FXUS65 KTWC 110359
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
859 PM MST THU DEC 10 2009

.SYNOPSIS...A SERIES OF WEAK DISTURBANCES IN THE WESTERLY FLOW ALOFT 
WILL BRING PERIODS OF HIGH CLOUDS TO SOUTHEAST ARIZONA WITH A FEW 
SPRINKLES POSSIBLE FRIDAY AND SATURDAY. THE LAST DISTURBANCE IN THIS 
SERIES WILL BRING A FEW SHOWERS MAINLY NEAR THE MOUNTAINS SUNDAY 
NIGHT. A RIDGE OF HIGH PRESSURE WILL BRING A WARMING TREND NEXT 
WEEK.

&&

.DISCUSSION...CURRENT SATELLITE TRENDS SHOW CLOUD COVER THAT MOVED 
THROUGH LATE AFTERNOON DISSIPATING...LEAVING MOST OF SE AZ CLEAR. 
EARLY EVENING RADAR TRENDS DID INDICATE AN AREA OF WEAK ECHOES 
ACROSS SOUTHERN PINAL COUNTY. HOWEVER...DRY LOW LEVELS LIKELY DID 
NOT ALLOW ANY PRECIP TO REACH THE GROUND. CLEAR SKIES AND LIGHT 
WINDS WILL ALLOW FOR TEMPS TO DROP OFF QUICKLY OVERNIGHT. CURRENT 
FORECASTED LOWS LOOK GOOD...SO NO CHANGES NEEDED. 

WEAK SHORT WAVE AND ASSOCIATED CLOUDINESS LOCATED OFF THE SOUTHERN 
CA COAST TO MOVE INLAND OVERNIGHT...BRINGING SOME MID AND HIGH LEVEL 
CLOUDINESS TO SE AZ BY DAYBREAK. THE REST OF THE INHERITED FORECAST 
LOOKS GOOD...SO NO CHANGES NEEDED. PLEASE REFER TO PREVIOUS 
DISCUSSION FOR MORE INFORMATION.   

&&

.AVIATION...MOSTLY CLEAR OVERNIGHT THEN VARIABLE CLOUDS AT OR ABOVE 
10K FT AGL INTO FRIDAY EVENING. SURFACE WINDS MOSTLY LESS THAN 10 
KTS THRU 13/06Z. AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS.

&&

.FIRE WEATHER...NO FIRE WEATHER CONCERNS AT THIS TIME.
 
&&

.PREV DISCUSSION...WESTERLY FLOW ALOFT WITH TROUGH STILL DOMINATING 
MOST OF COUNTRY DOWNSTREAM. EXPECT PATCHES OF MID AND HIGH CLOUD 
FILTERING IN FROM DIRTY WEST COAST RIDGE FROM TIME TO TIME. FIRST IN 
A SERIES OF IMPULSES COMING ONSHORE INTO SOUTHERN CALIFORNIA. COULD 
BRING A FEW SPRINKLES NEAR MOUNTAINS TOMORROW. ANOTHER WEAKNESS IN 
THE FLOW PUSHES QUICKLY THROUGH SATURDAY WITH THE MAIN SYSTEM COMING 
THROUGH THE AREA FROM THE WEST LATE SUNDAY INTO MONDAY. NOT MUCH 
MOISTURE OR DYNAMICS THIS FAR SOUTH...AND THIS SYSTEM IS NOT NEARLY 
AS COLD AS THE LAST STORM. SHOULD SEE A FEW SHOWERS AROUND BUT MOST 
OF THE WEATHER WILL BE NORTH OF OUR AREA. NOT REALLY MUCH COLD AIR 
INVOLVED AND WINDS WILL NOT BE A FACTOR.

BROAD LONG PERIOD RIDGE PHASING IN NEXT WEEK...BUT ACTUAL HEIGHT AND 
THICKNESS VALUES NOT THAT HIGH...TEMPERATURES RECOVERING TO 3 OR 5 
DEGREES ABOVE CLIMO. PROBABLY ON THE DIRTY SIDE WITH PATCHES OF MID 
AND HIGH CLOUD AT TIMES.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...NONE. 

$$

WEATHER.GOV/TUCSON