Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 231919
AFDGJT

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
1219 PM MST MON FEB 23 2015

.UPDATE...
ISSUED AT 1134 AM MST MON FEB 23 2015

ALLOWED THE WINTER ADVISORY FOR THE GRAND VALLEY AND THE WINTER
STORM WARNINGS FOR THE DEBEQUE-SILT CORRIDOR AND CENTRAL CO RIVER
VALLEY TO EXPIRE AT NOON. LIGHT SNOW WILL HANG AROUND IN PLACES
ALONG THE I-70 CORRIDOR THIS AFTERNOON BUT AMOUNTS ARE EXPECTED TO
BE AN INCH OR LESS. TEMPS NEAR OR BELOW FREEZING COULD ALSO KEEP
UNTREATED ROADS/SIDEWALKS SLICK. ALSO LET THE WINTER STORM WARNINGS
EXPIRE FOR THE ROAN/TAVAPUTS PLATEAU AND THE FLAT TOPS/WHITE RIVER
PLATEAU AS OVERALL FORCING SLOWLY SHIFTS SOUTHWARD.

SNOW SHOULD REMAIN WIDESPREAD ACROSS SE UT AND SW CO THROUGH THE
AFTERNOON...BUT MODELS INDICATING A LULL IN THE ACTIVITY OR JUST
SOME LIGHT SNOW THIS EVENING. ANOTHER BURST OF A COUPLE INCHES OF
SNOW THEN EXPECTED TOWARD SUNRISE FOR FAR SE UT AND SW CO AS THE
MAIN UPPER LOW CURRENTLY OVER CENTRAL CA MOVES ACROSS NRN AZ.

UPDATE ISSUED AT 1013 AM MST MON FEB 23 2015

SNOW REMAINED WIDESPREAD ACROSS SW CO THIS MORNING...PRETTY MUCH
FROM GRAND JCT AND ASPEN SOUTH. OBSERVATIONS INDICATING THE HEAVIER
SNOW FROM ABOUT MONTROSE/PARADOX VALLEY SOUTH. SNOW ALSO NOTED
ACROSS MUCH OF SE UT. THIS UNDER A BROAD AREA OF UPPER DIVERGENCE/
LOWER (MOISTURE)CONVERGENCE PLUS ISENTROPIC UPGLIDE AND A MOIST
DENDRITIC SNOW GROWTH ZONE. EARLY LOOK AT THIS MORNING`S MODELS SHOW
THE HEAVIER SNOW BAND SLOWLY SHIFTNIG SOUTH WITH SOME REDUCTION IN
UPPER LEVEL SUPPORT AS THE UPPER JET ACROSS NRN AZ AND NRN NM
PROGRESSES EASTWARD. WINTER STORM WARNINGS CONTINUE FOR SE UT AND
SW CO. STILL ASSESSING WHETHER OR NOT TO EXTEND THE HIGHLIGHTS
INTO TUE FOR AT LEAST THE AREAS FROM THE ABAJOS AND SAN JUANS
SOUTH.

LIGHT SNOW IN THE GRAND VALLEY THIS MORNING BELIEVED TO BE MAINLY
DUE TO MOISTURE IN SSW FLOW OVERRUNNING COLD AIR TRAPPED IN THE
VALLEY.  NAM12 AND HIGH RESOLUTION RAP MODELS SUGGEST THIS MOIST
OVERRUNNING DECREASES FOR THE GRAND VALLEY THIS AFTERNOON AS FLOW
ALOFT BEGINS TO TAKE ON A MORE NORTHERLY TACK. THESE MODELS ALSO
SHOW ONLY LIGHT SNOW ACCUMS THERE THIS AFTERNOON. WHETHER TO EXTEND
THE ADVISORY FOR THE GRAND INTO THIS AFTERNOON WILL PROBABLY BE A
LAST- MINUTE CALL AND SOMEWHAT DEPENDENT ON HOW MUCH TEMPS WARM TO
EASE THE THREAT OF ICY ROADS AND SIDEWALKS. BELIEVE THE NOONTIME
EXPIRATION OF THE WINTER HIGHLIGHT FOR THE DEBEQUE TO SILT
CORRIDOR AND THE CENTRAL CO RIVER VALLEY STILL LOOKS ON TRACK.

