677  
FXUS65 KPSR 230948  
AFDPSR  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE PHOENIX AZ  
248 AM MST WED MAY 23 2018  
   
SYNOPSIS
 
 
QUIET WEATHER IS EXPECTED ACROSS THE AREA THROUGH NEXT WEEK WITH  
NEAR NORMAL TEMPERATURES AND DRY CONDITIONS IN THE FORECAST.  
BREEZY CONDITIONS ARE LIKELY FRIDAY AND SATURDAY AS A LOW PRESSURE  
SYSTEM MOVES INTO NORTHERN ARIZONA. THIS SYSTEM WILL HANG AROUND  
THROUGH THE WEEKEND KEEPING HIGH TEMPERATURES IN THE 90S. WARMER  
TEMPERATURES ARE LIKELY FOR THE FIRST PART OF NEXT WEEK WITH HIGHS  
JUST OVER 100 DEGREES.  
 

 
   
DISCUSSION
 
 
A LARGE UPPER LEVEL TROUGH CENTERED OVER NORTHERN UTAH CONTINUES  
TO SLOWLY TRACK TO THE NORTH NORTHEAST WITH THE SOUTHERN EXTENT OF  
THE TROUGH EXITING ARIZONA BY THIS AFTERNOON. SOUTHWESTERLY FLOW  
ALOFT WILL REMAIN DOMINANT ACROSS THE DESERT SOUTHWEST OVER THE  
NEXT COUPLE DAYS WITH HEIGHTS SLOWLY RISING AND TEMPERATURES  
CLIMBING BACK TO ABOVE NORMALS BY THURSDAY. THE LARGE SCALE  
TROUGHING PATTERN OVER THE WESTERN U.S. STILL LOOKS TO BE THE MAIN  
INFLUENCE THROUGH NEXT WEEK WITH TWO SYSTEMS FORECAST TO AFFECT  
THE SOUTHWESTERN U.S.  
 
THE FIRST UPPER LEVEL LOW WILL START TO TAKE SHAPE TONIGHT OFF THE  
CALIFORNIA COAST, BECOMING A CLOSED LOW ON THURSDAY AND TRACKING  
EAST INTO CENTRAL CALIFORNIA BY LATE FRIDAY. HIGH AMPLITUDE  
RIDGING WILL SET UP OVER AT LEAST THE EASTERN PORTION OF THE  
DESERT SOUTHWEST THURSDAY AND FRIDAY BEFORE THE LOW FINALLY MOVES  
INLAND ON SATURDAY. WINDS WILL INCREASE AHEAD OF THE LOW ON FRIDAY  
AND SATURDAY WITH THE STRONGEST WIND GUSTS OF 25-30 MPH ON  
SATURDAY. SOUTHWESTERN IMPERIAL COUNTY WILL SEE WIND GUSTS CLOSER  
TO 40 MPH FRIDAY NIGHT AND AGAIN SATURDAY EVENING WITH SOME PATCHY  
BLOWING DUST A POSSIBILITY. THE STRONGER WINDS AND CONTINUED DRY  
CONDITIONS ON SATURDAY SHOULD RESULT IN ANOTHER DAY OF ENHANCED  
FIRE DANGER, BUT FOR NOW IT LOOKS LIKE WINDS WILL FALL SHORT OF  
RED FLAG CRITERIA.  
 
COOLER AIR WILL MOVE IN FROM THE WEST THIS WEEKEND AS THE LOW  
MOVES INTO THE DESERT SOUTHWEST. THIS WILL DROP HIGHS ON SATURDAY  
DOWN TO AROUND 90 DEGREES ACROSS SOUTHEAST CALIFORNIA AND INTO THE  
MIDDLE 90S OVER THE SOUTH-CENTRAL ARIZONA DESERTS. MODELS REMAIN  
IN GOOD AGREEMENT TRACKING THE LOW ACROSS NORTHERN ARIZONA  
SATURDAY NIGHT BEFORE STALLING THE LOW OVER THE GREAT BASIN  
SUNDAY AND MONDAY. THIS WILL KEEP TEMPERATURES A FEW DEGREES BELOW  
NORMALS ON SUNDAY, BUT AS THE LOW WEAKENS AND SHIFTS A BIT  
FURTHER NORTH ON MONDAY, HIGHS SHOULD AGAIN BE FLIRTING WITH THE  
100 DEGREE MARK.  
 
