FXUS65 KTWC 112042
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
155 PM MST FRI DEC 11 2009

.SYNOPSIS...A SERIES OF WEAK DISTURBANCES WILL BRING PERIODS OF HIGH 
CLOUDS TO SOUTHEAST ARIZONA TODAY AND SATURDAY...WITH ONLY A FEW 
LIGHT SHOWERS NEAR THE WHITE MOUNTAINS. A STRONGER STORM SYSTEM WILL 
BRING A CHANCE OF VALLEY RAIN AND MOUNTAIN SNOW LATE SUNDAY AND 
MONDAY. HIGH PRESSURE BUILDING OVER THE DESERT SOUTHWEST IS EXPECTED 
TO BRING A WARMING TREND THE REST OF NEXT WEEK.

&&

.DISCUSSION...A FEW PATCHES OF MID AND HIGH CLOUD WITH A WEAK 
INFLECTION IN OUR ZONAL WESTERLY FLOW PASSING EAST. ANOTHER IN THE 
SERIES OF WEAK IMPULSES TONIGHT WITH A THIRD LATE SATURDAY...AGAIN 
MAINLY SOME CLOUDS WITH THAT...VIRGA OR SPRINKLES NOT OUT OF THE 
QUESTION WITH A FEW LIGHT MOUNTAIN SHOWERS MAINLY NORTH OF OUR AREA.

MAIN TROUGH PUSHING INTO ARIZONA SUNDAY...AND INTO OUR AREA LATE 
SUNDAY INTO MONDAY. MODELS COMING TOGETHER IN CONTINUING TREND OF 
DEEPER TRAJECTORY AND THUS SLOWER TIMING...WHILE ALSO ALLOWING 
BETTER DYNAMICS AND MOISTURE FOR SOUTHEAST ARIZONA. STILL NOT A 
TERRIBLY COLD OR STRONG SYSTEM BUT EXPECT SCATTERED VALLEY RAIN AND 
LIKELY MOUNTAIN SNOW. BEST CONDITIONS COMING TOGETHER FOR 03Z TO 10Z 
MONDAY WITH INITIAL PIECE OF ENERGY...THEN REINFORCING SHOT 16Z TO 
21Z MONDAY. WE WILL ADJUST OUR CHANCE OF PRECIP UP WITH THE 
AFTERNOON FORECAST PACKAGE AND ISSUE A HAZARDOUS WEATHER OUTLOOK TO 
GIVE A HEADS-UP FOR A SYSTEM THAT COULD END UP BRINGING ADVISORY 
LEVEL SNOWS ABOVE 6K OR 7K FEET.

DIRTY RIDGE WILL LIKELY BRING A WARMING TREND THE REMAINDER OF NEXT 
WEEK IN A CHANGE OVER TO A BLOCKING PATTERN.

&&

.AVIATION...SCATTERED TO BROKEN DECKS OF MID AND HIGH 
CLOUDS...MOSTLY ABOVE 15K FEET AGL. WINDS LIGHT AT LESS THAN 10 KTS 
AND DIURNALLY/TERRAIN DRIVEN INTO SATURDAY. AVIATION DISCUSSION NOT 
UPDATED FOR TAF AMENDMENTS.

&&

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

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

$$

WEATHER.GOV/TUCSON