.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 519 AM MST MON FEB 23 2015

SNOWFALL CONTINUES ACROSS MOST OF THE SOUTHERN HALF OF THE
FORECAST AREA...AND NORTHWARD ACROSS THE I-70 CORRIDOR EARLY THIS
MORNING. ALREADY SIGNIFICANT AMOUNTS HAVE FALLEN FROM THE
UNCOMPAHGRE RIVER BASIN SOUTH TO THE NM BORDER...WITH MORE
EXPECTED THROUGH TODAY. SNOW IN THE CENTRAL VALLEYS FROM MOAB TO
GRAND JUNCTION TO EAGLE HAS BEEN MORE ON THE LIGHT SIDE. WILL DROP
THE ADVISORY FOR MOAB AND THE GRAND FLAT WITH THIS PACKAGE AS THAT
ZONE HAS RECEIVED VERY LITTLE SNOW...WITH NOT MUCH MORE EXPECTED.
HOWEVER WILL KEEP THE HIGHLIGHTS GOING FOR THE COLORADO I-70
CORRIDOR AS THOSE ZONES HAVE RECEIVED ENOUGH TO AFFECT
TRAVEL...AND MODEST AMOUNTS ARE STILL EXPECTED THROUGH THE
MORNING. HAVE ALSO OPTED TO END THE WARNINGS EARLY FOR THE
COLORADO TAVAPUTS AND THE FLATTOPS...TO COINCIDE WITH THE END
TIMING OF THESE I-70 CORRIDOR VALLEY ZONES WHICH EXPIRE AT NOON.

ON THE FLIP SIDE HAVE EXTENDED THE WARNING FOR UT ZONE 29 UNTIL
MIDNIGHT TO MATCH UP BETTER WITH THE HIGHLIGHTS FOR OTHER
SOUTHEAST UT AND SOUTHWEST CO ZONES. ALL OF SOUTHEAST UT AND
SOUTHWEST CO FROM AROUND THE LA SAL MOUNTAINS EAST TO THE
SOUTHERN SLOPES OF THE GRAND MESA AND THE WEST ELKS...AND
SOUTHWARD TO THE NM/AZ BORDERS WILL CONTINUE TO BE UNDER THE GUN
TODAY AS A MOIST AND UNSTABLE AIR MASS CONTINUES TO FLOW INTO THE
REGION. A CONVERGENT ZONE HAS DEVELOPED FROM AROUND BLANDING TO
MONTROSE AND WILL PERSIST MORE OR LESS THROUGH THE DAY. THIS IS
ALL THE RESULT OF A LOW PRESSURE CENTER THAT WILL CLOSE OFF OVER
CENTRAL CALIFORNIA TODAY...THEN MOVE INTO NORTHWEST AZ TONIGHT. AS
A RESULT A DEFORMATION ZONE WILL DEVELOP ACROSS THE SOUTHERN
PORTION OF OUR AREA AND KEEP MODERATE TO HEAVY SNOW INTO THE
EVENING OVER THE SOUTHERN ZONES. ENOUGH COOLING WILL HAVE OCCURRED
BY THIS AFTERNOON...THAT I DO NOT EXPECT SNOW TO CHANGE OVER...OR
EVEN MIX WITH TO RAIN EXCEPT POSSIBLY FOR BRIEF PERIODS IN THE
LOWEST SOUTHERN VALLEYS.

THE LOW WILL THEN MOVE INTO CENTRAL/SOUTHERN NEW MEXICO ON TUE
WITH PRECIPITATION PERSISTING INTO THE AFTERNOON OVER THE SOUTHERN
EDGE. HOWEVER SNOW INTENSITY LATE TONIGHT THROUGH TUE IS MOSTLY
EXPECTED TO BE LIGHT...ESPECIALLY WHEN COMPARED TO THE AMOUNTS
THIS STORM HAS ALREADY PRODUCED.

.LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 519 AM MST MON FEB 23 2015

SNOW FINALLY DIMINISHES ACROSS THE SOUTH AS THE LATEST STORM IS
FORCED TO THE SOUTHEAST TUESDAY NIGHT. HOWEVER...EXPECT SOME
LIGHT SNOW TO BEGIN ACROSS THE NORTHERN COLORADO MOUNTAINS LATER
IN THE NIGHT AS MOISTURE AHEAD OF AN APPROACHING SHORTWAVE TROUGH
TO THE NORTHWEST SWEEPS OVER THE AREA. EXPECT SNOW TO INCREASE AND
SPREAD INTO THE SOUTHERN MOUNTAINS AND ADJACENT VALLEYS WEDNESDAY
AND WEDNESDAY NIGHT AS THE SHORTWAVE TROUGH PASSES SOUTHEASTWARD
ACROSS THE AREA. IN FACT...A SERIES OF WAVES WILL PASS THROUGH THE
AREA DURING THE REMAINDER OF THE WEEK...MAINLY IMPACTING THE
COLORADO DIVIDE MOUNTAINS. A BIT DIFFICULT TO TIME THESE
DISTURBANCES THIS FAR OUT BUT GOES WITHOUT SAYING THAT THE PATTERN
HAS SHIFTED TO A MORE PROGRESSIVE...WETTER...AND COOLER REGIME.
IN FACT...FOR THOSE ALREADY DIGGING OUT ACROSS SOUTHEAST UTAH AND
SOUTHWEST COLORADO...MODELS ARE HINTING AT THE POTENTIAL FOR ANOTHER
SIGNIFICANT SNOW EVENT THIS WEEKEND. DETAILS A BIT SKETCHY AT THIS
POINT AS GFS AND EC NOT ENTIRELY ON THE SAME PAGE.

&&

.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 519 AM MST MON FEB 23 2015

SNOWFALL CONTINUES ACROSS MOST OF THE SOUTHERN HALF OF THE
FORECAST AREA...AND NORTHWARD ACROSS THE I-70 CORRIDOR EARLY THIS
MORNING. ALREADY SIGNIFICANT AMOUNTS HAVE FALLEN FROM THE
UNCOMPAHGRE RIVER BASIN SOUTH TO THE NM BORDER...WITH MORE
EXPECTED THROUGH TODAY. SNOW IN THE CENTRAL VALLEYS FROM MOAB TO
GRAND JUNCTION TO EAGLE HAS BEEN MORE ON THE LIGHT SIDE. WILL DROP
THE ADVISORY FOR MOAB AND THE GRAND FLAT WITH THIS PACKAGE AS THAT
ZONE HAS RECEIVED VERY LITTLE SNOW...WITH NOT MUCH MORE EXPECTED.
HOWEVER WILL KEEP THE HIGHLIGHTS GOING FOR THE COLORADO I-70
CORRIDOR AS THOSE ZONES HAVE RECEIVED ENOUGH TO AFFECT
TRAVEL...AND MODEST AMOUNTS ARE STILL EXPECTED THROUGH THE
MORNING. HAVE ALSO OPTED TO END THE WARNINGS EARLY FOR THE
COLORADO TAVAPUTS AND THE FLATTOPS...TO COINCIDE WITH THE END
TIMING OF THESE I-70 CORRIDOR VALLEY ZONES WHICH EXPIRE AT NOON.

ON THE FLIP SIDE HAVE EXTENDED THE WARNING FOR UT ZONE 29 UNTIL
MIDNIGHT TO MATCH UP BETTER WITH THE HIGHLIGHTS FOR OTHER
SOUTHEAST UT AND SOUTHWEST CO ZONES. ALL OF SOUTHEAST UT AND
SOUTHWEST CO FROM AROUND THE LA SAL MOUNTAINS EAST TO THE
SOUTHERN SLOPES OF THE GRAND MESA AND THE WEST ELKS...AND
SOUTHWARD TO THE NM/AZ BORDERS WILL CONTINUE TO BE UNDER THE GUN
TODAY AS A MOIST AND UNSTABLE AIR MASS CONTINUES TO FLOW INTO THE
REGION. A CONVERGENT ZONE HAS DEVELOPED FROM AROUND BLANDING TO
MONTROSE AND WILL PERSIST MORE OR LESS THROUGH THE DAY. THIS IS
ALL THE RESULT OF A LOW PRESSURE CENTER THAT WILL CLOSE OFF OVER
CENTRAL CALIFORNIA TODAY...THEN MOVE INTO NORTHWEST AZ TONIGHT. AS
A RESULT A DEFORMATION ZONE WILL DEVELOP ACROSS THE SOUTHERN
PORTION OF OUR AREA AND KEEP MODERATE TO HEAVY SNOW INTO THE
EVENING OVER THE SOUTHERN ZONES. ENOUGH COOLING WILL HAVE OCCURRED
BY THIS AFTERNOON...THAT I DO NOT EXPECT SNOW TO CHANGE OVER...OR
EVEN MIX WITH TO RAIN EXCEPT POSSIBLY FOR BRIEF PERIODS IN THE
LOWEST SOUTHERN VALLEYS.

