568
FXUS65 KPSR 211120
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
420 AM MST TUE APR 21 2026
UPDATE
UPDATED 12Z AVIATION DISCUSSION.
KEY MESSAGES
- DEPARTING HIGH PRESSURE WILL KEEP TEMPERATURES ACROSS THE REGION
AROUND 5 TO 8 DEGREES ABOVE DAILY NORMALS TODAY.
- A WEATHER SYSTEM WILL APPROACH FROM THE WEST THIS AFTERNOON,
RESULTING IN GUSTY WINDS ACROSS PORTIONS OF RIVERSIDE AND
IMPERIAL COUNTIES WHERE A WIND ADVISORY IS IN EFFECT.
- TEMPERATURES WILL COOL BACK TO NEAR NORMAL IN THE WAKE OF THE
PASSING WEATHER SYSTEM WITH CONTINUED BREEZY CONDITIONS FOR THE
REMAINDER OF THIS WEEK AND INTO THIS WEEKEND.
SHORT TERM /TODAY THROUGH WEDNESDAY/
LATEST MID-LVL WV IMAGERY AND 500 MB STREAMLINE ANALYSIS
REVEALS A BROAD RIDGE OF HIGH PRESSURE CURRENTLY CENTERED OVER
THE SOUTHERN ROCKIES WHILE A CLOSED LOW SITS OFF THE COAST OF N
CALIFORNIA AND THE PAC NW. TODAY, OUR FORECAST REGION WILL BE
LOCATED BETWEEN BOTH OF THESE FEATURES RESULTING IN INCREASING
SOUTHWESTERLY FLOW ALOFT. SOUTHCENTRAL AZ WILL STILL BE UNDER THE
INFLUENCE OF THE DEPARTING UPPER-LVL RIDGE THIS AFTERNOON WHERE
500 MB HGHTS WILL RANGE FROM 577-579 DAM, KEEPING HIGH TEMPS
AROUND 5 TO 8 DEGREES ABOVE NORMAL. FARTHER WEST IN SE CALIFORNIA,
LOWERING HGHTS FROM THE APPROACHING LOW PRESSURE SYSTEM WILL
RESULT IN SLIGHTLY COOLER TEMPERATURES, ALTHOUGH MOST LOWER DESERT
COMMUNITIES WILL STILL REACH UP TO 90 DEGREES WHICH IS A FEW
DEGREES ABOVE NORMAL. THE MAIN WEATHER CONCERNS THIS AFTERNOON AND
EVENING WILL BE A CORRIDOR OF STRONGER WINDS, ESPECIALLY ACROSS
WESTERN PORTIONS IMPERIAL AND RIVERSIDE COUNTIES. A WIND ADVISORY
IS IN EFFECT STARTING AT 3 PM PST FOR THE FAR SW CORNER OF
IMPERIAL COUNTY WHERE GUSTS UP TO 50-55 MPH CAN BE EXPECTED. THE
WESTERN PORTION OF JOSHUA TREE NP HAS ALSO BEEN INCLUDED IN THE
WIND ADVISORY THIS AFTERNOON WHERE GUSTS COULD REACH 35-40 MPH AT
TIMES. THE MAIN IMPACTS FROM THESE GUSTY WINDS WILL BE POTENTIAL
BLOWING/LOFTED DUST AND STRONGER CROSSWINDS ALONG I-8 AND I-10 IN
SE CALIFORNIA HEADING INTO THIS EVENING. WINDS WILL NOT BE AS
STRONG TODAY IN SOUTHCENTRAL AZ, HOWEVER IT WILL STILL BE BREEZY
THIS AFTERNOON WITH GUSTS REACHING 20-25 MPH.
LATE TONIGHT INTO WEDNESDAY, THE CLOSED LOW OFF THE COAST OF N
CALIFORNIA WILL BEGIN TO PROGRESS INLAND AND TRANSITION TO AN OPEN
TROUGH AS IT MOVES THROUGH THE INTERMOUNTAIN WEST. AT THE BASE OF
THE RESULTING TROUGH, A COMPACT 700-500 MB HGHT GRADIENT WILL RESULT
IN ANOTHER BOUT OF BREEZY CONDITIONS ON WEDNESDAY AFTERNOON. HOWEVER,
THE FOCUS OF THE STRONGEST WINDS WILL SHIFT INTO N ARIZONA AND
THE HIGH TERRAIN AREAS NE OF PHOENIX WHERE GUSTS COULD REACH 25-35
MPH. NEGATIVE 500 MB HGHT ANOMALIES ASSOCIATED WITH THE MAIN
TROUGH AXIS WILL OVERSPREAD THE FORECAST AREA ON WEDNESDAY,
RESULTING IN TEMPERATURES COOLING BACK DOWN TO SEASONAL LEVELS IN
THE MID TO UPPER 80S ACROSS THE LOWER DESERTS AND MID TO UPPER 70S
IN THE HIGH TERRAIN AREAS.
