592
FXUS65 KPSR 030531
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
1031 PM MST MON JUN 2 2025
UPDATE
UPDATED 06Z AVIATION DISCUSSION.
DISCUSSION
KEY MESSAGES:
- SLIGHT CHANCE (LESS THAN 20%) OF LIGHT SHOWERS TUESDAY NIGHT AND
WEDNESDAY, THEN SIGNIFICANT DRYING THE REMAINDER OF THE WEEK
- TEMPERATURES QUICKLY REBOUNDING TOWARDS NORMAL LEVELS DURING THE
MIDDLE OF THE WEEK, THEN ABOVE NORMAL LATE WEEK
EARLY AFTERNOON WV IMAGERY CLEARLY DEPICTS A COMPACT NEGATIVE PV
ANOMALY FILLING AND LIFTING INTO NE ARIZONA WHILE A SEPARATE
CIRCULATION CENTER HAS DETACHED FROM THE NORTHERN JET CORE OFF THE
CENTRAL CALIFORNIA COAST. WITH THE DEPARTURE OF THE INITIAL
VORTICITY CENTER, SHORTWAVE RIDGING AND INCREASING WEAK SUBSIDENCE
WILL BRIEFLY MOVE INTO THE FORECAST AREA OVER THE NEXT 24-36 HOURS,
HOWEVER ABUNDANT LINGERING MOISTURE MAY STILL SUPPORT A FEW SPOTTY
SHOWERS OVER HIGHER TERRAIN AREAS. IN FACT, SURFACE DEWPOINTS IN THE
LOWER/MIDDLE 60S ARE BEING SAMPLED ACROSS THE REGION WHILE OBJECTIVE
ANALYSIS SUGGESTS BOUNDARY MIXING RATIOS 10-12 G/KG STILL
ENCOMPASSING THE ENTIRE CWA. THIS ANOMALOUS LOW LEVEL MOISTURE (MORE
TYPICAL FOR MID JULY VS. EARLY JUNE) WILL SLOWLY, BUT STEADILY BE
ERODED AWAY SUCH THAT SHOWER CHANCES QUICKLY BEGIN TO EVAPORATE THE
NEXT FEW DAYS, AND MORE TYPICAL JUNE WEATHER RESUMES.
THE GREATEST FORECAST UNCERTAINTY IS THE INFLUENCE AND IMPACTS OF
THE AFOREMENTIONED CALIFORNIA VORTICITY CENTER AS IT EVENTUALLY
MIGRATES INLAND AND DETERIORATES SUBSTANTIALLY BECOMING RE-ABSORBED
INTO THE NORTHERN STREAM FLOW DOWNSTREAM OF THE FORECAST AREA LATE
TUESDAY INTO WEDNESDAY. DESPITE AN IMPRESSIVE APPEARANCE IN
SATELLITE IMAGERY, THERE ISN'T MUCH OPTIMISM OF BETTER RAINFALL
POTENTIAL WITH NOTABLY DRY AIR ENTRENCHED AROUND THE CIRCULATION AND
CURRENT IN SITU MOISTURE AVAILABILITY LIKELY FALLING CLOSER TO 7-8
G/KG BY ARRIVAL TIME. ENSEMBLES HAVE NARROWED DOWN UNCERTAINTY IN
TIMING AND MAGNITUDE OF THIS SYSTEM YIELDING BETTER FORECAST
CONFIDENCE, YET THIS STILL ONLY SUPPORTS LOCAL POPS MAXIMIZED AROUND
20%. NBM POP FORECASTS ARE ONCE AGAIN DISPLAYING A SUBJECTIVE HIGH
BIAS CONSIDERING THE VAST MAJORITY OF MODEL AND BUFR SOUNDING
OUTPUT, AND HAVE MADE NOTABLE REDUCTIONS TO THE AUTOMATED FORECAST.
