751
FXUS65 KPSR 312209
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
309 PM MST MON MAR 31 2025
SYNOPSIS
SEASONABLY WARM TEMPERATURES AND AFTERNOON BREEZY CONDITIONS
CONTINUE THROUGH THIS AFTERNOON. AN UNSETTLED WEATHER PATTERN THEN
TAKES HOLD TUESDAY AND PERSISTS THROUGH THE REST OF THE WEEK,
WITH TEMPERATURES COOLING BELOW. TUESDAY IS ALSO EXPECTED TO BE
THE WINDIEST DAY, WITH THE STRONGEST WINDS EXPECTED OVER SOUTHEAST
CALIFORNIA AND THE HIGH TERRAIN EAST OF PHOENIX. SLIGHT CHANCES
ALSO EXIST FOR LIGHT SHOWERS WEDNESDAY THROUGH THIS WEEKEND, BUT
MOST SHOWERS WILL FAVOR THE HIGHER TERRAIN TO THE NORTH AND EAST
OF PHOENIX.
DISCUSSION
OBJECTIVE ANALYSIS THIS AFTERNOON SHOWS ZONAL FLOW ACROSS MOST OF
SOUTHERN CONUS. THE DESERT SOUTHWEST HAS BEEN UNDER THIS ZONAL
FLOW FOR MULTIPLE DAYS NOW, BUT THIS WILL COME TO AN END TOMORROW
AS THE PATTERN SHIFTS AND A DEEP LONGWAVE TROUGH DROPS INTO AND
SITS OVER REGION FOR THE REMAINDER OF THE WEEK. FOR NOW, WEATHER
CONDITIONS THROUGH THIS AFTERNOON WILL REMAIN SIMILAR TO PREVIOUS
DAYS, WITH HIGH TEMPERATURES REACHING THE LOWER 80S ACROSS THE
LOWER DESERTS, SOME 20-30 MPH BREEZES, AND STREAM OF HIGH CLOUDS.
WHERE THERE WAS ONCE A LOT OF UNCERTAINTY IN THE FORECAST A FEW
DAYS AGO, THERE IS NOW HIGH CONFIDENCE (VERY LITTLE MODEL SPREAD)
IN THE OVERALL EVOLUTION AND SENSIBLE WEATHER IMPACTS EXPECTED
WITH THE LONGWAVE TROUGH MOVING DOWN INTO THE DESERT SOUTHWEST
THIS WEEK. THE LOW CIRCULATION WITH THE LONGWAVE TROUGH PATTERN IS
CURRENTLY SEEN NEAR THE PACIFIC NORTHWEST AND WILL BEGIN WORKING
SOUTHWARD TONIGHT AS THE LARGE SCALE PATTERN ACROSS THE PACIFIC
BECOME MORE AMPLIFIED. A STRONG 500MB WEST-EAST ORIENTED JET
(90-95KT) WILL LEAD THE TROUGH INTO THE SOUTHWEST. THIS STRONG JET
WILL LEAD TO WIDESPREAD BREEZIER CONDITIONS. GLOBAL ENSEMBLES SHOW
AN AXIS OF 700MB WINDS PEAKING IN INTENSITY OVER THE SOUTHERN
DESERTS TONIGHT THROUGH TUESDAY MORNING, WITH WIND MAGNITUDES UP
TO AROUND 45-60KTS. IF THE PEAK JET WINDS WERE TO INSTEAD PASS
OVERHEAD MORE DURING AFTERNOON HOURS THEN SURFACE WIND IMPACTS
WOULD LIKELY BE MORE CONSIDERABLE. REGARDLESS, WIND IMPACTS ARE
EXPECTED THIS EVENING THROUGH TUESDAY, MOST NOTABLY ACROSS
SOUTHEAST CA AND THE HIGHER TERRAIN SPOTS EAST OF PHOENIX. WIND
ADVISORIES ARE IN EFFECT FOR PORTIONS OF SOUTHEAST CA THIS EVENING
AND AGAIN TUESDAY AFTERNOON AND EVENING, WHERE WESTERLY JET WINDS
WILL BE STRONGEST AND ACCELERATIONS DUE TO DOWNSLOPING ARE
ANTICIPATED. THE ADVISORY WAS EXPANDED TO INCLUDE THE YUMA, AZ
AREA GIVEN MODEL SOUNDINGS SHOW WINDS REACHING UP TO 40 KTS
~1000FT ABOVE THE SURFACE AND HIGH HREF PROBABILITIES FOR WIND
GUSTS >40MPH (70-80%). WINDS ELSEWHERE ACROSS THE LOWER DESERTS
WILL LIKELY GUST MORE COMMONLY TO 20-30 MPH.
