FXUS65 KGJT 252211
AFDGJT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND JUNCTION CO
311 PM MST WED NOV 25 2009
.SHORT TERM...TONIGHT THROUGH FRIDAY...
DRY AND MOSTLY CLEAR CONDITIONS THROUGH THANKSGIVING NIGHT INTO
FRIDAY.
AN UPPER LEVEL RIDGE AXIS OVER THE GREAT BASIN WILL SLOWLY SHIFT TO
THE EAST THIS EVENING AND REDUCE THE NORTHWESTERLY FLOW ALOFT. THE
RIDGE CONTINUES TO TRACK EAST WITH THE AXIS REACHING EASTERN UT BY
LATE THURSDAY AFTERNOON OR EARLY EVENING AND OVER WESTERN CO
OVERNIGHT. A WEAK DISTURBANCE EMBEDDED IN THE RIDGE WILL SKIRT THE
NORTHERN CO MOUNTAINS BUT SHOULD ONLY INCREASE CLOUD COVER
SLIGHTLY. BY EARLY FRIDAY THE AXIS IS EAST OF THE CONTINENTAL
DIVIDE AND SOUTHWESTERLY FLOW ALOFT WILL START TO INCREASE.
EXPECT MODERATE ABOVE NORMAL DAYTIME TEMPERATURES. UNDER
MOSTLY CLEAR SKIES MINIMUM TEMPERATURES OVERNIGHT WILL DROP TO
NEAR NORMAL OR COLDER.
.LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY...
A PACIFIC TROUGH IS EXPECTED TO MOVE THROUGH SAT-SUN BUT CURRENTLY
DOES NOT LOOK LIKE TOO MUCH OF A SNOW-MAKER AS IT SPLITS AND WEAKENS.
BEST CHANCE OF SNOW LOOKS TO BE SAT NIGHT.
MODELS CONTINUE TO SHOW THIS TROUGH SPLITTING AS IT MOVES THROUGH A
LONGWAVE RIDGE OVER THE FAR WEST. ALL MODELS NOW SHOW THE SOUTHERN
PORTION CLOSING OFF AN UPPER LOW...RANGING FROM AZ IN THE 12Z ECWMF
TO SRN CA/BAJA IN THE 12Z GFS. WILL CONCENTRATE ON THE 700 MB FRONT
AS THE MAIN GENERATOR OF PRECIPITATION. FRONT MOVES INTO NE UT/NW CO
ABOUT MIDDAY SAT AND THEN SLIPS TO SE UT/SAN JUAN MTNS SAT NIGHT.
GFS CARRIES A BIT MORE FRONTOGENETIC FORCING THEN THE NAM...AS ITS
MORE SWWD POSITION OF THE CLOSED LOW ALLOWS COLDER AIR TO BETTER
PENETRATE THE FORECAST AREA. BUMPED UP POPS FOR SAT NIGHT...BUT WITH
DYNAMICS WEAK...OROGRAPHICS NOT IMPRESSIVE...AND MOISTURE LIMITED...
EXPECT FAIRLY LIGHT PRECIPITATION WHERE IT OCCURS.
AN EAST-WEST ORIENTED RIDGE OF HIGH PRESSURE WILL BRING DRY WEATHER
MONDAY. A STRONGER AND COLDER STORM THAN DROPS DOWN FROM THE NW
TUE-WED AND SHOULD OFFER A BETTER CHANCE OF PRECIPITATION ESPECIALLY
FOR THE WRN CO MTNS. SOME TIMING DIFFERENCES APPARENT...WITH THE GFS
FASTER AND EC ABOUT 12-18 HRS BEHIND...BUT BOTH LOOK TO BRING A
DECENT COLD FRONT AND SHOT OF DYNAMICS SOMETIME IN THE LATE TUE-WED
TIME PERIOD. THUS RAISED POPS TUE NIGHT AND WED IN RESPONSE.
&&
.AVIATION...
VFR EXPECTED TO LAST THROUGH FRIDAY.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...NONE.
UT...NONE.
&&
$$
SHORT TERM.....AS
LONG TERM......JAD
AVIATION.......PF
