358
FXUS65 KGJT 151750
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
1150 AM MDT Mon Jul 15 2024

.KEY MESSAGES...

- Above normal temperatures continue today with another round of
  showers and thunderstorms developing from late morning through
  the afternoon and into the evening. Main threats from storms
  will be lightning, strong outflow winds and small hail.

- Temperatures are expected to be closer to normal with daily
  thunderstorm chances during the remainder of the week and into
  the weekend as moisture is recycled under the area of high
  pressure over the region.

&&

.SHORT TERM /THROUGH TUESDAY/...
Issued at 349 AM MDT Mon Jul 15 2024

Nocturnal showers lingered during the early morning hours across
the northern and southern portions of the forecast area. In the
north, this activity appeared to be associated with a weak short
wave trough moving eastward along the southern Wyoming border.
Meanwhile, across the south there appeared to be a meso-vortex
left over from evening convection to the south of the forecast
area. Expect a few of these showers will persist through
sunrise and adjusted forecast to account for propagation and
slow dissipation of this activity.

The center of the high pressure system drifted south of the
forecast area and is expected to remain centered over the
central AZ/NM border for the next 36 hours. GEFS indicated
moisture levels currently in place will be quasi-static with
precipitable water levels hovering near 0.75" through short term
period which ranged from 100 to 140 percent of normal. At these
levels localized heavy rain is possible, but excessive rainfall
is unlikely. Storms redevelop from late morning into the early
afternoon, forming over terrain, then drifting over adjacent
valleys later in the day. Storms diminish in the evening, but
it`s likely that some showers will continue into the early
morning hours. Look for this scenario to play out again on
Tuesday.

Temperatures will be less hot, but still above normal today,
then decrease closer to normal on Tuesday in response to
increased clouds and showers. Tonight`s lows will continue to
run milder than normal.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Issued at 349 AM MDT Mon Jul 15 2024

High pressure continues to drive the forecast for eastern Utah
and western Colorado through next weekend. With the
aformentioned high centered over the Four Corners region on
Wednesday and Thursday, high temperatures continue to remain
around 5 degrees above normal for mid July. PWAT values remain
about 150% of normal through this period leading to afternoon
showers and storms in the mountains and enhanced cloud cover
area wide. Model soundings continue to show the presence of a
dry layer up to 10-15K feet which favors high-based
thunderstorms capable of producing gusty outflow winds, very
similar to what we`ve seen the last couple of days. A few storms
may produce heavy rain, but the dry surface layer paired with
PWAT values around 0.75" does not favor a widespread heavy rain
threat.

Looking ahead to Friday into the weekend, model spread increases
but the general consensus is that the center of high pressure
migrates slightly westward as an upper-level trough deepens
across the eastern CONUS. This helps temperatures drop a few
degrees back towards seasonal normals. The moisture forecast is
more unresolved and will depend on how weather systems evolve
east of the Divide and in the western Gulf. Right now ensemble
data holds PWATs around 150% of normal, but about 25% of ECMWF
Ens members show PWATs climbing above 1" next weekend. Something
to keep an eye on as the week progresses.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1146 AM MDT Mon Jul 15 2024

A relatively quiet morning should lead to an uptick and shower
and thunderstorm activity again this afternoon and evening.
Limited coverage over most areas reduces confidence in impacts
at most TAF sites where VCTS was used...with more confidence at
KTEX. However most TAF sites have some probability of seeing
gusty winds from nearby storms or from more organized outflow
boundaries from farther storm complexes. Will amened TAF sites
as these threats become more apparent from radar/satellite
trends. Otherwise VFR should hold over the next 24 hours.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

SHORT TERM...NL
LONG TERM...KAA
AVIATION...GJT