505  
FXUS65 KPSR 132339  
AFDPSR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE PHOENIX AZ  
439 PM MST TUE MAY 13 2025  
   
UPDATE  
UPDATED 00Z AVIATION DISCUSSION.  
 
 
   
SYNOPSIS  
 
A WEATHER DISTURBANCE PUSHING THROUGH THE REGION WILL RESULT IN  
GUSTY WINDS SLOWLY WEAKENING AND TEMPERATURES FALLING INTO A BELOW  
NORMAL RANGE THE NEXT COUPLE DAYS. HOWEVER, WEAK HIGH PRESSURE WILL  
BUILD BACK INTO THE AREA ALLOWING TEMPERATURES TO MODERATE BACK TO  
NEAR NORMAL LATER THIS WEEK. ANOTHER DRY WEATHER SYSTEM WILL SWEEP  
INTO THE SOUTHWEST EARLY NEXT WEEK YIELDING ANOTHER ROUND OF GUSTY  
WINDS AND COOLER THAN NORMAL TEMPERATURES.  
 
 
   
DISCUSSION  
 
EARLY AFTERNOON WV IMAGERY AND OBJECTIVE ANALYSIS DEPICTS NEGATIVE  
HEIGHT ANOMALIES MIGRATING INTO THE GREAT BASIN WITH THE TROUGH BASE  
AND ENHANCED JET CORE PROPAGATING THROUGH THE FORECAST AREA. WHILE  
THE MOST ROBUST HEIGHT FALLS WILL REMAIN WELL NORTH OF THE CWA, DEEP  
MIXING DEPTHS AND SUFFICIENT PRESSURE GRADIENT HAS RESULTED IN VERY  
GUSTY WINDS IMPACTING MUCH OF THE REGION. NOT SURPRISINGLY, THE MOST  
PRONOUNCED GUSTS HAVE BEEN MEASURED NEAR TERRAIN FEATURES, AND  
VARIOUS HEADLINE PRODUCTS REMAIN IN EFFECT THROUGH THIS EVENING. AS  
THE CIRCULATION CENTER EJECTS INTO THE CENTRAL/NORTHERN PLAINS  
WEDNESDAY, GRADIENT WILL RELAX FORCING WINDS BACK INTO A MORE  
TRADITIONAL LATE SPRING PATTERN. HOWEVER, H5 HEIGHTS WILL REMAIN  
DEPRESSED IN A 570-574DM RANGE YIELDING HIGH TEMPERATURES SOME 4F-8F  
BELOW THE DAILY NORMALS.  
 
FOLLOWING THE PASSAGE OF THE AFOREMENTIONED TROUGH, BROAD  
CYCLONIC/QUASI ZONAL FLOW WILL PREVAIL OVER THE SW CONUS THROUGH THE  
REMAINDER OF THIS WEEK WITH H5 HEIGHTS ONLY GRADUALLY REBOUNDING  
AROUND 576DM. AS THE LOWER/MIDDLE TROPOSPHERIC THERMAL PROFILES  
MODERATE, MODEL GUIDANCE SPREAD REMAINS EXTREMELY NARROW  
HIGHLIGHTING EXCELLENT FORECAST CONFIDENCE OF TEMPERATURES RETURNING  
TO NEAR NORMAL LEVELS. FORECAST UNCERTAINTY INCREASES EARLY NEXT  
WEEK AS OPERATIONAL AND ENSEMBLE GUIDANCE SHOW ANOTHER TROUGH WITH  
DEEP NEGATIVE HEIGHT ANOMALIES PROPAGATING INTO THE GREAT BASIN.  
ENSEMBLE MEMBERSHIP IS MOST DISPERSIVE WITH RESPECT TO THE DEPTH OF  
THIS TROUGH AND EQUATORWARD EXTENT OF THE COLD CORE AND ASSOCIATED  
VORTICITY CENTERS. OVERALL ENSEMBLE FORECAST TRENDS OF A DEEPER AND  
SLOWER TROUGH EVOLUTION MATCHES A CONCEPTUAL PREFERRED FLOW PATTERN  
UNDER THE CIRCUMSTANCES, AND WOULD STILL FAVOR THE SLOWER, DEEPER  
MODEL FORECASTS. REGARDLESS, THERE IS SUFFICIENT MODEL AGREEMENT  
SUGGESTING ANOTHER ROUND OF GUSTY WINDS AND COOLER TEMPERATURES  
IMPACTING THE REGION DURING THE FIRST HALF OF NEXT WEEK.  
 
