578
FXUS65 KPSR 170501
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
1000 PM MST MON MAR 16 2026
UPDATE
UPDATED AVIATION
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 TUESDAY/
THE STRONG HIGH PRESSURE THAT WILL DRIVE THIS WEEK'S HISTORIC
HEATWAVE HAS ALREADY DEVELOPED AND IS CENTERED JUST OFF THE
CALIFORNIA COAST. THE DESERT SOUTHWEST IS CURRENTLY ON THE EASTERN
PERIPHERY OF THIS HIGH, WITH THIN HIGH CIRRUS CRASHING DOWN FROM THE
NORTH, AFTER COMING AROUND THE TOP OF THE HIGH. WITH THE HIGH'S
CURRENT POSITIONING AND H5 HEIGHTS AROUND 582-584DAM OVER THE
REGION, WHICH IS ABOVE THE 90TH PERCENTILE OF CLIMATOLOGY, HIGH
TEMPERATURES THIS AFTERNOON WILL REACH THE LOW 90S IN SOUTH-CENTRAL
AZ TO MIDDLE 90S IN SOUTHEAST CA. THESE TEMPERATURES WILL BE UPWARDS
OF 13-17 DEGREES ABOVE NORMAL. UNFORTUNATELY, TODAY LOOKS LIKE THE
"COOLEST" DAY OF AT LEAST THE NEXT 7 DAYS. TEMPERATURES WILL WARM ~5
DEGREES HEADING INTO TOMORROW, AS THE CENTER OF THE HIGH NUDGES
CLOSER TO THE AREA, BECOMING CENTERED OVER LOS ANGELES BY THE END OF
THE DAY. A FEW SPOTS IN SOUTHEAST CA, THROUGH THE LOWER CO RIVER
VALLEY, MAY REACH 100F FOR THE FIRST TIME THIS YEAR TOMORROW, WITH
AROUND A 50% CHANCE AT EL CENTRO AND 25% CHANCE AT YUMA. THE HIGH
TEMPERATURES THE NEXT COUPLE OF DAYS WILL LEAD TO WIDESPREAD MINOR
HEATRISK, WITH AREAS OF MODERATE HEATRISK IN SOUTHEAST CA AND
SOUTHWEST AZ. MODERATE HEATRISK MEANS EVERYONE SENSITIVE TO HEAT IS
AT RISK OF HEAT-RELATED HEALTH IMPACTS, ESPECIALLY WITHOUT EFFECTIVE
COOLING AND HYDRATION.
BESIDES THE HEAT, THERE WILL BE SOME LINGERING BREEZINESS TODAY, AS
A RESULT OF A TIGHTENED PRESSURE GRADIENT FOLLOWING THE PASSING
SHORT-WAVE YESTERDAY. STRONGEST NORTHERLY BREEZES, GUSTS AS HIGH AS
25-35 MPH, WILL BE ALONG THE LOWER CO RIVER VALLEY AND PARTS OF
SOUTHEAST CA. HIGHER TERRAIN SPOTS OF SOUTH-CENTRAL ARIZONA SHOULD
ALSO ANTICIPATE SOME MARGINAL BREEZES TODAY THROUGH TOMORROW
MORNING, BUT PEAK GUSTS FOR THESE LOCATIONS SHOULD HOVER CLOSER TO
25 MPH.
LONG TERM /WEDNESDAY THROUGH SUNDAY/
BY WEDNESDAY, THE DESERT SOUTHWEST WILL FIND ITSELF DIRECTLY UNDER
THE CENTER OF THE HIGH, WITH HEIGHTS ALOFT REACHING UPWARDS OF 592-
594DM. TO PUT THINGS INTO PERSPECTIVE, SOUNDING CLIMATOLOGY DATA FOR
LAS VEGAS, FLAGSTAFF, AND TUCSON SHOW RECORD H5 HEIGHTS FOR MARCH
ARE AROUND 590DM AND APRIL 591DM, 593DM, AND 592DM RESPECTIVELY.
