Area Forecast Discussion
Issued by NWS Grand Junction, CO

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FXUS65 KGJT 082119

Area Forecast Discussion
National Weather Service Grand Junction CO
219 PM MST Mon Mar 8 2021

.SHORT TERM...(Tonight through Tuesday night)
Issued at 209 PM MST Mon Mar 8 2021

A shortwave trough is currently over central Colorado this afternoon
and will continue to quickly move eastward. Dry air is already
entraining on the backside side of the system as seen in the latest
satellite imagery. Mostly sunny to partly cloudy skies will allow
for a push in surface heating and a shot at record highs in some
locations. Deep mixing is promoting gusty winds associated with the
falling precip and in the clear spots. Conditions are still cloudy
along the Divide where snow showers are ongoing, but those are
expected to dissipate over the next few hours. Dry conditions return
tonight in the wake of the system and less clouds will result in
cooler lows compared to this morning.

Tomorrow the polar and sub-tropical jet will merge over the region
as a strong trough moves into the Pacific Northwest. A tight
gradient will remain over our area and keep the gusty winds going
through the day. By the afternoon valleys will be fairly windy
especially in portions of southeast Utah where speeds will approach
advisory criteria. Later in the day a lead shortwave out ahead of
the main trough will lift out over the Great Basin and clip the
northern half of the forecast area. Ascent will be more focused with
the jet to our northwest, but there will be some showers possible in
the Uinta mountains by the afternoon. As the wave progresses to the
northeast the lift will spread towards the Divide in the evening.
Models are generating precipitation across most of the higher
elevations especially during the evening. Highs tomorrow will be
cooler than today, but still above normal.

.LONG TERM...(Wednesday through Monday)
Issued at 209 PM MST Mon Mar 8 2021

A prolonged period of unsettled weather is set to begin Wednesday. A
quick moving shortwave will bring some mountain snow showers for the
morning before precipitation associated with the upstream cut off
low begins that afternoon. Model forecasts are still in agreement on
the progression of the low through Saturday. The low is progged to
reach the CA/AZ/NV border by Friday afternoon, and the Four Corners
region by Saturday afternoon. Despite the reasonably good agreement
between models, the GFS and GEFS are still trending a bit more
progressive than the ECMWF and its ensembles at the end of the long
term period, Saturday into Sunday. This could have an impact on how
much precipitation the Central and Southern Mountains ultimately see
from this storm.

Through Wednesday night, the Eastern Uintas and the Northern and
Central Colorado mountains will be favored. Current forecast totals
see them receiving 5-8 inches of snow at the higher elevations, with
locally higher amounts possible. Lower elevations in these areas
could see 3-5 inches. On Thursday, the precipitation shifts south,
bringing another 2-4 inches to the Central mountains, and 3-5 for
the Uncompahgre Plateau and San Juan Mountains. From Friday onward,
the snow will be focused mainly on the San Juan Mountains. Current
forecast guidance has another 8-10 inches of snow for the San Juans,
but this is where the uncertainty in the track of the low over the
weekend could really change things. It`s likely the forecast totals
for this period will change over the coming days as confidence

Summing it all up, the next 5-7 days are going to be a bit cooler
and unsettled, with temperatures right around average and
precipitation. Snow is expected to begin for the Northern and
Central Colorado mountains, and the Eastern Uintas, on Wednesday.
Over the course of Thursday and Friday, the precipitation will shift
south, affecting the Central and Southern Colorado mountains. By the
weekend, the snow will be focused mainly on the San Juans as the low
starts to lift northeast, before finally clearing out on Monday.


.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1031 AM MST Mon Mar 8 2021

High and mid-level cloudiness associated with a quick moving
system is moving through at this hour, but the back edge is
through KVEL and KCNY and will be working east over the next few
hours. KTEX has seen some shower activity already this morning,
and likely will continue for the next hour or two, leading to the
occasional MVFR conditions. From mid-afternoon onward, all TAF
sites should expect VFR conditions to prevail. Gusty winds are
likely this afternoon, and areas of LLWS overnight.




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