456
FXUS65 KGJT 290527
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
1127 PM MDT Tue May 28 2024

.KEY MESSAGES...

- Conditions mainly dry and breezy, with chances for isolated to
  scattered showers and thunderstorms over the higher terrain
  each afternoon/evening throughout the week and into early next
  week.

- Aside from a brief dip to near normal temperatures Thursday,
  expect above normal warmth this week.

&&

.SHORT TERM /THROUGH WEDNESDAY NIGHT/...
Issued at 152 PM MDT Tue May 28 2024

A modest bump in mid level moisture along with some limited
instability (CAPE of 500 J/kg or less and steep lapse rates) is
resulting in better coverage of showers and storms than seen in
previous couple days. Storms are isolated to widely scattered in
coverage and are favoring the high terrain. Very little shear
and weak upper level winds is keeping the storms fairly anchored
to the high terrain with weakening and quick dissipation as
these storms drift into the valleys, more prevalent up north as
the best moisture and instability remains here. So given the
weak forcing and limited residence time of these showers/storms,
expect storms to quickly dissipate with the loss of daytime
heating today with valleys remaining mostly dry. High
temperatures are much warmer today with 80s across many lower
valleys and upper 80s to near 90 in the Grand Valley and lower
desert valleys of east-central and southeast Utah.

On Wednesday, the gradient tightens ahead of a cold front that
is expected to move through Wednesday evening. This cold front
is associated with an upper level shortwave trough that will
pass to our north Wednesday night. So, as a result, it will be
breezier Wednesday afternoon with gusts in the 20 to 30 mph
range on average, with some gusts approaching 35 to 40 mph
possible across the north. Not much moisture is associated with
this system but enough instability and lift should result in
isolated to scattered showers and thunderstorms Wednesday
afternoon with better coverage across the north where some
showers/storms could linger through the late evening hours
Wednesday night. Gusty outflow winds seem to be the primary
concern with these storms with limited moisture at the low
levels. Given the flow is southwest and the front moves through
Wednesday evening, highs on Wednesday should remain warm with
highs 5 to 10 degrees above normal and a little higher than
today.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Issued at 152 PM MDT Tue May 28 2024

In the wake of the dry cold front that is expected to move
through Wednesday night, temperatures on Thursday will run 5-10
degrees cooler compared to the day previous. This will be most
noticeable across northeast Utah and northwest Colorado, where
temperatures are expected to top out around 5 degrees below
normal. Along and south of the I-70 corridor, temperatures will
be near to around 5 degrees above normal. These slightly cooler
temperatures will only last a day, as warm air pushes back north
in the wake of the departing upper level low. From Friday
onward, blended guidance favors a gradual warming trend with
temperatures of 5-10 degrees above normal across the board.
While this first upper level low tracks by to our north, the
combination of a weak westerly jet and the tightened pressure
gradient aloft will lead to breezy conditions Thursday and
Friday afternoon. Flow aloft then turns southwesterly by
Saturday, continuing the gradual warming trend and bringing in
some modest moisture. This moisture, along with the approaching
upper level trough, will lead to a slight expansion of storm
coverage over the higher terrain along the Divide during the
afternoon and evening hours. This trough is expected to move
overhead on Sunday, but models differ as to whether it remains
robust or washes out as it meets the mountains. If it holds
together, some more organized convection will be possible,
mainly across the higher terrain of northeast Utah and northwest
Colorado. If it washes out, look for status quo conditions on
Sunday...warm, breezy, and mostly sunny. One more trough will
brush by to our north early next week, although models disagree
quite a bit on timing and how far south this trough will reach.
What models do agree on, is that a piece of energy will break
away from this northern storm track and drift southwest, setting
up shop somewhere over SoCal as a cutoff low Monday or Tuesday.
In response to this deepening area of low pressure, a highly
amplified high pressure ridge will build north into the Great
Basin. Should this forecast verify, eastern Utah and western
Colorado are looking at a potentially prolonged period of
unusually warm and dry conditions next week.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1127 PM MDT Tue May 28 2024

Another round of scattered showers and thunderstorms will
develop over the higher terrain, focused along the Divide, after
18Z Wednesday with gusty outflow winds being the primary
concern. Outside of showers, breezy conditions are expected with
gusts of 20 to 25 kts out of the southwest. VFR will prevail
through the period.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

SHORT TERM...MDA
LONG TERM...BGB
AVIATION...TGJT