THAT WOULD PUT THIS RIDGE AS ONE OF THE STRONGEST EVER SEEN IN
RECORDED HISTORY FOR THE REGION, NOT ONLY FOR MARCH, BUT FOR APRIL
AS WELL. WITH THIS SETUP, THE THERMAL PROFILE WILL ALSO PUSH BEYOND
RECORD LEVELS, WITH ALL-TIME READINGS FOR MARCH LOOKING LIKELY AT
THE H7 AND H5 LEVELS. 850MB TEMPS WILL BE CLOSE TO ALL-TIME MARCH
RECORDS BY MID TO LATE WEEK, HELPING TO PUSH TEMPERATURES AT THE
SURFACE INTO THE TRIPLE DIGITS FOR MOST OF THE LOWER DESERTS. THE
FORECAST HIGH FOR PHOENIX ON WEDNESDAY IS TRIPLE DIGITS, WHICH IF
ACHIEVED, WOULD BECOME THE EARLY INSTANCE FOR PHOENIX, BESTING THE
PREVIOUS EARLIEST (MARCH 26TH) BY 8 DAYS. MARCH 26TH, 1988 IS
ACTUALLY THE ONLY MARCH DATE ON RECORD WHERE 100 DEGREES WAS
ACHIEVED IS PHOENIX, BUT SEVERAL DAYS WILL BE ADDED TO THIS LIST
THROUGH THIS HEATWAVE.
CONFIDENCE IS VERY HIGH, GIVEN SMALL MODEL SPREAD, THAT THE HIGH
WILL STRENGTHEN EVEN FURTHER BY THURSDAY WITH HEIGHTS REACHING 595-
597DM, WHICH IS AROUND MAX HEIGHT FOR THE MIDDLE OF SUMMER, AND WILL
CEMENT THIS HIGH PRESSURE AS THE STRONGEST ON RECORD FOR MARCH. THIS
WILL PUSH TEMPERATURES INTO UNCHARTED TERRITORY (AT LEAST BY LATE
WINTER AND EARLY SPRING STANDARDS), BOTH AT THE SURFACE AND
THROUGHOUT THE ATMOSPHERIC COLUMN. HIGHS THURSDAY THROUGH AT LEAST
SATURDAY WILL RANGE BETWEEN 103-109 DEGREES, WITH EVEN A LOW END
CHANCE FOR A FEW LOCATIONS TO REACH 110F DURING THIS WINDOW. THIS
WOULD PUT DAILY MAXTS 25-30 DEGREES ABOVE NORMAL AND DAILY RECORDS
MAY BE BROKEN BY 5-10 DEGREES. ON THE TOPIC OF RECORDS, THIS
HEATWAVE WILL ALSO BREAK MONTHLY ALL-TIME TEMPERATURES BY A FEW
DEGREES, AS THE VALUES CURRENTLY STAND AT 100, 102, AND 101 FOR
PHOENIX, YUMA, AND EL CENTRO RESPECTIVELY. THE MONTHLY RECORDS MAY
BE TIED OR BROKEN AS EARLY AS WEDNESDAY, BUT IF NOT BY THEN THEN
THEY WILL BE BROKEN ON THURSDAY.
WIDESPREAD MODERATE HEATRISK WILL DEVELOP ACROSS THE REGION IN
RESPONSE TO THE HISTORIC HEAT, WITH EVEN SOME LOCALIZED AREAS OF
MAJOR HEATRISK NOT OUT OF THE QUESTION. THE EXTREME HEAT WATCH HAS
BEEN UPGRADED TO A WARNING, BEGINNING WEDNESDAY ACROSS SOUTHEAST CA
AND THURSDAY FOR AZ DESERTS. THE WARNING WILL RUN THROUGH SUNDAY.