TEMPERATURES WILL DROP CONSIDERABLY MID-WEEK AS THE TROUGH DROPS
DOWN INTO THE AREA. THIS WILL BE A VERY COLD SYSTEM FOR THIS TIME
OF YEAR. TEMPERATURES AT 850MB ARE FORECAST TO DROP TO A MINIMUM
OF 2-4C OVER THE SOUTHERN DESERTS BY WEDNESDAY MORNING. TO PUT
THAT INTO CLIMATOLOGICAL PERSPECTIVE, 2-4C 850MB TEMPS THIS TIME
OF YEAR ARE BELOW THE 5TH PERCENTILE. THIS WILL RESULT IN MUCH
COOLER, BELOW NORMAL, TEMPERATURES. AROUND 10 DEGREES OF SURFACE
COOLING IS EXPECTED FROM THIS AFTERNOON TO TOMORROW AFTERNOON,
FOLLOWED BY ANOTHER 5-10 DEGREES INTO WEDNESDAY ACROSS SOUTH-
CENTRAL AZ. MOST OF SOUTH-CENTRAL AZ ARE NOT FORECAST TO GET ABOVE
70F WEDNESDAY. SIMILAR TEMPERATURES ARE FORECAST FOR THURSDAY AS
THE BROAD UPPER LOW REMAINS OVER THE AREA AND THEN A GRADUAL
WARMING TREND IS EXPECTED AS THE LOW WEAKENS AND EVENTUALLY MOVES
OUT TOWARD THE BEGINNING OF NEXT WEEK. THE GRADUAL DAILY WARMING
MAY CONTINUE ALL THE WAY THROUGH THE MIDDLE OF NEXT WEEK AND
BRING 90S BACK INTO THE PICTURE AGAIN.
AS FOR THE PROSPECT FOR RAIN WITH THIS COLD SYSTEM, ODDS ARE STILL
NOT VERY GOOD FOR THE LOWER DESERTS. TO START, THE BEST MOISTURE
OVER THE NEXT WEEK IS RIGHT NOW, BUT THERE IS NO FORCING TO DRIVE
ANY RAIN DEVELOPMENT, AND THEN CONDITIONS DRY INTO THE MIDDLE OF
THIS WEEK, AT LEAST FROM A PWAT STAND POINT, GOING FROM 0.6-0.8"
TODAY DOWN TO AROUND 0.4" TOMORROW THROUGH THE REST OF THE WEEK.
THIS INCOMING SYSTEM WILL BE VERY COLD, HOWEVER, AND THERE WILL BE
SOME DECENT DYNAMIC FORCING. THIS SHOULD HELP DRIVE SPOTTY SHOWERS
AROUND THE REGION, MOSTLY FAVORING HIGH TERRAIN AREAS OF AZ. THE
BEST SHOT AT RAIN IN THE LOWER DESERTS LOOKS LIKE WEDNESDAY, WHEN
THE BEST PVA MOVES ACROSS SOCAL AND SOUTHERN AZ AND MID-LEVEL
LAPSE RATES ARE STEEPEST (~7.5C/KM). MODEL SOUNDINGS DO SUGGEST A
MINIMAL AMOUNT OF SBCAPE WEDNESDAY AFTERNOON AND PROFILES SUGGEST
THE POTENTIAL FOR SPOTTY CONVECTIVE SHOWERS. LATEST NBM POPS ARE
HIGHEST FOR THE LOWER DESERTS ON WEDNESDAY AT AROUND 10-30%. THE
REST OF THIS WEEK AND WEEKEND SHOWERS WILL MOSTLY FOCUS IN THE
HIGH TERRAIN AS MENTIONED, WITH LOWER DESERTS AT <10% EACH DAY
THROUGH SUNDAY. ANY SHOWERS THAT DO DEVELOP ARE NOT LIKELY TO
PROVIDE ANY CONSEQUENTIAL RAINFALL AMOUNTS FOR THE LOWER DESERTS,
WITH THE 90TH PERCENTILE (10% CHANCE) STILL ONLY SHOWING
0.10-0.20". SNOW LEVEL WILL DROP TO AROUND 4500-5500'BY WEDNESDAY.
SO THERE IS THE POTENTIAL FOR SPOTTY SNOW SHOWERS AT HIGHER
ELEVATIONS, BUT WITH NO ACCUMULATIONS ANTICIPATED IN THE MARICOPA
AND SOUTHERN GILA COUNTY MOUNTAINS.
