907
FXUS65 KPSR 302058
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
158 PM MST THU APR 30 2026
KEY MESSAGES
- OUTFLOW WINDS FROM LATE AFTERNOON SHOWERS AND STORMS OVER
SOUTHEASTERN ARIZONA ARE LIKELY TO OVERSPREAD PORTIONS OF SOUTH
CENTRAL ARIZONA THIS EVENING, INCLUDING THE PHOENIX AREA,
BRINGING LOCALLY GUSTY WINDS AND PERHAPS SOME LOFTED DUST.
- BREEZY TO WINDY CONDITIONS WILL BECOME COMMON THIS WEEKEND,
ESPECIALLY BY SUNDAY, AS A LOW PRESSURE SYSTEM SLIDES EASTWARD
OFF THE PACIFIC EARLY NEXT WEEK.
- TEMPERATURES WILL WARM INTO THE MIDDLE NINETIES ACROSS THE
LOWER DESERTS THIS WEEKEND, FOLLOWED BY A COOLDOWN BACK INTO THE
EIGHTIES EARLY NEXT WEEK.
SHORT TERM /TODAY THROUGH FRIDAY/
EARLY AFTERNOON WV SATELLITE IMAGERY AND 500 MB RAP ANALYSIS
PLACE THE CENTER OF AN UPPER LEVEL LOW OVER THE NORTHERN BAJA,
MOVING EASTWARD OVER THE GULF OF CA. A 12Z SOUNDING TAKEN FROM THE
YUMA AREA THIS MORNING (SITE ID 17Y) CONFIRMS WHAT PHX ACARS
SOUNDINGS AND MODEL SOUNDINGS CONVEY, WHICH IS AN INCREASE IN
MIDLEVEL MOISTURE ALMOST ENTIRELY CONFINED TO A 3-6 KM AGL LAYER
AHEAD OF THIS UPPER LEVEL LOW. LOW LEVEL MOISTURE WILL REMAIN
RATHER SCANT AS THIS SYSTEM PASSES SOUTH OF THE FORECAST AREA OVER
THE NEXT 12-24 HOURS, HOWEVER, THE COOLER TEMPERATURES ALOFT
(ESPECIALLY TO OUR SOUTH) WILL BE ENOUGH IN COMBINATION WITH
MODEST MOISTURE TO DESTABILIZE THE ATMOSPHERE OVER SE AZ, WITH
100-350 J/KG MLCAPE DEVELOPING. UPPER LEVEL DIVERGENCE WILL BE
ENOUGH TO PRODUCE SCATTERED SHOWER ACTIVITY AHEAD OF THIS LOW AND
EVEN TRIGGER SOME CONVECTIVE ACTIVITY, RELEASING THE MODEST
INSTABILITY IN PLACE LATER THIS AFTERNOON. CHANCES FOR MEASURABLE
RAINFALL REMAIN ALMOST ENTIRELY OUTSIDE THE CWA, HOWEVER,
INVERTED-V MODEL SOUNDINGS UNDER THE STORMS WHICH DEVELOP IN
SOUTHEAST AZ WILL MEAN THAT EVEN WEAK SHOWERS/STORMS WILL BE
CAPABLE OF PRODUCING ROBUST DOWNDRAFTS AND LOCALLY STRONG WINDS AT
THE SURFACE. WITH ENOUGH COVERAGE OF SHOWERS AND STORMS, CAMS
HAVE COME INTO AGREEMENT THAT A SOMEWHAT ORGANIZED OUTFLOW MAY
PUSH NORTHWARD AND SWEEP SOUTH- CENTRAL AZ THIS EVENING, BRINGING
LOCALLY GUSTY WINDS AND POTENTIALLY LOFTED DUST.
IN THE WAKE OF THIS UPPER LOW, TRANSIENT RIDGING WILL SLIDE OFF
THE PACIFIC AND OVER THE WESTERN US, ESPECIALLY BY THE WEEKEND.
LINGERING MOISTURE ON FRIDAY MAY BE SUFFICIENT FOR SOME AFTERNOON
SHOWERS OVER THE FAR EASTERN AZ HIGH TERRAIN, BUT OTHERWISE, THE
REGION WILL BE COMPLETELY DRY. ANTICIPATE A CONTINUATION OF NEAR
TO SLIGHTLY ABOVE NORMAL TEMPERATURES, WITH AFTERNOON HIGHS
PEAKING IN THE LOWER 90S ACROSS THE SOUTH-CENTRAL AZ LOWER DESERTS
AND MIDDLE 90S FOR THE WESTERN DESERTS.
LONG TERM /SATURDAY THROUGH WEDNESDAY/
ANOTHER CLOSED LOW IS PROJECTED TO FORM FROM A SHORTWAVE TROUGH
ORIGINATING IN THE GULF OF ALASKA, BEFORE DEVELOPING INTO A CLOSED
LOW OFF THE COAST OF NORTHERN CALIFORNIA. THIS WILL HELP AMPLIFY THE
RIDGE OVER THE DESERT SW DRIVING TEMPERATURES INTO THE MIDDLE TO
UPPER 90S THIS WEEKEND. THIS NEXT CLOSED LOW IS EXPECTED TO MOVE
INLAND INTO NORTHERN CALIFORNIA BY SUNDAY EVENING, WHICH WILL MOST
LIKELY RETURN BREEZY TO WINDY CONDITIONS, COOLER TEMPERATURES, AND
POSSIBLY SOME HIGHER TERRAIN RAIN CHANCES. THIS MAY RESULT IN
LOCALLY ELEVATED FIRE WEATHER CONCERNS, PARTICULARLY SUNDAY
AFTERNOON INTO THE EARLY EVENING FOR PORTIONS OF THE LOWER COLORADO
RIVER VALLEY AND LA PAZ COUNTY. AFTERNOON HIGH TEMPERATURES EARLY
NEXT WEEK WILL FALL SOLIDLY INTO THE 80S ACROSS THE LOWER DESERTS,
AROUND 5 TO 8 DEGREES BELOW EARLY MAY NORMALS.
