Area Forecast Discussion
Issued by NWS Phoenix, AZ

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000 FXUS65 KPSR 231203 AAA AFDPSR AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE PHOENIX AZ 500 AM MST SUN NOV 23 2014 .UPDATE... UPDATED AVIATION AND FIRE WEATHER SECTIONS. && .SYNOPSIS... DRY NORTHWEST FLOW ALOFT WILL BE THE RULE THIS WEEKEND AND INTO EARLY NEXT WEEK FOR MOSTLY SUNNY DAYS...CLEAR NIGHTS...AND NEAR SEASONAL NORMAL HIGH TEMPERATURES. HIGH PRESSURE WILL REBUILD OVER THE REGION BY THE MIDDLE OF NEXT WEEK...PROVIDING CLEAR SKIES AND WELL ABOVE NORMAL AFTERNOON TEMPERATURES. NO PRECIPITATION IS EXPECTED FOR AT LEAST THE NEXT SEVEN DAYS. && .DISCUSSION... DRY NORTHWEST FLOW ALOFT IS IN PLACE ACROSS ARIZONA EARLY THIS MORNING...AS SEEN IN THE PLOT AND SOUNDING DATA. IR IMAGERY AT 1 AM SHOWED MOSTLY CLEAR SKIES ACROSS SERN CA AND ARIZONA...WITH JUST A BIT OF MOSTLY THIN HIGH CLOUD SPREADING IN FROM THE NORTHWEST. AS THE UPPER RIDGE AMPLIFIES JUST OFF THE WEST COAST TODAY...A SHORTWAVE WILL DIVE SOUTHEAST DOWN THE FRONT SIDE OF THE RIDGE AND PASS THRU THE FOUR CORNERS AREA...AND IN RESPONSE LOW/MID LEVEL GRADIENTS WILL TIGHTEN. THIS WILL LEAD TO BREEZY/WINDY CONDITIONS OVER THE WESTERN DESERTS...ESPECIALLY DOWN THE LOWER COLORADO RIVER VALLEY WHERE NORTH WINDS WILL DEVELOP TODAY AND EXCEED 30 MPH AT TIMES DURING THE MIDDLE OF THE DAY. FOR THE MOST PART WINDS WILL REMAIN A BIT BELOW WIND ADVISORY CRITERIA BUT THERE MAY BE ISOLATED INSTANCES OF WINDS PEAKING BETWEEN 35-40 MPH. OTHERWISE...HIGH TEMPS TODAY WILL HOVER NEAR SEASONAL NORMALS...BUT WILL FALL OF ACROSS SOUTH CENTRAL AZ MONDAY AS COOLER AIR FILTERS ACROSS THE DESERTS BEHIND THE PASSING SHORTWAVE. EXPECT HIGHS FALLING INTO THE 60S MONDAY OVER THE CENTRAL DESERTS...WITH A HIGH OF 67 FORECAST FOR PHOENIX UNDER SUNNY SKIES. FOR MONDAY INTO THE MIDDLE OF THE WEEK...DRY NORTHWEST FLOW ALOFT WILL PERSIST EACH DAY AS THE RIDGE TO OUR WEST CONTINUES TO AMPLIFY AND SHIFT EASTWARD. BY WEDNESDAY AFTERNOON THE RIDGE IS FORECAST TO MOVE INLAND OVER THE DESERT SOUTHWEST...WITH H5 HEIGHTS CLIMBING TO AROUND 585DM OVER THE WESTERN DESERTS. AS SUCH...EXPECT A WARMING TREND THRU MIDWEEK WITH HIGHS RISING MAINLY INTO THE MID 70S OVER THE LOWER DESERTS WEDNESDAY. DESPITE THE RIDGE BEGINNING TO FLATTEN A BIT THURSDAY...WARM AIR ALOFT WILL CONTINUE TO MIX TO THE SURFACE AND BEST PERFORMING GRIDDED GUIDANCE CALLS FOR HIGHS TO RISE SEVERAL MORE DEGREES...AND INTO THE LOWER 80S. THE HIGH AT PHOENIX WILL CLIMB TO 81...MORE THAN 10 DEGREES ABOVE THE NORMAL VALUE OF 70 DEGREES. THERE WILL BE OCCASIONAL HIGH CLOUDS MOVING THRU THE FLOW EACH DAY