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000
FXUS65 KFGZ 071757
AFDFGZ

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE FLAGSTAFF AZ
1045 AM MST SAT DEC 7 2013

.SYNOPSIS...A VERY COLD AIR MASS WILL REMAIN ACROSS NORTHERN ARIZONA
THROUGH EARLY NEXT WEEK WITH TEMPERATURES REMAINING WELL BELOW
AVERAGE. ANOTHER STORM SYSTEM WILL BRING SNOW TO THE AREA THIS
WEEKEND. SNOW IS EXPECTED TO BEGIN ACROSS NORTHWESTERN ARIZONA THIS
AFTERNOON AND SPREAD EASTWARD TONIGHT...ENDING ON SUNDAY.

&&

.DISCUSSION...LOW CLOUDS ARE QUICKLY OVERSPREADING NRN AZ THIS
MORNING AS SOME LOW LEVEL PACIFIC MOISTURE MOVES EASTWARD. THE MAIN
CLOUD BAND ASSOCIATED WITH THE APPROACHING COLD FRONT WAS LOCATED
OVER SW UTAH...SRN NV...AND INTO SRN CALIF THIS MORNING.

MODELS...INCLUDING THE GFS...ECMWF...NAM...AND SREF...ALL CONTINUE TO
TREND DRIER WITH THIS SYSTEM. GIVEN THIS TREND...WILL NEED TO
CONSIDER LOWERING SNOWFALL AMOUNTS AND REMOVING WINTER WEATHER
ADVISORIES FROM SOME LOCATIONS WITH THE ISSUANCE OF THE AFTERNOON
FCST PACKAGE.

&&

.PREV DISCUSSION (4 AM)...A COLD LONG-WAVE TROUGH REMAINS OVER THE
WEST WITH A SHORTWAVE TROUGH RAPIDLY MOVING ESE INTO THE GREAT BASIN
AT THIS TIME. THIS SHORTWAVE FEATURE IS STILL ON TRACK TO MOVE
ACROSS NORTHERN ARIZONA THIS AFTERNOON THROUGH SUNDAY MORNING...BUT
LATEST INDICATIONS ARE IT WILL BE SLIGHTLY LESS AMPLIFIED AND STAY A
BIT FARTHER TO THE NORTH. STILL SHOULD HAVE GOOD UPSLOPE WINDS AND
SUFFICIENTLY COLD TEMPERATURES IN THE CLOUD LAYER FOR EFFICIENT ICE
CRYSTAL GROWTH...HOWEVER THE BEST AND DEEPEST MOISTURE WILL REMAIN
FROM NEAR THE AZ/UT BORDER NORTHWARD. HAVE THEREFORE TRIMMED
SNOWFALL AMOUNTS SLIGHTLY FOR THE MOGOLLON RIM AREA WITH THE LATEST
FORECAST PACKAGE. SNOW LEVELS LOOK TO DROP RAPIDLY TO MOST VALLEY
FLOOR LOCATIONS EXCEPT FOR THE LOWEST ELEVATIONS OF SOUTHERN YAVAPAI
COUNTY. ALSO LOOK FOR WINDY CONDITIONS TODAY AND THIS EVENING...WITH
GUSTS UP TO 40 MPH IN HIGH ELEVATION AREAS FROM THE MOGOLLON RIM
NORTHWARD AS WELL AS THE LITTLE COLORADO RIVER VALLEY.

WINTER WEATHER ADVISORIES REMAIN IN EFFECT FOR MOST OF THE HIGHER
ELEVATION ZONES OF NORTHERN ARIZONA...AND HAVE ADDED THE BLACK MESA
AND CHUSKA MOUNTAIN ZONES IN NORTHEASTERN ARIZONA. SEE PRODUCT
WSWFGZ FOR ADDITIONAL DETAILS.

THE LATEST MODEL RUNS HAVE TRENDED TOWARD A STRONGER TRAILING
SHORTWAVE TROUGH FOR SUNDAY NIGHT/MONDAY...ALTHOUGH AT THIS POINT
MOST DO NOT FEATURE ANY PRECIPITATION. CANT RULE OUT SOME MORE SNOW
SHOWERS WITH THIS FEATURE...SO HAVE ADDED SLIGHT CHANCES IN THE
FORECAST.

RIDGING OVER THE EASTERN PACIFIC MIDWEEK WILL PRODUCE NORTHWEST FLOW
ALOFT AND BREEZY NORTHEAST SURFACE WINDS. THE RIDGE FLATTENS BY THE
LATTER HALF OF THE WEEK ALLOWING A MODERATING WESTERLY FLOW TO MOVE
ACROSS THE DESERT SOUTHWEST.

&&

.AVIATION...FOR THE 12Z PACKAGE...EXPECT VFR CONDITIONS THROUGH
16Z-18Z...WITH INCREASING MID-LEVEL CLOUDS. SCT MVFR/IFR CONDITIONS
IN -SHSN WILL DEVELOP FROM KKNB TO KGCN AFT 20Z-22Z. THIS AREA WILL
SPREAD SOUTH AND EAST AND INCREASE IN COVERAGE THROUGH 23Z-01Z. BY
01Z-03Z...MOST SITES WILL SEE MVFR/IFR CONDITIONS IN -SHSN/SHSN WITH
AREAS OF LIFR AND ISOLD VLIFR OVER THE MOGOLLON RIM AND TOWARD THE
HIGHER TERRAIN NEAR KRQE. SFC WNDS WILL INCREASE TO 15-25KTS WITH
GUSTS TO 35KTS MOST AREAS FROM 18Z SATURDAY THROUGH 02Z-04Z SUNDAY.
AVIATION DISCUSSION NOT UPDATED FOR AMENDMENTS.

&&

.FGZ WATCHES/WARNINGS/ADVISORIES...

WINTER WEATHER ADVISORY FROM 2 PM TODAY TO 5 AM MST SUNDAY
FOR AZZ004-006.

WINTER WEATHER ADVISORY FROM 5 PM TODAY TO 11 AM MST SUNDAY
FOR AZZ007-008-015-038.

WINTER WEATHER ADVISORY FROM 6 PM TODAY UNTIL 2 PM MST SUNDAY FOR
AZZ011-039.

WINTER WEATHER ADVISORY FROM 8 PM TODAY TO 2 PM MST SUNDAY
FOR AZZ016>018.


&&

$$

PUBLIC.........DB/ONTON
AVIATION.......TC

FOR NORTHERN ARIZONA WEATHER INFORMATION VISIT WEATHER.GOV/FLAGSTAFF