AREA FORECAST DISCUSSION

 
 FXUS65 KPSR 160440
 AFDPSR
 
 AREA FORECAST DISCUSSION
 NATIONAL WEATHER SERVICE PHOENIX AZ
 940 PM MST WED OCT 15 2008
 
 SOUTH-CENTRAL AND SOUTHWEST ARIZONA...AND SOUTHEAST CALIFORNIA 
 FORECAST DISCUSSION
 
 .SYNOPSIS...
 HIGH PRESSURE ALOFT WILL BUILD OVER THE REGION THE NEXT COUPLE OF 
 DAYS RESULTING IN ADDED WARMING THROUGH FRIDAY. TEMPERATURES BY THE 
 WEEKEND WILL BE WELL ABOVE NORMAL...PERHAPS APPROACHING THE CENTURY
 MARK AT THE WARMEST DESERT SPOTS. A WEAK DISTURBANCE EXPECTED TO 
 PASS ACROSS THE REGION EARLY NEXT WEEK WILL BRING SOME MINOR COOLING 
 ALONG WITH AN INCREASE IN CLOUDS. THERE WILL ALSO BE A SLIGHT CHANCE 
 OF SHOWERS SUNDAY NIGHT AND MONDAY OVER THE SOUTH-CENTRAL HIGHER 
 TERRAIN. 
 
 &&
 
 .DISCUSSION...
 DOWNSLOPE/DRAINAGE FLOW HAS BECOME REESTABLISHED ACROSS THE FORECAST 
 AREA THIS EVENING. BREEZY CONDITIONS EXPECTED AGAIN OVERNIGHT ACROSS 
 THE HIGHER TERRAIN EAST OF PHOENIX AND IN THE TONTO NATIONAL FOREST 
 FOOTHILLS. CURRENT FORECAST REFLECTS THIS AND ONLY MINOR TWEAKS WERE 
 MADE TO THE SHORT-TERM DATABASE...MAINLY FOR DEWPOINTS.
 
 PREVIOUS DISCUSSION...
 LIKELY TO GET LCLLY BREEZY AGAIN NEXT COUPLE OF LATE NIGHTS/MORNINGS 
 OVER SCNTRL AZ AS GRADS TIGHTEN A BIT EACH NIGHT. MODEL RH PROGS 
 SHOW NOT MUCH CHANCE OF ANY CLOUD COVER NEXT DAY OR TWO. SO FULL 
 SUNSHINE...ALONG WITH BUILDING HEIGHTS ALOFT...WILL SERVE TO GIVE 
 FURTHER DAYTIME WARMING THRU FRIDAY...WITH PEAK TEMPS LIKELY FRIDAY 
 OR SATURDAY.
 
 MEANWHILE...CUTOFF LOW OFF THE CENTRAL BAJA COAST IS PROGGED TO OPEN 
 UP AND EVENTUALLY LIFT NEWD TOWARDS THE DESERT SW OVER THE WEEKEND 
 ...GIVING SOME INCREASE IN CLOUDS ACROSS THE AREA BY SATURDAY AND
 SUNDAY. DOUBT IF THEY WILL BE SUFFICIENT TO LOWER TEMPS MUCH. BY 
 LATE SUNDAY AND MONDAY ANOTHER SHORTWAVE TROUGH WILL LIFT TOWARDS 
 THE REGION FROM THE PACIFIC AND WILL INJECT A BIT MORE MOISTURE INTO 
 THE AREA. MODEL FORECAST SOUNDINGS HINT THAT WE MAY HAVE SUFFICIENT 
 MOISTURE BY SUNDAY NIGHT AND MONDAY TO WARRANT A SLIGHT CHANCE OF 
 SHOWERS OVER ZONE 24. MID SHIFT INTRODUCED THIS POSSIBILITY...AND 
 THIS STILL APPEARS REASONABLE. AS THE SHORTWAVE PUSHES ACROSS THE 
 REGION...WILL PROBABLY SEE A SLIGHT LOWERING OF OUR MAX TEMPS EARLY 
 NEXT WEEK. 
 
 &&
 
 .AVIATION...
 NO AVIATION CONCERNS ANTICIPATED THROUGH THURSDAY EVENING. PRESSURE 
 GRADIENT WILL AGAIN TIGHTEN OVERNIGHT...RESULTING IN AN EASTERLY 
 FLOW AROUND 20 KT AT 1500 FT AGL IN THE PHOENIX METRO AREA. 
 HOWEVER...AT THE SURFACE WINDS WILL BE CONSIDERABLY 
 LIGHTER...GENERALLY LESS THAN 5 KT. THE DOWNSLOPE FLOW WILL SUBSIDE 
 DURING THE MID-MORNING THU...THOUGH A FEW GUSTS TO AROUND 15 KT WILL 
 BE POSSIBLE DURING THE LATE-MORNING AS THE ATMOSPHERE MIXES OUT. A 
 SWITCH OVER TO UPSLOPE WESTERLY IS NOT EXPECTED THU AFTERNOON.
 
 NEAR THE CO RIVER VALLEY (KYUM/KIPL/KBLH)...DRAINAGE FLOW OVERNIGHT 
 WILL GENERALLY REMAIN LIGHT THROUGH THE PERIOD.
 
 AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
 
 &&
 
 .FIRE WEATHER...
 FRIDAY THROUGH SUNDAY...
 HIGH PRESSURE ALOFT WILL CONTINUE BUILDING NORTH OVER OUR AREA WITH 
 SUNNY AND WARMER WEATHER FRIDAY. A FLOW ALOFT FROM THE SOUTH AND 
 SOUTHWEST WILL BRING SOME CLOUDINESS MAINLY OVER SOUTHEAST 
 CALIFORNIA AND SOUTHWEST ARIZONA SATURDAY...AND MAINLY OVER 
 SOUTHWEST AND SOUTH-CENTRAL ARIZONA SUNDAY. HOWEVER...IT WILL BE 
 ANOTHER WARM DAY SATURDAY AND TEMPERATURES ARE ONLY EXPECTED TO DROP 
 BACK SLIGHTLY SUNDAY.
 
 THE ATMOSPHERE IS NOT EXPECTED TO BE QUITE AS DRY...BUT IT WILL 
 STILL BE RELATIVELY DRY WITH LOW AFTERNOON RH VALUES AND MINIMAL 
 OVERNIGHT RECOVERY. SOMEWHAT MORE RECOVERY IN RH IS EXPECTED BY 
 EARLY SUNDAY MORNING. WINDS ARE EXPECTED TO REMAIN GENERALLY LIGHT.
 
 &&
 
 .PSR WATCHES/WARNINGS/ADVISORIES...
 
 AZ...NONE.
 
 CA...NONE.
 
 &&
 
 

 
 NATIONAL WEATHER SERVICE PHOENIX IS ON THE INTERNET AT
 
 WEATHER.GOV/PHOENIX
 
 DISCUSSION...HIRSCH/ESTLE
 AVIATION...HIRSCH
 FIRE WEATHER...ELLIS
 
 
 

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