494
FXUS65 KPSR 241119
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
419 AM MST SUN MAY 24 2026
UPDATE...UPDATED AVIATION DISCUSSION
KEY MESSAGES
- ABOVE NORMAL TEMPERATURES WILL COOL INTO A BELOW NORMAL CATEGORY
DURING THE LATTER HALF OF THE WEEK.
- INCREASING WIND SPEEDS WITH OCCASIONALLY STRONGER GUSTS WILL
DEVELOP ACROSS PARTS OF THE AREA THROUGH THE MIDDLE OF THE WEEK.
- A CHANCE OF SHOWERS AND A FEW THUNDERSTORMS WILL EXIST OVER AREAS
SOUTH AND EAST OF PHOENIX SUNDAY NIGHT AND MONDAY, ALBEIT WITH
LIMITED RAINFALL POTENTIAL.
SHORT TERM /TODAY THROUGH MONDAY/
AN INTENSIFYING SUBTROPICAL JET STREAK AND ATTENDANT UPPER LOW
APPROACHING FROM THE EAST PACIFIC WILL IMPACT THE AREA OVER THE NEXT
48 HOURS, AND HERALD THE BEGINNING OF A PERIOD OF UNSETTLED WEATHER
THROUGH THE MIDDLE OF THE WEEK. THIS FEATURE WILL DISPLACE SHORTWAVE
RIDGING TODAY WITH MODEST HEIGHT FALLS ARRIVING MONDAY, WHILE ALSO
ALLOWING DEEP SOUTHERLY FLOW AND PLACEMENT OF THE FORECAST AREA
WITHIN A VERY FAVORABLE LEFT FRONT QUADRANT OF THE UPPER JET. THE
RESULTANT FLOW PATTERN WILL FORCE THE IMPORT OF HIGHER MOISTURE
VALUES IN THE H7-H5 LAYER BY THIS AFTERNOON, THOUGH FORECAST
SOUNDINGS STILL LIMIT MIXING RATIOS AT 5 G/KG THROUGH THE
TROPOSPHERIC COLUMN. IMPRESSIVE ASCENT MECHANISMS WILL MOVE INTO
SOUTHERN ARIZONA THIS AFTERNOON ACTING ON MODEST ELEVATED
INSTABILITY, AND HREF MEMBERSHIP CONTINUES TO ADVERTISE ISOLATED DEEP
CONVECTION AROUND THE TUCSON AREA. A DEEP SUB-CLOUD DRY LAYER WITH
T/TD SPREADS BETTER THAN 50F WILL PROMOTE STRONG, GUSTY OUTFLOW
WINDS BEING ABSORBED IN THE GENERAL SOUTHERLY FLOW. WHILE RECENT
HRRR ITERATIONS ARE MORE AGGRESSIVE THAN ITS HREF COUNTERPARTS,
THERE IS A CONSENSUS DEPICTING QUASI-ORGANIZED OUTFLOW SURGING INTO
NORTHERN PINAL COUNTY LATE AFTERNOON/EARLY EVENING WHICH COULD
CONCEIVABLY IMPORT SOME LOFTED DUST TOWARDS THE PHOENIX METRO. A
RESIDUAL ISOLATED SHOWER WOULD NOT BE INCONCEIVABLE, BUT WOULD TEND
TO BECOME FOCUSED OVER HIGHER TERRAIN AREAS TO THE EAST OF PHOENIX.
AS THE CORE OF THE UPPER LOW DRAWS OVERHEAD MONDAY, LAPSE RATES WILL
STEEPEN MORE NOTICEABLY RESULTING IN MUCAPE ~200 J/KG MATERIALIZING
OVER THE EASTERN PART OF THE CWA. WITH A LESSER SUB-CLOUD DRY LAYER
OVER HIGH TERRAIN LOCATIONS AND THE BEST ASCENT OCCURRING OVERNIGHT,
THE OPPORTUNITY FOR RAINFALL WILL INCREASE THROUGH MONDAY MORNING IN
GILA COUNTY. HOWEVER FOR THE MOST PART, HREF MEAN QPF BARELY
ECLIPSES 0.01" THOUGH PERSISTENT ROBUST MOIST ASCENT IN THE
MIDLEVELS WILL ENSURE SEVERAL OPPORTUNITIES FOR MINOR ACCUMULATIONS.
