356  
FXUS65 KPSR 200535 AAA  
AFDPSR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE PHOENIX AZ  
1035 PM MST THU OCT 19 2017  
   
UPDATE...UPDATED AVIATION DISCUSSION
 
 

 
   
SYNOPSIS
 
 
A WEAK UPPER DISTURBANCE WILL SHIFT EASTWARD OUT OF ARIZONA THIS  
EVENING, WITH DRIER AIR OVERSPREADING THE REGION FROM WEST TO  
EAST. WINDS WILL INCREASE AS A COLD FRONT MOVES EASTWARD TONIGHT  
AND TOMORROW, BRINGING COOLER TEMPERATURES THIS WEEKEND. HIGH  
PRESSURE WILL REBUILD OVER THE REGION INTO EARLY NEXT WEEK  
LEADING TO WELL ABOVE NORMAL TEMPERATURES.  
 

 
   
DISCUSSION
 
 
SATELLITE IMAGERY FROM THIS AFTERNOON SHOWS A NARROW BAND OF  
ASCENT FOCUSED OVER GILA COUNTY INTO EAST-CENTRAL ARIZONA,  
ACCOMPANYING A WEAK SHORTWAVE DISTURBANCE MOVING THROUGH THE  
REGION. SHOWERS AND A FEW THUNDERSTORMS HAVE BEEN OBSERVED SINCE  
EARLY THIS MORNING, BUT WITH THE LEADING EDGE OF DRIER AIR ALOFT  
SPREADING EASTWARD, SHOULD CONTINUE TO SEE RAPID WEST-EAST CLEARING  
THROUGH THIS EVENING.  
 
A WEAK COLD FRONT WILL MOVE THROUGH THE REGION TOMORROW AFTERNOON,  
RESULTING IN INCREASING WESTERLY WINDS ACROSS THE ENTIRE AREA.  
SUSTAINED SPEEDS AROUND 15-20 MPH, WITH SOME GUSTS TO 30 MPH,  
ACROSS THE LOWER DESERTS OF SOUTH-CENTRAL AND SOUTHWEST ARIZONA  
WILL BE POSSIBLE. EVEN STRONGER WINDS ARE EXPECTED LOCALLY ACROSS  
PARTS OF SOUTHEAST CALIFORNIA, AND A WIND ADVISORY HAS BEEN  
ISSUED FOR SOUTHWEST IMPERIAL COUNTY (INCLUDING A SEGMENT OF I-8)  
BEGINNING THIS EVENING THROUGH LATE FRIDAY EVENING. PATCHY BLOWING  
SAND AND BLOWING DUST WILL ALSO BE POSSIBLE MAINLY ACROSS  
IMPERIAL COUNTY TOMORROW AFTERNOON. WINDS WILL WEAKEN INTO  
SATURDAY WHILE TURNING OUT OF THE NORTH ACROSS THE LOWER COLORADO  
RIVER VALLEY, AS HIGH PRESSURE BUILDS OVER THE GREAT BASIN.  
LOCALLY GUSTY WINDS WILL STILL BE POSSIBLE HERE, WHILE EVEN DRIER  
LOW-LEVEL AIR CONTINUES TO SPREAD INTO THE SOUTHWEST.  
 
THE OTHER MORE PLEASANT EFFECT ON OUR WEATHER WILL BE THE MODEST  
COOLING TREND THAT WILL TAKE PLACE, AS HIGH TEMPERATURES IN THE  
UPPER 80S TO LOWER 90S ARE LIKELY TOMORROW, AND MID-80S FOR HIGH  
TEMPERATURES ON SATURDAY. UNFORTUNATELY, THIS WILL BE SHORT-LIVED,  
AS PATTERN AMPLIFICATION OCCURS IN RESPONSE TO A VERY STRONG RIDGE  
OF HIGH PRESSURE BUILDING JUST EAST OF THE PACIFIC COAST. WELL  
ABOVE-NORMAL TEMPERATURES WILL RETURN BY MONDAY, APPROACHING  
RECORD LEVELS ON TUESDAY. THE HEAT WILL MODERATE SLIGHTLY LATER  
IN THE WEEK IN RESPONSE TO NORTHERN ROCKIES UPPER TROUGH, BUT  
HIGHS WILL STILL REMAIN IN THE 90S AT MOST LOWER DESERT LOCATIONS.  
 

 
   
AVIATION
 
 
 
SOUTH-CENTRAL ARIZONA INCLUDING KPHX, KIWA, AND KSDL:  
 
AFTER A PERIOD OF TYPICAL EASTERLY DRAINAGE WINDS THROUGH THE  
REMAINDER OF TONIGHT AND EARLY FRIDAY MORNING, WESTERLY WINDS ARE  
EXPECTED TO DEVELOP EARLIER THAN NORMAL AS A PACIFIC WEATHER SYSTEM  
APPROACHES FROM THE WEST , DURING THE MID-MORNING HOURS ON FRIDAY.  
STRONGER BREEZES ARE LIKELY DURING THE AFTERNOON AND EARLY EVENING  
HOURS FRIDAY, WITH THESE WESTERLY WINDS PERSISTING WELL INTO THE  
NIGHT. CLOUDINESS WILL BE LIMITED TO FEW-SCT HIGH CIRRUS LAYERS  
DURING THE ENTIRE TAF PERIOD.  
 
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:  
 
A PACIFIC WEATHER SYSTEM APPROACHING FROM THE WEST WILL BRING  
GRADUALLY INCREASING WESTERLY WINDS TO KBLH AND INCREASING  
SOUTHWESTERLY WINDS AT KIPL. WIND GUSTS AS HIGH AS 30 KTS ARE  
POSSIBLE BY LATE MORNING/EARLY AFTERNOON AT BOTH TAF SITES. THERE IS  
ALSO A CHANCE FOR SOME BLOWING DUST, BUT CONFIDENCE IS TOO LOW TO  
INCLUDE DUST IN THE TAFS AT THIS TIME. CLOUDINESS WILL BE LIMITED TO  
FEW-SCT HIGH CIRRUS LAYERS DURING THE ENTIRE TAF PERIOD.  
 

 
   
FIRE WEATHER
 
 
SUNDAY THROUGH WEDNESDAY:  
A WARMING TREND BEGINS SUNDAY WITH TEMPERATURES REBOUNDING CLOSE  
TO 10F ABOVE NORMAL ON MONDAY AND TUESDAY. MINIMUM HUMIDITIES WILL  
REMAIN BELOW 15% (EVEN AT HIGHER TERRAIN LOCATIONS) AND OVERNIGHT  
RECOVERY WILL BE FAIR TO GOOD (AT BEST). WINDS WILL BE LIGHT  
OVERALL (FAVORING NORTH AND NORTHWEST DIRECTIONS DURING THE  
DAYTIME) EXCEPT FOR BREEZY EASTERLY WINDS ON WEDNESDAY.  
 

 
   
SPOTTER INFORMATION STATEMENT
 
 
SPOTTERS SHOULD FOLLOW STANDARD REPORTING PROCEDURES.  
 

 
   
PSR WATCHES/WARNINGS/ADVISORIES
 
 
AZ...NONE.  
CA...WIND ADVISORY UNTIL 11 PM PDT FRIDAY FOR CAZ562.  
 

 
 

 
 
VISIT US ON FACEBOOK, TWITTER, AND AT WEATHER.GOV/PHOENIX  
 
DISCUSSION...ROGERS  
AVIATION...PERCHA  
FIRE WEATHER...AJ  
 
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