GENERAL LONGWAVE TROUGHING WILL CONTINUE TO LINGER ACROSS THE SW
CONUS THROUGH LATE WEEK, HOWEVER MIDLEVEL HEIGHTS WILL GRADUALLY
INCREASE WITH THE EJECTION OF THE SECOND SHORTWAVE AND SUBTROPICAL
RIDGING STRENGTHENING OVER SOUTH TEXAS. ENSEMBLE MEMBERSHIP IS IN
VERY GOOD AGREEMENT WITH THIS EVOLUTION AS H5 HEIGHTS RISE INTO A
584-588DM RANGE BY THE END OF THE WEEK. THIS TYPE OF RANGE IS FAIRLY
TYPICAL FOR EARLY JUNE, AND A NARROW GUIDANCE SPREAD YIELDS GOOD
CONFIDENCE OF TEMPERATURES RETURNING TO A NORMAL RANGE DURING THE
LATTER HALF OF THE WEEK. BY EARLY NEXT WEEK, ENSEMBLE SPREAD GROWS
SLIGHTLY DEPENDING ON THE EXPANSE OF SUBTROPICAL RIDGE RETROGRESSION
WITH SOME OF THE MORE AGGRESSIVE MODELING SUGGESTING H5 HEIGHTS
CLOSER TO 592DM WHICH WOULD BE A DECENT PROXY FOR TEMPERATURES
FLIRTING WITH 110F. REGARDLESS, A RETURN OF WIDESPREAD MODERATE
HEATRISK TO THE REGION BY THIS WEEKEND SEEMS INEVITABLE, BUT
FORTUNATELY NOT YET NEAR MAJOR/EXTREME LEVELS.
AVIATION
UPDATED AT 0530Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, KDVT:
LIGHT AND VARIABLE WINDS WILL CONTINUE THROUGH THE OVERNIGHT AND
MORNING AT MOST TAF SITES. AT KPHX, WINDS WILL BE LIGHT NW'RLY
BETWEEN 08-12Z AND AT KIWA, WINDS WILL GO SOUTHEASTERLY AROUND
10Z. A PERIOD OF SOUTHERLY CROSSWINDS IS ANTICIPATED EARLY
TOMORROW AFTERNOON BEFORE GOING MORE SOUTHWESTERLY LATER IN THE
AFTERNOON. WINDS AT KPHX WILL THEN GO WESTERLY IN THE EVENING
BEFORE DOING THEIR DIURNAL TRANSITION BACK SOUTHEASTERLY DURING
THE OVERNIGHT HOURS INTO WEDNESDAY. FEW CLOUDS WITH BASES AOA 7-8
KFT WILL CLEAR OUT DURING THE OVERNIGHT HOURS WITH FEW CLOUDS
(WITH BASES AOA 10 KFT) MOVE BACK IN TOMORROW AFTERNOON AND
EVENING.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
SOUTHERLY WINDS ARE ANTICIPATED AT KBLH AND SOUTHEASTERLY WINDS AT
KIPL THROUGH THE ENTIRE TAF PERIOD. WIND SPEEDS WILL GENERALLY BE
AOB 10 KT AT KIPL AND AROUND 5-15 KT AT KBLH, WITH THE HIGHER
SPEEDS EXPECTED DURING THE AFTERNOON AND EVENING TIMEFRAME. SKIES
WILL REMAIN CLEAR.
FIRE WEATHER
AN UNUSUALLY MOIST ENVIRONMENT WILL PERSIST OVER THE REGION THE NEXT
COUPLE DAYS WITH EVEN A FEW LINGERING SHOWERS ARE POSSIBLE TUESDAY
AND WEDNESDAY. HOWEVER, WETTING RAIN CHANCES REMAIN VERY LOW (UNDER
15%) WITH MOST DISTRICTS LIKELY REMAINING DRY. THIS PATTERN WILL
QUICKLY TRANSITION BACK TO MORE TYPICAL DRY CONDITIONS AND
SEASONABLE TEMPERATURES DURING THE LATTER HALF OF THE WEEK. MINIMUM
AFTERNOON HUMIDITY LEVELS GENERALLY 20-30% THROUGH WEDNESDAY SHOULD
DEGRADE NEAR 15-25% LATER IN THE WEEK, THEN NEAR SINGLE DIGITS OVER
THE WEEKEND. FAIR TO GOOD OVERNIGHT RECOVERY OF 40-60% WILL
CORRESPONDINGLY RETREAT INTO A POOR TO FAIR RANGE OF 20-40% LATE IN
THE WEEK. WINDS SHOULD BE FAIRLY TYPICAL FOR LATE SPRING WITH THE
USUAL AFTERNOON UPSLOPE GUSTINESS.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...NONE.
CA...NONE.
DISCUSSION...18/YOUNG
AVIATION...BERISLAVICH
FIRE WEATHER...YOUNG/18
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