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fxus65 kgjt 110950 
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Area forecast discussion 
National Weather Service Grand Junction Colorado 
350 am MDT Sat Oct 11 2008 


..windy conditions with High Mountain snow expected through 
tonight... 


Short term...today through Sunday night... 
strong storm over the Great Basin will be bringing a variety of 
weather to eastern Utah and western Colorado over the next 24 
hours. Surface front remains stationary early this morning from a kpuc to 
kvel to kcag line. This front will be retreating back to the north 
today as a warm front as the associated upper level low over 
southern Nevada kicks northeast late this morning. Strong pressure 
gradient out ahead of the front will be firmly established over 
eastern Utah and western Colorado...with windy to very windy 
conditions expected today. Will be issuing a Wind Advisory for much 
of southeast and east central Utah...along with the valleys of 
southwest and west central Colorado for today. Sustained wind around 
30 miles per hour with gusts to 50 miles per hour expected...with even higher gusts 
possible near showers and thunderstorms this afternoon. 


As for precipitation potential over the next 24 hours...models 
remain consistent with developing a line of showers and 
thunderstorms along the cold front later this morning across eastern 
Utah...with the front and showers advancing east this afternoon and 
evening. Deep southerly flow and warm air advection will keep light orographic 
precipitation spilling out over the San Juans...with heavier convective 
showers moving in this afternoon. Severe wind gust potential very 
possible throughout the day with 700 mb winds running 50 to 60 kts. 
Snow levels will initially be above 10k...but will lower overnight 
with the passing front...although moisture will be diminishing at 
the same time. Combination and wind and snow and early season 
nature of the storm...necessitates the issuance of winter 
highlights for the high country. Have decided to expand the winter 
weather advisories to include the northern and central mountains of 
western Colorado...with up to 8 inches of new snow possible 
overnight as the front pushes through. 


On Sunday...continued breezy conditions over the forecast area with 
much cooler temperatures. A few showers hang on across the northern 
zones as moisture wraps around the low lifting northeast across 
Wyoming. Expect widespread valley freezes Sunday night as skies 
clear and winds decouple under clearing skies. This will likely 
impact the entire forecast area...with the lower valleys of west 
central Colorado and southeast Utah also freezing...including Grand 
Junction. 


Long term...Monday through Saturday... 
as the low center drifts along the US/Canada border from eastern Montana 
into North Dakota...the trailing trough axis moves across the 
forecast area on Monday. The moisture is prognosticated to be very meager... 
but a few showers may be possible over the favored slopes of the far 
northern mountains in the cold air. The chances remain quite low so 
have kept the probability of precipitation generally below mention for the zone forecast. The 
air mass remains cold with daytime temperatures 8-12 degrees f below normal. 
By Tuesday morning we begin to see good warming at 700 mb. However...due 
to the increased stability and dry air mass...the morning lows on 
could be as cold as or colder than Monday morning's. Temperatures 
begin a recovery Tuesday under sunny skies and warming aloft. A 
remnant of the hang-back trough lingers over the Desert Southwest... 
but a zonal flow dominates beyond midweek over the forecast area. By 
late in the week the flow becomes southwest as a low amplitude ridge 
develops over the Southern Plains. Look for temperatures to reach 
normal values by midweek climbing a few degrees higher by the end of 
the period. Dry conditions will continue. 


&& 


Aviation... 
strong and marginally unstable southwest flow aloft today will 
produce areas of mechanical turbulence over the mountains. The 
strongest most dangerous turbulence will occur along the north side 
of mountain ridges and peaks. Surface inversions will be weak and 
shallow this morning...with low-level wind shear a concern at 
all airports. A cold front will blast through the area late this 
afternoon and evening bringing areas of MVFR and local IFR conditions 
to the mountains due to rain and snow showers as well as 
thunderstorms. 


&& 


Gjt watches...warnings...advisories... 
Colorado...winter weather advisories in effect for areas above 10000 feet 
for the southwest and south-central mountains from noon today 
to midnight tonight...zones 09/12/18/19. 
Winter weather advisories in effect for areas above 9000 feet 
for the northern and central mountains from 3 PM today until 
6 am Sunday morning...zones 04/10/13. 
Wind Advisory until 6 PM MDT this evening for much of west 
central and southwest Colorado...including zones 
06/07/11/17/20/21/22/23. 
Utah...Winter Weather Advisory in effect for the eastern Uinta 
Mountains through this evening...zone 23. 
Wind Advisory for east central and southeast Utah until 6 PM 
MDT this evening...including zones 22/27/28/29. 


$$ 


Short term.....Jdc 
long term......joe+eh 
aviation.......jdc