000 FXUS65 KPSR 231758 AFDPSR AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PHOENIX AZ 1055 AM MST MON NOV 23 2009 .SYNOPSIS... MOSTLY CLEAR NIGHTS AND SUNNY DAYS ARE EXPECTED TO CONTINUE THROUGH THANKSGIVING DAY. HIGH PRESSURE ALOFT BETWEEN HAWAII AND BAJA CALIFORNIA WILL BUILD NORTHEAST OVER OUR AREA WITH WARMER WEATHER WEDNESDAY AND THANKSGIVING DAY. TEMPERATURES WILL RISE TO WELL ABOVE AVERAGE FOR LATE NOVEMBER BY THANKSGIVING DAY...IN THE UPPER 70S TO NEAR 80 DEGREES IN THE DESERT AREAS INCLUDING PHOENIX...YUMA AND EL CENTRO. A PACIFIC LOW PRESSURE SYSTEM IS EXPECTED TO MOVE SOUTHEAST ACROSS THE 4 CORNERS AND BRING MUCH COOLER WEATHER TO OUR AREA BY SUNDAY. IT WILL ALSO BE WINDY THIS WEEKEND...ESPECIALLY SUNDAY WITH THE STRONGEST WINDS DOWN THE LOWER COLORADO RIVER VALLEY. && .DISCUSSION... UNDER SUNNY SKIES...TEMPERATURES WERE GENERALLY CLOSE TO THE SAME LATE THIS MORNING COMPARED WITH THE SAME TIME YESTERDAY...EXCEPT 1 TO 2 DEGREES LOWER IN PORTIONS OF SOUTH-CENTRAL ARIZONA INCLUDING THE GREATER PHOENIX AREA...AND 4 TO 8 DEGREES WARMER IN EASTERN RIVERSIDE COUNTY. IT WAS ALSO UP TO 6 DEGREES COOLER IN JOSHUA TREE NATIONAL PARK. WINDS WERE GENERALLY CALM OR LIGHT...EXCEPT FROM THE NORTH 15 TO 25 MPH DOWN PORTIONS OF THE LOWER COLORADO RIVER VALLEY 10 TO 20 MPH IN JOSHUA TREE NATIONAL PARK...AND 5 TO 15 MPH IN HIGHER ELEVATIONS ELSEWHERE. MOSTLY CLEAR NIGHTS AND SUNNY DAYS ARE EXPECTED TO CONTINUE AT LEAST THROUGH THANKSGIVING. HIGH PRESSURE ALOFT BETWEEN HAWAII AND BAJA CALIFORNIA WILL BUILD NORTHEAST OVER OUR AREA WITH TEMPERATURES RISING TO WELL ABOVE AVERAGE FOR LATE NOVEMBER WEDNESDAY AND THANKSGIVING DAY. HIGHS IN THE DESERT AREAS INCLUDING PHOENIX...YUMA AND EL CENTRO ARE EXPECTED TO BE IN THE UPPER 70S TO NEAR 80 DEGREES BY THANKSGIVING DAY WITH LITTLE CHANGE FRIDAY. SURFACE HIGH PRESSURE BUILDING NORTH AND EAST OF OUR AREA WILL BRING SOME BREEZINESS AT TIMES FROM THE NORTH AND EAST BY WEDNESDAY AND THANKSGIVING. IN FACT...BREEZINESS FROM THE NORTH HAS ALREADY INCREASED SOMEWHAT IN PORTIONS OF SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA...ESPECIALLY FROM JOSHUA TREE NATIONAL PARK EAST TO THE LOWER COLORADO RIVER VALLEY AND DOWN THE LOWER COLORADO RIVER VALLEY TODAY AND THIS IS EXPECTED TO CONTINUE INTO MID WEEK. A PACIFIC LOW PRESSURE SYSTEM IS EXPECTED TO MOVE SOUTHEAST ACROSS THE 4 CORNERS SUNDAY. HIGH CLOUDS ARE EXPECTED TO MOVE SOUTHEAST ACROSS OUR AREA FRIDAY AND/OR