THE LOW WILL THEN MOVE INTO CENTRAL/SOUTHERN NEW MEXICO ON TUE
WITH PRECIPITATION PERSISTING INTO THE AFTERNOON OVER THE SOUTHERN
EDGE. HOWEVER SNOW INTENSITY LATE TONIGHT THROUGH TUE IS MOSTLY
EXPECTED TO BE LIGHT...ESPECIALLY WHEN COMPARED TO THE AMOUNTS
THIS STORM HAS ALREADY PRODUCED.

.LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 519 AM MST MON FEB 23 2015

SNOW FINALLY DIMINISHES ACROSS THE SOUTH AS THE LATEST STORM IS
FORCED TO THE SOUTHEAST TUESDAY NIGHT. HOWEVER...EXPECT SOME
LIGHT SNOW TO BEGIN ACROSS THE NORTHERN COLORADO MOUNTAINS LATER
IN THE NIGHT AS MOISTURE AHEAD OF AN APPROACHING SHORTWAVE TROUGH
TO THE NORTHWEST SWEEPS OVER THE AREA. EXPECT SNOW TO INCREASE AND
SPREAD INTO THE SOUTHERN MOUNTAINS AND ADJACENT VALLEYS WEDNESDAY
AND WEDNESDAY NIGHT AS THE SHORTWAVE TROUGH PASSES SOUTHEASTWARD
ACROSS THE AREA. IN FACT...A SERIES OF WAVES WILL PASS THROUGH THE
AREA DURING THE REMAINDER OF THE WEEK...MAINLY IMPACTING THE
COLORADO DIVIDE MOUNTAINS. A BIT DIFFICULT TO TIME THESE
DISTURBANCES THIS FAR OUT BUT GOES WITHOUT SAYING THAT THE PATTERN
HAS SHIFTED TO A MORE PROGRESSIVE...WETTER...AND COOLER REGIME.
IN FACT...FOR THOSE ALREADY DIGGING OUT ACROSS SOUTHEAST UTAH AND
SOUTHWEST COLORADO...MODELS ARE HINTING AT THE POTENTIAL FOR ANOTHER
SIGNIFICANT SNOW EVENT THIS WEEKEND. DETAILS A BIT SKETCHY AT THIS
POINT AS GFS AND EC NOT ENTIRELY ON THE SAME PAGE.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)
ISSUED AT 1013 AM MST MON FEB 23 2015

THIS WINTER STORM IS SLOWLY WINDING DOWN BUT PLENTY OF AVIATION
CONCERNS WILL CONTINUE OVER THE NEXT 24 HOURS. SNOW LOOKS TO
CONTINUE ACROSS SOUTHWEST COLORADO TO SOUTHEAST UTAH...WITH
MVFR/IFR IMPACTS TO THE SOUTHERN FORECAST TERMINALS A HIGH
PROBABILITY TO CONTINUE THROUGH TUESDAY. IMPROVEMENT ALONG THE
WESTERN INTERSTATE 70 CORRIDOR SHOULD OCCUR AFTER 20Z WITH IFR
CONDITIONS HANGING IN AT CNY AND GJT LATE THIS MORNING AND VFR IN
THE COLORADO AND EAGLE VALLEYS TO THE EAST. OBSCURATION OF THE
TERRAIN WILL PERSIST OVER THE NEXT 24 HOURS AS WELL.


&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...WINTER STORM WARNING UNTIL MIDNIGHT MST TONIGHT FOR COZ009>012-
     014-017>023.

UT...WINTER STORM WARNING UNTIL MIDNIGHT MST TONIGHT FOR UTZ022-029.

     WINTER STORM WARNING UNTIL 6 AM MST TUESDAY FOR UTZ028.

&&

$$

UPDATE...JAD
SHORT TERM...EH
LONG TERM...NL
AVIATION...TGJT


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