AREA FORECAST DISCUSSION

 
 FXUS65 KPSR 171013
 AFDPSR
 
 AREA FORECAST DISCUSSION
 NATIONAL WEATHER SERVICE PHOENIX AZ
 310 AM MST SAT MAY 17 2008 
 
 SOUTH-CENTRAL AND SOUTHWEST ARIZONA...AND SOUTHEAST CALIFORNIA 
 FORECAST DISCUSSION
 
 .SYNOPSIS...
 A WARMING TREND WILL CONTINUE THROUGH THE WEEKEND...AS A STRONG 
 RIDGE OF HIGH PRESSURE MOVES OVER THE DESERT SOUTHWEST. TEMPERATURES 
 SUNDAY AND MONDAY WILL BE THE WARMEST OF THE SEASON THUS FAR...WELL 
 ABOVE NORMAL FOR THIS TIME OF YEAR. MOSTLY CLEAR NIGHTS AND SUNNY 
 DAYS WILL CONTINUE THROUGH MID-WEEK. A STRONG LOW PRESSURE SYSTEM 
 WILL DEVELOP OVER UTAH BY THURSDAY...WHICH WILL BRING BREEZY AND 
 COOLER WEATHER...ALONG WITH A SLIGHT CHANCE OF SHOWERS FOR PARTS
 OF SOUTH-CENTRAL ARIZONA.
 
 &&
 
 .DISCUSSION...
 MOSTLY SUNNY SKIES WILL BE THE RULE TODAY AS A STRONG ANTICYCLONIC 
 CIRCULATION CONTINUES TO AMPLIFY NEAR NORTHERN CALIFORNIA. THE 
 LATEST WATER VAPOR IMAGERY INDICATED SEVERAL BANDS OF MAINLY 
 HIGH-LEVEL CLOUDS THAT WERE STREAKING ACROSS THE INTERMOUNTAIN 
 WEST...BUT THEY SHOULD THIN OUT WITH TIME. THE MODELS REMAIN IN 
 FAIRLY GOOD AGREEMENT IN SHIFTING THE WESTERN RIDGE SLOWLY TOWARD 
 THE EAST...WITH THE CENTER OF THIS SYSTEM MOVING OVER THE DESERTS
 BY MONDAY. THIS TREND WAS ALREADY EVIDENT YESTERDAY...AND THE MAIN 
 IMPACT FOR ALL ZONES REMAINS NEAR RECORD...OR RECORD HIGH 
 TEMPERATURES FOR SUNDAY AND MONDAY. FOR PHOENIX...THE FIRST 100 
 DEGREE DAY OF THE SEASON LOOKS TO ARRIVE ON SUNDAY...WITH PERHAPS 
 MONDAY AND TUESDAY EVEN HOTTER. 
 MUCH HIGHER MAX TEMPS STILL APPEAR TO BE A MAJOR CONCERN OUT WEST 
 INCLUDING SOUTHWEST ARIZONA AND PARTICULARLY FAR SOUTHEAST CALIF. 
 IMPERIAL/EL CENTRO AS WELL AS YUMA AND BLYTHE COULD TOP OUT AT 110 
 DEGREES ON SUNDAY AND MONDAY. THICKNESSES DONT CHANGE MUCH ON TUES.
 EXCESSIVE HEAT WATCH WAS ISSUED TO COVER THESE HEALTH CONCERNS.
 