ADDITIONAL DEEP CONVECTION MAY ERUPT LATER MONDAY AFTERNOON WITH
PEAK HEATING AND LINGERING MIDLEVEL MOISTURE WITH DRY LIGHTNING AND
GUSTY OUTFLOW WINDS THE GREATEST THREAT. HOWEVER, ANY ACTIVITY
SHOULD BE SHORT-LIVED AS DRY AIR AND SUBSIDENCE ARRIVING BEHIND A
PASSING TROUGH AXIS SHUTS DOWN THE THREAT BY MONDAY EVENING.
LONG TERM /TUESDAY THROUGH SATURDAY/
THERE IS NOW RESOUNDING AGREEMENT AMONG THE FULL SUITE OF ENSEMBLES
THAT DEEP NEGATIVE HEIGHT ANOMALIES ENTERING THE PACIFIC NW WILL
DESCEND INTO CENTRAL/SOUTHERN NEVADA MIDWEEK AS THE NORTH AMERICAN
FLOW PATTERN EVOLVES INTO A HIGH AMPLITUDE BLOCK. THIS EVOLUTION
WILL FAVOR THE DEVELOPMENT OF A LARGE CUTOFF TEMPORARILY STALLING
JUST NW OF THE FORECAST AREA BEFORE FILLING AND LIFTING INTO THE
NORTHERN ROCKIES LATE IN THE WEEK. TEMPERATURES MAY COOL AS MUCH AS
5F-10F BELOW NORMAL DURING THE MIDDLE OF THE WEEK, AND NARROWING
NUMERICAL GUIDANCE SPREAD YIELDS IMPROVED FORECAST CONFIDENCE.
PREVAILING DEEP WESTERLY FLOW WILL ENSURE DRY WEATHER THROUGH THIS
PERIOD DESPITE THE COLD CORE ALOFT SKIRTING THE NORTHWEST PARTS OF
THE CWA.
THE MOST IMPACTFUL ASPECT OF THIS SYSTEM SHOULD BE INCREASED WIND
SPEEDS AS A STRONG JET CORE AND SEASONALLY IMPRESSIVE HEIGHT FALLS
SURGE INTO THE REGION. THE INITIAL ROUND OF HEIGHT FALLS AND LEADING
EDGE OF STRONGER JET WINDS WILL PUNCH INTO SOUTHERN CALIFORNIA LATE
TUESDAY, THEN SWEEP ACROSS THE ENTIRE CWA ON WEDNESDAY. THIS SETUP
ALONG WITH THE DEEPENING WINDWARD MARINE LAYER AND POTENTIAL PASSAGE
OF A MIDTROPOSPHERIC FRONT WILL FAVOR STRONG SUNDOWNER WINDS AND
POSSIBLE MOUNTAIN ROTORS AND HYDRAULIC JUMPS ACROSS WESTERN IMPERIAL
COUNTY TUESDAY AND WEDNESDAY WHERE ADVISORIES MAY BE NECESSARY.
OTHERWISE, DEEP MECHANICAL MIXING SHOULD TAP HIGHER MOMENTUM 20-30KT
WINDS THROUGH THE BOUNDARY LAYER ACROSS THE ENTIRE CWA WEDNESDAY
AFTERNOON RESULTING IN AN ENHANCED FIRE DANGER GIVEN FAIRLY LOW
HUMIDITY LEVELS AND VERY RECEPTIVE DRY FUELS. AS MIDLEVEL HEIGHTS
START FILLING AND THE COLD CORE SLOWLY LIFTS NORTH THURSDAY AND
FRIDAY, WIND SPEEDS WILL GRADUALLY RELAX WHILE TEMPERATURES EDGE
HIGHER.