A SIMILAR SCENARIO SEEMS LIKELY FOR THE LATTER HALF OF NEXT WEEK  
WITH A BRIEF RIDGING TAKING HOLD BEFORE ANOTHER PACIFIC LOW  
POTENTIALLY NEARS THE REGION. THIS WOULD BRING A WARMING TREND  
THROUGH THE MIDDLE OF NEXT WEEK AND TEMPERATURES LIKELY TOPPING  
100 DEGREES STARTING NEXT TUESDAY. MUCH HIGHER MODEL SPREAD COME  
INTO PLAY THEREAFTER AS THIS NEXT PACIFIC LOW DEVELOPS OFF THE  
WEST COAST. ENSEMBLE MEANS FROM THE GEFS AND EUROPEAN BOTH SHOW  
THE LOW APPROACHING THE WEST COAST SOMETIME LATE NEXT WEEK, VERY  
SIMILAR TO THE PREVIOUS COUPLE TROUGHS. THIS PREFERRED SOLUTION  
WOULD COOL TEMPERATURES BACK DOWN CLOSER TO NORMALS AT SOME POINT  
LATE NEXT WEEK.  
 

 
   
AVIATION
 
 
SOUTH-CENTRAL ARIZONA INCLUDING KPHX, KIWA, AND KSDL...  
SOUTHEAST CALIFORNIA/SOUTHWEST ARIZONA INCLUDING KIPL AND KBLH:  
 
AN UPPER LEVEL LOW PRESSURE SYSTEM CENTERED OVER THE GREAT BASIN HAS  
BEGUN TO RETREAT NORTH-NORTHEASTWARD THIS EVENING. ALOFT (AOA  
FL100), THIS WILL MEAN WEAKENING SOUTHWESTERLY FLOW TONIGHT AND  
THROUGH THE DAY WEDNESDAY. SURFACE WINDS WILL FAVOR SOUTHWEST AND  
WEST DIRECTIONS UNTIL 08Z-09Z BEFORE TRANSITIONING TO FAMILIAR  
DRAINAGE/DOWNVALLEY PATTERNS. DURING THE DAY WEDNESDAY, ANTICIPATE  
SIMILAR DIRECTIONAL PATTERNS AS WERE OBSERVED ON TUESDAY WITH  
PROLONGED SOUTHEAST AND SOUTH DIRECTIONS LASTING WELL PAST NOON  
BEFORE TRENDING SOUTHWEST DURING THE LATTER PART OF THE AFTERNOON.  
OTHERWISE, CLEAR SKIES.  
 

 
   
FIRE WEATHER
 
 
FRIDAY THROUGH TUESDAY:  
DRY CONDITIONS WILL PREVAIL ACROSS THE DISTRICTS THROUGH THE  
HOLIDAY WEEKEND WITH TEMPERATURES A COUPLE DEGREES ABOVE NORMAL  
THURSDAY AND FRIDAY COOLING BACK NEAR NORMALS OVER THE WEEKEND.  
AFTERNOON MINIMUM HUMIDITY LEVELS WILL MOSTLY FALL IN A 5-10%  
RANGE WITH GENERALLY POOR OVERNIGHT RECOVERIES. WIND SPEEDS WILL  
BEGIN TO INCREASE FRIDAY ACROSS SE CALIFORNIA, THEN ACROSS THE  
REMAINDER OF THE DISTRICTS ON SATURDAY. WIND GUSTS APPROACHING A  
25-30MPH RANGE WILL BE LIKELY AND WOULD LEAD TO AN ELEVATED FIRE  
DANGER, PARTICULARLY ON SATURDAY.  
 

 
   
SPOTTER INFORMATION STATEMENT
 
 
SPOTTER ACTIVATION WILL NOT BE NEEDED.  
 

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

 
 

 
 
DISCUSSION...KUHLMAN  
AVIATION...AJ  
FIRE WEATHER...JG/MO  
 
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