 LATEST MEDIUM RANGE MODELS COME INTO BETTER AGREEMENT FOR THE 
 MID-WEEK TIME FRAME...AND THEY DEPICT AN UNSEASONABLY STRONG 
 COLD-CORE LOW OVER UTAH. THUS WE OPTED TO INTRODUCE SOME SLIGHT 
 CHANCES OF SHOWERS FOR PORTIONS OF SOUTH-CENTRAL ARIZONA...ON 
 FRIDAY. BEST CHANCES WILL BE ACROSS THE HIGHER ELEVATIONS NEAR GLOBE.
 THERE WILL BE A LOT OF ENERGY ASSOCIATED WITH THIS COLD-CORE 
 SYSTEM...AND GFS TRENDS THE JETSTREAM WINDS TO EXCEED 100 KTS FROM 
 ABOUT LATE WEDNESDAY INTO LATE THURSDAY. STRONG OROGRAPHIC EFFECTS 
 MAY COME INTO PLAY...AND LATER SHIFTS MAY NEED TO DEFINE THIS 
 BETTER. EARLY FRIDAY LOOKS TO BE THE PRIME TIME FOR GETTING SOME 
 ACTIVITY AND FOR NOW I WILL FOCUS ON THE AREA NORTHEAST OF PHOENIX. 
 MODELS KEEP SOME LINGERING MOISTURE WELL NORTH OF US BY LATE FRIDAY 
 AND INTO NEXT WEEKEND...FOR A RETURN TO MORE SEASONAL WEATHER ACROSS 
 ALL ZONES.
 
 &&
 
 .AVIATION...
 STRONG HIGH PRESSURE BUILDS INTO THE REGION OVER THE WEEKEND INTO 
 EARLY NEXT WEEK. EXPECT MOSTLY CLEAR SKIES AND LIGHT SURFACE WINDS 
 FOR THE NEXT 24 HOURS.
 
 AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
 
 &&
 
 .FIRE WEATHER...
 HIGH PRESSURE WILL FIRMLY BE OVER THE REGION BY MONDAY. TEMPERATURES 
 WILL BE AT NEAR-RECORD LEVELS. RH LEVELS WILL FALL INTO THE SINGLE 
 DIGITS DURING THE AFTERNOON HOURS WHILE BREEZY SOUTHWESTERLY WINDS 
 DEVELOP. THE VERY WARM/DRY WEATHER WILL REMAIN THROUGH TUESDAY. BY 
 WEDNESDAY...A BROAD-SCALE LOW PRESSURE SYSTEM WILL BEGIN TO DEVELOP 
 OVER THE WESTERN HALF OF THE U.S. THIS WILL QUICKLY BRING TEMPS DOWN 
 AND RH LEVELS UP...AS WELL AS INCREASE WINDS ACROSS THE REGION. AT 
 THIS TIME THE PROBABILITY FOR SHOWERS/THUNDERSTORMS IS NEAR ZERO... 
 THOUGH THIS COULD CHANGE AS WE MOVE INTO NEXT WEEK AND MODELS COME 
 INTO BETTER AGREEMENT.
 
 &&
 
 .CLIMATE...
 
 CLIMATE INFORMATION FOR SELECT STATIONS ACROSS THE NWS PHOENIX CWA.
 
                 NORMAL HIGH        RECORD HIGH       FORECAST HIGH
   STATION     5/18  5/19  5/20   5/18  5/19  5/20   5/18  5/19  5/20
 PHOENIX        94    95    95     107   105   106    103   106   106
 YUMA           94    94    95     109   109   110    110   112   110
 CASA GRANDE    96    96    97     109   109   107    102   105   105
 GLOBE          84    84    85      96    97   100     92    96    96
 EL CENTRO      94    95    95     110   108   111    107   110   108
 BLYTHE         94    95    95     110   108   110    108   110   108
 
 &&
 
 .PSR WATCHES/WARNINGS/ADVISORIES...
 
 AZ...EXCESSIVE HEAT WATCH FROM SUNDAY MORNING THROUGH SUNDAY EVENING
      FOR AZZ020-021-025-026.
 
      EXCESSIVE HEAT WATCH FROM MONDAY MORNING THROUGH MONDAY EVENING
      FOR AZZ020-021-025-026.
 
 CA...EXCESSIVE HEAT WATCH FROM SUNDAY MORNING THROUGH SUNDAY EVENING
      FOR CAZ031-032.
 
      EXCESSIVE HEAT WATCH FROM MONDAY MORNING THROUGH MONDAY EVENING
      FOR CAZ031-032.
 
 &&
 
 

 
 NATIONAL WEATHER SERVICE PHOENIX IS ON THE INTERNET AT 
 WEATHER.GOV/PHOENIX
 
 DISCUSSION...SIPPLE
 AVIATION...MEYERS
 FIRE WEATHER...INIGUEZ
 
 
 
 

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