SATURDAY AHEAD OF THIS SYSTEM. TEMPERATURES ARE EXPECTED TO DROP BACK SOMEWHAT FRIDAY...AND MORE SO SATURDAY. THEN...THE LOW PRESSURE SYSTEM IS EXPECTED TO BRING MUCH COOLER WEATHER TO OUR AREA BY SUNDAY. IT WILL ALSO BE WINDY THIS WEEKEND...ESPECIALLY SUNDAY WITH THE STRONGEST WINDS DOWN THE LOWER COLORADO RIVER VALLEY WHERE A WIND ADVISORY MAY BE NEEDED. THIS SYSTEM LOOKS AS IF IT WILL BE DRY FOR OUR AREA WITH PRECIPITATION EXPECTED TO STAY NORTH AND EAST OF OUR AREA. && .AVIATION... SOUTHEAST CA...SOUTHWEST AND SOUTH CENTRAL AZ...INCLUDING KIPL... KBLH...KPHX...AND KIWA. EXCEPT FOR OCCASIONAL THIN HI CIRRUS...AOA 20K FEET...SKIES TO BE MOSTLY CLEAR NEXT 24 HOURS ALL AIRFIELDS. FOR THE MOST PART WINDS WILL BE RATHER LIGHT AND DIURNAL...EXCEPT DOWN THE LOWER CO RIVER VALLEY TODAY. SURFACE HIGH DEVELOPING TO OUR NORTH WILL TIGHTEN GRADIENT DOWN THE RIVER...AND CAUSE BREEZY NORTH WINDS TO DEVELOP AT KBLH AFTER ABOUT 18Z. EXPECT OCNL GUSTS BETWEEN 20-25KT STARTING EARLY THIS AFTERNOON AND THEN TAPERING OFF SHORTLY AFTER SUNSET. OTHERWISE NO AVIATION CONCERNS. VFR CONDITIONS EXPECTED ALL AIRFIELDS NEXT 24 HOURS. AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS. && .FIRE WEATHER... WEDNESDAY THROUGH SUNDAY... HIGH PRESSURE ALOFT WILL DOMINATE THE WEATHER PATTERN WEDNESDAY AND THURSDAY...WITH MOSTLY CLEAR OR CLEAR SKIES EXPECTED EACH DAY...AND RELATIVELY LIGHT WINDS. HIGH TEMPERATURES WILL CONTINUE WELL ABOVE SEASONAL NORMALS...ALONG WITH VERY DRY AIR OVER THE DESERTS. MANY LOCALES WILL SEE MINIMUM RH VALUES IN THE SINGLE DIGITS...WITH MODEST RECOVERY AT NIGHT. FORECAST MODELS IN BETTER AGREEMENT REGARDING A CHANGE IN THE WEATHER DEVELOPING OVER THE WEEKEND. A LOW PRESSURE SYSTEM WILL BE SETTLING IN OVER THE DESERT SOUTHWEST... LEADING TO A SUBSTANTIAL COOLING TREND FRIDAY THROUGH SUNDAY. HIGH TEMPERATURES MAY FALL AROUND 15 DEGREES OVER THIS TIME FRAME WITH HIGHS SUNDAY EXPECTED IN THE MID 60S OVER MOST OF THE LOWER DESERTS. THIS WILL BE RATHER DRY SYSTEM FOR OUR AREA WITH NO PRECIPITATION IN THE FORECAST AT THIS TIME. HOWEVER HUMIDITY WILL BE ON THE INCREASE...PARTLY DUE TO INCREASING LOW LEVEL MOISTURE AND ALSO COOLING TEMPERATURES. BREEZY OR LOCALLY WINDY WEATHER IS LIKELY OVER THE WEEKEND AS WELL. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...NONE. CA...NONE. && $$ NATIONAL WEATHER SERVICE PHOENIX IS ON THE INTERNET AT WEATHER.GOV/PHOENIX DISCUSSION...ELLIS AVIATION...CB FIRE WEATHER...CB