Thompson, Utah Weather Forecast Discussion

332
FXUS65 KGJT 101152
AFDGJT
Area Forecast Discussion
National Weather Service Grand Junction CO
552 AM MDT Wed Sep 10 2025
.KEY MESSAGES...
- Showers and thunderstorms continue today, with more
  widespread wetting rains and localized flash flooding
  concerns.
- Thursday and Friday will see widespread showers and
  thunderstorms return with additional wetting rains. Potential
  exists for strong to severe storms on Thursday with strong
  gusty winds, hail and localized flash flooding possible,
  especially on recent burn scars.
- Temperatures will trend cooler Thursday and beyond with fall-
  like conditions expected.
&&
.SHORT TERM /THROUGH THURSDAY/...
Issued at 340 AM MDT Wed Sep 10 2025
Subtle wiggles in the flow are still allowing isolated
convection to continue through the early morning hours once
again as the atmosphere remains unstable with enough lift and
moisture to produce nocturnal convection. It appears some accas
remains present according to nighttime satellite imagery,
indicative of instability. A deep closed low to our west will
deepen over Nevada and California today, allowing the southwest
gradient to tighten over the Four Corners area and shift the
high pressure ridge to our southeast over the Texas Panhandle.
We will start the day off with enough sun to heat things up for
another day of above normal temperatures. We will see breezy
southwest winds, especially across eastern Utah and portions of
western Colorado near the state line, with gusts in the 20 to 35
mph range this afternoon. This heating will also allow for
showers and thunderstorms to develop once again by late morning
into the afternoon, initially over the high terrain but becoming
more widespread later in the afternoon and into the evening.
PWAT anomalies will continue to creep upwards along the western
Colorado Divide, with values approaching 150 percent of normal
by late afternoon and evening. CAPE will be in the 300 to 500
J/kg range with 20 kts of shear, so some stronger storms are
possible with gusty winds, small hail and brief heavy rain
possible leading to localized flash flooding concerns if any
stronger cells move over recent burn scars. Moisture will be on
the increase this evening into the overnight hours with the
monsoonal moisture plume working its way northward around the
high to our southeast in addition to a shortwave moving through
the flow, allowing for overnight convection to continue but be
more widespread.
Thursday looks like a very interesting day weather wise as a 100
kt jet streak from the closed low sets up across Utah, putting
eastern Utah and western Colorado in the favored left exit
region for favorable dynamic lift. Both the HREF and the HRRR
indicate strong shear in the realm of 40 to 50 kts with CAPE
approaching 500 to 1000 J/kg, which is significant for the
western slope. If this instability and shear is realized, we
could potentially see some strong to severe storms, especially
across the Four Corners northward towards the I-70 corridor,
with strong to severe wind gusts and hail potential. Convection
will be ongoing through the morning but the stronger convection
doesn`t look to ramp up until late Thursday morning into the
afternoon and evening with storm motion looking fairly robust.
SPC has southeast Utah and much of west-central to southwest
Colorado in a Marginal Risk for severe weather which makes sense
given the instability and shear indicated by the models. In
addition to strong to severe storms, storms will be capable of
heavy rain which could result in flooding concerns, especially
for areas of steep terrain and recent burn scars that will need
to be monitored closely. One caveat could be morning cloud cover
from overnight convection and shower activity tonight into
Thursday morning, but the models are showing much of the area
with little to no CIN.
&&
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Issued at 352 PM MDT Tue Sep 9 2025
Moisture continues to funnel into western Colorado, and eastern Utah
to a lesser extent, Thursday night into Friday leading to
elevated precipitation chances, cooler temperatures, and the
potential for burn scar flash flooding. A stronger pressure
gradient also sets up by Friday bringing breezy winds to the
region. We`ll be keeping an eye on the potential for small
perturbations in the upper level flow to enhance the coverage of
convection on Friday PM but this will be easier resolved in the
CAMs as they are integrated into the forecast blends.
Drier air works in from the west, but there`s a timing discrepancy
between global ensembles. The GEFS brings drier air in on Saturday,
24-36 hours faster than the ECMWF which wants to slowly evacuate
mositure from the forecast area from south to north throughout the
weekend. This will be something to keep an eye on over the next few
days, especially if you have outdoor plans. Seasonal temperatures
return Sunday. Afternoon thunderstorm chances pick back up again
next week with a troughy pattern aloft.
&&
.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 548 AM MDT Wed Sep 10 2025
Isolated thunderstorms continue this morning across northwest
Colorado with VCTS possible at KHDN, KEGE and KASE through 15Z.
Southwest winds will increase across the area late this morning
into the afternoon with another round of storms developing over
the higher terrain initially with a bit more coverage late
afternoon into the evening hours. Most TAF sites will have
potential impacts, especially late in the day so included a
PROB30 group for -TSRA. VFR should prevail for most areas the
majority of the day with MVFR in any showers/storms with gusty
winds and locally heavy rain possible. Showers and storms look
to continue through the overnight hours.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...None.
UT...None.
&&
$$
SHORT TERM...MDA
LONG TERM...KAA
AVIATION...TGJT

NWS GJT Office Area Forecast Discussion