Winter Storm Warning 9, NWS Grand Junction, CO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
239 PM MST THU MAR 6 2014

.SHORT TERM...(TONIGHT THROUGH FRIDAY NIGHT)
ISSUED AT 239 PM MST THU MAR 6 2014

THE FORECAST STILL LOOKS ON TRACK. THE 18Z NAM MATCHES THE GFS
TIMING STARTING NORTHERN MTN SHOWERS SOON AFTER SUNSET. JET
WEAKENS AS THE SYSTEM WORKS OVER THE REGION TONIGHT. WIDESPREAD
SHOWERS ARE EXPECTED ALONG THE COLD FRONT BECOMING MORE SCATTERED
IN COVERAGE BEHIND. THE FRONT WORKS THROUGH NE UTAH
9-11PM...THROUGH ALONG A LINE FROM VAIL PASS TO MEXICAN HAT UTAH
BY SUNRISE...THEN THROUGH ALL OF THE FORECAST AREA BEFORE NOON
FRIDAY. SNOW LEVELS DROP TO THE NORTHERN VALLEY BOTTOMS BY
SUNRISE...TO AROUND 8KFT MSL SOUTH. CONVECTION WILL PRODUCE
OCCASIONAL GRAUPEL AT LOWER ELEVATIONS THAN THE SNOW LINE. THE
-26C COLD CORE WORKS OVER THE NORTH IN THE AFTERNOON AND TO THE
CENTRAL CONTINENTAL DIVIDE FRIDAY NIGHT. INSTABILITY IS STILL
PRESENT OVER SW CO FRIDAY AFTERNOON SO ADDED ISOLATED
THUNDERSTORMS TO THE WEATHER WORDING ALONG WITH SMALL HAIL. ALSO
ADDED AFTERNOON ICE PELLETS TO THE NW COLORADO ZONES.

HIGHLIGHTS LOOK ON TRACK. THE NW SAN JUANS MAY GET CLOSE TO
ADVISORY CRITERIA. NW CO ADVISORIES MAY NEED TO BE EXTENDED INTO
FRIDAY EVENING. A SECOND DISTURBANCE PROVIDES SOME LIFT FRIDAY
NIGHT ON THE BACK SIDE OF THE LARGER TROUGH. T700 OF -8C ACROSS
THE NORTH WILL ADD SOME SNOW EFFICIENCY. BUT OVERALL SNOW DENSITY
IS EXPECTED TO BE A SPRING-LIKE 10:1 OR SO.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 239 PM MST THU MAR 6 2014

THE TROUGH DROPS SOUTH OF COLORADO SATURDAY AND EXHIBITS SOME
SPLITTING AS ENERGY PUSHES THE BASE INTO EXTREME EASTERN AZ WHILE
THE NORTHERN PART SHEARS EAST INTO THE MID-MISSISSIPPI VALLEY. DRIER
AIR SPREADS IN FROM THE NORTHWEST AS THIS OCCURS. SCATTERED SHOWERS
WILL PERSIST OVER THE SAN JUAN MOUNTAINS AND ALONG THE CENTRAL
DIVIDE SATURDAY MORNING AND OVER THE SAN JUANS SATURDAY AFTERNOON AS
THE SHEAR AXIS SLIPS SOUTH OF THE CO BORDER.

UPPER LEVEL RIDGING WILL BRING MOSTLY SUNNY AND DRY CONDITIONS
SUNDAY WITH MODERATING TEMPS. RIDGE BREAKS DOWN BY MONDAY AS THE
NEXT PACIFIC STORM MOVES INLAND...WITH MONDAY PERHAPS THE WARMEST
DAY NEXT WEEK UNDER WESTERLY FLOW ALOFT. BOTH THE 12Z GFS AND ECMWF
SHOW A 700 MB COLD FRONT REACHING NE UT BY MON EVENING AND PUSHING
TO THE SAN JUANS BY TUE MORNING. THE GFS KEEPS IT OVER THE SOUTH
THROUGH TUESDAY WHILE THE MORE AMPLIFIED ECMWF DRIVES IT INTO NM AS
SECONDARY ENERGY UPSTREAM DIGS THE TROUGH ACROSS ERN UT/WRN CO.
MONDAY CURRENTLY LOOKS DRY THOUGH LIGHT PRECIPITATION MAY REACH THE
FAR NORTHERN MOUNTAINS MONDAY AFTERNOON. THE BETTER CHANCE OF
PRECIPITATION IS MONDAY NIGHT AND TUESDAY.

A CHANCE OF SHOWERS SHOULD LINGER WED IN NW FLOW AS THE UPPER RIDGE
REBOUNDS OVER THE INTERMOUNTAIN WEST. DRY WEATHER IS ANTICIPATED
THURSDAY. ECMWF IS FASTER THAN THE GFS BRINGING THE NEXT PACIFIC
SYSTEM ASHORE OVER THE PACNW AS THE ACTIVE WEATHER PATTERN CONTINUES.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 239 PM MST THU MAR 6 2014

VFR AT ALL TAF SITES THROUGH 06Z TONIGHT. AREAS OF SNOW AND MTN
TOP OBSCURATIONS WILL INCREASE OVER THE MOUNTAINS NORTH OF
I-70 00-06Z...SPREADING INTO THE CENTRAL MTNS 06-12Z...AND SOUTHERN
MOUNTAINS 12-18Z.

SHOWERS WILL PRODUCE PERIODS OF MVFR CIGS AND VSBY AT KVEL
03-12Z. PERIODS OF MVFR/IFR CONDITIONS TO IMPACT KASE...KEGE
09-15Z... AND KTEX 12-18Z. ALL OTHER TAF SITES WILL SEE VFR EXCEPT
SCT MVFR IN -SHRAGS. LOCAL WIND GUSTS OF 30-40 MPH ARE POSSIBLE
NEAR SHOWERS PRODUCING CONVECTIVE TURBULENCE.

AFTER 18Z SHOWERS BECOME MORE CONVECTIVE AND SCATTERED IN NATURE
WITH MTNS FREQUENTLY OBSCURED AND OCCASIONAL MVFR/ISOLD IFR
CONDITIONS AT ALL TAF SITES. ISOLATED AFTERNOON THUNDERSTORMS
POSSIBLE OVER THE SAN JUAN MTNS INCLUDING KTEX.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

CO...WINTER WEATHER ADVISORY FROM 11 PM THIS EVENING TO 8 PM MST
     FRIDAY ABOVE 9000 FEET FOR THE COZ009-010-012.

     WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 PM MST
     FRIDAY COZ004-013.

UT...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 PM MST
     FRIDAY ABOVE 9000 FEET FOR THE UTZ023.

&&

SHORT TERM...JOE
LONG TERM...JAD
AVIATION...JOE