000
FXUS65 KGJT 280939
AFDGJT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
300 AM MST TUE DEC 28 2010
...STRONG WINTER STORM TO AFFECT THE AREA WEDNESDAY THROUGH FRIDAY...
.SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT...
HEIGHTS FALL TUESDAY AS NEXT MAJOR WINTER STORM BEGINS TO EVOLVE AND
ORGANIZE ALONG THE CNTRL COAST AND INTO THE WRN GRT BASIN. FOR THE
MOST PART OUR CWA WILL BE CLOUDY ACROSS THE NORTH BUT DRY...
TRANSITIONING TO TO SUNNY ACROSS THE EXTREME SWRN PORTION OF THE
CWA. THE FLOW ALOFT WILL BEGIN TO BACK TO THE WEST-SOUTHWEST TUE
NIGHT AS THE POTENT WINTER DIGS INTO THE GRT BASIN BUT LITTLE IF
ANY PCPN IS EXPECTED FOR OUR FA.
WEDNESDAY A STRONG POLAR JET DIGS INTO THE UPSTREAM SIDE OF THE GRT
BASIN TROF CAUSING RAPID DEEPENING AND CYCLOGENESIS. AT THE SAME
TIME PCPN BEGINS TO SPREAD EWRD ACROSS OUR CWA AS BAROCLINIC ZONE TO
THE WEST BECOMES MORE DEFINED. H7 WINDS ALSO INCREASE TO THE 30-
40KT RANGE PROVIDING GOOD OROGRAPHIC ASCENT FOR MOISTURE WHICH
EXCEEDS 3G/KG. TEMPS START OUT AROUND -6 C AT H7 AND GENERALLY GO NO
HIGHER...BELIEVE AT THIS TIME THE SRN VALLEYS WILL SEE MOSTLY SNOW.
SO FAR MDL SNOW AMOUNTS IMPRESSIVE WITH BLANDING AND DURANGO GETTING
WELL OVER A FOOT OF NEW SNOW BY THU AFTERNOON. THIS IS ALSO
CORROBORATED BY BUFKIT SOUNDING FCST...SO WILL EXPEND THE CURRENT
WINTER STORM WATCH TO INCLUDE MOST OF THE SRN VALLEYS. FOR THE LOWER
CENTRAL VALLEYS LIKE GJT IT APPEARS MORNING PCPN WILL FALL AS SNOW
THEN CHANGE TO RAIN DURING THE AFTERNOON...THEN BACK TO SNOW AGAIN
WED NIGHT. AS FOR THE NRN VALLEYS AND PLATEAU COUNTRY QPF/SNOW
AMOUNTS LOOK QUITE A BIT LIGHTER SO WILL LET THE DAY SHIFT LOOK AT
LATER MDL DATA AND ACCESS POTENTIAL SNOW AMOUNTS. A STRONG SURFACE
COLD FRONT ACCOMPANIED BY A BURST OF SNOWFALL WILL MOVE ACROSS NE
UTAH WEDNESDAY EVENING AND THEN PROGRESS SEWRD TO AROUND GJT BY 10-
12Z. THIS WILL BE THE BEGINNING OF THE HEAVIEST PCPN AS UPPER LEVEL
SYNOPTIC FORCING PEAKS WHILE COLD ADVECTION LOWERS THE SNOW LEVEL TO
THE LOWEST VALLEYS.
AT THE LAST MINUTE I DECIDED TO ADD CO ZONES 2 AND 5 TO THE WINTER
STORM WATCH AS AREA OF CONVERGENCE PASSES FROM SW TO NE ACROSS THIS
REGION.
.LONG TERM...THURSDAY THROUGH MONDAY NIGHT
WINTER STORM CONTINUES AS CLOSED LOW AND COLD FRONT WILL BE JUST
ENTERING CWA. ALL MODELS CONTINUE TO AGREE ON FRONT PASSING DURING
THE MORNING HOURS FOR ERN UT AND EXTREME WRN CO AND AS IT DOES...
IT WILL BE THE FOCUS FOR PERIODS OF HEAVY SNOWFALL. NAM/GFS/SREF
ALSO CONTINUE TO PINPOINT MOISTURE CONVERGENCE FOR 12HR PERIOD ALONG
AND JUST N OF GRAND VALLEY. THIS SIGNATURE HAS INDICATED DECENT
SNOWFALL AMTS IN THE PAST SO WILL KEEP AN EYE ON FURTHER MODEL RUNS
AND LET DAY SHIFT HAVE A LOOK BEFORE ISSUING ANY HIGHLIGHTS FOR
VALLEY. AS PREVIOUSLY STATED...HEAVIEST SNOWFALL WILL OCCUR THUR
MORNING WITH FROPA WHILE SNOW CONTINUES OVER SAN JUANS. FRONT WILL
BE THRU CWA LATE AFTN AS TEMPS START TO PLUMMET BEHIND FRONT.
BY FRI MORNING...CENTER OF CLOSED LOW WILL HAVE SHIFTED OVR PLAINS
WITH SNOW TAPERING OFF WITH HEAVIER SNOWSHOWERS OVER FAVORED
MOUNTAINOUS TERRAIN. IN FACT...SPORADIC SNOW SHOWERS CAN BE
EXPECTED THRU EARLY SAT MORNING AS W/NW FLOW SETS UP.
AS HAS BEEN STATED SINCE THIS STORM FORMED...TEMPS WILL DROP
CONSIDERABLY FOR NEW YEARS EVE AND BEYOND WITH HIGHS REACHING
SINGLE TO MID-TEENS AND LOWS WELL BELOW ZERO IN MANY PLACES.
REMEMBER TO STAY BUNDLED UP FOR ANY ACTIVITIES FRIDAY NIGHT AND
ENSURE PETS ARE LOOKED AFTER OR BROUGHT INSIDE.
FOR REMAINING LONG-TERM...SATURDAY AND BEYOND...MODELS DO NOT
HAVE GOOD HANDLE ON NEXT SYSTEM TO INCLUDE SPEED...TIMING...DEPTH...
LOCATION...ETC. THUS....MADE NO CHANGES TO CURRENT GRIDS LEAVING SCHC
SNOW SHOWERS FOR HIGHER ELEVATIONS.
&&
.AVIATION...
VFR CONDITIONS TODAY AND TONIGHT WITH CLOUDS ON THE INCREASE FROM
WEST TO EAST EARLY WED MORNING.
&&
CO...WINTER STORM WATCH FOR ALL MOUNTAIN ZONES AND SOUTHERN
VALLEYS WEDNESDAY THROUGH FRIDAY...ZONES 02/03/04/05/09/10/12/
13/17/18/19/21/22/23.
UT...WINTER STORM WATCH FOR ALL MOUNTAIN ZONES AND SOUTHERN
VALLEYS WEDNESDAY THROUGH FRIDAY...ZONES 22/23/25/28/29.
&&
$$
SHORT TERM...MC
LONG TERM....TGR
AVIATION.....TGR
