941  
FXUS65 KPSR 162020  
AFDPSR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE PHOENIX AZ  
120 PM MST FRI MAY 16 2025  
   
..KEY MESSAGE
 
 
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 1722Z.  
 
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, KDVT:  
NO AVIATION WEATHER CONCERNS ARE ANTICIPATED THROUGH THE FORECAST  
PERIOD. TYPICAL DIURNAL TRENDS WILL BE COMMON AT ALL TERMINALS, WITH  
THE EXCEPTION OF A MORE NW'RLY COMPONENT THIS EVENING. SPEEDS WILL  
REMAIN AT OR BELOW 8 KTS THROUGH THIS AFTERNOON, BUT INTERMITTENT  
GUSTS INTO THE TEENS WILL BE POSSIBLE AT THE PHOENIX THIS AFTERNOON  
INTO THE EVENING. MOSTLY CLEAR SKIES WILL PREVAIL OVER THE REGION.  
 
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:  
NO AVIATION WEATHER CONCERNS ARE ANTICIPATED THROUGH THE FORECAST  
PERIOD. KIPL WILL BE E'RLY THROUGH THIS AFTERNOON, GOING W'RLY BY  
TONIGHT. KBLH WILL BE PREDOMINANTLY S'RLY. WINDS AT BOTH TERMINALS  
WILL GENERALLY BE AOB 10KTS, BUT LOOK TO INCREASE NEAR THE END OF  
THE TAF PERIOD, ESPECIALLY AT KBLH WITH SPEEDS INCREASING INTO THE  
TEENS. MOSTLY CLEAR SKIES WILL PREVAIL OVER THE REGION.  
 

 
   
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...RYAN  
FIRE WEATHER...18/KUHLMAN  
 
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