Area Forecast Discussion
Issued by NWS Grand Junction, CO

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS65 KGJT 251746 AAA
AFDGJT

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1046 AM MST THU DEC 25 2014

UPDATED FOR AVIATION DISCUSSION

.UPDATE...
ISSUED AT 906 AM MST THU DEC 25 2014

ADDED SEVERAL ADVISORIES IN ANTICIPATION OF ACCUMULATING SNOW
OCCURRING AT LOWER ELEVATIONS THAN ORIGINALLY EXPECTED. ZONE 7
PICKED UP A COUPLE OF INCHES IN A SHORT AMOUNT OF TIME THIS
MORNING AND THE HEAVIER SNOW IS STILL YET TO COME. WEBCAMS SHOW
SNOW ACCUMULATION ON ROADS IN MOST VALLEYS AND IMPACTS ARE
EXPECTED TO CONTINUE THROUGH TOMORROW AFTERNOON. EXPECTING UT
ZONE 29 WILL SEE LESS SNOW IN SOUTHERN AREAS BUT MORE UP IN
CANYONLANDS NATL PARK AND DEADHORSE STATE PARK. WITH TEMPERATURES
COOLING ALOFT...EXPECTING SNOW RATIOS TO INCREASE THROUGHOUT THE
NEXT 24 HOURS.

&&

.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 351 AM MST THU DEC 25 2014

THE CHRISTMAS STORM OF 2014 WAS GENERALLY BEGINNING AS ADVERTISED
THIS EARLY MORNING WITH WARM-SECTOR SNOW SPREADING INTO THE
NORTHERN ZONES AFTER MIDNIGHT. AT 3 AM SNOTEL SITES HAD NOT
REGISTERED ACCUMULATIONS BUT STEAMBOAT SPRINGS ROADS WERE
SNOWPACKED.

THE UPPER TROUGH WILL DIG THROUGH THE GREAT BASIN TODAY CLOSING
OVER UTAH BY THIS AFTERNOON. IT SLOWLY PROGRESSES TO THE FOUR
CORNERS TONIGHT THEN BEGINS TO OPEN AND LIFT THROUGH COLORADO ON
FRIDAY. THIS STORM HAS DECENT COLD AIR...-30C AT 500MB...BUT
MARGINAL MOISTURE...0.39 PW. ITS 85KT JET NOSE LINGERS OVER
SOUTHERN COLORADO THROUGH THE DAY PROVIDING UPPER DIVERGENCE. THE
BEST LOW LEVEL CONVERGENCE OCCURS THIS MORNING ACROSS THE NORTH
WITH THE COLD FRONT. THEN A WEAK CONVERGENT CENTER LINGERS OVER
THE CENTRAL COLORADO MOUNTAINS THROUGH FRIDAY. LAPSE RATES OVER
THE CENTRAL CO MTNS INCREASE TO 7.5 C/KM THIS AFTERNOON AND AGAIN
ON FRIDAY AFTERNOON ADDING A CONVECTIVE COMPONENT TO THIS STORM.
THIS WILL PRODUCE SOME LARGE LOCAL VARIATION IN SNOW AMOUNTS.
WITH THIS IN MIND HAVE ISSUED ADVISORIES FOR THE GUNNISON BASIN
AND THE PAGOSA SPRINGS ZONE THROUGH FRIDAY EVENING.

A RAIN SNOW MIX MAY OCCUR THIS AFTERNOON BELOW 5000FT BUT
OTHERWISE THIS STORM WILL BE ALL SNOW. BY FRIDAY EVENING MOST
MOUNTAIN RANGES WILL SEE 6-12 INCHES. THE EASTERN VALLEYS WILL
HAVE 2-4 INCHES WITH ALL BUT SE UTAH VALLEYS RECEIVING SOME LIGHT
ACCUMULATIONS.

.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 351 AM MST THU DEC 25 2014

AT THE BEGINNING OF THE EXTENDED PERIOD THE MODELS MOVE THE MAIN
UPPER TROUGH EAST OF THE AREA. DRIER NW FLOW ALOFT SPREADS OVER
THE AREA...BRINGING A BRIEF RESPITE FROM THE UNSETTLED WINTER
WEATHER. SATURDAY SHOULD BE THE DRIEST DAY IN THE FORECAST BECAUSE
THE NEXT WEATHER SYSTEM WILL START INFLUENCING WEATHER OVER NE UT
AND NW CO SAT EVENING. A STRONG JET PARALLELING THE OR AND WA
COAST WILL CAUSE THIS NEXT SYSTEM TO DIG INTO PACNW AND THE GREAT
BASIN SUN NIGHT. BY SUNRISE MONDAY THE POLAR FRONT WILL EXTEND
FROM NORTHERN CA THROUGH SOUTHERN NV...UT AND CO. THE ARCTIC FRONT
WITH A MINUS 36 TO 36 DEGREE COLD CORE DRIVES SOUTH INTO THE
NORTHERN ROCKIES AND HIGH PLAINS. FAIRLY STRONG WEST WINDS
ALOFT...DECENT MOISTURE AND THE LEFT EXIT REGION OF A STRONG JET
ARE TIMED OVER THE FORECAST AREA MONDAY AND MONDAY NIGHT...WITH
THE EC BEING STRONGEST WITH THESE FEATURES. HAVE INCREASED THE
CLOUD COVER ACROSS THE AREA AND INCREASED THE CHANCE OF PRECIP
IN THE SUN NIGHT THRU TUESDAY TIME FRAME.

TUESDAY AND WEDNESDAY...THE MODEL CONSENSUS CLOSES OFF A TIGHT
500 MB LOW OVER THE WESTERN GREAT BASIN THEN RETROGRADES IT JUST
OFF THE SOUTHERN CA COAST. DEFORMATION ZONE CLOUDS WITH LESSENING
PRECIPITATION CHANCES REMAIN OVER THE AREA TUE AND WED.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON)
ISSUED AT 1046 AM MST THU DEC 25 2014

CHALLENGING TAF PERIOD AS UPPER LEVEL LOW SLOWLY SLIDES EAST
SOUTHEAST FROM UT. VARIABLE AND LOW CIGS AND VSBY WILL OCCUR ALONG
WITH PERIODS OF -SHSN/-SN. SNOW FOR THE VALLEY TAFS IN ERN UT AND
WRN CO WILL END THIS EVENING WHILE IT SHOULD CONTINUE AT THE MTN
TAF SITES MORE OR LESS THROUGH 18Z FRI. INSERTED LLWS FOR KASE
THROUGH 02Z THIS EVENING AS MTN TOP WINDS BLOWING OUT OF THE
SOUTHWEST CONSIDERABLY STRONGER THAN SFC WIND.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...WINTER WEATHER ADVISORY UNTIL 6 PM MST FRIDAY FOR COZ001-002-007.

     WINTER WEATHER ADVISORY UNTIL 3 PM MST FRIDAY FOR COZ006-020.

     WINTER WEATHER ADVISORY UNTIL MIDNIGHT MST FRIDAY NIGHT FOR
     COZ005-023.

     WINTER WEATHER ADVISORY UNTIL MIDNIGHT MST FRIDAY NIGHT FOR
     COZ003-004-008>010-012>014-017>019.

UT...WINTER WEATHER ADVISORY UNTIL 6 PM MST FRIDAY FOR UTZ023-025-028.

     WINTER WEATHER ADVISORY UNTIL 3 PM MST FRIDAY FOR UTZ024-027-029.

&&

$$

UPDATE...JAM
SHORT TERM...JOE
LONG TERM...CC
AVIATION...BEN



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.