FXUS65 KTWC 072125
AFDTWC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TUCSON AZ
225 PM PM MST MON DEC 7 2009

.SYNOPSIS...A STRONG WINTER STORM WILL BRING WIDESPREAD VALLEY RAIN 
AND SIGNIFICANT MOUNTAIN SNOW TO SOUTHEAST ARIZONA TONIGHT INTO 
MIDDAY TUESDAY. DRIER CONDITIONS WEDNESDAY FOLLOWED BY ANOTHER 
CHANCE OF VALLEY RAIN AND MOUNTAIN SNOW THURSDAY INTO FRIDAY.

&&

.DISCUSSION...KEMX WSR-88D DETECTED SCATTERED-NUMEROUS 25-35 DBZ 
ECHOES MOVING NEWD ACROSS SE PINAL COUNTY AND FAR WRN/CENTRAL PIMA 
COUNTY AT 2115Z. THE REST OF SE AZ WAS VOID OF PRECIP ECHOES AT THIS 
TIME. SIGNIFICANT WINTER WEATHER SYSTEM APPROACHING SE AZ THIS 
AFTERNOON. 07/12Z GFS/NAM/ECMWF REMAINED IN GOOD AGREEMENT AND 
CONTINUED TO DEPICT DEEPER-LAYER MOISTURE ACROSS SE AZ TONIGHT-TUE 
MORNING. THIS PERIOD IS COINCIDENT WITH SYNOPTIC-SCALE FORCING AS 
PER 700-300 MB NEGATIVE DIV-Q AND OMEGA FIELDS. STRONG JET DYNAMICS 
WILL ALSO SUPPORT POTENTIALLY SIGNIFICANT PRECIP EVENING. FOR 
INSTANCE...07/12Z GFS PROGGED 160 KT 250 MB JET MAX OVER THE AREA 
TONIGHT. 

THE UPSHOT...BLIZZARD WARNING IS IN EFFECT THIS EVENING-MIDDAY TUE 
ABOVE 8K FT ZONES 19/30 AS WELL AS WINTER STORM WARNING BETWEEN 6-8K 
FT. ALSO...WINTER STORM WARNING IS IN EFFECT SAME PERIOD FOR ABOVE 
6K FT FOR ZONES 33-35...TUCSON METRO AREA SEWD. AND...WIND ADVISORY 
IS IN EFFECT FROM TUCSON EWD/SWD FROM 11 PM MST TONIGHT-NOON TUE. 

EXPECTED TOTAL SNOW ACCUMULATIONS BY WED MORNING...UP TO 18 INCHES 
IN THE WHITES...12-14 INCHES IN THE PINALENOS...UP TO A FOOT IN THE 
CATALINA/RINCONS...AND UP TO 10 INCHES IN THE MOUNTAINS OF COCHISE/ 
SANTA CRUZ COUNTIES. LIQUID AMOUNTS PERHAPS AS MUCH AS ONE INCH 
NORTH OF TUCSON...OTHERWISE QPF/S TO BE GENERALLY LESS THAN ONE HALF 
OF AN INCH. 

SHORTWAVE RIDGE ALONG THE CALIFORNIA COAST WED WILL FLATTEN AND MOVE 
EWD ACROSS THE AREA WED NIGHT. DRY CONDITIONS WED AND WED NIGHT 
THOUGH RIDGE TO BE FAIRLY DIRTY WITH MID AND HIGH-LEVEL MOISTURE TO 
MOVE ACROSS THE AREA. THEREAFTER...A SERIES OF DISTURBANCES PROGGED 
TO MOVE MAINLY ACROSS THE GREAT BASIN REGION THUR INTO THE WEEKEND. 
ENOUGH MOISTURE TO SUPPORT A SLIGHT CHANCE OF VALLEY RAIN AND 
MOUNTAIN SNOW SHOWERS NE OF TUCSON THRU THIS PERIOD...WITH A SLIGHT 
CHANCE OF RAIN/MOUNTAIN SNOW SHOWERS TUCSON METRO AREA THUR-FRI.

DAYTIME HIGH TEMPS TUE ABOUT 10 DEGS OR SO BELOW NORMAL. WARMER WED 
WITH HIGH TEMPS THUR-MON TRENDING EITHER CLOSE TO NORMAL OR A FEW 
DEGS BELOW NORMAL.

&&

.AVIATION...CLOUD DECKS GENERALLY AROUND 4-7K FT AGL THROUGH 18Z 
TUESDAY. SCT -SHRA MAINLY NW KTUS THRU 00Z...THEN WIDESPREAD MVFR 
CONDITIONS DUE TO SHRA/HIGHER TERRAIN SHSN DURING THE 00Z-18Z PERIOD 
TUESDAY. SURFACE WINDS SWLY/WLY 15-30 KTS WITH GUSTS OF 30-45 KTS. 
CONDITIONS IMPROVING WITH DECREASING CLOUDS/PRECIP AND LESS WIND 
DURING THE 18Z-23Z PERIOD TUESDAY. AVIATION DISCUSSION NOT UPDATED 
FOR TAF AMENDMENTS.

&&

.FIRE WEATHER...A STRONG STORM SYSTEM WILL BRING WIDESPREAD VALLEY 
RAIN AND MOUNTAIN SNOW ESPECIALLY TONIGHT THROUGH MIDDAY TUESDAY. 
BREEZY TO WINDY CONDITIONS WILL ALSO ACCOMPANY THIS SYSTEM. DRIER 
CONDITIONS WILL OCCUR WEDNESDAY. ENOUGH MOISTURE FOR A CHANCE OF 
RAIN AND MOUNTAIN SNOW THURSDAY INTO SATURDAY AS A SERIES OF 
DISTURBANCES MOVE ACROSS THE AREA. BREEZY TO OCCASIONALLY WINDY 
CONDITIONS MAY ALSO ACCOMPANY THESE SYSTEMS.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
  BLIZZARD WARNING IN EFFECT FROM 5 PM THIS EVENING TO NOON MST 
   TUESDAY ABOVE 8000 FEET FOR AZZ019-030.

  WINTER STORM WARNING IN EFFECT FROM 5 PM MST THIS EVENING TO 
   NOON MST TUESDAY BETWEEN 6000 AND 8000 FEET FOR AZZ019-030.

  WINTER STORM WARNING IN EFFECT FROM 5 PM MST THIS EVENING TO
   NOON MST TUESDAY ABOVE 6000 FEET FOR AZZ033>035.
  
  WIND ADVISORY IN EFFECT FROM 11 PM MST TONIGHT TO NOON MST 
   TUESDAY FOR ZONES 019-030-033>035.

$$

BF

WEATHER.GOV/TUCSON