FXUS65 KPSR 292210
AFDPSR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PHOENIX AZ
305 PM MST SUN NOV 29 2009
.SYNOPSIS...
A STRONG LOW PRESSURE SYSTEM MOVING ACROSS NORTHERN MEXICO WILL
BRING COOL AND UNSETTLED WEATHER THROUGH MONDAY. THE BEST THREAT FOR
PRECIPITATION WILL BE EAST OF PHOENIX...WITH SHOWERS AND ISOLATED
THUNDERSTORMS ACTIVITY TAPERING OFF TONIGHT. SOME SNOW IS FORECAST
IN THE MOUNTAINS MONDAY AND CLEARING IS EXPECTED TUESDAY. PLENTIFUL
SUNSHINE AND NEAR NORMAL TEMPERATURES WILL PREVAIL THROUGH THE REST
OF THE WEEK.
&&
.DISCUSSION...
WV/VIS SATELLITE AT THIS HOUR CLEARLY SHOWS THE ROTATION OF THE LOW
CENTERED OVER THE NORTHERN GULF OF CA...WITH MID AND LOW LEVEL
CLOUDS INCREASING OVER THE SOUTH-CENTRAL DESERTS. CURRENT RADAR
IMAGERY/LIGHTNING REVEAL SMALL BANDS OF SHOWERS WITH EMBEDDED
THUNDERSTORMS SLOWLY ROTATING THROUGH EAST CENTRAL PORTIONS OF THE
STATE...MOVING WEST ACROSS SOUTHERN GILA COUNTY. THE COLD CORE OF
THE LOW WILL REMAIN SOUTH OF OUR AREA...BUT THERE IS ENOUGH COLD AIR
ALOFT AND INSTABILITY FOR THESE STORMS TO CONTINUE TO FORM THE REST
OF THE AFTERNOON. AS SUCH...KEEPING CHANCE POPS GOING FOR THE
PHOENIX AREA...CHANCES DECREASING WEST OF MARICOPA COUNTY AND AS WE
GO INTO THE EVENING HOURS. THE BEST THREAT FOR FOR RAIN AND SHOW
SHOWERS WILL BE OVER THE HIGHER MOUNTAIN TERRAIN EAST OF GLOBE
TONIGHT.
MODELS CONTINUE TO SHOW GOOD AGREEMENT ON THE TRACK AND INTENSITY OF
THE CLOSED LOW THROUGH MONDAY...GRADUALLY MOVING EAST ACROSS NRN
MEXICO AND INTO WEST TEXAS TUESDAY. BASED ON THE SLOW MOVEMENT OF
THE LOW...WRAP-AROUND MOISTURE WILL REMAIN INTACT OVER THE HIGHER
TERRAIN OF ZONE 24/SOUTHERN GILA COUNTY TONIGHT AND MONDAY...AND
WITH THE COLD AIRMASS...RAIN WILL CHANGE TO SNOW ABOVE 5000 FEET
WITH ONE TO TWO INCHES ACCUMULATION POSSIBLE AFTER MIDNIGHT. THE
SNOW LEVEL WILL LOWER TO 4500 EARLY MONDAY AS THE STORM CENTER MOVES
FARTHER AWAY FROM THE AREA. THUS...LITTLE OR NO ADDITIONAL SNOW
ACCUMULATION IS EXPECTED MONDAY.
BY MONDAY MORNING...LESS CLOUD COVER OVER OUR WESTERN ZONES WILL
LEAD TO BETTER RADIATIONAL COOLING TO MAXIMIZE THE COLD AIR MASS.
SOME ENHANCED WINDS ON THE BACK SIDE OF THE LOW WILL KEEP LOW TEMPS
IN CHECK AND ABOVE FREEZING...TUESDAY MORNING WILL LIKELY BE THE
COLDEST DAY...IN THE ABSENCE OF MUCH CLOUD COVER.
TUESDAY THROUGH FRIDAY...THE LOW PRESSURE SYSTEM SWEEPS ACROSS TEXAS
AND THE UPPER RIDGE REMAINS PERCHED OFF THE WEST COAST WITH LITTLE A
GRADUAL INCREASE IN HEIGHTS/THICKNESSES. THE RESULT...A DRIER NWLY
FLOW ALOFT THAT WILL LEAD TO MOSTLY SUNNY SKIES AND A SLOW WARMING
TREND FOR THE WORK WEEK...WITH DAYTIME HIGHS BACK IN THE LOW 70S.
BY THE WEEKEND...THE ERN PAC RIDGE BECOMES MORE AMPLIFIED...ALLOWING
FOR A SERIES OF SHORT WAVES TO SLIDE DOWN THE EAST SIDE OF THE RIDGE
INTO THE PAC NORTHWEST. THIS WILL AMPLIFY THE TROF PATTERN OVER THE
NORTHERN ROCKIES...BRINGING INCREASED WINDS AND SLIGHTLY COOLER
TEMPERATURES TO OUR FORECAST AREA.
&&
AVIATION...
KPHX/KIWA...
THUNDERSTORMS WILL IMPACT KIWA...AND POSSIBLY KPHX...OVER THE NEXT
COUPLE OF HOURS WITH THE POSSIBILITY OF LIGHTNING...GUSTY WINDS UP
TO 30 MPH...AND PEA-SIZE HAIL. THUNDERSTORM ACTIVITY SHOULD CEASE
AFTER 00Z. FOR THE REST OF THE FCST PERIOD THERE SHOULD BE NO
HAZARDS WITH LIGHTER NE WINDS 5-10 MPH EXPECTED.
KIPL/KBLH...
NO CONCERNS AS WINDS WILL STAY LIGHT AND MINIMAL CLOUD COVER.
AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS.
&&
.FIRE WEATHER...
TUESDAY THROUGH SATURDAY...
WEAK HIGH PRESSURE AND MOSTLY CLEAR SKIES ARE EXPECTED TUESDAY AND
WEDNESDAY...WITH WARMER AND DRIER WEATHER. MODELS ARE SHOWING
VARYING SOLUTIONS BEYOND MID WEEK...WITH THE ECMWF FAVORING A FAST
MOVING...DRY...SHORTWAVE DISTURBANCE TO ROTATE THROUGH THE AREA
THURSDAY/EARLY FRIDAY TIME FRAME. THE MAIN IMPACT /IF THIS PANS OUT/
WILL BE INCREASING WINDS. BOTH MODELS INDICATE RIDING TO ONCE AGAIN
PREVAIL LATE FRIDAY INTO THE WEEKEND.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...NONE.
CA...NONE.
&&
$$
NATIONAL WEATHER SERVICE PHOENIX IS ON THE INTERNET AT
WEATHER.GOV/PHOENIX
DISCUSSION...MEYERS
AVIATION...WATERS
FIRE WEATHER...WANEK
