799
FXUS65 KGJT 171728
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
1128 AM MDT Wed Jul 17 2024

.KEY MESSAGES...

- Temperatures are expected to remain a few degrees above normal
  with daily thunderstorm chances through the remainder of the
  week and into the weekend as moisture is recycled under the
  area of high pressure over the region.

- Threats from thunderstorms will mainly be from gusty outflow
  winds though a few storms will be capable of producing smaller
  hail and moderate to heavy rainfall rates. Overall flooding
  threats remain low.

- The combination of high based storms, gusty outflow winds and
  lightning will keep also keep a threat of new wildfire starts
  in the picture.

&&

.SHORT TERM /THROUGH THURSDAY/...
Issued at 309 AM MDT Wed Jul 17 2024

High pressure remains south of the forecast area today leaving
the region under westerly flow aloft. Models were consistent in
predicting a roughly 0.2" decrease in precipitable water over
the area as flow taps into drier air to west. As a result,
expecting fewer storms over eastern Utah and the western border
zones of Colorado this afternoon and evening. In contrast,
expect scattered to numerous showers and thunderstorms along the
Continental Divide and adjacent valleys again today. The main
threat from these storms will be lightning, small hail and gusty
outflow winds. Localized heavy rain is possible, mainly in the
eastern San Juan Mountains. Meanwhile, drying will allow
temperatures to rise by 3 to 5 degrees for most of the forecast
area. The exception will be in the San Juan Mountains where
storms will be more numerous with some of this activity
spreading southeastward across lower elevations from Durango
eastward to Pagosa Springs. Increased clouds and showers in
these areas are expected to result in a few degrees of cooling.

Expect the usual downturn in moist convection during the evening
in response to diurnal cooling. The high begins to shift
westward on Thursday and at the same time, moisture levels begin
to rise again, especially across the south. Consequently,
expect showers and thunderstorms to increase in coverage which
will be most noticeable in eastern Utah and far western Colorado
after today`s downturn in activity. Storm characteristics will
be similar to today with a slight uptick in the potential for
heavy in southwest Colorado. Temperatures are expected to
continue to cool over the southern zones while increasing across
the north.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Issued at 309 AM MDT Wed Jul 17 2024

With deep lows over the Gulf of Alaska and the Hudson Bay, and
strong ridging over the Western States in a blocking pattern, expect
little change in the weather across eastern Utah and Western
Colorado through the extended forecast period. Thursday evening, the
high that has been dominating our weather will be centered over
northern Arizona slowly working its way into the Great Basin by
Saturday where it sets up camp. This will bring near record
temperatures to much of the Intermountain West, but being only on
the eastern fringes of this high, temperatures across the region
will remain near normal through next Tuesday. The moist surge of
monsoonal moisture continues Friday with widely scattered showers
and thunderstorms across the higher terrain along and north of the I-
70 corridor, more widespread through the central and southern
Colorado mountains. As the high settles into the Great Basin
Saturday into next week, drier air moves into the northern areas to
limit convection to isolated showers and thunderstorms each
afternoon and evening along and north of the I-70 corridor while
widely scattered storms continue through the central and southern
mountains.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1124 AM MDT Wed Jul 17 2024

Slightly drier conditions suggest a downturn in convective
coverage today and early radar and satellite trend concur.
Storms developing over ridges in the next few hours will take a
slow drift southward...some surviving into the adjacent valleys.
Confidence overall is low due to the lesser storm coverage but
forecast for now favors KTEX KDRO and KASE for a passing storm
with VCTS used elsewhere. Gusty winds continue to be the main
threat from the storms today and could exceed 40 mph under the
right conditions. Clearing tonight and VFR holds over the next
24 hours.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

SHORT TERM...NL
LONG TERM...DB
AVIATION...GJT