AREA FORECAST DISCUSSION

 
 FXUS65 KTWC 220933
 AFDTWC
 
 AREA FORECAST DISCUSSION
 NATIONAL WEATHER SERVICE TUCSON AZ
 233 AM MST SUN NOV 22 2009
 
 .SYNOPSIS...WEATHER SYSTEMS WILL CONTINUE TO PASS NORTH OF OUR AREA. 
 OTHER THAN SOME OCCASIONAL PATCHES OF HIGH CLOUDS...SOUTHEAST 
 ARIZONA WILL REMAIN DRY WITH MOSTLY CLEAR SKIES AND WARM DAYTIME 
 TEMPERATURES.
 
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 .DISCUSSION...WATER VAPOR IMAGERY SHOWS A TROUGH MOVING THROUGH NEW 
 MEXICO WITH THE TAIL END OF THE SYSTEM DRAPED ACROSS SOUTHERN 
 ARIZONA. MEANWHILE...ANOTHER SYSTEM IS MOVING INTO THE PACIFIC 
 NORTHWEST AND WILL MOVE INTO THE CENTRAL ROCKIES/PLAINS BY LATE 
 MONDAY. AS A RESULT...DRY NORTHWESTERLY FLOW BEHIND THIS SYSTEM WILL 
 PREVAIL ACROSS THE DESERT SOUTHWEST. 
 
 RIDGING WILL BUILD IN TO THE NORTHWEST OF ARIZONA...MAINLY OVER THE 
 GREAT BASIN DURING THE MIDDLE OF THE WEEK...WITH MODELS INDICATING A 
 WEAK LOW UNDERCUTTING THE RIDGE. PLACEMENT OF THIS WEAK LOW DIFFERS 
 AMONG THE MODELS BUT WE SHOULD NOT SEE MUCH AFFECT ANYWAY WITH TEMPS 
 REMAINING LEVEL DURING THE TIME FRAME AND THE OCCASIONAL PATCH OF 
 HIGH CIRRUS CLOUDS MOVING THROUGH THE REGION.  
 
 TOWARDS THE LATTER PART OF THE WEEK THE RIDGE SHIFTS EASTWARD AS 
 ANOTHER PACIFIC SYSTEM MAKES ITS WAY INTO THE PAC NW. BEYOND FRIDAY 
 THE MODELS DIFFER WITH THE ECMWF DROPPING THE TROUGH MUCH FARTHER 
 SOUTH AND STRONGER THAN THE GFS. I TRIMMED HIGH TEMPS SEVERAL 
 DEGREES FOR NEXT WEEKEND...BUT IF EURO IS CORRECT I AM NOT NEARLY 
 COLD ENOUGH. PLENTY OF TIME TO MAKE FURTHER ADJUSTMENTS. IN 
 ADDITION...I ALSO INTRODUCED SINGLE DIGIT POPS FOR SATURDAY AND THIS 
 MESHES WELL WITH SURROUNDING OFFICES.  
 
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 .AVIATION...FEW TO SCT CIRRUS GENERALLY ABOVE 20K FT FROM TIME TO 
 TIME NEXT 24 HOURS. NORMAL DIURNAL WIND TRENDS ARE EXPECTED AT THE 
 TERMINAL SITES...WITH SURFACE WINDS GENERALLY LESS THAN 10 KTS. 
 AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.
 
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 .FIRE WEATHER...AN EXITING WEATHER SYSTEM WILL RESULT IN A LITTLE 
 COOLER DAYTIME TEMPERATURES ACROSS SOUTHEAST ARIZONA WITH DRY 
 CONDITIONS CONTINUING. THERE MAY BE SOME AFTERNOON AND EARLY EVENING 
 BREEZES ACROSS THE HIGHER TERRAIN TO THE NORTH AND EAST OF TUCSON 
 TODAY. HOWEVER...WINDS ARE EXPECTED TO REMAIN WELL BELOW CRITICAL 
 FIRE WEATHER THRESHOLDS.
 
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 .TWC WATCHES/WARNINGS/ADVISORIES...NONE.
 
 

 
 MOLLERE
 
 WEATHER.GOV/TUCSON
 
 
 

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