964
FXUS65 KGJT 031118
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
518 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 450 AM MDT Wed Jul 3 2024

A deep northwest flow pattern will remain in place over the Rockies
into early next week as a ridge stays anchored over the West and
deep trough over the eastern CONUS. This will keep SubTropical
moisture shunted into the lower latitudes leaving a mainly dry
forecast in place for our CWA with temperatures near normal through
the end of the week gradually pushing above as we head into the
weekend. The deep eastern trough will allow several fronts to drop
through the High Plains leading to Gulf moisture being forced up the
lee side hills. This could lead to a few storms along the divide
late in the forecast but confidence is low this will occur until the
Western High migrates far enough inland...which isn`t until the
middle of next week. This is likely good news for those cutting hay
after the prolonged wet spell...but possibly bad news for fire
weather interests. Localized critical fire weather conditions are
likely to occur each afternoon as humidity in the lower elevations
drop into the single digits and lower teens and deep mixing promotes
stronger wind gusts.

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 517 AM MDT Wed Jul 3 2024

VFR conditions expected over the next 24 hour with afternoon
breezes bringing gusts of 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