 
   
AVIATION  
UPDATED AT 2340Z.  
 
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, KDVT:  
GUSTY WSW WINDS WILL BE THE PRIMARY AVIATION CONCERN DURING THE  
TAF PERIOD UNDER FEW HIGH CLOUDS. GUSTS TO AROUND 25 KTS WILL  
PERSIST INTO EARLY THIS EVENING, EVENTUALLY SUBSIDING BY 03-04Z.  
THOUGH W-SW WINDS ARE ANTICIPATED TO PREVAIL THROUGH THE OVERNIGHT  
HOURS, DIRECTIONS MAY TRY TO SHIFT S-SE OR BECOME VRB FOR A PERIOD  
EARLY WEDNESDAY MORNING. CONFIDENCE IS TOO LOW TO INCLUDE S-SE  
WINDS EARLY WEDNESDAY MORNING AT ANY OF THE TERMINALS EXCEPT FOR  
KIWA, SO HAVE OPTED FOR TEMPO VRB GROUPS AT THE OTHER SITES, WITH  
SPEEDS AOB 6 KTS DURING THAT TIMEFRAME. WINDS WILL ONCE AGAIN  
INCREASE LATE WEDNESDAY MORNING OUT OF THE WEST, BUT SPEEDS SHOULD  
REMAIN MOSTLY AOB 11 KTS WITH OCCASIONAL AFTERNOON GUSTS INTO THE  
UPPER TEENS.  
 
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:  
GUSTY WINDS AND THE POTENTIAL FOR BRIEF VISIBILITY RESTRICTIONS  
FROM BLOWING DUST WILL CONTINUE TO BE THE PRIMARY AVIATION  
CONCERNS AT THE SOUTHEAST CALIFORNIA TERMINALS UNDER MOSTLY CLEAR  
SKIES. WINDS WILL REMAIN WESTERLY AT KIPL AND SOUTHWESTERLY AT  
KBLH THROUGH EARLY WEDNESDAY MORNING BEFORE SHIFTING NW AT BOTH  
TERMINALS BETWEEN 10-15Z. AT KIPL, GUSTS OF 30-35 KT ARE EXPECTED  
THROUGH MUCH OF THE EVENING AND WILL DECREASE AND EVENTUALLY  
SUBSIDE DURING THE OVERNIGHT/EARLY MORNING HOURS. AT KBLH, GUSTS  
TO AROUND 25 KTS WILL BE COMMON DURING THROUGH THE EARLY EVENING  
AND SHOULD CEASE AROUND 04-05Z.  
 
 
   
FIRE WEATHER  
 
WEAKENING WIND SPEEDS AND COOLING TEMPERATURES WILL REDUCE THE FIRE  
DANGER THE NEXT SEVERAL DAYS, HOWEVER ANOTHER INCOMING SYSTEM WILL  
ALLOW WINDS TO STRENGTHEN AGAIN OVER THE WEEKEND. UNDER MORE TYPICAL  
SPRINGTIME UPSLOPE GUSTINESS, MINIMUM HUMIDITY VALUES WILL FALL INTO  
THE TEENS THE NEXT SEVERAL DAYS FOLLOWING POOR TO FAIR OVERNIGHT  
RECOVERY OF 20-50%. GUSTY WINDS WILL MATERIALIZE AGAIN THIS WEEKEND  
WITH THE NEXT WEATHER DISTURBANCE, HOWEVER COOLING TEMPERATURES AND  
INCREASED HUMIDITY LEVELS MAY PRECLUDE WIDESPREAD CRITICAL  
CONDITIONS. AT THIS TIME, SATURDAY AFTERNOON POSES THE GREATEST  
THREAT OF AN ELEVATED FIRE DANGER.  
 
 
   
PSR WATCHES/WARNINGS/ADVISORIES  
 
AZ...RED FLAG WARNING UNTIL 8 PM MST THIS EVENING FOR AZZ133.  
 
CA...WIND ADVISORY UNTIL 5 AM PDT WEDNESDAY FOR CAZ562.  
 
WIND ADVISORY UNTIL 2 AM PDT WEDNESDAY FOR CAZ563-566-567.  
 
 
 
 
 
DISCUSSION...18/SMITH  
AVIATION...WHITTOCK  
FIRE WEATHER...18  
CLICK HERE TO GO TO PREVIOUS BULLETINS.
The Nexlab AZ Page
The Nexlab CA Page
Main Text Page