839
FXUS65 KPSR 192300
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
400 PM MST FRI DEC 19 2025
UPDATE
UPDATED AVIATION
KEY MESSAGES
- DRY AND TRANQUIL WEATHER CONDITIONS WITH WELL ABOVE NORMAL
TEMPERATURES WILL PREVAIL ACROSS THE REGION THROUGH EARLY NEXT WEEK.
- A MORE UNSETTLED WEATHER PATTERN IS LIKELY TO DEVELOP LATER NEXT
WEEK WITH COOLER TEMPERATURES AND INCREASED PRECIPITATION CHANCES
SHORT TERM /TODAY THROUGH SATURDAY/
UNSEASONABLY WARM WEATHER REMAINS IN PLACE TO FINISH OUT THE WEEK AS
AFTERNOON READINGS WILL TOP OUT AROUND 10-15 DEGREES ABOVE NORMAL.
THIS IS THANKS TO A STRONG RIDGE SITUATED OVER THE DESERT SOUTHWEST
WITH THE CENTER OF THE HIGH POSITIONED TO THE WEST OF THE BAJA
PENINSULA. THIS PATTERN WILL PERSIST INTO THE WEEKEND ALLOWING FOR
CONTINUED WELL ABOVE NORMAL TEMPERATURES AS WELL AS DRY, TRANQUIL
WEATHER CONDITIONS. AFTERNOON TEMPERATURES ON SATURDAY ARE EXPECTED
TO BE AROUND 2-3 DEGREES COOLER THAN TODAY AS HIGHS ACROSS THE LOWER
DESERTS ARE FORECAST TO TOP OUT IN THE MID TO UPPER 70S.
LONG TERM /SUNDAY THROUGH LATE NEXT WEEK/
UPPER-LEVEL RIDGING WILL CONTINUE TO DOMINATE THE OVERALL WEATHER
PATTERN ACROSS THE DESERT SOUTHWEST THROUGH THE FIRST HALF OF NEXT
WEEK, CONTINUING THE DRY AND TRANQUIL CONDITIONS. TEMPERATURES WILL
CONTINUE TO REMAIN UNSEASONABLY WARM AS AFTERNOON HIGHS TOP OUT IN
THE UPPER 70S TO AROUND 80 DEGREES ACROSS THE LOWER DESERTS. THERE
CONTINUES TO BE A HIGH PROBABILITY (>70% CHANCE) OF PHOENIX AT LEAST
TYING TO EVEN BREAKING DAILY RECORD HIGHS BOTH ON SUNDAY AND MONDAY
ACCORDING TO THE LATEST NBM.
A MORE UNSETTLED WEATHER PATTERN THEN IS LIKELY TO ENSUE HEADING
TOWARDS THE MIDDLE AND LATTER PORTION OF NEXT WEEK AS THE UPPER-
LEVEL RIDGE SHIFTS EASTWARD INTO THE SOUTHERN PLAINS, ALLOWING A
DEEP TROUGH TO BUILD JUST OFF THE WEST COAST. THE DETERMINISTIC AND
ENSEMBLE MODEL SUITE CONTINUE TO DIVERGE SIGNIFICANTLY ON THE
OVERALL STRENGTH AND POSITIONING OF THE TROUGH AS IT DEEPENS OFF THE
WEST COAST, LEADING TO A LOW CONFIDENCE FORECAST HEADING TOWARDS THE
LATTER PORTION OF NEXT WEEK. ABUNDANT MOISTURE IS LIKELY TO SPREAD
NORTHEASTWARD FROM THE SUBTROPICAL PACIFIC INTO THE REGION FROM LATE
TUESDAY INTO WEDNESDAY, WITH BOTH THE EPS AND GEFS SHOWING PWATS
RISING ABOVE 200% OF NORMAL. GUIDANCE IS SHOWING A LEAD SHORTWAVE
OUT AHEAD OF THE MAIN TROUGH MOVING THROUGH THE GREAT BASIN, WHICH
COMBINED WITH THE MOISTURE THAT WILL BE IN PLACE, COULD GENERATE
SHOWER ACTIVITY ACROSS PORTIONS OF THE REGION DURING THE DAY ON
WEDNESDAY. PRECIPITATION CHANCES AFTER WEDNESDAY WILL THEN BE
DEPENDENT ON THE OVERALL STRENGTH AND POSITIONING OF THE MAIN TROUGH
OFF THE WEST COAST AS IT EVENTUALLY MIGRATES INLAND. WITH MORE
ABUNDANT CLOUD COVER AND POTENTIAL PRECIPITATION AS WELL AS THE
DECREASING HEIGHTS ALOFT, TEMPERATURES ARE LIKELY TO COOL DOWN LATER
NEXT WEEK BY ABOUT 5-10 DEGREES FROM THE READINGS EARLIER IN THE
WEEK BUT STILL REMAIN ABOVE NORMAL.
AVIATION
UPDATED AT 2300Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT; AND
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
NO WEATHER ISSUES WILL EXIST THROUGH SATURDAY EVENING UNDER PERIODS
OF THICKENING HIGH CIRRUS DECKS. WINDS WILL REMAIN VERY LIGHT WITH
ONLY SUBTLE DIURNAL/NOCTURNAL DIRECTIONAL SHIFTS. EXTENDED PERIODS
OF VARIABLE AND/OR CALM CONDITIONS WILL BE COMMON.
FIRE WEATHER
HIGH PRESSURE ACROSS THE REGION WILL CONTINUE TO PROMOTE DRY AND
TRANQUIL WEATHER AS WELL AS UNSEASONABLY WARM TEMPERATURES, 10 TO 15
DEGREES ABOVE NORMAL, INTO EARLY NEXT WEEK. WINDS WILL GENERALLY BE
LIGHT UNDER 15 MPH. AFTERNOON MINRHS WILL RANGE BETWEEN 20-35% WITH
GOOD OVERNIGHT RECOVERIES OF 40-70%. A MORE UNSETTLED PATTERN IN
FORM OF COOLER TEMPERATURES AND INCREASED PRECIPITATION CHANCES IS
LIKELY LATER NEXT WEEK.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...NONE.
CA...NONE.
SHORT TERM...SMITH
LONG TERM...LOJERO
AVIATION...18
FIRE WEATHER...LOJERO
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