FXUS65 KTWC 061150
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
450 AM MST SUN DEC 6 2009

.SYNOPSIS...DRY CONDITIONS WILL PREVAIL TODAY. A STRONG WINTER STORM 
SYSTEM WILL THEN APPROACH THE AREA FROM THE NORTHWEST ON MONDAY. 
THIS SYSTEM IS EXPECTED TO BRING WIDESPREAD VALLEY RAIN AND 
SIGNIFICANT MOUNTAIN SNOW TO SOUTHEAST ARIZONA PARTICULARLY MONDAY 
NIGHT INTO MIDDAY TUESDAY. DRIER CONDITIONS WEDNESDAY FOLLOWED BY 
ANOTHER CHANCE OF VALLEY RAIN AND MOUNTAIN SNOW THURSDAY INTO FRIDAY.

&&

.DISCUSSION...A CLEAR SKY PREVAILED OVER THE AREA EARLIER THIS 
MORNING AS LAST NIGHTS THICK CLOUD COVER PUSHED OFF RAPIDLY TO THE 
EAST. RECENTLY INFRARED IMAGERY WAS SHOWING SOME MOISTURE BEING 
PULLED NORTH FROM THE GULF OF CALIFORNIA AND SPREAD NORTHEAST OVER 
PARTS OF MARICOPA/PINAL/PIMA COUNTIES. YESTERDAYS CLOUD COVER 
ASSOCIATED WITH A WEATHER SYSTEM CURRENTLY MOVING THROUGH UTAH. TO 
THE NORTHWEST OF THIS SYSTEM IS ANOTHER THAT IS GATHERING STRENGTH 
OVER THE PACIFIC NORTHWEST. THIS IS THE SYSTEM THAT WILL BRING THE 
MUCH ADVERTISED SHOT OF DECENT VALLEY RAIN AND PERIODS OF HEAVY 
MOUNTAIN SNOW. MODELS ARE STILL SHOWING THAT PRIME TIME WILL BE 
MONDAY INTO TUESDAY WITH RAPID CLEARING TUESDAY NIGHT. WILL CONTINUE 
THE WINTER STORM WATCH ABOVE 6000 FEET. BEFORE THEN THE PRESSURE 
GRADIENT WILL BE INCREASING FOR BREEZY TO LOCALLY WINDY MONDAY WITH 
WINDS STAYING UP OVERNIGHT.

A BREAK IN THE WEATHER WEDNESDAY BEFORE ANOTHER SERIES OF SYSTEMS 
IMPACTS THE AREA FOR ANOTHER CHANCE OF SHOWERS THURSDAY INTO EARLY 
NEXT WEEKEND. 

&&

.AVIATION...SCATTERED DECKS AROUND 7-9KFT AGL BECOMING BROKEN DECKS 
LATER TODAY INTO TONIGHT. SURFACE WINDS LESS THAN 10 KTS BECOMING 
SLY/SWLY 10-20 KTS AND GUSTY. AVIATION DISCUSSION NOT UPDATED FOR 
TAF AMENDMENTS.

&&

.FIRE WEATHER...DRY CONDITIONS TODAY THOUGH SOME AFTERNOON BREEZES 
PARTICULARLY SOUTH AND EAST OF TUCSON ARE EXPECTED. A STRONG STORM 
SYSTEM WILL THEN IMPACT SOUTHEAST ARIZONA MONDAY AFTERNOON INTO 
TUESDAY. THIS SYSTEM WILL BRING WIDESPREAD VALLEY RAIN AND MOUNTAIN 
SNOW PARTICULARLY MONDAY NIGHT THROUGH MIDDAY TUESDAY. BREEZY TO 
WINDY CONDITIONS WILL ALSO ACCOMPANY THIS SYSTEM. SOMEWHAT DRIER 
CONDITIONS WEDNESDAY THEN A SERIES OF DISTURBANCES WILL MOVE ACROSS 
THE AREA THURSDAY INTO SATURDAY. ENOUGH MOISTURE FOR A CHANCE OF 
RAIN AND MOUNTAIN SNOW THURSDAY INTO SATURDAY. BREEZY TO 
OCCASIONALLY WINDY CONDITIONS MAY ALSO OCCUR WITH THESE SYSTEMS.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
  WINTER STORM WATCH MONDAY AFTERNOON THROUGH TUESDAY AFTERNOON 
   (08/00Z - 09/00Z) AZZ019-030-033>035 ABOVE 6000 FEET.

$$

WEATHER.GOV/TUCSON