181
FXUS65 KPSR 191658
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
958 AM MST THU MAR 19 2026
UPDATE...UPDATED 18Z AVIATION DISCUSSION
KEY MESSAGES
- A HISTORIC MARCH HEATWAVE WILL PRODUCE RECORD SHATTERING LOWER
DESERT HIGH TEMPERATURES EXCEEDING 100 DEGREES THROUGH AT LEAST
THE WEEKEND AND POSSIBLY INTO NEXT WEEK.
- AN EXTREME HEAT WARNING IS IN EFFECT ACROSS SOUTHEAST
CALIFORNIA, WILL GO INTO EFFECT TODAY ACROSS THE ARIZONA
DESERTS, AND WILL CONTINUE 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 FRIDAY/
WEDNESDAY SAW MONTHLY HIGH TEMPERATURE RECORDS FALL IN PHOENIX,
YUMA, AND EL CENTRO. UNFORTUNATELY, THOSE NEW RECORDS SET
YESTERDAY ARE FORECAST TO BE SUPERSEDED TODAY AND LIKELY AGAIN ON
FRIDAY. THIS UNPRECEDENTED MARCH HEATWAVE IS THANKS TO A RECORD
STRONG RIDGE OF HIGH PRESSURE FOR THIS TIME OF YEAR, OF WHICH
CURRENT 500 MB RAP ANALYSIS PLACES THE CENTER OVER THE CA-NV-AZ
TRI-STATE AREA. ANALYZED H5 HEIGHTS HAVE ALREADY TIPPED INTO A
595-596 DAM RANGE, WITH ENSEMBLES IN GOOD AGREEMENT ON THE
STRENGTH OF THE RIDGE PEAKING LATER TODAY AROUND 597 DAM. THOUGH
THE STRENGTH OF THE RIDGE WILL WANE FRIDAY AND ESPECIALLY DURING
THE WEEKEND, STRONG ANTICYCLONIC SUBSIDENCE SHOULD REMAIN
RELATIVELY STATIONARY (OTHER THAN A SLIGHT EASTWARD DRIFT) OVER
THE DESERT SOUTHWEST LATE THIS WEEK, ALLOWING FOR LOWER LEVEL
THERMAL PROFILES TO RAPIDLY WARM AND DEVELOP A VERY WARM AIRMASS
ACROSS THE REGION. THIS AIRMASS MAY PROVE DIFFICULT TO DISLODGE OR
EVEN MODIFY BY A MEANINGFUL AMOUNT HEADING INTO NEXT WEEK.
FORECAST HIGHS ACROSS THE LOWER DESERTS WILL RANGE FROM AROUND 100F-
106F TODAY AND 102F-108F FRIDAY - LIKELY THE PEAK OF THIS EVENT.
THESE FORECAST HIGHS REPRESENT VALUES AROUND 25F ABOVE DAILY NORMALS
AND 7F-10F ABOVE DAILY RECORDS (SEE CLIMATE SECTION). WIDESPREAD
MODERATE HEATRISK IS ANTICIPATED, WITH EVEN LOW-END MAJOR HEATRISK
FOR SOME AREAS ON FRIDAY. DUE TO THE UNPRECEDENTED NATURE OF THIS
HEATWAVE, THE TIMING COINCIDING WITH A WEEKEND, AND MANY OUT-OF-
STATE VISITORS AND FOLKS NOT ACCLIMATED TO THIS LEVEL OF HEAT,
THIS EVENT WILL BE QUITE IMPACTFUL. EXTREME HEAT WARNINGS ARE
ALREADY IN EFFECT FOR SOUTHEAST CA AND WILL GO INTO EFFECT TODAY
FOR THE ARIZONA DESERTS. THESE WARNINGS WILL REMAIN IN EFFECT
THROUGH SUNDAY. REMEMBER TO STAY HYDRATED, TAKE FREQUENT BREAKS IN
THE SHADE OR IN AIR CONDITIONS SPACES IF YOU ARE PLANNING OUTDOOR
ACTIVITIES, AND CHECK ON YOUR FAMILY, FRIENDS, AND NEIGHBORS!
THIS CAN BE A DANGEROUS LEVEL OF HEAT FOR THOSE NOT TAKING PROPER
PRECAUTIONS AND FOR THOSE THAT ARE SENSITIVE TO THE HEAT.
