FXUS65 KFGZ 060402
AFDFGZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
900 PM MST SAT DEC 5 2009
.SYNOPSIS...EXPECT INCREASING CLOUDS...COLD TEMPERATURES...AND WINDY
CONDITIONS THROUGH 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...THE FIRST IN A SERIES OF UPPER LEVEL DISTURBANCES...IS
CURRENTLY MOVING THROUGH UTAH AND WILL AFFECT NORTHERN ARIZONA
OVERNIGHT TONIGHT WITH INCREASING MID AND HIGH LEVEL CLOUDS AND A
CHANCE FOR WIDELY SCATTERED TO SCATTERED VERY LIGHT SNOW OR FLURRIES
FROM INTERSTATE 40 NORTH. THE ATMOSPHERE IS STILL VERY DRY THIS
EVENING WITH DEW POINT VALUES RANGING FROM AROUND -5 DEGREES TO +5
FAHRENHEIT. WINDS WILL BE A LITTLE STRONGER OVERNIGHT TONIGHT...
ESPECIALLY IN THE HIGHER ELEVATIONS AS THE PRESSURE GRADIENT
INCREASES ACROSS THE AREA. FOR TONIGHT WITH BREEZY CONDITIONS
DEVELOPING...EXPECT WARMER SUNDAY MORNING LOW TEMPERATURES...NOT AS
COLD AS THE LOW TEMPS FROM THIS MORNING. LOWERED SUNDAY MORNING'S
MIN TEMPS IN THE DIGITAL GRIDDED FORECAST BY 1 TO 2 DEGREES...NOT
ENOUGH TO WARRANT AN UPDATE OF THE TEXT PRODUCTS. CURRENT GUIDANCE
GOING A LITTLE COLDER FOR TONIGHT...OVERNIGHT LOW TEMPS COULD BE A
LITTLE DIFFICULT TO FORECAST DEPENDING UPON IF THE WINDS STAY UP IN
SOME LOCATIONS.
STILL ON TRACK FOR A MAJOR STORM MOVING THROUGH THE REGION WITH
SIGNIFICANT SNOWFALL ABOVE 5500 FEET BEGINNING MONDAY AFTERNOON AND
CONTINUING INTO MONDAY EVENING AND EARLY TUESDAY MORNING WEST AND
CENTRAL...THEN LATE TUESDAY MORNING EARLY TUESDAY AFTERNOON EAST.
ELEVATION BELOW 5000 FEET LIKELY TO SEE SIGNIFICANT RAINFALL...ANY
MOISTURE FROM THIS STORM WILL BE MOST WELCOME...WITH MOST AREAS
HAVING VERY DRY CONDITIONS.
&&
.PREVIOUS DISCUSSION /330 PM MST/...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 06Z PACKAGE...HIGH AND MID LEVEL CLOUDS WILL
MOVE OFF TO THE EAST WITH SCATTERED LOW CLOUDS DEVELOPING FROM 2500
TO 4000 FT AGL THIS EVENING AND LASTING THROUGH 06/06Z. EXPECT
MAINLY VFR CONDITIONS WITH LCL MVFR DUE TO LOW CIGS. BREEZY
SOUTHWEST SFC WINDS ARE ALSO EXPECTED IN THE 10 TO 20 MPH RANGE WITH
GUSTS UP TO 30 MPH DURING THE DAYLIGHT HOURS. 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..................TC/JJ
AVIATION/FIRE WEATHER...BOHLIN
VISIT WEATHER.GOV/FLAGSTAFF FOR NORTHERN ARIZONA WEATHER INFORMATION.