BUT OVERALL EXPECT SUNNY OR MOSTLY SUNNY DAYS AND GENERALLY CLEAR NIGHTS. TOWARD THE END OF THE WEEK...GUIDANCE CALLS FOR THE RIDGE TO CONTINUE TO FLATTEN AS THE FLOW PATTERN BECOMES MORE ZONAL AND PROGRESSIVE. DESPITE ENSEMBLE MEMBERS BECOMING VERY MESSY WITH TIME...OPERATIONAL GFS AND ECMWF RUNS AGREE THAT FAR SERN AZ AND SRN AZ WILL STAY UNDER A RATHER DRY WESTERLY FLOW ALOFT THRU SATURDAY WITH OCCASIONAL HIGH CLOUDS MOVING THRU THE FLOW. HIGH TEMPS WILL START TO FALL OFF BUT SHOULD REMAIN WELL ABOVE SEASONAL NORMALS EACH DAY. && .AVIATION... SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL... WESTERLY FLOW ABOVE THE SURFACE WILL TURN NORTHERLY THIS MORNING AS A DRY FRONT SAGS SOUTHWARD THROUGH ARIZONA. AIRFIELDS WILL FAVOR A NORTHERLY COMPONENT BY MIDDAY. SUSTAINED SURFACE WINDS ARE EXPECTED TO REMAIN AT OR BELOW 12 KNOTS. OVERNIGHT...WINDS JUST ABOVE THE SURFACE WILL BE NORTHEASTERLY BUT WILL BE MORE VARIABLE AT THE SURFACE DUE TO LOCAL TERRAIN INFLUENCES. SKIES WILL BE CLEAR EXCEPT FOR THIN CIRRUS. SOUTHEAST CALIFORNIA AND SOUTHWEST ARIZONA...INCLUDING KIPL AND KBLH... STRONG NORTHERLY LOWER LEVEL WINDS ABOVE THE SURFACE COMBINED WITH LIGHT WINDS AT THE SURFACE WILL LEAD TO AREAS OF LOW LEVEL WIND SHEAR UNTIL ABOUT 16-17Z THIS MORNING. NORTHERLY SURFACE WINDS WILL DEVELOP BY MID MORNING...STRONGEST OVER AND NEAR THE LOWER COLORADO RIVER VALLEY WITH GUSTS OF 25-30 KTS AND ISOLATED 35 KTS...BEFORE SLOWLY WEAKENING BY LATE AFTERNOON. WINDS WILL NOT BE QUITE AS STRONG OVER THE IMPERIAL VALLEY BUT GUSTS OF 20-25 KTS WILL BE COMMON. SURFACE WINDS WILL BE MUCH LIGHTER OVERNIGHT THOUGH THE LOWER LEVELS ABOVE THE SURFACE WILL BE STRONGER...NOT ENOUGH TO WARRANT MENTION OF LLWS AT THIS TIME. SKIES WILL BE CLEAR EXCEPT FOR THIN CIRRUS. AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS. && .FIRE WEATHER... TUESDAY THROUGH SATURDAY... STRONG SURFACE HIGH PRESSURE CENTERED OVER COLORADO WILL LEAD TO LOCALIZED NORTH AND NORTHEAST BREEZINESS TUESDAY. LIGHT WINDS CAN THEN BE EXPECTED ACROSS THE FORECAST AREA WEDNESDAY THROUGH SATURDAY. TEMPERATURES WILL START OFF A BIT BELOW NORMAL TUESDAY FOLLOWED BY A SUBSTANTIAL WARMING TREND WEDNESDAY AND THURSDAY AS A RIDGE OF HIGH PRESSURE BUILDS OVER THE REGION. AS THE RIDGE WEAKENS LATE IN THE WEEK...TEMPERATURES WILL NUDGE DOWNWARD. MINIMUM HUMIDITIES WILL REMAIN LOW...10-15 PERCENT...WITH MODEST OVERNIGHT RECOVERY. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...NONE. CA...NONE. && $$ VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX DISCUSSION...CB AVIATION....AJ FIRE WEATHER...AJ

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