594
FXUS65 KPSR 170003
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
503 PM MST FRI MAY 16 2025
UPDATE
UPDATED 00Z AVIATION DISCUSSION.
KEY MESSAGES
1) GUSTY WINDS OVER THE WEEKEND RESULTING TARGETED ADVISORIES AND
LOCALLY ELEVATED FIRE DANGER
2) SUBSTANTIAL WARMING TREND LATTER HALF OF NEXT WEEK RESULTING IN
WIDESPREAD MODERATE HEATRISK
DISCUSSION
WEATHER PATTERN OVERVIEW:
BROADLY CYCLONIC FLOW CONTINUES OVER THE SW CONUS WITH A SUBTLE, BUT
OTHERWISE INNOCUOUS SHORTWAVE EJECTING OVER NORTHERN MEXICO EARLY
THIS AFTERNOON. HOWEVER, WV IMAGERY SHOWS A ROBUST UPSTREAM JET CORE
WITH A STRONG VORTICITY CENTER NEARING THE PACIFIC NW POISED TO
BUCKLE THE FLOW PATTERN AND CREATE DEEP NEGATIVE HEIGHT ANOMALIES
OVER THE GREAT BASIN THIS WEEKEND. HEIGHT FALLS WILL BEGIN TO IMPACT
THE CWA SATURDAY WITH THE LEADING JET MAX CRESTING THE COASTAL RANGE
DURING AN EXTREMELY FAVORABLE AFTERNOON TIME FRAME FOR DOWNSLOPING
WINDS AND MOUNTAIN ROTORS. IN FACT, GFS BUFR SOUNDINGS CONTINUE TO
SUGGEST 40-50KT COMPRESSED IN THE SFC-H9 LAYER SURGING DOWN THE
LEEWARD SIDE OF THE SAN DIEGO MOUNTAINS SATURDAY EVENING WHERE
ADVISORIES CURRENTLY EXIST. HOWEVER, WITH THE INITIAL SHORTWAVE
ALREADY EJECTING TOWARDS THE CENTRAL HIGH PLAINS BY SUNDAY MORNING
AND SECESSION OF HEIGHT FALLS, THE STRONGEST ADVISORY LEVEL WINDS
SHOULD BE RATHER SHORT LIVED.
BEHIND THE FIRST WAVE, A SECONDARY ROBUST NEGATIVE PV ANOMALY WILL
DIG INTO THE TROUGH AXIS LATE SUNDAY AND MONDAY ACTING TO REINFORCE
COOLER TROPOSPHERIC TEMPERATURES AND A HIGHER MOMENTUM AIRMASS
ALOFT. HOWEVER, RECENT MODEL TRENDS ARE KEEPING BULK OF ENERGY
CONFINED TO FAR NORTHERN ARIZONA; AND WITHOUT NOTABLE HEIGHT FALLS,
A REDUCED PRESSURE/THERMAL GRADIENT AND PROXIMITY SOUTH OF THE JET
CORE WILL KEEP WIND SPEEDS AND GUSTS MORE MUTED THAN PREVIOUS
FORECASTS. ANY MODEST MOISTURE INTRUSION AHEAD OF THIS SYSTEM ALSO
APPEARS REDUCED WITH ONLY 4-5 G/KG MIXING RATIO NOWHERE NEAR
SUFFICIENT TO ACHIEVE SATURATION UNDER WARMER MIDLEVEL THERMAL
PROFILES LOCATED ON THE ANTI-CYCLONIC SIDE OF THE JET CORE. GIVEN
THE TREND IN EVOLUTION, TEMPERATURE FORECASTS ARE NOT NEARLY AS COOL
AS PREVIOUS ITERATIONS, YET STILL AROUND 5F BELOW NORMAL DURING THE
FIRST PART OF NEXT WEEK.
WITH THE DOWNSTREAM FLOW PATTERN BRIEFLY PROGRESSIVE AND RE-
ORIENTING INTO A RENEWED BLOCKING CONFIGURATION, THE ENTIRE TROUGH
STRUCTURE WILL DISLODGE INTO THE PLAINS BY THE MIDDLE OF THE WEEK
RESULTING IN PRONOUNCED HEIGHT RISES AND LONGWAVE RIDGING BECOMING
ESTABLISHED OVER THE SW CONUS. ENSEMBLE MEAN FORECASTS SUGGEST H5
HEIGHTS REACHING AT LEAST 586DM DURING THE LATTER HALF OF THE WEEK
WITH SOME OF THE MORE AGGRESSIVE MEMBERS STILL AROUND 590DM PEAK
HEIGHTS. NEVERTHELESS, MASSIVE DOWNSTREAM BLOCKING OVER THE EASTERN
CONUS AND ATLANTIC BASIN WILL ENSURE A STAGNANT PATTERN AND SOME
MANNER OF RIDGING STUCK OVER THE FORECAST AREA. THERE ARE SOME
ENSEMBLE MEMBERS ATTEMPTING TO REALIGN THE BLOCKING PATTERN AND
ERODE THE RIDGE AXIS WITH PACIFIC FLOW BY THE END OF NEXT WEEK,
HOWEVER THESE TYPE OF BLOCKING PATTERNS TYPICALLY TAKE LONGER THAN
MODELS INDICATE TO BREAK DOWN. REGARDLESS, RATHER WIDESPREAD
MODERATE HEATRISK SHOULD TAKE HOLD OF THE AREA TOWARDS THE END OF
NEXT WEEK WITH TEMPERATURES NEARLY 10F ABOVE NORMAL.
