Old Snowmass, Colorado Weather Forecast Discussion

530
FXUS65 KGJT 231129
AFDGJT
Area Forecast Discussion
National Weather Service Grand Junction CO
529 AM MDT Tue Sep 23 2025
.KEY MESSAGES...
- Showers will be likely norther of I-70 in Colorado through the
  morning before shifting mainly to the High Country this
  afternoon along with a threat of thunderstorms.
- Snow levels around 10000 feet through the morning will keep a
  threat of accumulating snow over the high peaks of the
  northern and central mountains.
- Temperatures drop to 5 to 15 degrees below normal today.
- Drier air returns tomorrow with the next chances for
  precipitation arriving by late in the week near the 4 Corners.
&&
.SHORT TERM /THROUGH WEDNESDAY/...
Issued at 218 AM MDT Tue Sep 23 2025
It is going to feel more fall-like today in a post-frontal
airmass that is going to start out fairly soggy and dry out
through the day. Radar and satellite imagery should tell the
main story with a good spin sitting over our northern CWA early
this morning. This northern stream low will make up the
downstream portion of the developing Omega block...low pressure
off the SoCal coast and a blocking high over PacNW makes up the
remainder. Moisture transport vectors show a decent fetch of
Gulf moisture being pulled back West across our northern CWA
through the morning as the low swings into central Colorado.
This moisture plume is however likely getting disrupted by the
strength of ongoing strong convection over the Southern and
Central Plains early this morning. However this over-running
pattern should continue to bring fairly high chances of rain
north of I-70 in Colorado. With much cooler temperatures aloft
expect there will be noticeable blanket of snow over the higher
peaks of the northern and central mountains before clouds begin
to lift through the afternoon. So far the Vail Pass cam looks
good. Subsidence and drier air will continue to erode the
moisture from West to East through the afternoon though enough
moisture and instability will be around for scattered showers
and thundestorms over the eastern 1/3 of the CWA through sunset.
Temperatures look to end up some 5 to 15 degrees below normal
behind the front today...though overall warmer than yesterday in
the southern valleys thanks to more sunshine and afternoon
breezes. Fairly chilly night in store as skies clear and drier
air moves in. Would not be surprised to see some morning
stratus/fog in some of the river valleys but confidence not very
high at just where yet. Near freezing temperatures are probable
(>60%) in the Upper Yampa River Valley and Gunnison Basin
tonight. Freezing or below in the higher valleys and terrain above
10000 feet can be expected. More sun and quiet conditions
expected on Wednesday as temperatures rebound back closer to
normal.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
Issued at 218 AM MDT Tue Sep 23 2025
Dry air overtakes the region on Wednesday as the jet stream
currently providing the moisture tap for the region moves southward.
Conditions remain seasonable until a ridge builds in on Thursday
providing enough warm air advection to lift temperatures into the
low to mid 80s for the lower valleys.
The residence of dry air will be short lived, with an unsettled
weather patter regaining control Thursday night into Friday.
Moisture will hang over the southern half of the forecast area
before spreading north into the weekend. Global ensembles hold onto
this moisture well into next week. While there is a lot of time for
things to change between now and then, one can expect the forecast
to trend wetter and cooler this weekend after a warmer and drier
second half of the week.
&&
.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 529 AM MDT Tue Sep 23 2025
Low clouds...precipitation and fog are impacting TAF sites over
portions of western Colorado including KHDN...KASE and KGUC
where MVFR and occasional IFR conditions have been recorded.
This will continue through the morning and with impacts and KEGE
as the clouds slowly lift and thunderstorms become a threat
through the late afternoon hours. Gusty outflow winds will be
the main concern as drier air mixes into the region. Skies will
clear and conditions generally improve in most areas. There will
be a chance of low clouds and fog to form in some of the river
valleys overnight but confidence too low to place in TAFs attm.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...None.
UT...None.
&&
$$
SHORT TERM...15
LONG TERM...KAA
AVIATION...TGJT

NWS GJT Office Area Forecast Discussion