELL INTO OR EVEN THROUGH THE MAJORITY
OF NEXT WEEK. ENSEMBLE MEAN H5 HEIGHTS ARE NOW SHOWN TO STAY
CLOSER TO THE 97TH PERCENTILE OF CLIMATOLOGY INTO AT LEAST THE
MIDDLE OF NEXT WEEK AND NEARLY CERTAIN TO STAY ABOVE THE 90TH
PERCENTILE. THIS MEANS THE HEAT WILL NOT GO AWAY NEXT WEEK AND
TEMPERATURES ARE LIKELY TO STAY AT OR JUST ABOVE DAILY RECORDS
THROUGH AT LEAST THE FIRST HALF OF NEXT WEEK. NBM FORECAST HIGHS
HAVE RISEN BY SEVERAL DEGREES DURING THE MIDDLE PART OF NEXT WEEK
WITH LOWER DESERT READINGS STAYING MOSTLY IN THE UPPER 90S, OR
15-20 DEGREES ABOVE NORMAL.
AVIATION
UPDATED AT 0455Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT; AND
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
NO AVIATION WEATHER CONCERNS UNDER MOSTLY CLEAR SKIES CAN BE
EXPECTED THROUGHOUT THE TAF PERIOD. WINDS WILL CONTINUE TO EXHIBIT
THE TYPICAL DIURNAL TENDENCIES WITH SPEEDS AOB 10 KTS. PERIODS OF
VARIABLE TO EVEN CALM CONDITIONS CAN BE EXPECTED, ESPECIALLY
BEFORE THE DIURNAL SWITCHOVER.
FIRE WEATHER
A HISTORIC HIGH PRESSURE WILL LEAD TO RECORD TEMPERATURES, VERY
DRY CONDITIONS, SEASONAL WINDS, AND MOSTLY SUNNY SKIES THROUGH THE
REST OF THE WEEK. HIGH TEMPERATURES WILL WARM TO AROUND 25
DEGREES ABOVE NORMAL FOR THURSDAY-SATURDAY BEFORE GRADUALLY
DROPPING OFF SUNDAY AND THROUGH EARLY NEXT WEEK. HOWEVER
TEMPERATURES NEXT WEEK WILL STILL BE AROUND 20 DEGREES ABOVE
NORMAL. ABNORMALLY HOT AND VERY DRY CONDITIONS WILL TRANSLATE TO
MINRH READINGS OF 5-10% TODAY CONTINUING INTO NEXT WEEK.
OVERNIGHT RECOVERIES WILL NOT BE GREAT, WITH VALUES DROPPING TO
15-35% THROUGH THE WEEKEND.
CLIMATE
DAILY RECORD HIGHS THROUGH EARLY NEXT WEEK:
DATE PHOENIX YUMA EL CENTRO
---- ------- ---- ---------
3/18 95 IN 2017 96 IN 2017 95 IN 2007
3/19 96 IN 2017 98 IN 2017 96 IN 2017
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
PSR WATCHES/WARNINGS/ADVISORIES
AZ...EXTREME HEAT WARNING UNTIL 8 PM MST SUNDAY FOR AZZ530.
EXTREME HEAT WARNING FROM 11 AM THURSDAY TO 8 PM MST SUNDAY FOR
AZZ531>555-559-561.
CA...EXTREME HEAT WARNING UNTIL 8 PM PDT SUNDAY FOR CAZ561>570.
SHORT TERM...BERISLAVICH/KUHLMAN
LONG TERM...KUHLMAN
AVIATION...LOJERO
FIRE WEATHER...BERISLAVICH/BENEDICT/KUHLMAN
CLIMATE...18/KUHLMAN
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