957
FXUS65 KGJT 241128
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
528 AM MDT Sun Aug 24 2025

.KEY MESSAGES...

- Widespread convection is expected this afternoon, with
  frequent lightning, heavy rain, gusty winds, and maybe some
  small hail the concerns.

- There is increased concern for flash flooding and debris flows
  in sensitive areas, especially for recent burn scars, through
  mid week.

- Widespread precipitation and much cooler temperatures are
  expected to linger through the end of the coming week.

&&

.SHORT TERM /THROUGH MONDAY/...
Issued at 249 AM MDT Sun Aug 24 2025

The pocket of drier air that resulted in a downturn in activity
across northwest Colorado earlier is still evident along the
northern and central Divide, both in lower dew points and in clearer
skies. To the south and west, deeper moisture is in control. Showers
have been ongoing across the southern half of eastern Utah through
the night, and show little inclination to die off. This could pose
some interesting challenges once the sun rises today. Moisture is
expected to slosh back in across the north, with widespread showers
and thunderstorms developing. The big question then becomes storm
mode...will we see more convective precipitation, or more
stratiform. A significant amount of morning cloud cover will favor a
more stratiform storm mode, as it will limit the amount of
instability that can develop, while morning clearing will have the
opposite effect. Model guidance, both deterministic hi-res models,
and ensemble guidance, are favoring the development of 500-1000 J/kg
of instability across much of the region. This is the result of both
expected morning clearing, and some extra oomph from a passing
shortwave. That synoptic level forcing, with all the moisture we
have around, can be enough to overcome some cloud cover that
overstays its welcome this morning. So the odds are good (>60%) that
we`ll see a convective storm mode, at least to start. This means the
potential for heavy rain producers, especially with the slow storm
motion under the high. Areas prone to issues with heavy rain, such
as slot canyons, steep terrain, and recent burn scars, will be at an
increased risk for flash flooding and debris flows. If planning to
travel or recreate outdoors today, stay weather-aware, and have
multiple ways to receive warnings. Temperatures will run cooler
today, close to normal for late August...low 90s for the desert
valleys, 60s for the mountain towns.

As moisture remains elevated, and outflows from afternoon convection
bounce around, look for convection to linger well into the overnight
period tonight. That will keep things mild and muggy. Another round
of precipitation is expected to develop tomorrow afternoon, but
we`re reaching the point where its getting more difficult to clear
out in the morning. With each round of overnight convection, we
increase the probability that clouds and showers will linger through
the morning. So we will start to see storm mode transition to more
widespread stratiform with embedded stronger convection tomorrow
afternoon. This will also result in temperatures cooling even
further, with highs running 3-5 degrees below normal tomorrow
afternoon.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Issued at 249 AM MDT Sun Aug 24 2025

Moisture advection strengthens Tuesday evening into Wednesday which
will keep stratiform precipitation chances elevated through the
overnight hours. Once again, we may see a decrease in afternoon
thunderstorm coverage in favor of a more stratiform rain across much
of eastern Utah and western Colorado.

Moisture begins to retreat to the north late Wednesday into
Thursday. Depending on the timing of this moisture retreat, we could
see a transition back to convective precipitation south of I-70 on
Thursday. If so, periods of moderate to heavy rainfall and lightning
chances will reenter the forecast. Temperatures will remain 5-10
degrees below normal through the week, thanks to all the clouds and
showers.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 525 AM MDT Sun Aug 24 2025

Showers have lingered across southeast Utah, and mid level
clouds continue to rotate across the entire region. Some
clearing this morning will give way to widespread showers and
thunderstorms this afternoon. Most terminals have a good chance
of seeing thunderstorms at least in vicinity, if not directly
impacting the terminal locations. KCNY, KTEX, KGUC, and KDRO
have the highest chances of seeing direct impacts from gusty,
erratic winds, lightning, and heavy rain at the airport. After
00z, expect activity to gradually transition to more stratiform
rain showers, with diminishing threats of heavy rain and
lightning. Winds will be light and terrain driven when not
influenced by convection. VFR conditions will prevail, but drops
into MVFR/IFR with heavy rain will be possible.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

CO...None.
UT...None.

&&

$$

SHORT TERM...BGB
LONG TERM...KAA/TGJT
AVIATION...TGJT