036
FXUS65 KPSR 172300
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
400 PM MST WED DEC 17 2025
UPDATE
UPDATED AVIATION
KEY MESSAGES
- WELL ABOVE NORMAL TEMPERATURES AND DRY CONDITIONS WILL PERSIST
ACROSS THE REGION INTO AT LEAST EARLY NEXT WEEK.
- A CHANGE IN THE WEATHER PATTERN IS EXPECTED LATER NEXT WEEK
POTENTIALLY BRINGING PRECIPITATION CHANCES AND COOLER TEMPERATURES.
SHORT TERM /TODAY THROUGH THURSDAY/
CONDITIONS ACROSS THE SOUTHWESTERN CONUS REMAIN QUIET AS
UNSEASONABLY STRONG HIGH PRESSURE CONTINUES TO SIT OVER THE REGION.
OVER THE GREAT BASIN, A LOW-AMPLITUDE SHORTWAVE IS HELPING TO KEEP
OUR RIDGE RELATIVELY FLAT AND HEIGHTS A BIT SUPPRESSED COMPARED TO
YESTERDAY. NONETHELESS, 500MB HEIGHTS REMAIN AROUND THE 90TH
PERCENTILE FOR THIS TIME OF YEAR, OWING TO THE AMOUNT OF WARM AIR
CURRENTLY OVER THE FORECAST AREA. THIS WILL TRANSLATE TO A
CONTINUATION OF SURFACE TEMPERATURES RUNNING AROUND 10 DEGREES ABOVE
NORMAL FOR THE MIDDLE OF DECEMBER. LOWER DESERT HIGHS THIS AFTERNOON
WILL RANGE IN THE MIDDLE TO UPPER 70S, WITH AREAS IN AND AROUND THE
IMPERIAL VALLEY GETTING CLOSE TO 80 DEGREES ONCE AGAIN.
WITH LITTLE FLUCTUATION IN THE DAY-TO-DAY FORECAST, SIMILAR
AFTERNOON HIGHS CAN BE EXPECTED FOR THURSDAY.
LONG TERM /FRIDAY THROUGH MID NEXT WEEK/
AFTER THE NORTHERN U.S. TROUGH EXITS INTO THE PLAINS STATES ON
THURSDAY, THE CENTER OF THE EASTERN PACIFIC RIDGE WILL MOVE CLOSER
TO OUR REGION LATE THURSDAY INTO FRIDAY WITH H5 HEIGHTS PEAKING OVER
THE DESERT SOUTHWEST BETWEEN 585-587DM EARLY ON FRIDAY. THIS PEAK IN
HEIGHTS WILL HELP TO BOOST TEMPERATURES STARTING FRIDAY WITH THE NBM
SHOWING HIGHS MOSTLY BETWEEN 78-81 DEGREES. THE PROGRESSIVE PATTERN
ACROSS THE NORTHERN TIER STATES WILL THEN SEND ANOTHER TROUGH ACROSS
THE PACIFIC NORTHWEST/NORTHERN ROCKIES LATER ON FRIDAY INTO SATURDAY
WHICH SHOULD FLATTEN THE RIDGE SLIGHTLY AND LOWER HEIGHTS MORE INTO
A 582-584DM RANGE ON SATURDAY. THIS BACK AND FORTH OF SLIGHTLY
RISING AND LOWERING OF HEIGHTS LOOKS TO CONTINUE THROUGH EARLY NEXT
WEEK WITH MONDAY SHOWING ANOTHER TEMPORARY BUMP IN HEIGHTS. OVERALL,
THIS WILL CONTINUE TO ALLOW FOR THE UNSEASONABLY WARM TEMPERATURES
TO LAST INTO AT LEAST EARLY NEXT WEEK WITH READINGS STAYING NEAR 15
DEGREES ABOVE NORMAL.
THE LATTER HALF OF NEXT WEEK SHOULD BRING A PATTERN CHANGE WITH
MODELS SHOWING DECENT AGREEMENT OF A DEEP PACIFIC TROUGH SETTING UP
OFF THE WEST COAST AND THE RIDGE GRADUALLY MOVING TO THE EAST. THERE
IS STILL UNCERTAINTY WITH THE EVOLUTION OF THE TROUGH AND ITS
STRENGTH, BUT ENSEMBLES ARE QUITE CONSISTENT IN SHOWING DECENT
MOISTURE BEGINNING TO SPREAD INTO OUR REGION FROM THE SOUTHWEST
AHEAD OF THE TROUGH BY AROUND NEXT WEDNESDAY. PRECIPITATION CHANCES
MAY BECOME POSSIBLE AT SOME POINT LATER NEXT WEEK, BUT CONFIDENCE
REMAINS QUITE LOW FOR THE TIMING. THE WEATHER SYSTEM IS EXPECTED TO
BE QUITE WARM, SO ANY PRECIPITATION ACROSS THE AREA SHOULD FALL AS
RAIN.
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 THURSDAY EVENING UNDER SOME
INCREASE IN HIGH CIRRUS DECKS. WIND SPEEDS WILL REMAIN EXTREMELY
LIGHT, SUCH THAT EVEN THE TYPICAL AFTERNOON WESTERLY SWITCH IN THE
PHOENIX AREA MAY ONLY REALIZE A VARIABLE COMPONENT BEFORE REVERTING
TO EASTERLY. WINDS ACROSS SE CALIFORNIA WILL FAVOR A GENERAL NW
DIRECTION. EXTENDED PERIODS OF NEARLY CALM CONDITIONS WILL BE
COMMON.
FIRE WEATHER
PERSISTENT HIGH PRESSURE ACROSS THE REGION WILL RESULT IN WARM AND
DRY CONDITIONS INTO EARLY NEXT WEEK. HIGHS IN THE UPPER 70S TO THE
LOWER 80S WILL BE COMMON ACROSS THE LOWER DESERTS, OR 10 TO 15
DEGREES ABOVE DAILY NORMALS. WINDS WILL OVERALL BE LIGHT AND FOLLOW
FAMILIAR DIURNAL PATTERNS. MINRHS WILL RANGE FROM 15-25% WHILE
OVERNIGHT RECOVERIES WILL GENERALLY REMAIN FAIR UP TO 40-70%.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...NONE.
CA...NONE.
SHORT TERM...RW
LONG TERM...KUHLMAN
AVIATION...18
FIRE WEATHER...KUHLMAN
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