AVIATION
UPDATED AT 1827Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
SOUTH TO SOUTHEAST WINDS WILL CONTINUE TO VEER TOWARD A
WEST/SOUTHWEST COMPONENT HEADING INTO THIS AFTERNOON. SPEEDS WILL
INCREASE THIS AFTERNOON WITH GUSTS CLIMBING TO AROUND 20-25 KTS
AND BRIEFLY HIGHER AT TIMES BEFORE SUBSIDING THIS EVENING. CAN'T
RULE OUT SOME DUST GETTING LOFTED TO CREATE SOME SLANTWISE
VISIBILITY CONCERNS THROUGH AROUND SUNSET. WIND DIRECTIONS ARE
FORECAST TO REMAIN OUT OF THE WEST/SOUTHWEST THROUGH THE PERIOD
WITH NO OVERNIGHT EASTERLY SHIFT ANTICIPATED. SCT, TO AT TIMES
BKN, HIGH CIRRUS CLOUDS WILL BE COMMON THROUGHOUT THE PERIOD WITH
PERHAPS A FEW LOW CUMULUS AT AROUND 6 KFT POSSIBLE DURING THE
AFTERNOON HOURS.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
STRONG WINDS WILL BE THE MAIN AVIATION WEATHER ISSUE THROUGHOUT
THE TAF PERIOD. KIPL WILL SEE STRONG WESTERLY GUSTS UPWARDS OF
25-30 KTS CONTINUE THROUGHOUT THE EVENING WITH SOME STRONGER GUSTS
TO AROUND 35 KTS POSSIBLE AT TIMES THIS AFTERNOON INTO THE
EVENING. AS A RESULT, BLOWING DUST WILL BE A CONCERN THAT COULD
RESULT IN LOWERED SURFACE AND/OR SLANTWISE VISIBILITIES. EXPECT
THESE STRONGER GUSTS TO SUBSIDE DURING THE OVERNIGHT HOURS WHILE
SUSTAINED WINDS REMAIN ELEVATED. AT KBLH, WINDS WILL FAVOR A
SOUTHWESTERLY COMPONENT WITH AFTERNOON AND EARLY EVENING GUSTS
INCREASING INTO THE 20-25 KT RANGE BEFORE GRADUALLY SUBSIDING
DURING THE LATE EVENING HOURS. SCT, TO AT TIMES BKN, HIGH-CIRRUS
CLOUDS WILL COMMON THROUGHOUT THE PERIOD WITH PERHAPS A FEW LOW
CUMULUS AT AROUND 5 KFT, MAINLY NEAR KIPL, POSSIBLE THROUGH THE
AFTERNOON HOURS.
FIRE WEATHER
SEASONAL TEMPERATURES ARE EXPECTED TODAY WITH TEMPERATURES
COOLING BELOW NORMAL BY TUESDAY AND REMAINING BELOW NORMAL THROUGH
THE REMAINDER OF THE WORKWEEK. MOSTLY DRY CONDITIONS ARE EXPECTED
THROUGHOUT THE WEEK AS WELL, WITH THE EXCEPTION OF SLIGHT CHANCES
FOR RAIN ON WEDNESDAY AFTERNOON AND AGAIN FRIDAY INTO THIS WEEKEND,
BUT THESE CHANCES WILL BE CONFINED MOSTLY TO THE HIGHER TERRAIN
TO THE NORTH AND EAST OF PHOENIX. TODAY WILL BE BREEZY,
PARTICULARLY ACROSS THE WESTERN DESERTS, AND THEN THE STRONGEST
WINDS ARE EXPECTED ON TUESDAY. EXPECT THE HIGHEST WIND SPEEDS
ACROSS SE CA, MAINLY IMPERIAL COUNTY, AND ACROSS THE HIGHER
TERRAIN OF MARICOPA AND GILA COUNTIES. ELEVATED FIRE WEATHER
CONCERNS MAY OCCUR FOR A FEW HOURS TUESDAY AFTERNOON AND EVENING,
WHEN WINDS ARE STRONGEST AND RHS LOWEST. DESPITE STRONGEST WINDS
BEING IN IMPERIAL AND GILA COUNTIES, MOST ELEVATED CONDITION LOOK
TO BE FROM E RIVERSIDE COUNTY THROUGH LA PAZ AND N MARICOPA
COUNTIES, WHERE MINRHS WILL FALL TO 10-15%. MINRHS WILL BE AROUND
20-30% WEDNESDAY-THURSDAY AND THEN 10-20% FRIDAY ONWARD. OVERNIGHT
RECOVERIES WILL BE FAIR TO GOOD MOST DAYS, GENERALLY AROUND
40-70%.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...WIND ADVISORY UNTIL 2 AM MST TUESDAY FOR AZZ532.
WIND ADVISORY FROM 3 PM TUESDAY TO 2 AM MST WEDNESDAY FOR AZZ532.
CA...WIND ADVISORY UNTIL 2 AM PDT TUESDAY FOR CAZ560-563-565>567.
WIND ADVISORY FROM 3 PM TUESDAY TO 2 AM PDT WEDNESDAY FOR CAZ560-
563-565>567.
WIND ADVISORY UNTIL 5 AM PDT WEDNESDAY FOR CAZ562.
DISCUSSION...BENEDICT
AVIATION...SMITH
FIRE WEATHER...BENEDICT/WHITTOCK
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