000
FXUS65 KGJT 032200
AFDGJT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
300 PM MST WED DEC 3 2008
.SHORT TERM...TONIGHT THROUGH FRIDAY...
NORTHWEST FLOW REMAINS OVER THE FORECAST AREA THIS AFTERNOON WITH
AREAS OF LIGHT SNOW CONTINUING ACROSS PORTIONS OF THE CENTRAL AND
NORTHERN MOUNTAINS OF WESTERN COLORADO. ANOTHER SHORTWAVE TROUGH
WILL APPROACH THE AREA FROM THE NORTHWEST TONIGHT AND MOVE ACROSS
THE AREA THURSDAY. THIS WILL BRING AN INCREASED CHANCE OF SNOW THE
NORTH AND HAVE DECIDED TO HOIST AN WINTER WEATHER ADVISORY FOR THE
NORTHERN MOUNTAINS OF WESTERN COLORADO. AS THE TROUGH APPROACHES
THE FLOW ALOFT WILL BACK TOWARD THE WEST TONIGHT IN WEAK WARM AIR
ADVECTION. THIS WILL BRING AN INCREASE IN MID AND HIGH CLOUDS WITH
THE LOWER LEVELS SATURATING OVERNIGHT ACROSS THE NORTH. THE FLOW IS
PROGGED TO VEER TO THE NORTHWEST THURSDAY BRINGING WEAK COLD AIR
ADVECTION. FORCING WILL BE A COMBINATION OF OROGRAPHIC AND WEAK
DYNAMIC WITH NORTHWEST FACING SLOPES OF THE GORE AND ELK MOUNTAINS...
ELKHEAD AND PARK MOUNTAINS AND THE FLATTOPS BEING FAVORED. THIS LOOKS
LIKE A LOW END ADVISORY EVENT WITH SNOW AMOUNTS IN THE 3 TO 7 INCH
RANGE WITH HEAVIEST SNOWFALL FROM AROUND VAIL PASS NORTHWARD. WINDS
ARE NOT PROGGED TO BE TOO STRONG WITH THIS SYSTEM SO EXPECT BLOWING
AND DRIFTING SNOW TO BE LOCALIZED. AREAS OF SNOW TO DEVELOP ACROSS
THE SOUTH CENTRAL AND SOUTHERN MOUNTAINS OF WESTERN COLORADO THURSDAY
AS THE TROUGH PUSHES THROUGH BUT AMOUNTS SHOULD BE MINIMAL.
DRIER AND MORE STABLE AIR WILL SPREAD INTO THE AREA THURSDAY NIGHT
BEHIND THE TROUGH WITH SNOWFALL DIMINISHING THROUGH THE EVENING.
DRY NORTHWEST FLOW WILL PREVAIL ACROSS THE AREA ON FRIDAY. A LITTLE
COOLER ON THURSDAY WITH PERSISTENCE OR SLIGHT WARMING OF TEMPERATURES
FOR FRIDAY.
.LONG TERM...FRIDAY THROUGH TUESDAY...A NORTHWEST FLOW WITH VARYING
AMOUNTS OF MID/HI LEVEL MOISTURE WILL BE OVER THE REGION THROUGH
EARLY SUNDAY. NO PRECIPITATION IS EXPECTED BUT THERE WILL BE
PERIODS OF CLOUDINESS. TEMPS WILL REMAIN 5-8 DEGREES ABOVE SEASONAL
NORMALS.
SUNDAY-WEDNESDAY...PREVIOUS FORECAST MODELS HAVE BEEN INDICATING
VASTLY DIFFERENT SOLUTIONS ON HOW THE CLOSED LOW OFF SRN CALIFORNIA
EVOLVES...AND THERE IS NO DIFFERENCE TODAY. GFS NEVER REALLY BRINGS
THE LOW EASTWARD AND ONSHORE AND INSTEAD AMPLIFIES THE RIDGE ALONG
THE WEST COAST. THAT PRODUCES A NW FLOW WITH EMBEDDED WAVES OVER OUR
CWA. MEANWHILE THE EC IS PROGRESSIVE WITH CLOSED LOW AND EJECTS IT
INTO THE SWRN U.S. BY LATE SUNDAY AFTERNOON. FROM A FORECASTER
STANDPOINT THIS IS VERY PROBLEMATIC AND INSPIRES LOW CONFIDENCE.
HPC ALSO NOW FAVORS THE EC SOLUTION WHICH IS A REVERSAL FROM
YESTERDAY. TO COMPLICATE THE ENTIRE PICTURE THE NEW 12Z EC JUST
CAME IN AND SHOWS A COMPLETE REVERSAL...WHICH FOLLOWS THE GFS AND
KEEPS THE LOW OFFSHORE. ON THE OTHER HAND BOTH NOW AGREE ON A SHORT
WAVE DROPPING DOWN IN THE NWRLY FLOW MONDAY...WHICH LOOKS LIKE IT
COULD PROVIDE SHOWERS OVER THE NRN MTNS. HAVE GENERALLY INCREASED
POPS A LITTLE AROUND MONDAY THEN TAPERING OFF BY MID-WEEK WITH TEMPS
REMAINING A FEW DEGREES ABOVE SEASONAL NORMALS.
&&
.AVIATION...
LOCALIZED MVFR CIGS AND VSBY WILL OCCUR OVER THE MOUNTAINS OF
WESTERN COLORADO THROUGH ABOUT 03Z THIS EVENING FROM AROUND KASE AND
KRIL NORTH. AFTERWARD...INCREASING AREAL COVERAGE OF MVFR TO IFR
CONDITIONS IN SNOW NORTH OF A LINE FROM KASE TO KRIL TO KVEL AS AN
UPPER LEVEL TROUGH APPROACHES. AFTER 07Z WIDESPREAD MVFR TO IFR
CONDITIONS IN SNOW ARE EXPECTED OVER THE MOUNTAINS GENERALLY NORTH OF
A LINE FROM KASE TO KEEO WITH CONDITIONS CONTINUING THROUGH THE DAY
THURSDAY. OTHERWISE...AREAS OF MVFR TO LOCALIZED IFR EXPECTED OVER
THE CENTRAL AND SOUTHERN MOUNTAINS OF WESTERN COLORADO AND NORTHEAST
UTAH LATE TONIGHT AND THURSDAY. VFR TO PREVAIL IN THE FOUR CORNERS
VICINITY.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
.CO...WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING UNTIL MIDNIGHT
THURSDAY NIGHT FOR THE NORTHERN MOUNTAINS...ZONES 4/10/13.
.UT...NONE.
$$
SHORT TERM.....TAL
LONG TERM......MC
AVIATION.......TAL