THIS WILL BE THE EARLIEST HEAT WARNING ON RECORD, SINCE HEAT
PRODUCTS STARTED, WITH THE CURRENT EARLIEST INSTANCE OCCURRING
BETWEEN APRIL 26TH AND 30TH OF 2020. ONE, SOMEWHAT POSITIVE,
TAKEAWAY FROM THIS HEATWAVE IS THAT THE SUN ANGLE IS LOWER AND
LENGTH OF DAY IS SHORTER THAN DURING THE SUMMER. FOR THIS REASON,
THERE WILL BE RELIEF FROM THE DAYTIME HEAT DURING THE OVERNIGHT AND
MORNING HOURS. MORNING LOW TEMPERATURES WILL LIKELY BREAK DAILY WARM
LOW RECORDS AS WELL, BUT LOWS IN THE 60S TO LOW 70S WILL OFFER MORE
RELIEF THAN THE 80S TO LOW 90S SEEN DURING THE SUMMER. IT IS
IMPORTANT TO NOTE THOUGH TO NOT GET FOOLED BY THE NICE MORNINGS AND
AVOID GETTING CAUGHT OFF GUARD BY THE RAPID HEATING FROM MID-MORNING
THROUGH EARLY-AFTERNOON. TEMPERATURES WILL WARM VERY FAST BETWEEN 8
AM AND 1 PM, WITH TEMPERATURES LATE WEEK LIKELY REACHING THE 90S
BEFORE NOON.
WHEN WILL THE HEATWAVE END? WELL, THERE IS A GOOD SIGNAL THAT THIS
HISTORIC HIGH PRESSURE WILL WEAKEN AND FLATTEN OUT LATE- WEEKEND
THROUGH EARLY NEXT WEEK, WITH POTENTIALLY A SHORTWAVE TROUGH MOVING
THROUGH THE REGION, BUT COMING OUT OF A HISTORIC HEATWAVE IT WILL
TAKE A STRONG LOW TO COOL THINGS DOWN SIGNIFICANTLY AND THERE IS
CURRENTLY NO SIGN OF ONE IN THE EXTENDED OUTLOOK. SO, WITH THE
CHANGE EARLY NEXT WEEK, THERE IS A GOOD CHANCE HIGH TEMPERATURES
WILL FALL BACK BELOW 100 (60-80% CHANCE), BUT HIGHS LOOK TO REMAIN
ABOVE 90 DEGREES THROUGH THE END OF THE WEEK, WITH NBM ODDS OF >90F
AT 80-90% CHANCE.
THIS MIGHT BE A RECORD NUMBER OF USES OF THE WORD "RECORD" IN AN
AFD.
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 NEXT
WEEK. HIGH TEMPERATURES WILL BE 10-15 DEGREES ABOVE NORMAL TODAY
BEFORE INCREASING TO 25-30 DEGREES ABOVE NORMAL FROM MIDWEEK THROUGH
THIS WEEKEND. ABNORMALLY HOT AND VERY DRY CONDITIONS WILL TRANSLATE
TO MINRH NEAR 10% THE NEXT FEW AFTERNOONS BEFORE READINGS DROP
CLOSER 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.
BREEZY TO LOCALLY WINDY CONDITIONS ARE ONGOING TODAY AND WILL
CONTINUE THROUGH TONIGHT, MAINLY OVER THE ARIZONA HIGH TERRAIN AND
THE LOWER COLORADO RIVER VALLEY, WITH THE STRONGEST GUSTS (25-35
MPH) FOCUSED OVER THE LATTER AREA. THE BREEZY CONDITIONS, COMBINED
WITH LOW RH VALUES WILL RESULT IN ELEVATED TO ISOLATED AREAS OF
CRITICAL FIRE WEATHER CONDITIONS. HOWEVER, WITH THE LIMITED SCOPE OF
ENHANCED WINDS, NO FIRE WEATHER PRODUCTS ARE NEEDED AT THIS TIME.
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
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...BENEDICT
LONG TERM...BENEDICT/RW
AVIATION...18
FIRE WEATHER...BENEDICT
CLIMATE...18/KUHLMAN
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page