947
FXUS65 KPSR 170951
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
251 AM MST TUE MAR 17 2026
KEY MESSAGES
- A HISTORIC MARCH HEATWAVE THROUGH THIS WEEKEND WILL PRODUCE
RECORD SHATTERING LOWER DESERT HIGH TEMPERATURES EXCEEDING 100
DEGREES BEGINNING WEDNESDAY.
- AN EXTREME HEAT WARNING WILL TAKE EFFECT WEDNESDAY ACROSS
SOUTHEAST CALIFORNIA AND THURSDAY ACROSS ARIZONA DESERTS,
AND CONTINUING 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 WEDNESDAY/
HEAT CONTINUES TO BUILD ACROSS THE WESTERN U.S. AS A RECORD
STRENGTH HIGH PRESSURE SYSTEM SLOWLY MOVES EASTWARD TOWARD THE
COAST OF CENTRAL CALIFORNIA. AS WE HAVE SAID SINCE LAST WEEK, THIS
RIDGE WILL BRING UNPRECEDENTED HEAT FOR THE MONTH OF MARCH
STARTING WEDNESDAY AND LASTING THROUGH THE WEEKEND. THE CURRENT
583-587DM H5 HEIGHTS WILL QUICKLY RISE TODAY REACHING RECORD
HEIGHTS FOR THIS TIME OF YEAR LATER IN THE DAY AND CONTINUE TO
RISE THROUGH WEDNESDAY NIGHT.
TEMPERATURES OVER THE PAST COUPLE OF DAYS HAVE REMAINED FAIRLY
STABLE, BUT THAT WILL CHANGE STARTING TODAY AS WE HEAT UP INTO
THE MID 90S FOR THE PHOENIX AREA TO AS HOT AS THE UPPER 90S ACROSS
SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA. THIS WILL RESULT IN
AREAS OF MODERATE HEATRISK ACROSS THE LOWER DESERTS. THE CENTER OF
THE RIDGE IS THEN FORECAST TO MOVE OVER SOUTHERN CALIFORNIA
STARTING EARLY WEDNESDAY, WHILE ALSO STRENGTHENING AT THE SAME
TIME. THIS IS EXPECTED TO PUSH HIGHS ON WEDNESDAY TO 98-102
DEGREES ACROSS SOUTH-CENTRAL ARIZONA TO 100-104 DEGREES ACROSS
SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA. EXTREME HEAT WARNINGS
BEGIN ON WEDNESDAY ACROSS SOUTHEAST CALIFORNIA AND THE REST OF THE
AREA STARTING THURSDAY.
LONG TERM /THURSDAY THROUGH MONDAY/
MODELS ALL AGREE THIS RIDGE WILL BECOME THE STRONGEST RIDGE THE
SOUTHWESTERN U.S. HAS EVER EXPERIENCED DURING THE MONTH OF MARCH
AND POTENTIALLY EVEN DURING THE ENTIRE WINTER/EARLY SPRING TIME
FRAME. H5 HEIGHTS ARE NOW FORECAST TO PEAK AT AROUND 595-596DM ON
THURSDAY BEFORE GRADUALLY LOWERING FRIDAY AND THROUGH THE WEEKEND
AS THE RIDGE CENTER BARELY MOVES. NBM FORECAST TEMPERATURES ARE
STILL SHOWING HIGHS PEAKING ON FRIDAY AND SATURDAY BETWEEN 103-109
DEGREES ACROSS THE LOWER DESERTS, WHICH IS BETWEEN 7-10 DEGREES
ABOVE DAILY RECORDS. WIDESPREAD HIGH-END MODERATE HEATRISK TO
LOW-END MAJOR HEATRISK WILL IMPACT THE AREA FROM THURSDAY THROUGH
AT LEAST SATURDAY BEFORE THE WEAKENING RIDGE FINALLY ALLOWS
TEMPERATURES TO START TO DECREASE.
THE RIDGE WILL CONTINUE TO WEAKEN THIS WEEKEND, ESPECIALLY BY
SUNDAY AS A IT IS LIKELY TO GET FLATTENED FROM A PASSING
SHORTWAVE TROUGH WELL TO OUR NORTH. H5 HEIGHTS ARE EXPECTED TO
FALL TO AROUND 582-585DM BY SUNDAY AND MOSTLY STAY IN THAT RANGE
THROUGH THE FIRST PART OF NEXT WEEK. EVEN WITH THESE LOWER
HEIGHTS, THEY WILL STILL STAY ABOVE THE 90TH PERCENTILE OF
CLIMATOLOGY. TEMPERATURES WILL BE SLOW TO DROP OFF DUE TO NO
ACTUAL FRONT MOVING THROUGH THE REGION AND ONLY RELYING ON THE
GRADUAL WEAKENING OF THE RIDGE. FORECAST TEMPERATURES STILL HAVE
HIGHS TOPPING 100 DEGREES SUNDAY AND EASILY INTO THE UPPER 90S
NEXT MONDAY. THE WEATHER PATTERN INTO THE MIDDLE PART OF NEXT WEEK
IS LIKELY TO KEEP SLIGHT RIDGING IN PLACE RESULTING IN CONTINUED
DRY WEATHER WHILE MAINTAINING WELL-ABOVE NORMAL TEMPERATURES
MOSTLY IN THE LOW TO MID 90S.
AVIATION
UPDATED AT 0500Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT; AND
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
NO SIGNIFICANT WEATHER ISSUES WILL EXIST THROUGH TUESDAY NIGHT UNDER
PERSISTENT HIGH CIRRUS DECKS. IN THE PHOENIX METRO, CONFIDENCE IS
GOOD THAT E/NE WINDS WILL PREVAIL THROUGH MID AFTERNOON WITH THE
SWITCH TO WESTERLY SOMEWHAT LATER THAN THE PAST SEVERAL DAYS. NORTH
WINDS WILL BE FAVORED OVER SE CALIFORNIA WITH LIGHT NOCTURNAL
WESTERLIES AT KIPL, WHILE KBLH WILL LACK THE STRONGER GUSTS
EXPERIENCED THE PAST COUPLE DAYS.
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 25-30 DEGREES
ABOVE NORMAL FOR THURSDAY-SATURDAY BEFORE GRADUALLY DROPPING OFF
SUNDAY AND THROUGH EARLY NEXT WEEK. ABNORMALLY HOT AND VERY DRY
CONDITIONS WILL TRANSLATE TO MINRH NEAR 10% TODAY BEFORE READINGS
DROP TO 5-10% WEDNESDAY THROUGH THIS WEEKEND. OVERNIGHT
RECOVERIES WILL NOT BE GREAT, WITH VALUES AROUND 20-40% THROUGH
WEDNESDAY MORNING BEFORE DROPPING TO 15-35% THROUGH THE REMAINDER
OF THE WEEK.
CLIMATE...
DAILY RECORD HIGHS THROUGH THE WEEKEND:
DATE PHOENIX YUMA EL CENTRO
---- ------- ---- ---------
3/17 99 IN 2007 101 IN 2007 101 IN 2007
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
PSR WATCHES/WARNINGS/ADVISORIES
AZ...EXTREME HEAT WARNING FROM 11 AM WEDNESDAY TO 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 FROM 11 AM WEDNESDAY TO 8 PM PDT SUNDAY FOR
CAZ561>570.
SHORT TERM...KUHLMAN
LONG TERM...KUHLMAN
AVIATION...18
FIRE WEATHER...BENEDICT/KUHLMAN
CLIMATE...18/KUHLMAN
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