396
FXUS65 KGJT 172321
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
521 PM MDT Mon Jun 17 2024

.KEY MESSAGES...

- Windy, dry conditions continue this evening with winds gusting
  to 35 to 45 mph across the region. Red Flag Warnings remain in
  place for southeast Utah and southwest and west-central
  Colorado through 10 PM.

- A cold front will move from the northwest corner of the
  forecast area across the remainder of the forecast area by
  sunrise Tuesday. As a result, Tuesday`s highs will be nearly
  10 degrees below normal in the north to near normal in the
  south.

- Unsettled conditions return Thursday with afternoon showers
  and thunderstorms expected into the weekend. Exceptional
  precipitable water levels are expected to produce some
  heavier rain later this week.

&&

.SHORT TERM /THROUGH TUESDAY NIGHT/...
Issued at 251 PM MDT Mon Jun 17 2024

Prefrontal southwest winds were stronger this afternoon than on
Sunday as models had predicted and gusts were solidly in the 35
to 45 mph range. The front itself stretched south-southwest from
southwest Wyoming to west-central Utah and just beyond the
northeast corner of the forecast area as 20Z this afternoon.
Ahead of the front, shallow cumulus were evident in satellite in
a 50 to 75 mile band southeast of the front with a scattering of
cumulus over western Colorado. Meanwhile, except for the north,
temperatures were running a bit cooler than at this time
yesterday.

Models indicated that the trough over the northern Rockies
associated with the cold front will shift eastward moving over
the northern High Plains by 12Z/Tues. In response, the cold
front will move from northeast Utah to just south of the
forecast area`s southern border by sunrise Tuesday. Winds will
decrease behind the front, but won`t diminish entirely for much
of the region. Moisture is limited with the front/trough
passage, but there is at least a small chance for isolated
shower/thunderstorm activity across the northern zones.
Overnight lows will be noticeably cooler tonight for all but the
southernmost zones where cooling will be more modest.

The area will experience a break from the heat on Tuesday and
with little moisture to work with, showers are highly unlikely.
Temperatures dip by 15 to 20 degrees across the north, around 10
degrees for the central zones and closer to 5 degrees in the
south. Quiet weather conditions persist Tuesday night and
morning lows Wednesday should be a bit milder.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Issued at 251 PM MDT Mon Jun 17 2024

Southwest flow remains over the region with general troughiness
across the west and a high pressure ridge to our east on
Wednesday. Aside from a few isolated storms possible along the
western Colorado divide mountains, expect above normal
temperatures and dry conditions as temperatures warm a good 7
degrees or so from Tuesday`s brief cooldown. As this trough
moves further eastward, the southerly flow will tap into some
deeper moisture from the Gulf. Specific humidities and mixing
ratios both jump up quite a bit to 7 g/kg or higher with PWAT
increasing to almost 200 to 240 percent of normal, especially
for central and southern areas. This equates to PWAT of 0.75 to
1 inch fairly widespread with PWAT over an inch for southeast
Utah and southwest Colorado near and around the Four Corners
region. This deeper moisture spreads further north on Friday to
east-central Utah and west- central Colorado with PWAT over an
inch as the trough to our west finally pushes across the region.
So, what will start off as hot and dry Wednesday into early
Thursday will turn cooler and unsettled with scattered to
widespread showers and thunderstorms late Thursday into Friday.
We could see some beneficial rain with this system as this
moisture push looks legit, even though it might take some time
for the lower levels to saturate early on Thursday but Friday
should bode well for wetting rain.

A ridge of high pressure moves in by Saturday, drying things out
fairly well as this moisture is pushed east, although there
always seems to be some lingering pockets of moisture left
behind to generate at least isolated to scattered afternoon
storms over the high terrain. Cannot rule that out. However, the
general trend is for a return to hot and dry conditions,
especially by Sunday into early next week as this ridge axis
amplifies over the Rockies with the high centered over northern
Mexico and southern Arizona/New Mexico. Upper 90s to triple
digit heat look to be in the picture for the lower desert
valleys of west- central Colorado, east-central Utah and
southeast Utah during this time.

&&

.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 521 PM MDT Mon Jun 17 2024

Strong southerly winds ahead of an approaching cold front will
bring frequent gusts in the 25 to 45 mph range with some gusts
over 55 mph possible near the frontal passage. Winds should turn
more to the West near the frontal then a distinct shift to the
North/Northwest with the frontal passage. Gusts of 30 to 40 mph
behind the frontal passage should gradually decrease to less
than 10 mph by sunrise. Otherwise VFR conditions are expected
though some patchy blowing dust is possible.

&&

.FIRE WEATHER...
Issued at 251 PM MDT Mon Jun 17 2024

Red Flag Warnings remain in effect through 10 PM this evening
for southeast Utah and portions of southwest and west-central
Colorado. Winds will continue to gust to between 35 and 45 mph
across the region late this afternoon and early this evening
ahead of a cold front. The front will track southeastward across
the northern and central zones this evening moving to the
southern border of the forecast area late tonight. Relative
humidity will recover later tonight while winds gradually
subside behind the front.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

CO...Red Flag Warning until 10 PM MDT this evening for COZ203-207-
     290>293.
UT...Red Flag Warning until 10 PM MDT this evening for UTZ490-491.

&&

$$

SHORT TERM...NL
LONG TERM...MDA
AVIATION...TGJT
FIRE WEATHER...TGJT