177  
FXUS65 KPSR 280939  
AFDPSR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE PHOENIX AZ  
240 AM MST WED JUN 28 2017  
   
UPDATE
 
AVIATION AND FIRE WEATHER DISCUSSIONS.  
 

 
   
SYNOPSIS
 
 
A DRY AIRMASS WILL REMAIN OVER THE REGION THROUGH THE REST OF THE  
WEEK WITH TEMPERATURES MODERATING CLOSER TO AVERAGE. THOUGH HIGH  
TEMPERATURES WILL FINALLY DROP BELOW 110 DEGREES, READINGS WILL  
STILL END UP IN A SLIGHTLY ABOVE NORMAL RANGE THROUGH EARLY NEXT  
WEEK. SKIES WILL REMAIN MOSTLY CLEAR AS THE MONSOON WIND PATTERN  
HAS YET TO BE ESTABLISHED AND STORM ACTIVITY WILL STAY WELL SOUTH  
ACROSS MEXICO.  
 

 
   
DISCUSSION
 
 
LARGE SCALE TROUGHING EDGING SOUTHWARD ACROSS THE PACIFIC  
NORTHWEST AND THE GREAT BASIN HAS ALLOWED FOR A SIGNIFICANT DROP  
IN 500MB HEIGHTS FROM 592DM YESTERDAY TO AROUND 588DM CURRENTLY.  
THE SLIGHT COOLING OVER THE PAST COUPLE DAYS WILL CONTINUE TODAY  
WITH HIGHS OVER MOST LOWER DESERT SPOTS DROPPING BELOW 110  
DEGREES. THE DRY AIR THAT HAS ALREADY OVERTAKEN THE REGION WILL  
LIKELY PERSIST THROUGH THE REST OF THE WEEK RESULTING IN GOOD  
NOCTURNAL COOLING AND OVERNIGHT LOWS MAINLY IN THE 70S EXCEPT FOR  
CENTRAL PARTS OF PHOENIX.  
 
LATER THIS WEEK, 500MB HEIGHTS DO BEGIN TO INCREASE A BIT AS THE  
TROUGHING TO OUR NORTH SHIFTS OVER THE CENTRAL AND EASTERN U.S.  
AFTER HIGHS JUST BELOW 110 THROUGH FRIDAY, WE SHOULD SEE A COUPLE  
DEGREES OF WARMING ON SATURDAY WITH THE HIGHER HEIGHTS RESULTING  
IN HIGHS AROUND 110. ALTHOUGH 500MB HEIGHTS STABILIZE THIS  
WEEKEND NEAR 592DM AND STAY THERE INTO EARLY NEXT WEEK, A SLIGHT  
BOOST IN LOW LEVEL MOISTURE (AFTERNOON SURFACE DEWPOINTS 35-40  
DEGREES) SHOULD KEEP HIGHS JUST BELOW 110 SUNDAY THROUGH TUESDAY.  
THIS MOISTURE UPTICK WILL HOWEVER STILL BE INSUFFICIENT FOR ANY  
MONSOON ACTIVITY TO BE SEEN ACROSS THE AREA AS BOTH THE GFS AND  
EUROPEAN ARE IN GOOD AGREEMENT KEEPING LOW LEVEL FLOW EITHER OUT  
OF THE WEST OR NORTH THROUGH NEXT WEDNESDAY. THERE ARE INDICATIONS  
WE MAY MANAGE TO SEE A SWITCH TO SOUTHEASTERLY LOW LEVEL FLOW  
LATE NEXT WEEK WHICH COULD BE ENOUGH TO BRING AT LEAST A LOW GRADE  
MONSOONAL MOISTURE FLOW OUT OF NORTHERN MEXICO.  
 

 
   
AVIATION
 
 
SOUTH-CENTRAL ARIZONA INCLUDING KPHX, KIWA, AND KSDL:  
 
A SERIES OF WEAK PACIFIC WEATHER SYSTEMS WILL MOVE INTO THE WESTERN  
STATES NORTH OF AZ. INCREASING WINDS ALOFT WILL MIX DOWN TO THE  
SURFACE RESULTING IN GUSTY WEST TO SOUTHWEST WINDS DURING THE  
AFTERNOON AND EVENING HOURS. THROUGH 20Z WED, LIGHT AND VARIABLE  
WINDS UNDER 6 KNOTS. CLEAR SKIES. FROM 20Z TUE THROUGH 03Z WED,  
INCREASING WEST TO SOUTHWEST WINDS 10 TO 15 KNOTS WITH GUSTS TO 20.  
CLEAR SKIES.  
 
 
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:  
 
A SERIES OF WEAK PACIFIC WEATHER SYSTEMS WILL MOVE INTO THE WESTERN  
STATES NORTH OF AZ. INCREASING WINDS ALOFT WILL MIX DOWN TO THE  
SURFACE RESULTING IN GUSTY WEST TO SOUTHWEST WINDS DURING THE  
AFTERNOON AND EVENING HOURS. THROUGH 20Z TUE, LIGHT AND VARIABLE  
WINDS UNDER 6 KNOTS. CLEAR SKIES. FROM 20Z TUE TO 03Z WED,  
INCREASING SOUTHWEST WINDS 10 TO 15 KNOTS. CLEAR SKIES.  
 
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.  
   
FIRE WEATHER
 
 
 
FRIDAY THROUGH SUNDAY:  
 
DRY WESTERLY FLOW ALOFT OVER THE REGION WILL RESULT IN CLEAR SKIES.  
SLIGHTLY ABOVE-NORMAL TEMPERATURES ARE EXPECTED. MINIMUM RELATIVE  
HUMIDITY WILL RANGE FROM 5 TO 8 PERCENT. GOOD OVERNIGHT RECOVERY.  
AFTERNOON SOUTHWEST WINDS 10 TO 20 MPH EACH DAY.  
 
MONDAY AND TUESDAY:  
 
AN INCREASE IN MOISTURE FROM MEXICO IS EXPECTED OVER SOUTHEAST AZ.  
MINIMUM RELATIVE HUMIDITY WILL RANGE FROM 8 TO 12 PERCENT. AFTERNOON  
SOUTH TO SOUTHWEST WINDS 5 TO 15 MPH. THERE IS A SLIGHT CHANCE OF  
AFTERNOON THUNDERSTORM ACTIVITY OVER THE MOUNTAINS OF SOUTHERN GILA  
COUNTY TUESDAY. FAIR OVERNIGHT RECOVERY.  
 

 
   
SPOTTER INFORMATION STATEMENT
 
 
SPOTTERS SHOULD FOLLOW STANDARD REPORTING PROCEDURES.  
 

 
   
PSR WATCHES/WARNINGS/ADVISORIES
 
 
AZ...NONE.  
CA...NONE.  

 
 

 
 
VISIT US ON FACEBOOK, TWITTER, AND AT WEATHER.GOV/PHOENIX  
 
DISCUSSION...KUHLMAN  
AVIATION...VASQUEZ  
FIRE WEATHER...VASQUEZ  
 
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