168  
FXUS65 KPSR 110536  
AFDPSR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE PHOENIX AZ  
1036 PM MST MON FEB 10 2025  
   
UPDATE
 
UPDATED AVIATION DISCUSSION.  
 

 
   
SYNOPSIS
 
 
A MUCH ANTICIPATED PATTERN CHANGE WILL OCCUR OVER THE NEXT FEW DAYS,  
AS A DEEP TROUGH OF LOW PRESSURE DEVELOPS OVER THE WESTERN U.S. THIS  
TROUGH WILL BRING MUCH COOLER TEMPERATURES AND MULTIPLE ROUNDS OF  
DESERT RAIN/MOUNTAIN SNOW TO PORTIONS OF SOUTHCENTRAL AZ. THE BEST  
CHANCES FOR MEASURABLE PRECIPITATION ACROSS OUR REGION WILL BE ON  
WEDNESDAY AND AGAIN LATE THURSDAY INTO FRIDAY. THIS SYSTEM WILL ALSO  
BRING GUSTY WINDS TO PORTIONS OF SOUTHEAST CA AND THE AZ HIGH  
TERRAIN. TEMPERATURES WILL FALL BELOW AVERAGE ON WEDNESDAY, AND  
SHOULD REMAIN NEAR NORMAL THROUGH THE REST OF THIS WEEK.  
 

 
   
DISCUSSION
 
 
LATEST IR WATER VAPOR AND VISIBLE SATELLITE IMAGERY SHOW A BROAD  
TROUGH OF LOW PRESSURE DEEPENING OVER THE PACIFIC NW. MEANWHILE, A  
BROAD RIDGE OF HIGH PRESSURE ENCOMPASSES THE DESERT SOUTHWEST,  
BUT IS EXPECTED TO WEAKEN AND PUSH OFF TO THE EAST. TROUGHING WILL  
BECOME THE DOMINANT FEATURE OVER THE INTERMOUNTAIN WEST STARTING  
ON TUESDAY WHICH WILL RESULT IN NOTICEABLY COOLER TEMPERATURES AND  
BREEZY CONDITIONS ACROSS SE CALIFORNIA AND THE AZ HIGH TERRAIN.  
AS THE FIRST OF SEVERAL SHORTWAVES ROUNDS THE BASE OF THE MAIN  
TROUGH TOMORROW AFTERNOON, BREEZY TO WINDY CONDITIONS WILL DEVELOP  
ACROSS IMPERIAL COUNTY. A WIND ADVISORY HAS BEEN ISSUED FOR THE  
TYPICAL WINDY SPOT AT MOUNTAIN SPRINGS IN SW IMPERIAL COUNTY FROM  
LATE TONIGHT THROUGH TUESDAY NIGHT WHERE WINDS ARE EXPECTED TO  
GUST BETWEEN 50-55 MPH. ELSEWHERE ACROSS THE LOWER DESERTS AND  
HIGH, GUSTS AROUND 25-30 MPH WILL BE COMMON TUESDAY AFTERNOON. DUE  
TO THE ARRIVAL OF NEGATIVE 500 MB HGHT ANOMALIES, HIGHS ON TUESDAY  
WILL BE AROUND 8 TO 10 DEGREES COOLER THAN TODAY, TOPPING OUT  
MAINLY IN THE UPPER 60S TO AROUND 70 DEGREES.  
 
