FXUS65 KFGZ 052233
AFDFGZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
330 PM MST SAT DEC 5 2009

.SYNOPSIS...EXPECT INCREASING CLOUDS...COLD TEMPERATURES...AND WINDY 
CONDITIONS TODAY AND SUNDAY AHEAD OF A MAJOR WINTER STORM SYSTEM 
DEVELOPING NORTH OF ARIZONA. THIS STORM WILL AFFECT NORTHERN AND 
CENTRAL ARIZONA FROM MONDAY INTO TUESDAY MORNING. SNOW LEVELS 
WILL RANGE FROM 5000 TO 6000 FEET WITH HEAVY SNOW ACCUMULATIONS 
ABOVE 6000 FEET...ESPECIALLY ALONG THE MOGOLLON RIM AND WHITE 
MOUNTAINS. AT LOWER ELEVATIONS SOUTH OF THE RIM...EXPECT PERIODS OF 
MODERATE TO HEAVY RAINFALL.

&&

.DISCUSSION...A MAJOR WESTERN U.S. TROUGH CONTINUES TO DEVELOP THIS 
AFTERNOON. THE FIRST EFFECTS FOR OUR AREA WILL BE INCREASING 
SOUTHWEST WINDS AND CONTINUED COLD TEMPERATURES. THERE IS A SLIGHT 
CHANCE OF SOME LIGHT SNOW SHOWERS ACROSS THE REGION LATE TONIGHT 
THROUGH SUNDAY...BUT THE CURRENT VERY DRY AIR MASS WILL LIMIT THIS 
ACTIVITY. 

FORECAST MODELS ARE IN GOOD AGREEMENT THAT THE NEXT SHORTWAVE WILL 
DIVE DOWN THE WEST COAST MONDAY...THEN MOVE ACROSS OUR AREA LATE 
MONDAY INTO EARLY TUESDAY. A MOISTURE PLUME IS EXPECTED TO DEVELOP 
FROM OFF THE PACIFIC WITH PRECIPITATION BEGINNING OVERNIGHT SUNDAY. 
AS THE MAIN SYSTEM APPROACHES MONDAY...PRECIPITATION WILL INCREASE 
WITH STRONG UPSLOPE FLOW AND MODERATE SYNOPTIC LIFT. SNOW LEVELS 
WILL START OFF AT 5500-6500 FT. THE MAIN EVENT IS STILL EXPECTED 
MONDAY NIGHT INTO EARLY TUESDAY WITH A PERIOD OF HEAVY SNOW ABOVE 
5000-6000 FEET...AND SUBSTANTIAL RAINFALL AT THE LOWER ELEVATIONS. 
STRONG SOUTHWEST WINDS...SUSTAINED AT 25 TO 35 MPH...GUSTING TO 
40-55 MPH...WILL ALSO CREATE BLOWING AND DRIFTING SNOW AND VERY 
HAZARDOUS TRAVEL CONDITIONS. BLIZZARD CONDITIONS ARE NOT OUT OF THE 
QUESTION FOR A BRIEF TIME MONDAY NIGHT. BY THE TIME THE SYSTEM MOVES 
EAST OF OUR AREA TUESDAY...TOTAL SNOWFALL OF 1-2 FEET IS POSSIBLE 
ABOVE 6000 FEET...WITH LIGHTER AMOUNTS DOWN TO THE 5000 FOOT LEVEL. 
A WINTER STORM WATCH REMAINS IN EFFECT FROM MONDAY INTO TUESDAY 
MORNING...THOUGH FOR THE WHITE MTNS THE WATCH WAS DELAYED UNTIL 
MONDAY AFTERNOON.

A BREAK IN THE WEATHER IS FORECAST FROM MIDDAY TUESDAY THROUGH EARLY 
THURSDAY. HOWEVER...THE LATEST FORECAST MODELS INDICATE A RETURN TO 
MOIST FLOW OFF THE PACIFIC BY LATE IN THE WEEK. IN ADDITION... 
ANOTHER SHORTWAVE MAY MOVE THROUGH WITH MODERATE SNOW AND VALLEY 
RAIN A POSSIBILITY ONCE AGAIN...PRECIP CHANCES IN OUR FORECAST ARE 
IN THE 20-40 PERCENT RANGE FOR NOW.  

STAY TUNED FOR THE LATEST UPDATES CONCERNING THE UPCOMING WINTRY 
WEATHER. 

&&

.AVIATION...FOR THE 00Z PACKAGE...THROUGH 06Z SUN...VFR CONDITIONS 
WITH BKN-OVC CIGS WITH BASES AOA 15 KFT MSL. AFT 06Z SUN...HIGH 
CLOUDS MOVE OFF TO THE EAST...WITH UPSLOPE STRATUS DEVELOPING BY 12Z 
ALONG THE MOGOLLON RIM AND WHITE MOUNTAINS...WITH LCL MVFR CIGS AND 
A SLIGHT CHANCE OF -SHRA/-SHSN ALONG AND NORTH OF THE MOGOLLON RIM.  
AFT 15Z SUNDAY...SOUTHWEST WINDS 15-20 KT WITH GUSTS TO 30 KT. 
AVIATION DISCUSSION NOT UPDATED FOR AMENDMENTS.

&&

.FGZ WATCHES/WARNINGS/ADVISORIES...WINTER STORM WATCH FROM MONDAY 
MORNING THROUGH TUESDAY MORNING FOR ELEVATIONS ABOVE 5000 FEET FOR 
AZ ZONES AZZ004>013-015-016-018-038>040.

WINTER STORM WATCH FROM MONDAY AFTERNOON THROUGH TUESDAY MORNING 
ABOVE 5500 FEET FOR AZ ZONES AZZ014-017. 

&&
$$

PUBLIC..................JJ / NP
AVIATION/FIRE WEATHER...41

VISIT WEATHER.GOV/FLAGSTAFF FOR NORTHERN ARIZONA WEATHER INFORMATION.