FXUS65 KGJT 261303
AFDGJT
COZ001>014-017>023-UTZ022>025-027>029-262200-

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
603 AM MST SAT DEC 26 2009

.UPDATE...REMOVED HEADLINES FOR EXPIRED WINTER WEATHER PRODUCTS.
&&

.SHORT TERM...TODAY THROUGH SUNDAY NIGHT

LARGE STORM SYSTEM OVER THE MIDWEST CONTINUING TO AFFECT OUR
FORECAST AREA AS MOISTURE WRAPS BACK WESTWARD. LIGHT SNOW PERSISTING
OVER THE NRN MTNS...WITH SNOTELS INDICATING UPWARDS OF 3-7 INCHES
OF VERY FLUFFY SNOW IN PLACES IN THE NRN CO MTNS OVER THE LAST 12
HRS. BLOWING SNOW INDICATED AT RABBIT EARS AND VAIL PASSES ON
CDOT ROAD REPORTS EARLIER. LIGHT SNOW ALSO AT MEEKER AT TIMES EARLY
THIS MORNING.

NW CO ON THE FRINGE OF THE ISENTROPIC UPGLIDE AND WEAK Q-FORCING THAT
IS MORE PRONOUNCED OVER ERN WY/NE CO. NAM/GFS MODELS WEAKEN THIS OVER
NW CO THIS MORNING AS THE MIDWEST LOW SLOWLY MOVES E. PRESSURE
GRADIENT ALSO GRADUALLY RELAXES FOR A LESSENING OF THE WIND AND
THREAT OF WIDESPREAD BLOWING SNOW. MODELS KEEP THE AIR VERY MOIST
AND NEARLY ISOTHERMAL FROM MTN TOP LEVEL DOWN IN NW CO...SO EXPECT
LIGHT SNOW TO REMAIN LIKELY FOR THE NRN AND CENTRAL MTNS TODAY IN
VERY STABLE NORTHERLY FLOW...BUT ACCUMS GENERALLY ONLY AROUND AN INCH
ANTICIPATED. PLAN TO LET THE WINTER WEATHER ADVISORY EXPIRE AT 600 AM
THIS MORNING.

PRECIP CHANCES CONTINUE TO DECREASE TONIGHT WITH SUN-SUN NIGHT
LOOKING DRY. SURFACE HIGH PRESSURE PUSHES IN FROM THE NW ON SUN FOR
STABLE CONDITIONS AT THE SURFACE. WEAK PAC SHORTWAVE UNDERCUTS THE
WESTERN RIDGE AND CROSSES ON SUNDAY FOR PARTLY SUNNY SKIES.
TEMPERATURES WILL GRADUALLY WARM OVER THE HIGHER ELEVATIONS...BUT
COLD AIR WILL REMAIN TRAPPED IN THE VALLEYS AND BE SLOWER TO MODIFY.
PATCHY FOG AT NIGHT AS A RESULT...ESPECIALLY IN THE ERN UINTA BASIN.

.LONG TERM...MONDAY THROUGH FRIDAY...

THE MID-RANGE MODELS HAVE A FAIR CONSENSUS FOR THE WORK WEEK. BY
MONDAY THE MAIN RIDGELINE WILL HAVE PASSED EAST OF THE AREA AND SW
FLOW ALOFT WILL DOMINATE. A SPLIT TROUGH WILL EXTEND FROM THE PACNW
TO BAJA CA WITH THE MAIN ENERGY SOUTH OF THE US BORDER. THIS DOMINATE
TROUGH IN THE SPLIT WILL ROTATE NE MONDAY AND MONDAY NIGHT. A
SHORTWAVE TROUGH WILL EJECT OUT AHEAD OF THE MAIN TROUGH WITH PLENTY
OF WARM AND MOIST ADVECTION SPREADING FROM AZ AND NM INTO SW CO BY
MONDAY EVENING. HAVE BOOSTED CLOUDS AND POPS FROM SOUTH TO NORTH TO
SHOW THIS.

BY TUESDAY AFTERNOON THE CENTRAL AND SOUTHERN PORTIONS OF THE SPLIT
TROUGH SHOULD BE MOVING THROUGH THE FORECAST AREA AND BY NIGHTFALL
THE FLOW ALOFT WILL SWITCH TO THE NORTHWEST. THE GFS AND ECMWF AGREE
VERY WELL UP TO THIS POINT. MODEL DIFFERENCES APPEAR IN THE TUE NIGHT
THROUGH THURSDAY MODEL SOLUTIONS. THE MOIST NORTHWEST FLOW ALOFT IS
PRESENT IN EACH SOLUTION...BUT THE ECMWF BRINGS A STRONGER SHORTWAVE
TROUGH THROUGH THE AREA WED. THE GFS SHOWS THIS FEATURE AS NOT MUCH
MORE THAN A CHANNELED VORT MAX. STILL...THE AREAS OF AGREEMENT
JUSTIFY CONTINUING MOSTLY CLOUDY CONDITIONS AND A CHANCE OF PRECIP.
BOTH MODELS SHOW CLEARING AND RIDGING THU AND FRI.

&&

.AVIATION...

AREAS OF SNOW SHOWERS WILL PERSIST OVER THE COLORADO NORTHERN AND
CENTRAL MOUNTAINS AND NORTHWEST PLATEAU THIS MORNING...DECREASING
SLOWLY THIS AFTERNOON. THESE WILL CAUSE AREAS OF MVFR/IFR CIGS AND
VSBYS OVER THE NORTHERN CONTINENTAL DIVIDE AND HIGH PASSES...RABBIT
EARS AND VAIL PASSES IN PARTICULAR...AND ALSO AT SOME LOWER ELEVATION
AIRPORTS FROM I-70 NORTH.  PATCHY FOG POSSIBLE AS WELL THIS MORNING.
VFR CONDITIONS ARE EXPECTED FOR SE UT AND SW CO TODAY.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

CO...NONE.
UT...NONE.

$$

UPDATED......CJC
SHORT TERM...JAD
LONG TERM....CJC
AVIATION.....CJC

$$