OUR ATTENTION WILL THEN TURN TOWARD WEDNESDAY WHEN WE WILL SEE  
INCREASING MOISTURE AND CHANCES FOR LIGHT SHOWERS ACROSS OUR  
REGION. THROUGHOUT THE DAY, A STRENGTHENING 500 MB JET ON THE  
BACK SIDE OF THE LARGE-SCALE TROUGH WILL BRING A PLUME OF PACIFIC  
MOISTURE INTO OUR REGION FROM W TO E. ENSEMBLE MEMBERS CONTINUE  
TO INDICATE PWAT VALUES INCREASING TO AROUND 0.8-0.9" ACROSS  
SOUTHEAST CA AND UP TO 0.5-0.7" ACROSS SOUTHCENTRAL AZ BY  
WEDNESDAY AFTERNOON WHICH IS ABOVE THE 90TH PERCENTILE OF  
CLIMATOLOGY FOR THIS TIME OF YEAR. THE CORRIDOR OF THE UPPER-LVL  
JET WILL REMAIN SITUATED MAINLY OVER NORTHERN AZ WHICH WILL RESULT  
IN THE BEST FORCING AND LIFT. THEREFORE, PRECIPITATION CHANCES  
WILL BE HIGHEST (40-50%) NORTH AND EAST OF PHOENIX. CHANCES FOR  
THE CENTRAL DESERTS WILL BE AROUND 20-30% WEDNESDAY NIGHT. BELOW  
NORMAL TEMPERATURES ARE ALSO ANTICIPATED ON WEDNESDAY WITH HIGHS  
ONLY MANAGING TO REACH THE LOW TO MID 60S ACROSS THE LOWER  
DESERTS AND MID 50S IN THE HIGH TERRAIN.  
 
AFTER THE FIRST WAVE OF SHOWER ACTIVITY DEPARTS THE AREA, THERE  
WILL BE A BRIEF REPRIEVE IN RAIN CHANCES ACROSS THE REGION ON  
THURSDAY BEFORE A STRONGER SHORTWAVE TROUGH ARRIVES LATE THURSDAY  
INTO EARLY FRIDAY. THERE STILL LOOKS TO BE A FAIRLY ROBUST FRONTAL  
BOUNDARY WHICH WILL PROGRESS FROM W TO E THROUGH THE DAY ON  
FRIDAY, BRINGING A LINE OF SHOWERS THROUGH OUR REGION. BOTH THE AZ  
HIGH TERRAIN AND LOWER DESERTS COULD RECEIVE SOME BENEFICIAL  
WETTING RAINS. THE LATEST WPC QPF FORECAST FOR FRIDAY SHOWS A  
FAIRLY TIGHT GRADIENT IN PRECIP TOTALS RANGING ANYWHERE FROM 0.10"  
IN S MARICOPA COUNTY TO 0.50" IN N MARICOPA COUNTY. THE HIGHER  
TERRAIN AREAS NORTH OF PHOENIX WILL HAVE THE BEST SHOT AT SEEING  
TOTALS EXCEEDING 0.50". MARGINAL THUNDERSTORM CHANCES WILL ALSO  
EXIST FRIDAY AFTERNOON, AROUND 5-10% ACROSS THE REGION, AS THE  
THERMODYNAMIC PROFILES ARE ADVERTISING SB CAPE VALUES UP TO 100  
J/KG. SNOW LEVELS ARE EXPECTED TO REMAIN FAIRLY HIGH (6000-6500  
FEET) THROUGHOUT THE EVENT, SO WE ARE NOT ANTICIPATING ANY MAJOR  
ISSUES WITH ACCUMULATING SNOWS AT THIS TIME.  
 

 
   
PREVIOUS DISCUSSION
 
 
HEADING INTO SATURDAY, THIS POTENT TROUGH WILL CONTINUE TO PUSH  
EASTWARD, WITH LINGERING SHOWER ACTIVITY POSSIBLE FOR THE HIGHER  
TERRAIN AREAS OF SOUTH-CENTRAL ARIZONA. RIDGING BUILDING IN FROM  
THE WEST LOOKS TO BE A CERTAINTY AT THIS POINT, WITH MINOR  
ENSEMBLE DIFFERENCES REGARDING HOW STRONG THIS RIDGE WILL BECOME  
ACROSS THE REGION HEADING INTO NEXT WEEK. THUS, EXPECT DRIER AND  
WARMING CONDITIONS TO ONCE AGAIN ENCOMPASS THE REGION DURING THIS  
PERIOD.  
 

 
   
AVIATION
 
UPDATED AT 0535Z.  
 
