658
FXUS65 KPSR 182057
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
157 PM MST MON MAY 18 2026
KEY MESSAGES
- AN OVERALL BROAD SCALE TROUGHING PATTERN WILL PERSIST OVER THE
WESTERN U.S., RESULTING IN TEMPERATURES REMAINING RIGHT AROUND
SEASONAL NORMS THROUGH THE REST OF THIS WEEK.
- DRY CONDITIONS, WITH NO THREAT OF RAIN, AND SEASONAL AFTERNOON
BREEZES ARE EXPECTED THROUGH THE NEXT 7 DAYS.
SHORT TERM /TODAY THROUGH TUESDAY/
LATEST GOES W INFRARED AND VISIBLE SATELLITE IMAGERY INDICATES A
BROAD TROUGH OF LOW PRESSURE ENCOMPASSING THE WESTERN HALF OF THE
U.S. WITH MULTIPLE EMBEDDED SHORTWAVES ROTATING AROUND THE TROUGH
AXIS. THE ROBUST SHORTWAVE WHICH WAS RESPONSIBLE FOR GUSTY WINDS,
BLOWING DUST, AND CRITICAL FIRE WEATHER IN OUR REGION YESTERDAY
HAS SINCE LIFTED INTO THE S ROCKIES AND IS NOW BRINGING A ROUND OF
SEVERE WEATHER TO THE CENTRAL PLAINS. AS THE TROUGH AXIS PASSES
OVER THE DESERT SOUTHWEST THIS AFTERNOON, NEGATIVE 500 MB HEIGHT
ANOMALIES WILL CONTINUE TO OVERSPREAD THE AREA, RESULTING IN A
MILD AFTERNOON ACROSS THE LOWER DESERTS. HIGHS THIS AFTERNOON ARE
FORECAST TO TOP OUT IN THE MID 80S ACROSS THE LOWER DESERTS, WITH
ONLY 10-20% CHANCES OF REACHING 90F IN THE MAIN POPULATION CENTERS
INCLUDING PHOENIX AND YUMA. DRY AIR WILL CONTINUE TO FILTER INTO
THE REGION FROM THE NW AND CAUSE SFC DEWPOINTS TO CRASH INTO THE
20S AND 30S ACROSS AZ AND EVEN INTO THE SINGLE DIGITS IN SOUTHEAST
CA. THIS INTRUSION OF DRY AIR WILL RESULT IN COOL OVERNIGHT
TEMPERATURES WITH LOWS FALLING INTO THE MID 50S TO LOW 60S ACROSS
THE LOWER DESERTS.
ON TUESDAY, A FOLLOW-ON SHORTWAVE TROUGH WILL DIVE THROUGH THE GREAT
BASIN REGION, BUT WILL BE MUCH WEAKER THAN THE ONE WE EXPERIENCED ON
SUNDAY. THIS SHORTWAVE WILL AGAIN RESULT IN ENHANCED BREEZINESS
ALONG THE LOWER COLORADO RIVER VALLEY WHERE NORTHERLY GUSTS AS HIGH
AS 20-30 MPH WILL DEVELOP EARLY MORNING THROUGH MIDDAY. INCREASING
SW FLOW ALOFT OVER AZ WILL ALSO RESULT IN BREEZY CONDITIONS, MAINLY
OVER THE HIGHER TERRAIN OF NORTHERN AND EASTERN AZ. ELSEWHERE ACROSS
THE LOWER DESERTS WIND SPEEDS WILL BE MUCH LIGHTER, GENERALLY BELOW
15 MPH. DUE TO THE POSITIONING OF THE TROUGH CENTERED OVER THE
GREAT BASIN, 500 MB HGHTS WILL NOT CHANGE MUCH AND THUS HIGH
TEMPERATURES TUESDAY AFTERNOON WILL ONLY WARM BY A FEW DEGREES
INTO THE MID 80S TO LOWER 90S WHICH IS STILL BELOW NORMAL.