AVIATION
UPDATED AT 1120Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
THE MAIN AVIATION CONCERN THROUGH TONIGHT WILL BE THE POTENTIAL
FOR GUSTY SOUTHEASTERLY OUTFLOW WINDS EARLY EVENING. UNTIL THEN,
EXPECT TYPICAL DIURNAL WIND TRENDS AND CLEAR SKIES. EXPECTED
CONVECTION STARTING NEAR TUCSON LATE AFTERNOON MAY SEND GUSTY
WINDS TOWARD AT LEAST KIWA AND POTENTIALLY WELL INTO THE PHOENIX
AREA, THOUGH CONFIDENCE IS STILL SOMEWHAT LOW. ALSO CAN'T RULE OUT
A FEW SHOWERS OR EVEN WEAK THUNDERSTORM MAKING THEIR WAY TOWARD
SOUTHEASTERN PHOENIX EARLY TO MID EVENING WITH THE MAIN CONCERN
BEING ERRATIC WIND SHIFTS AND A BRIEF PERIOD OF GUSTY WINDS OF
20-30 KTS. OUTSIDE OF THE POTENTIAL FOR OUTFLOW SOUTHEASTERLY
WINDS, WIND DIRECTIONS WILL FAVOR THE SOUTHWEST FROM THIS
AFTERNOON THROUGH AT LEAST MIDNIGHT SUNDAY NIGHT.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
NO MAJOR AVIATION WEATHER IMPACTS ARE EXPECTED THROUGH THE NEXT 24
HOURS. WINDS WILL FAVOR A SE'RLY COMPONENT AT KIPL, UNTIL A W-SW
SHIFT THIS EVENING, AND S'LRY COMPONENT AT KBLH THROUGH THE TAF
PERIOD. AFTERNOON WIND GUSTS UP TO 20-25 KTS ARE EXPECTED AGAIN AT
KBLH DURING THE AFTERNOON, WITH LESS GUSTINESS AT KIPL. SKIES
WILL BE CLEAR TO MOSTLY CLEAR THROUGH TONIGHT.
FIRE WEATHER
SLIGHTLY ABOVE NORMAL TEMPERATURES WILL BRIEFLY COOL INTO A BELOW
NORMAL CATEGORY DURING THE MIDDLE OF THE WEEK. MINIMUM AFTERNOON
HUMIDITY LEVELS WILL FALL INTO A 10-20% RANGE WITH MOSTLY FAIR TO
GOOD OVERNIGHT RECOVERY OF 30-50%, THOUGH SOME AREAS WILL
OCCASIONALLY ONLY REACH POOR RECOVERY NEAR 20% AT TIMES. AN INCREASE
IN MIDLEVEL MOISTURE LATE THIS AFTERNOON WILL RESULT IN A SLIGHT
CHANCE FOR SHOWERS/THUNDERSTORMS IN SOUTHERN ARIZONA LEADING TO
LOCALLY GUSTY OUTFLOW WINDS AND THE POTENTIAL FOR A FEW LIGHTNING
STRIKES MOVING TOWARDS SOUTHERN GILA COUNTY. A 20% THUNDERSTORM
THREAT WILL CONTINUE IN FAR EASTERN DISTRICTS MONDAY THOUGH LIMITED
ACCUMULATING RAINFALL SHOULD BE ANTICIPATED, AND THE THREAT FOR NEW
WILDFIRE STARTS DUE TO LIGHTNING STRIKES WILL BE HEIGHTENED. TYPICAL
AFTERNOON UPSLOPE GUSTINESS OF 15-25 MPH WILL BE COMMON EARLY THIS
WEEK WITH SPEEDS INCREASING MARKEDLY DURING THE MIDDLE OF THE WEEK.
STRONGER GUSTS OVER EASTERN DISTRICT HIGH TERRAIN AND THROUGH THE
LOWER COLORADO RIVER VALLEY WEDNESDAY COMBINED WITH LOW RH AND DRY
FUELS WILL RESULT IN AN ELEVATED FIRE DANGER, THOUGH COOLER
TEMPERATURES AND HIGHER HUMIDITY LEVEL MAY PRECLUDE CRITICAL
CONDITIONS.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...NONE.
CA...NONE.
SHORT TERM...18/WHITTOCK
LONG TERM...18
AVIATION...KUHLMAN
FIRE WEATHER...18
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