643
FXUS65 KGJT 152352
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
552 PM MDT Thu Aug 15 2024

.KEY MESSAGES...

- Tranquil conditions remain in place this evening and through
  Friday.

- Monsoonal moisture returns showers Saturday, mostly in
  eastern Utah and along the Colorado state line.

- More robust monsoonal moisture will impact the region Sunday
  and beyond. Showers and thunderstorms will bring back the
  threat of localized flooding Sunday and into the new work
  week.

&&

.SHORT TERM /THROUGH FRIDAY/...
Issued at 237 PM MDT Thu Aug 15 2024

Drier conditions under a transitory ridge have brought a pause to
the monsoonal shower activity across the region. Lower relative
humidities and waning August sunlight are also finding morning lows
trending down on the mountains, which is helping morning drainage
winds return some cooler air to the valleys as well. Afternoon highs
will hover around the climatological average through tomorrow,
with a slight warming trend heading into the weekend. For now,
the near term looks to remain mostly dry with scattered cumulus
clouds popping on the terrain features today and tomorrow.
Enough remnant moisture remains in the mountains to see an
isolated shower or two in northern Colorado and perhaps south
along the Continental Divide of the Central Mountains. Winds
turn more southwesterly Friday afternoon ahead of an approaching
low coming ashore in the PACNW. Breezy conditions are expected
along the Wyoming border of the CWA. Our northern counties will
see some of the stronger winds aloft mix down Friday afternoon,
with wind gusts around 20 mph expected. Desert valleys will
surge into the middle and upper 90`s, while up the hill, 80`s
and 70`s can be expected Friday. Available moisture is expected
to be in shorter supply tomorrow and should produce another
quiet day on the West Slope, after another cool morning.

&&

.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
Issued at 237 PM MDT Thu Aug 15 2024

By Saturday, the high pressure that has been over the Desert
Southwest blocking the monsoonal moisture will have slid to the east
over West Texas as a deep cold low drops down off the coast of the
Pacific Northwest. This sets up a weak omega-ish blocking pattern
across the CONUS with the troughing pattern over the eastern United
States that models, ensembles and otherwise, are in agreement will
last at least through the coming week to hold the door open to a
moderate monsoonal flow up off the Gulf of California through
Arizona into eastern Utah and Western Colorado. This will boost
PWAT`s from 0.3-0.4 inches on Friday up to 0.7-0.9 inches
Saturday and 0.8 to 1.2 inches Sunday through much of next week.
Given these conditions, expect isolated to scattered showers
and thunderstorms over the higher terrain Saturday afternoon and
evening. Sunday and Monday, coverage will be widely scattered
to widespread over the higher terrain of the region with
isolated to scattered storms moving off the terrain over the
lower valleys through the afternoon and evening. These storms
may produce periods of heavy rain and, with a weak flow aloft,
may lead to flash flooding risks due to slow moving and/or
training storms. By mid week, the high builds over New Mexico to
reduce the monsoonal flow somewhat with the afternoon and
evening storm coverage backing off to widely scattered across
the region, but the risks for flash flooding will continue.
Temperatures will be about five degrees above normal Saturday,
but will drop to near normal Sunday into next week with more
cloud cover and increased shower activity. Mid week looks to
warm back to about five degrees above normal with morning skies
clearing out allowing stronger diurnal heating.

&&

.AVIATION /00Z TAFS THROUGH 00Z SATURDAY/...
Issued at 545 PM MDT Thu Aug 15 2024

VFR conditions are forecast through the TAF period. Generally
light, terrain driven winds across the region through forecast
with occasional gusts up to 20 knots tomorrow afternoon.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

SHORT TERM...LTB
LONG TERM...DB
AVIATION...KAA