LONG TERM /THURSDAY THROUGH MONDAY/
ENSEMBLE MEMBERS AND DETERMINISTIC GUIDANCE CONTINUES TO INDICATE
QUASI-ZONAL FLOW RETURNING TO THE DESERT SOUTHWEST THURSDAY AND
FRIDAY WHICH WILL RESULT IN TEMPERATURES REMAINING NEAR TO
SLIGHTLY ABOVE NORMAL. A COMPRESSED 500 MB HGHT GRADIENT WILL
PREVAIL OVER THE DESERT SOUTHWEST RESULTING IN CONTINUED BREEZY TO
LOCALLY WINDY CONDITIONS THROUGH THE END OF THIS WEEK WITH
AFTERNOON GUSTS REACHING 20-30 MPH. A PROGRESSIVE PATTERN WILL
CONTINUE INTO THIS WEEKEND AS A SERIES OF MOSTLY DRY WEATHER
SYSTEMS PASSES NORTH OF THE REGION. THE STRONGEST SHORTWAVE LOOKS
TO ARRIVE ON SUNDAY WHICH WILL COOL TEMPERATURES TO AROUND 3 TO 5
DEGREES BELOW NORMAL ACROSS THE REGION. BOTH THE MEAN OF THE GEFS
AND EPS SHOW NEGATIVE HGHT ANOMALIES PERSISTING OVER THE DESERT
SOUTHWEST WELL INTO NEXT WEEK WHICH WILL KEEP TEMPERATURES AT
LEAST NEAR NORMAL TO SLIGHTLY BELOW NORMAL TO FINISH OFF THE MONTH.
AVIATION
UPDATED AT 1120Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
AN EXTENDED PERIOD OF A SOUTHERLY CROSS RUNWAY WINDS EARLY TUESDAY
AFTERNOON, THEN LOCALLY GUSTY WINDS LATE AFTERNOON/EVENING WILL BE
THE MAIN WEATHER CONCERNS AS THICKER CIRRUS DECKS GRADUALLY CLEAR.
EAST WINDS WINDS EARLY THIS MORNING WILL BECOME SOUTHERLY CROSS
WINDS BY LATE THIS MORNING, WITH SPEEDS IN EXCESS OF 10 KT BEFORE
VEERING SW MID/LATE AFTERNOON. GUSTS NEAR 20KT WILL BE LOCALLY
POSSIBLE AROUND SUNSET TUESDAY WITH THE PREPONDERANCE OF MODEL
OUTPUT SUGGESTING WINDS NOT COMPLETING THE NOCTURNAL EASTERLY
SWITCH UNTIL CLOSER TO SUNRISE WEDNESDAY MORNING, IF AT ALL.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
STRONG, GUSTY WINDS TUESDAY LATE AFTERNOON/EVENING WILL BE THE
PRIMARY WEATHER CONCERN AS THICKER HIGH CIRRUS DECKS GRADUALLY
CLEAR. CONFIDENCE IS GOOD THAT WESTERLY WINDS AT KIPL WILL REMAIN
IN PLACE WHILE SOUTHERLY/SOUTHWESTERLY WINDS WILL BE PREFERRED AT
KBLH. GUSTS 20-25KT WILL MATERIALIZE TUESDAY AFTERNOON WITH GUSTS
LIKELY STRENGTHENING ABOVE 30KT AT KIPL DURING THE EVENING.
FIRE WEATHER
A PROGRESSIVE PATTERN WITH MULTIPLE DRY WEATHER SYSTEMS PASSING
NORTH OF THE REGION WILL RESULT IN BREEZY CONDITIONS AND PERIODS
OF ELEVATED FIRE WEATHER THROUGHOUT THIS WEEK. RELATIVE HUMIDITY
IS NOT EXPECTED TO FLUCTUATE MUCH, BOTTOMING OUT AROUND 8-15%
EACH AFTERNOON. OVERNIGHT RECOVERIES WILL REMAIN POOR TO FAIR OVER
THE NEXT SEVERAL NIGHTS. THE STRONGEST WINDS WILL RESIDE IN SE
CALIFORNIA THIS AFTERNOON AND EVENING WHERE GUSTS UP TO 25-35 MPH
(LOCALLY HIGHER) WILL BE POSSIBLE. THESE STRONGER WINDS COUPLED
WITH VERY DRY CONDITIONS (RH AS LOW AS 10%) WILL RESULT IN A BRIEF
PERIOD OF NEAR CRITICAL FIRE WEATHER CONDITIONS THIS AFTERNOON.
WIDESPREAD BREEZY CONDITIONS WITH GUSTS AROUND 20-30 MPH WILL
CONTINUE EACH AFTERNOON THROUGH THE REMAINDER OF THIS WEEK,
RESULTING IN PERSISTENT ELEVATED FIRE WEATHER.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...NONE.
CA...WIND ADVISORY FROM 3 PM THIS AFTERNOON TO MIDNIGHT PDT TONIGHT
FOR CAZ560.
WIND ADVISORY FROM 3 PM THIS AFTERNOON TO 8 AM PDT WEDNESDAY FOR
CAZ562.
SHORT TERM..SALERNO
LONG TERM...SALERNO
AVIATION...18/BERISLAVICH
FIRE WEATHER...SALERNO
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