FORECAST CONFIDENCE & DEVIATIONS:
CONFIDENCE IN TEMPERATURE FORECASTS REMAINS VERY GOOD THROUGH THE
WEEKEND WITH SOMEWHAT LOWER CONFIDENCE EARLY NEXT WEEK, ALBEIT
IMPROVING GIVEN THE CONSOLIDATING TREND AMONG MODELING SUITES
KEEPING SHORTWAVE ENERGY FURTHER TO THE NORTH. SHOULD THIS SYSTEM
END UP DIGGING FARTHER SOUTH, TEMPERATURES WOULD BE A FEW DEGREES
COOLER THAN CURRENT FORECASTS WHILE WINDS EARLY NEXT WEEK COULD BE
SOMEWHAT STRONGER. WITH A VERY FAVORABLE PATTERN, HAVE CONTINUED TO
INCREASE WIND SPEEDS SATURDAY AFTERNOON AND EVENING OVER THE
AUTOMATED NBM. FORECAST CONFIDENCE FOR HOTTER TEMPERATURES DURING
THE LATTER HALF OF THE FORECAST PERIOD REMAINS GOOD, BUT SOME
ADJUSTMENTS TO THESE READINGS (MAYBE A 1F-3F HIGHER) MAY EVENTUALLY
OCCUR, ESPECIALLY OVER THE MEMORIAL DAY WEEKEND DEPENDING ON THE
PATTERN EVOLUTION.
AVIATION
UPDATED AT 0000Z.
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, KDVT:
ONLY MINOR AVIATION CONCERNS WILL EXIST DURING THE TAF PERIOD
UNDER OCCASIONAL FEW-SCT HIGH CLOUDS. WINDS WILL MAINTAIN A
WESTERLY COMPONENT THROUGH MUCH OF THE EVENING AND SHIFT SE BY
07-09Z. MID MORNING SATURDAY, WINDS WILL BEGIN TO VEER FROM SE TO
S, CREATING A LIGHT (AOB 10 KTS) SOUTHERLY CROSS-RUNWAY COMPONENT
AT KPHX AND KDVT, AND A LIGHT SOUTHWESTERLY CROSSWIND AT KIWA LATE
MORNING/MIDDAY. BY THE AFTERNOON (20-21Z), ANTICIPATE WINDS TO
ESTABLISH A PREVAILING SOUTHWESTERLY DIRECTION, WITH GUSTS TO
AROUND 15-20 KTS DEVELOPING.
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:
GUSTY SOUTHWEST WINDS ON SATURDAY WILL BE THE PRIMARY AVIATION
CONCERN DURING THE TAF PERIOD UNDER OCCASIONAL FEW-SCT HIGH
CLOUDS. WINDS WILL SHIFT FROM SE TO WSW AT KIPL WITHIN THE NEXT
FEW HOURS AND MAINTAIN WSW THROUGH THE OVERNIGHT HOURS. WINDS AT
KBLH WILL FAVOR SSW THROUGH MUCH OF THE PERIOD, VEERING GRADUALLY
OUT OF THE SW SATURDAY. EXPECT SPEEDS TO REMAIN AOB 11 KTS THROUGH
APPROXIMATELY 15Z SATURDAY MORNING. SPEEDS WILL BEGIN TO PICK UP
AT BOTH THE TERMINALS AFTER THAT TIME, WITH SOUTHWESTERLY GUSTS TO
BETWEEN 25-30 KTS BECOMING COMMON SATURDAY AFTERNOON.
FIRE WEATHER
WIND SPEEDS WILL INCREASE MARKEDLY SATURDAY WITH GUSTS 20-30 MPH
BECOMING COMMON IN THE AFTERNOON RESULTING IN AN ELEVATED FIRE
DANGER. MINRHS WILL FALL INTO A 10-15% RANGE SATURDAY ACROSS THE
EASTERN DISTRICTS WITH READINGS ACROSS THE WESTERN DISTRICTS
IMPROVING TO 20-25%. HUMIDITY LEVELS WILL INCREASE MODESTLY SUNDAY
PRECLUDING CRITICAL CONDITIONS DESPITE HEIGHTENED WIND SPEEDS.
OVERNIGHT RECOVERY WILL BE FAIR TO POOR WITH READINGS BETWEEN 20-30%
OVER THE EASTERN DISTRICTS AND 30-50% OVER THE WESTERN DISTRICTS
WITH SOME IMPROVEMENT EARLY NEXT WEEK. VERY WARM AND DRY WEATHER
WILL RETURN DURING THE MIDDLE OF NEXT WEEK WITH MINRH IN THE SINGLE
DIGITS FOLLOWING POOR OVERNIGHT RECOVERY, HOWEVER WIND SPEEDS WILL
BE MUCH WEAKER AS HIGH PRESSURE STARTS BUILDING INTO THE REGION.
PSR WATCHES/WARNINGS/ADVISORIES
AZ...NONE.
CA...WIND ADVISORY FROM 2 PM SATURDAY TO 7 AM PDT SUNDAY FOR CAZ562.
WIND ADVISORY FROM 4 PM SATURDAY TO 2 AM PDT SUNDAY FOR CAZ563-
566-567.
DISCUSSION...18/KUHLMAN
AVIATION...WHITTOCK
FIRE WEATHER...18/KUHLMAN
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