LONG TERM /SATURDAY THROUGH WEDNESDAY/
A FEW PIECES OF SHORTWAVE ENERGY IN THE NORTHERN STREAM ARE
ADVERTISED BY ENSEMBLES PASSING OVERTOP THE RIDGE THIS WEEKEND,
ACTING TO DAMPEN HEIGHTS ALOFT AND DISLODGE THE INITIAL ANTICYCLONE
EAST OF THE REGION. HOWEVER, LOWER TROPOSPHERIC TEMPERATURES DO NOT
HAVE TIME TO RESPOND BY SATURDAY, AND NAEFS MEAN H8 TEMPERATURES
WELL IN EXCESS OF CFSR CLIMATOLOGICAL MAXIMUM VALUES FOR MID-LATE
MARCH SHOULD SUPPORT HIGHS SIMILAR TO WHAT IS FORECAST TODAY. BY
SUNDAY, FORECAST HIGHS FALL MORE INTO A 99F-102F RANGE, THEN LIKELY
1F-2F COOLER MONDAY, BUT STILL FLIRTING WITH THE TRIPLE DIGITS FOR
MANY OF THE TYPICALLY HOTTER LOWER DESERT LOCALES. ENSEMBLES MEAN H5
HEIGHTS BOTTOM OUT AROUND 582-585 DAM SOMETIME SUNDAY INTO
MONDAY, STILL IN EXCESS OF THE 97TH PERCENTILE OF CLIMATOLOGY.
DURING THE MIDDLE OF NEXT WEEK, THE TREND IN THE LAST FEW FORECAST
PACKAGES HAS BEEN FOR WARMER TEMPERATURES AS ANOTHER STRONG YET MORE
TRANSIENT RIDGE FORMS UNDER AN ANTICYCLONICALLY CURVED JET
STREAK. THOUGH THE RIDGING SHOULD BE LOWER AMPLITUDE COMPARED TO
THE CURRENT RIDGE, AND ANTICYCLONIC SUBSIDENCE WILL BE SHORTER
LIVED (LIKELY PEAKING IN ITS INFLUENCE SOMETIME TUESDAY), H5
HEIGHTS ARE STILL SHOWN TO RISE INTO A 587-590 DAM RANGE. THIS
WILL SUPPORT A GRADUAL WARMING INTO THE MIDDLE OF THE UPCOMING
WORKWEEK, WITH COVERAGE OF 100F+ TEMPERATURES INCREASING YET
AGAIN. ALL THIS IS TO SAY THAT CONFIDENCE IS GROWING 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 1702Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT; AND
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
NO MAJOR AVIATION CONCERNS EXPECTED THROUGHOUT THE TAF PERIOD.
WINDS WILL MOSTLY FOLLOW DIURNAL TRENDS WITH A LIGHT SSE DIRECTION
BEFORE THIS AFTERNOON'S WESTERLY SHIFT. SPEEDS WILL BE AOB 10 KTS
UNDER CLEAR SKIES. OUT AT THE WESTERN TERMINALS PROLONGED PERIOD
OF VRB WILL BE COMMON.
FIRE WEATHER
A HISTORIC HIGH PRESSURE WILL LEAD TO RECORD TEMPERATURES, VERY
DRY CONDITIONS, SEASONAL WINDS, AND MOSTLY SUNNY SKIES INTO THIS
WEEKEND. HIGH TEMPERATURES WILL BE AROUND 25 DEGREES ABOVE NORMAL
THROUGH SATURDAY BEFORE GRADUALLY DROPPING OFF SUNDAY AND MONDAY.
ABNORMALLY HOT AND VERY DRY CONDITIONS WILL TRANSLATE TO MINRH
READINGS OF 5-10% THROUGH THE NEXT 7 DAYS. OVERNIGHT RECOVERIES
WILL BE POOR, WITH VALUES BETWEEN 15-35% THROUGH SATURDAY NIGHT.
HUMIDITIES IMPROVE SLIGHTLY EARLY NEXT WEEK PRIMARILY FOR VALLEY
LOCATIONS IN THE WESTERN DESERTS LIKE THE YUMA AREA, LOWER
COLORADO RIVER VALLEY, IMPERIAL VALLEY, AND LOWER GILA RIVER
VALLEY, ESPECIALLY WITH RESPECT TO OVERNIGHT RECOVERIES.
CLIMATE
DAILY RECORD HIGHS THROUGH EARLY NEXT WEEK:
DATE PHOENIX YUMA EL CENTRO
---- ------- ---- ---------
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
3/25 99 IN 2025 99 IN 1896 99 IN 2025
PSR WATCHES/WARNINGS/ADVISORIES
AZ...EXTREME HEAT WARNING UNTIL 8 PM MST SUNDAY FOR AZZ530.
EXTREME HEAT WARNING UNTIL 8 PM MST SUNDAY FOR AZZ531>555-559-
561.
CA...EXTREME HEAT WARNING UNTIL 8 PM PDT SUNDAY FOR CAZ561>570.
SHORT TERM...WHITTOCK
LONG TERM...WHITTOCK
AVIATION...RYAN
FIRE WEATHER...WHITTOCK/BERISLAVICH
CLIMATE...18/KUHLMAN
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