SOUTH CENTRAL ARIZONA INCLUDING KPHX, KIWA, KSDL, AND KDVT:  
WINDS WILL CONTINUE TO FOLLOW TYPICAL DIURNAL TRENDS THROUGH EARLY  
TOMORROW MORNING. WEST TO SOUTHWEST WINDS WILL THEN PICK UP  
TOMORROW AFTERNOON WITH PEAK GUSTS UP TO 20-25 KT. THERE WILL BE A  
PERIOD BETWEEN 17-20Z WHERE WINDS MAY FAVOR MORE OF A SOUTHERLY  
COMPONENT BEFORE THE WESTERLY COMPONENT FULLY SETS IN. GUSTINESS  
WILL THEN SUBSIDE TOMORROW EVENING BY 3-4Z. SKC WILL PREVAIL  
THROUGH TONIGHT WITH MID AND HIGH CLOUDS THEN RETURNING AROUND  
SUNRISE TOMORROW, WITH BASES MOSTLY AT OR ABOVE 12K FT AGL THIS  
TAF PERIOD.  
 
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:  
WESTERLY WINDS WILL CONTINUE AT KIPL THROUGH THE TAF PERIOD, WITH  
SOME OCCASIONAL GUSTS UP AROUND 20-25 KT POSSIBLE FOR THE NEXT FEW  
HOURS. GUSTS UP TO 25-30 KTS ARE THEN EXPECTED TOMORROW AFTERNOON  
AND EVENING. LIGHT WINDS WILL FAVOR W TO SW TONIGHT, WITH SOME  
LIGHT VARIABILITY. WESTERLY BREEZES THEN PICK UP AROUND 20Z  
TOMORROW WITH GUSTS UP TO 20-25 KTS IN THE AFTERNOON AND EVENING.  
MID AND HIGH CLOUDS, WITH BASES AOA 18K FT AGL WILL RETURN TONIGHT  
AND PREVAIL THROUGH MIDDAY BEFORE CLEARING, FOLLOWED BY ANOTHER  
ROUND TOMORROW NIGHT.  
 

 
   
FIRE WEATHER
 
 
DRY AND QUIET WEATHER CONDITIONS CONTINUE FOR TODAY. HOWEVER,  
CHANGES IN THE WEATHER PATTERN WILL RESULT IN BREEZY TO LOCALLY  
WINDY CONDITIONS FOR TUESDAY AFTERNOON. SOME ELEVATED FIRE WEATHER  
CONDITIONS ARE POSSIBLE FOR HIGHER TERRAIN AREAS OF THE EASTERN  
DISTRICTS FOR TUESDAY AFTERNOON/EVENING, AS MINRH'S WILL HOVER  
AROUND 15-20% AND 25-35 MPH WIND GUSTS. MULTIPLE WEATHER  
DISTURBANCES ARE THEN EXPECTED TO AFFECT OUR REGION DURING THE  
LATTER HALF OF THE WEEK, RESULTING IN CONTINUED COOL  
TEMPERATURES, OCCASIONAL BREEZY WINDS, AND HIGHER HUMIDITIES. THE  
FIRST ROUND WILL BEGIN ON WEDNESDAY, WITH INCREASED CWR'S AROUND  
20-40% FOR THE EASTERN DISTRICTS. EVEN BETTER PRECIPITATION  
CHANCES ARE LIKELY BY LATE THURSDAY INTO FRIDAY, WHERE CWR'S JUMP  
TO THE 20-50% (60-90%) RANGE FOR THE WESTERN (EASTERN) DISTRICTS.  
GRADUALLY DRIER CONDITIONS WILL FILTER INTO THE REGION GOING  
THROUGH THIS WEEKEND.  
 

 
   
PSR WATCHES/WARNINGS/ADVISORIES
 
 
AZ...NONE.  
CA...WIND ADVISORY UNTIL 10 PM PST TUESDAY FOR CAZ562.  
 

 
 

 
 
DISCUSSION...SALERNO/YOUNG  
AVIATION...BENEDICT  
FIRE WEATHER...YOUNG  
 
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