BY THE MIDDLE OF THE UPCOMING WORK WEEK, CONFIDENCE IN THE FORECAST
DECREASES CONSIDERABLY. ENSEMBLES DISAGREE ON THE TIMING OF WHEN
THIS CLOSED LOW EVENTUALLY PROGRESSES OUT OF THE REGION OR IF IT
SIMPLY "FILLS IN" AND WEAKENS AS STRONGLY POSITIVE MIDLEVEL HEIGHT
ANOMALIES BUILD/SPREAD FROM THE PACIFIC NORTHWEST. REGARDLESS, ALL
EVIDENCE CURRENTLY POINTS TO THE FORECAST AREA REMAINING DRY, AND A
WARMING TREND BEGINNING DURING THE MIDDLE OF THE UPCOMING WORK WEEK
AFTER A FEW DAYS OF BELOW NORMAL TEMPERATURES.
AVIATION
UPDATED AT 1700Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:
THE PRIMARY WEATHER CONCERN WILL BE THE POTENTIAL FOR GUSTY OUTFLOW
WINDS THIS EVENING AS MID/HIGH CLOUD DECKS GENERALLY INCREASE
THROUGH THE EVENING/OVERNIGHT. CONFIDENCE IS VERY GOOD THAT EAST
WINDS WILL GRADUALLY SWITCH TO WEST THROUGH THE AFTERNOON WITH A
PERIOD OF VARIABILITY (140V240) OR LIGHT SOUTHERLY CROSS RUNWAY
WINDS BEFORE FINALIZING THE WIND SHIFT. FORECAST CONFIDENCE
DETERIORATES AFTER THIS AS SHRA/TSRA IN FAR SE ARIZONA ATTEMPTS TO
SEND SOME FORM OF AN OUTFLOW BOUNDARY NORTH TOWARDS THE PHOENIX AREA
TERMINALS THIS EVENING. ARRIVAL TIMING, MAGNITUDE OF GUSTS, AND
IMPACTS REMAIN VERY UNCERTAIN, HOWEVER A MID EVENING ARRIVAL WITH
GUSTS AROUND 20KT ARE A MODEL CONSENSUS. SOME LOFTED DUST/HAZE
AFFECTING SLANTWISE VSBY SEEMS LIKELY WITH RESTRICTIONS TO SFC VSBY
CARRYING FAR LOWER ODDS. GUSTS MAY PERSIST FOR A FEW HOURS INTO THE
OVERNIGHT BEFORE SETTING ON A MODEST E/SE COMPONENT THROUGH MID
MORNING.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
LOCALLY GUSTY WEST WINDS WILL BE THE PRIMARY WEATHER ISSUE THROUGH
FRIDAY AFTERNOON UNDER PERIODS OF MID/HIGH CLOUD DECKS. CONFIDENCE
IS GOOD THAT W/NW WIND DIRECTIONS WILL BE PREFERRED THROUGH THE
PERIOD ACROSS SE CALIFORNIA. SUNDOWNER GUSTS 20-30 KT APPEAR LIKELY
AT KIPL THROUGH LATE EVENING BEFORE RELAXING OVERNIGHT. SOME
VARIABILITY IN WIND DIRECTIONS IS POSSIBLE FRIDAY MORNING AFTER
SUNRISE.
FIRE WEATHER
DRY CONDITIONS AND TEMPERATURES WARMING FROM NEAR NORMAL INTO A
SLIGHTLY ABOVE NORMAL CATEGORY WILL BE OBSERVED THROUGH THE
WEEKEND. A LOW PRESSURE SYSTEM WILL MOVE INLAND FROM OFF THE CA
COAST LATE THIS WEEKEND, RESULTING IN WIDESPREAD BREEZY TO LOCALLY
WINDY CONDITIONS. GUSTY AFTERNOON WINDS COULD COMBINE WITH LOW
HUMIDITIES TO PRODUCE ELEVATED TO NEAR CRITICAL FIRE WEATHER FOR
PORTIONS OF THE WESTERN DISTRICTS INCLUDING THE LOWER COLORADO
RIVER VALLEY ON SUNDAY. AFTERNOON MINRHS IN A 8-15% RANGE WILL BE
COMMON THROUGH SATURDAY, INCREASING SLIGHTLY INTO A 10-20% RANGE
SUNDAY AND 15-25% RANGE EARLY NEXT WEEK. OVERNIGHT RECOVERIES WILL
VARY WIDELY, FROM A 40-70% RANGE TONIGHT ACROSS THE EASTERN
DISTRICTS AND YUMA AREA TO AS LOW AS 25% IN THE WESTERN DESERTS,
THEN DECREASE AREAWIDE INTO A 20-50% RANGE FRIDAY AND SATURDAY
NIGHTS.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...NONE.
CA...NONE.
SHORT TERM...WHITTOCK
LONG TERM...WHITTOCK/RYAN
AVIATION...18
FIRE WEATHER...WHITTOCK
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