Area Forecast Discussion
Issued by NWS Grand Junction, CO

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000
FXUS65 KGJT 210604
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1104 PM MST SAT DEC 20 2014

.SHORT TERM...(TONIGHT THROUGH SUNDAY NIGHT)
ISSUED AT 355 PM MST SAT DEC 20 2014

LATEST SATELLITE IMAGERY SHOWS PLENTY OF CLOUDS MOVING INTO THE
AREA FROM THE NW AS THE FIRST DISTURBANCE MOVES OVER THE
AREA...SETTING THE STAGE FOR TOMORROW. FOR THE REMAINDER OF THE
EVENING AND OVERNIGHT...MODELS PICKING UP ON SOME PRECIP FOR
AREAS MAINLY N OF THE SAN JUANS WITH A RAIN TO RAIN-SNOW MIX FOR
LOWER VALLEYS AND SOME ACCUMULATING SNOW FOR THE HIGHER
TERRAIN.  MAYBE 1 TO 3 INCHES...GENERALLY FOR THE NRN MTNS THOUGH
THE CENTRAL MTNS MIGHT SEE THAT MUCH TOO. HOWEVER...THESE AMTS
HAVE NOTHING ON WHAT WE CAN EXPECT STARTING TOMORROW.

THE JET STREAM THAT HAS STAYED TO OUR NORTH FOR QUITE SOME TIME
HAS FINALLY BEGUN TO DROP DOWN FROM THE NORTH AND ALSO BECOME A
BIT MORE MERIDIONAL THAN PREVIOUS RUNS. THIS PUTS WESTERN COLORADO
IN THE COLDER SECTOR WHILE ALSO KEEPING MUCH OF THE STATE IN THE
FAVORABLE LEFT EXIT REGION OF THE JET. THIS REGION WILL CAUSE
PLENTY OF UPLIFT FOR EFFICIENT SNOW. GUIDANCE ALSO SHOWS PLENTY OF
MOISTURE IN THE AREA WITH HIGH SPECIFIC HUMIDITIES IN PLACE. ALL
THE ABOVE MEANS WE ARE PRIMED FOR SOME ACCUMULATING SNOWFALL.

SPOTTY PRECIP WILL START SUNDAY MORNING BEFORE BECOMING MORE
STEADY NOON ONWARDS WITH THE HEAVIEST PRECIP EXPECTED FROM SUNDAY
AFTERNOON THROUGH MONDAY MORNING. SOME HIGHLIGHTS INCLUDE A FOOT
TO OVER 2 FEET OF SNOW FOR THE PARK/GORE AND ELKHEAD MTNS MAINLY
DUE TO A WRLY FLOW THAT WILL BECOME NRLY AS THE STORM EVOLVES ALLOWING
SNOW TO KEEP PILING UP. SIMILAR AMOUNTS ARE ALSO POSSIBLE FOR THE
CENTRAL MTNS. THE NRN PORTIONS OF THE WRN SAN JUANS WILL LIKELY
SEE OVER A FOOT BUT NOT SOLD ON SRN PORTIONS SO LEFT IN ADVISORY
FOR NOW...LATER SHIFTS MAY NEED TO UPGRADE. ISSUED A WARNING FOR
THE CRAIG/MEEKER/HAYDEN AREA WITH 6 TO 10 INCHES OF SNOW POSSIBLE
THOUGH AREAS IN THE EAST AND SOUTH PORTIONS OF THE ZONE WILL SEE
THE HIGHEST AMOUNTS. ALSO ANTICIPATE WARNING AMTS EAST OF RIFLE
ALONG I-70 INCREASING AS YOU TRAVEL TO VAIL PASS. FOR RIFLE AND
AREAS WEST ALONG I-70 THROUGH DEBEQUE CANYON MAY SEE 2 TO 4 INCHES
THOUGH TEMPS WILL BE HOVERING RIGHT AROUND FREEZING.

AS THE 140KT+ JET MOVES OVERHEAD...SOME OF THESE WINDS ARE
EXPECTED TO MIX DOWN CAUSING GUSTS ANYWHERE FROM 30 TO POSSIBLY 50
MPH (AT THE HIGHEST ELEVATIONS) CREATING WHITEOUT CONDITIONS FROM
TIME TO TIME. IMPORTANT TO MENTION THAT MOST OF THESE WINDS WILL
BE FELT AT HIGHER ELEVATIONS THOUGH WINDS ALONG THE CO/WY BORDER
COULD GET FAIRLY BREEZY FROM TIME TO TIME SUNDAY.

.LONG TERM...(MONDAY THROUGH SATURDAY)
ISSUED AT 355 PM MST SAT DEC 20 2014

SNOW CONTINUES MONDAY AS THE 140-150KT CORE OF THE 300 MB JET MOVES
FROM NORTHEASTERN UT INTO SOUTHWESTERN CO...AND A 700 MB COLD FRONT
PUSHES SOUTH ACROSS THE FORECAST AREA. SNOW WILL BE HEAVY AT TIMES
MONDAY...AND TRAVEL CONDITIONS OVER THE MOUNTAINS WILL BE POOR.
WITH 700 MB WINDS OF 40-50 KTS ACROSS THE NORTH...EXPECT STRONG
WINDS OVER THE MTNS CREATING AREAS OF BLOWING SNOW. A FEW AREAS MAY
EXPERIENCE NEAR BLIZZARD CONDITIONS WITH GUSTS EXCEEDING 45 MPH...
ESPECIALLY ABOVE TIMBERLINE ACROSS THE PARK AND GORE RANGES AND
POSSIBLY AS FAR SOUTH AS VAIL PASS ON MONDAY. FOR THE ERN UINTA
MTNS...CONCERN ABOUT SNOW AND BLOWING SNOW WITH THE FRONTAL PASSAGE
AND UPPER JET AND ITS IMPACT ON TRAVEL PROMPTED THE WINTER STORM
WATCH THERE DESPITE SNOW AMOUNTS ON THE LOW SIDE. LOWERED MAX TEMPS
ON MONDAY WITH ABUNDANT CLOUD COVER AND COLDER AIR MOVING IN.

