110  
FXUS65 KPSR 251127  
AFDPSR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE PHOENIX AZ  
427 AM MST WED APR 25 2018  
   
UPDATE
 
UPDATED AVIATION AND FIRE WEATHER DISCUSSIONS.  
 

 
   
SYNOPSIS
 
 
VERY WARM AND DRY CONDITIONS WILL LAST INTO THE COMING WEEKEND  
WITH PERIODS OF HIGH CLOUDS. LOWER DESERT HIGH TEMPERATURES WILL  
REACH INTO THE MIDDLE TO UPPER 90S EACH DAY, OR ROUGHLY 10 DEGREES  
ABOVE NORMAL. SOME MODEST COOLING IS POSSIBLE THIS WEEKEND, BUT  
ABOVE NORMAL TEMPERATURES SHOULD STILL PERSIST. A SLIGHT CHANCE  
FOR SHOWERS WILL EXIST ACROSS SOUTHERN GILA COUNTY FRIDAY AND  
SATURDAY AFTERNOON AS A WEAK STORM SYSTEM MOVES ACROSS THE AREA.  
 

 
   
DISCUSSION
 
 
WEAK UPPER LEVEL RIDGING THIS MORNING WILL AMPLIFY ACROSS THE  
INTERIOR WEST THROUGH THURSDAY. THIS AMPLIFICATION WILL BE IN  
RESPONSE TO A DEEP PACIFIC TROUGH OFF THE WEST COAST AS IT SLOWLY  
DRIFTS EASTWARD. TEMPERATURES WILL CHANGE VERY LITTLE TODAY WITH  
NEARLY IDENTICAL HIGHS OVER THE AREA AS YESTERDAY. SLIGHTLY  
HIGHER HEIGHTS ALOFT SHOULD ADD ANOTHER DEGREE OR SO ON THURSDAY  
AS MANY LOWER DESERT SPOTS GET CLOSE TO 100 DEGREES.  
 
DESPITE THE UPPER LEVEL RIDGING OVER THE DESERT SOUTHWEST, A  
BACKDOOR COOL FRONT STILL LOOKS TO QUICKLY MOVE IN FROM NEW MEXICO  
FRIDAY MORNING, POSSIBLY REACHING AS FAR WEST AS EASTERN MARICOPA  
COUNTY. COOLING EFFECTS FROM THIS FRONT WILL BE VERY MINIMAL OVER  
EASTERN ARIZONA, BUT IT WILL BRING A DECENT LOW AND MID LEVEL  
MOISTURE PUSH. LOW LEVEL MIXING RATIOS OF 7-8 G/KG WILL BE  
SUFFICIENT ENOUGH FOR SOME ISOLATED SHOWER AND THUNDERSTORM  
ACTIVITY FRIDAY AFTERNOON/EVENING OVER GILA COUNTY. LIGHT  
SOUTHWESTERLY STEERING FLOW WILL KEEP ANY ACTIVITY OVER THE HIGH  
TERRAIN, SO THE LOWER DESERTS WILL STILL BE DEVOID OF ANY RAIN.  
 
MODELS ARE NOW IN GOOD AGREEMENT WITH THE TRACK OF THE PACIFIC  
TROUGH THROUGH FRIDAY AS IT SLOWLY MOVES ONSHORE OVER NORTHERN  
CALIFORNIA AND OREGON BY FRIDAY NIGHT. HIGHS FRIDAY MAY DROP A  
DEGREE OR TWO AS 500MB HEIGHTS FALL FROM AROUND 580DM TO  
576-578DM, BUT ANY REAL NOTICEABLE COOLING WILL WAIT UNTIL THIS  
WEEKEND. MAINLY DAYTIME RAIN CHANCES FOR GILA COUNTY WILL LAST  
THROUGH SATURDAY AS THE THE MOISTURE REMAINS IN PLACE. BY SATURDAY  
AFTERNOON, DIVERGENCE ALOFT WILL INCREASE AHEAD OF THE PACIFIC  
TROUGH GIVING SLIGHTLY BETTER CHANCES OF SHOWERS AND THUNDERSTORMS  
TO GILA COUNTY, BUT DRY AIR WILL QUICKLY OVERTAKE THE STATE FROM  
THE WEST BY SATURDAY EVENING.  
 
THE TROUGH IS FORECAST TO SLOWLY DRIFT INTO THE GREAT BASIN AND  
NORTHERN PORTIONS OF THE DESERT SOUTHWEST SATURDAY INTO SUNDAY.  
THIS WILL AID IN FURTHER COOLING AS HIGHS BY SUNDAY DROP DOWN TO  
NEAR NORMALS. HIGHER MODEL SPREAD IS SEEN GOING INTO NEXT WEEK,  
BUT THE GENERAL CONSENSUS SHOWS A SHORTWAVE TROUGH DIVING DOWN THE  
BACKSIDE OF THE LARGE SCALE TROUGH, POSSIBLY REACHING AS FAR  
SOUTH AS THE DESERT SOUTHWEST. THOUGH FORECAST CONFIDENCE IS  
SOMEWHAT LOW, IT SEEMS FAIRLY LIKELY TEMPERATURES WILL DROP INTO  
THE 80S FOR A FEW DAYS NEXT WEEK. RAIN CHANCES WITH ANY POTENTIAL  
TROUGH STILL LOOK FAIRLY LOW DUE TO NO SIGNIFICANT INCREASES IN  
MOISTURE, SO CHANCES WILL LIKELY BE CONFINED TO HIGH TERRAIN  
AREAS.  
 

 
   
AVIATION
 
 
SOUTH-CENTRAL ARIZONA INCLUDING KPHX, KIWA, AND KSDL:  
 
THERE ARE NO MAJOR AVIATION WEATHER CONCERNS FOR WEDNESDAY. LIGHT  
DIURNAL WINDS WILL PREVAIL AT ALL TAF SITES.  
 
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:  
 
THERE ARE NO MAJOR AVIATION WEATHER CONCERNS FOR WEDNESDAY AS  
WINDS WILL REMAIN FAIRLY LIGHT AND FOLLOW DIURNAL TRENDS.  
 
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.  
 

 
   
FIRE WEATHER
 
 
FRIDAY THROUGH TUESDAY...  
VERY WARM TEMPERATURES WILL PERSIST THROUGH SATURDAY BEFORE  
COOLING SLIGHTLY BY SUNDAY. A WEAK WEATHER DISTURBANCE AND MODEST  
MOISTURE INCREASE WILL BRING A SLIGHT CHANCE FOR THUNDERSTORMS,  
PRIMARILY FOR GILA COUNTY, ON SATURDAY AFTERNOON. ANY RAINFALL  
AMOUNTS WILL BE MINIMAL AND CONDITIONS FAVORABLE FOR DRY LIGHTNING  
WILL EXIST. OTHERWISE, SOME AFTERNOON BREEZES ARE POSSIBLE EACH  
DAY, WITH THE STRONGEST GUSTS ON MONDAY AND TUESDAY AFTERNOONS.  
 

 
   
SPOTTER INFORMATION STATEMENT
 
 
SPOTTERS ARE ENCOURAGED TO FOLLOW STANDARD REPORTING PROCEDURES.  
 

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

 
 

 
 
DISCUSSION...KUHLMAN  
AVIATION...DEEMER  
FIRE WEATHER...DEEMER  
 
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