687
FXUS65 KGJT 030842
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
242 AM MDT Wed Jul 3 2024

.KEY MESSAGES...

- A few showers and thunderstorms are possible over the San Juan
  Mountains this afternoon while high pressure dominates else-
  where.

- This drier regime brings the return of near critical fire
  weather conditions across northern portions of Colorado and
  Utah today. However, coverage remains localized so the Fire
  Weather Watch has been cancelled.

- Dry and warm conditions persist through the Holiday weekend
  and likely into early next week.

&&

.SHORT TERM /THROUGH THURSDAY/...
Issued at 242 AM MDT Wed Jul 3 2024

Dry air continues to infiltrate the Western Slope in earnest, as
noted on the 00Z GJT sounding which had a precipitable water of
0.36 inches...significantly less than the 1.12 inches just 24
hours prior! This shift is thanks to the prominent northwest
flow dominating eastern Utah and western Colorado aloft, as a
ridge of high pressure amplifies over the Pacific Ocean while
troughing engulfs the central CONUS. We won`t see much change in
the synoptic pattern through the short term period as the high
remains relatively stationary, apart from strengthening farther
north before a gradual shift inland on Thursday afternoon. As a
result, look for continued dry weather and a return to warmer
temperatures. One exception will be across portions of the San
Juan Mountains where, thanks to a weak wave brushing the area on
the backside of the larger trough to the east, isolated showers
and thunderstorms will be possible this afternoon and early
evening. Gusty outflow winds will be the primary concern though
brief wetting rain is possible. Little to no convection is
expected on Thursday.

The other thing of note in the short term is the potential for
near critical fire weather conditions today. Mixing under the
ridge paired with a jet nosing into the northern zones will
bring an uptick in winds this afternoon. Confidence is high
regarding humidities dropping into the upper single digits to
low teens this afternoon across northeast Utah and northwest
Colorado but how strong the winds will be...that`s where
uncertainty remains. Yesterday`s forecast was borderline for
wind gusts of 25 mph or greater, and for three hours or more,
and that is once again the case this morning. Overall, the
probability of seeing wind gusts of 25 mph or greater together
with those lower humidities is 30 to 40 percent for northwest
Colorado while portions of northeast Utah are in the 50 to 60
percent range. There are some areas where the probability is 80
to 90 percent, but it is too localized or not of a long enough
duration to justify upgrading the Fire Weather Watch.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Issued at 242 AM MDT Wed Jul 3 2024

The high amplitude pattern that has been anchored over the higher
latitudes will be migrating to the mid latitudes by midweek. It will
look more like a mid-winter triple R pattern with the higher than
normal heights to our West effectively shutting down the monsoon as
the Northwest flow dominates the pattern over the interior West.
PWAT currently 2-4 Std Dev above normal will plunge to below normal
by late week as dry air spreads back into the region. This is good
news for your swamp cooler which will actually push out cold air
again as dew points drop back into the 20s and 30s...but maybe not
so good news on the fire weather front. Low afternoon humidity and
afternoon wind gusts could create pockets of critical fire weather
even with temperatures hovering near to slightly below normal in the
latter half of the week and heading into the weekend. Isolated
afternoon storms may linger in the eastern and southern mountains
Wednesday afternoon before any residual moisture gets wrung out.
Otherwise a mainly dry forecast looks on track to end out the week.
The Western Ridge pattern looks to hold well into next though it
will migrate a bit farther inland. Hence the 6-10 day outlook calls
for good chances of above normal temperatures moving back in and the
drier than normal pattern continuing.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1107 PM MDT Tue Jul 2 2024

VFR conditions expected over the next 24 hour with afternoon
breezes on Wednesday bringing some gusts to 25 to 30 mph at area
TAFs.

&&

.FIRE WEATHER...
Issued at 242 PM MDT Tue Jul 2 2024

A system brushing the north today will bring a slight uptick in
wind gusts this afternoon. Winds will largely remain less than
25 mph but there will be some localized periods of 30 mph across
portions of northeast Utah and northwest Colorado. Given the
decreased confidence on more widespread duration and coverage
of winds, opted to cancel the Fire Weather Watch. Otherwise,
mostly dry and warmer weather prevails through the end of the
week and this weekend as high pressure remains overhead.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

SHORT TERM...MMS
LONG TERM...15
AVIATION...TGJT
FIRE WEATHER...TGJT