THE NORTHWEST OROGRAPHIC FLOW BECOMES NORTHERLY MONDAY AFTERNOON...
WHICH THEN PERSISTS THROUGH MONDAY EVENING. THE VERY MOIST DENDRITIC
SNOW GROWTH ZONE LOWERS TO OR BELOW MTN TOP LEVEL IN COLD ADVECTION
BEHIND THE FRONT TO TAKE FULL ADVANTAGE OF THE OROGRAPHIC LIFT. A
BIT CONCERNED THAT THE 12Z Q-G DIAGNOSTICS FAVORED LARGE-SCALE
DOWNWARD MOTION MONDAY...THOUGH. NORTH FLOW AND LOW-LEVEL MOISTURE
BANKED UP AGAINST THE FLATTOPS/ROAN PLATEAU SHOULD KEEP SNOW IN THE
CRAIG AND MEEKER AREAS MONDAY EVENING...BUT WILL NOT BE AS FAVORABLE
FOR THE STEAMBOAT SPGS.

THE UPPER JET AND LOW LEVEL MOISTURE SEEM SLOWER TO PUSH EAST MONDAY
NIGHT AND TUESDAY THAN EARLIER MODEL RUNS. CHANCE OF SNOW PERSISTS
IN THE NRN AND CENTRAL CO MTNS TUE. A LULL IN THE PRECIPITATION
EXPECTED WEDNESDAY UNDER TEMPORARY RIDGING AS THE NEXT PACIFIC STORM
MOVES INTO WA/OR. GFS AND ECMWF CONTINUE TO PUSH IT ACROSS OUR AREA
CHRISTMAS DAY WHILE THE CANADIAN DIGS IT DOWN THE CA COAST WED
NIGHT AND NOT PREFERRED. BOTH GFS AND ECMWF CONTINUE THE TREND OF
THE WAVE BEING FLATTER AND A LITTLE FARTHER NORTH...THOUGH ECMWF
SEEMS TO VACILLATE WITH THE AMPLITUDE BETWEEN ITS EVENING AND
MORNING MODEL RUNS. WILL KEEP THE BETTER CHANCE OF PRECIPITATION
OVER THE NRN AND CENTRAL MTNS FOR NOW.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT)
ISSUED AT 1100 PM MST SAT DEC 20 2014

A FEW ISOLATED SHOWERS OVER WEST CENTRAL COLORADO WILL CONTINUE
THROUGH 12Z...LOWERING VIS AND CIGS AT KASE...KEGE...AND K5SM.
KVEL`S VISIBILITY WILL FLUCTUATE THROUGHOUT THE NIGHT WITH LOW
CIGS STILL BEING AN ISSUE.

CONDITIONS WILL BEGIN TO DETERIORATE NOTICABLY AFTER 12Z SATURDAY
MORNING AT THE NORTHWEST AND WEST CENTRAL COLORADO AIRPORTS WITH A
SIGNIFICANT INFLUX OF MOISTURE BRINGING WIDESPREAD PRECIP. THE
SOUTHERN VALLEYS OF SE UTAH AND SW COLORADO ARE EXPECTED TO REMAIN
DRY. MOUNTAIN TOP WINDS WILL INCREASE SUBSTANTIALLY DURING THE
AFTERNOON ON SUNDAY ACROSS THE NORTH AND FILTER INTO SOUTHERN UTAH
AND COLORADO AS WELL. LLWS WILL HAVE TO BE WATCHED FOR AS WINDS
BEGIN TO FILTER DOWN TO THE SFC. EXPECT WIDESPREAD MTN
OBSCURATIONS BY SUNDAY AFTERNOON AT ALL MTN TAF SITES AND VALLEYS
EAST OF GJT.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...WINTER WEATHER ADVISORY FROM NOON SUNDAY TO MIDNIGHT MST MONDAY
     NIGHT FOR COZ014.

     WINTER STORM WARNING FROM 6 PM SUNDAY TO MIDNIGHT MST MONDAY
     NIGHT FOR COZ018.

     WINTER WEATHER ADVISORY FROM 6 PM SUNDAY TO 6 PM MST MONDAY FOR
     COZ017-019.

     WINTER STORM WARNING FROM 6 AM SUNDAY TO MIDNIGHT MST MONDAY
     NIGHT FOR COZ002-010-012.

     WINTER STORM WARNING UNTIL MIDNIGHT MST MONDAY NIGHT FOR COZ004-
     013.

     WINTER WEATHER ADVISORY FROM NOON SUNDAY TO 6 PM MST MONDAY FOR
     COZ003.

     WINTER STORM WARNING FROM NOON SUNDAY TO 6 PM MST MONDAY FOR
     COZ007>009.

     WINTER STORM WARNING FROM 6 AM SUNDAY TO 6 PM MST MONDAY FOR
     COZ005.

UT...WINTER STORM WATCH FROM LATE SUNDAY NIGHT THROUGH MONDAY
     AFTERNOON FOR UTZ023.

&&

$$

SHORT TERM...TGR
LONG TERM...JAD
AVIATION...JAM


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