LONG TERM /WEDNESDAY THROUGH SUNDAY/
THROUGH THE REST OF THE WEEK, GLOBAL ENSEMBLES DEPICT A LASTING
WEAK LONGWAVE TROUGH PATTERN ACROSS THE DESERT SOUTH, WITH NEUTRAL
HEIGHT ANOMALIES AND NO SIGNIFICANT SHORTWAVES ROLLING THROUGH
THE REGION. THIS WILL TRANSLATE TO RATHER SEASONAL WEATHER
CONDITIONS, BUT WITH A SLOW DAY-TO-DAY WARMING TREND. HIGH
TEMPERATURES ARE FORECAST TO BE NEAR NORMAL THROUGH THE END OF THE
WORK WEEK - HIGHS IN THE MIDDLE TO UPPER 90S. MEANWHILE MORNING
LOWS ARE EXPECTED TO BE NEAR TO SLIGHTLY BELOW NORMAL, LARGELY DUE
TO DRY AIR/LOW HUMIDITY AND LIMITED CLOUD COVER. IT IS NOT UNTIL
THE WEEKEND WHEN ODDS OF HIGH TEMPERATURES REACHING THE 100 DEGREE
MARK SPIKES BACK UP TO AROUND 30-60%, AS THE LONGWAVE TROUGH
ACROSS THE DESERT SOUTHWEST BREAKS DOWN. CONDITIONS WILL REMAIN
DRY THROUGH THIS WEEKEND, WITH NO THREAT OF RAIN, AND SEASONAL
WIND PATTERNS ARE EXPECTED, WITH LIGHT WINDS THROUGH THE OVERNIGHT
AND MORNING HOURS AND AFTERNOON UPSLOPE BREEZES UP TO 15-25 MPH.
AVIATION
UPDATED AT 1710Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
NO MAJOR AVIATION WEATHER CONCERNS EXPECTED THROUGHOUT THE TAF
PERIOD. WESTERLY WINDS WILL PREVAIL THROUGH THIS EVENING WITH SOME
OCCASIONAL AFTERNOON GUSTS INTO THE UPPER TEENS. WINDS WILL RESUME
THEIR MORE TYPICAL DIURNAL PATTERN TONIGHT THROUGH TUESDAY WITH
EASTERLY WINDS EXPECTED DURING THE OVERNIGHT AND EARLY MORNING
HOURS FOLLOWED BY A WESTERLY SHIFT BY THE LATE MORNING/EARLY
AFTERNOON. A FEW-SCT CLOUDS BETWEEN 6-8 KFT WILL PREVAIL INTO
EARLY THIS AFTERNOON BEFORE A FEW HIGH CLOUD DECKS MOVE IN DURING
THE LATE AFTERNOON FOLLOWED BY CLEAR SKIES DURING THE LATE
EVENING/OVERNIGHT.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
NO MAJOR AVIATION WEATHER CONCERNS UNDER MOSTLY CLEAR SKIES CAN BE
EXPECTED THROUGHOUT THE TAF PERIOD. NORTHERLY WINDS WILL PREVAIL
THROUGH THIS AFTERNOON BEFORE BACKING MORE OUT OF THE WEST TO
NORTHWEST THIS EVENING. WIND GUSTS UPWARDS OF 20-25 KTS WILL
CONTINUE ACROSS KBLH THROUGH THIS AFTERNOON BEFORE GUSTS SUBSIDE
EARLY THIS EVENING. AT KIPL, WINDS WILL GENERALLY REMAIN AOB 10
KTS THROUGHOUT THE PERIOD.
FIRE WEATHER
SEASONAL TEMPERATURES WITH DRY CONDITIONS WILL PERSIST THROUGH THE
END OF THIS WEEK. DAILY AFTERNOON HUMIDITY VALUES WILL BOTTOM OUT
AROUND 5-15% EACH DAY WITH POOR TO FAIR OVERNIGHT RECOVERIES AT
25-50%. AFTER TODAY SEASONAL WIND PATTERNS ARE EXPECTED THROUGH
THE REST OF THE WEEK, WITH AFTERNOON UPSLOPE BREEZES UP TO 15-25
MPH AND THE ONLY EXCEPTION BEING ANOTHER BRIEF ENHANCED NORTHERLY
WIND DOWN THE COLORADO RIVER ON TUESDAY MORNING. THERE IS NO RAIN
IN THE FORECAST THROUGH THIS WEEKEND.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...NONE.
CA...NONE.
SHORT TERM...SALERNO
LONG TERM...BENEDICT
AVIATION...LOJERO
FIRE WEATHER...BENEDICT/SALERNO
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