766
FXUS65 KGJT 082317
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
517 PM MDT Mon Jul 8 2024

.KEY MESSAGES...

- Rising temperatures bring the potential for heat related
  watches or advisories as early as Thursday.

- Afternoon/evening showers and thunderstorms are possible each
  day for the San Juan Mountains and central Colorado mountains
  through early next week.

&&

.SHORT TERM /THROUGH TUESDAY NIGHT/...
Issued at 320 PM MDT Mon Jul 8 2024

High pressure will remain over the Great Basin and Desert
Southwest in the near term. Dry northwest flow aloft will limit
afternoon/evening shower and thunderstorm activity to areas
along the central and southern Colorado portion of the
Continental Divide. The moisture fueling this activity was
working under the ridge from the east where deeper moisture
resides. Sunny skies will drive temperatures 3 to 5 degrees
above normal Tuesday. However, with few clouds and a dry
airmass, overnight lows are expected to dip below seasonal
norms both tonight and Tuesday night.

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Issued at 320 PM MDT Mon Jul 8 2024

Circulation around the high pressure over the Great Basin
Wednesday will pull limited moisture southeast along and east
of the Divide, but enough for some cumulus development through
the afternoon and even an isolated shower or thunderstorm.
Probabilities are a bit higher to the south where the clockwise
flow turns northeasterly to pull more moisture off the Front
Range over the Divide into the San Juans. The high pressure will
gradually slide east over the Rocky Mountains by Saturday where
it will want to hang out going into next week. This opens the
door to deep monsoonal moisture moving up off the Gulf of
California into the Great Basin through the weekend and into
Wyoming by Monday. Guidance indicated continued isolated showers
and thunderstorms along the Divide favoring the southern
mountains each afternoon through the week. Saturday and Sunday
show an uptick in shower coverage with showers and thunderstorms
becoming more scattered as they spread north and west over the
higher terrain south of the I-70 corridor. Models don`t really
show support for advection of moisture into the region, so the
moisture source is likely evapotranspiration due to clear skies
and intense warming under the high pressure. Early next week,
model solutions diverge with some pushing the high east onto the
Plains while the others keep it in place over the Rockies, its
favored position. We`ll see which models are right. Also, with
deep monsoonal moisture on three sides, models want to slip some
moisture into the region under the high for widely scattered
showers and thunderstorms across the higher terrain of eastern
Utah and Western Colorado Monday. Again, I`ll believe that when
I see it, not that it can`t happen, but the. models need to
figure out what to do with the high, split it to the southwest
over the Four Corners and east onto the plains, or shift it
southeast over the panhandle of Texas to allow the moisture to
move into the region. If the high remains anchored over the the
Rocky Mountains, we`ll stay on the dry side with isolated
showers and thunderstorms fed by evapotranspiration.

Temperatures Wednesday will run five to eight degrees above
normal through the lower elevations and near normal in the
mountains. By the weekend as the high pressure moves in,
temperatures will warm to five to ten degrees above normal with
the mountains warming to almost five degrees above normal. These
temperatures are assuming cloud buildups going into the weekend
will limit diurnal heating, but if the clouds don`t form, the
weekend temperatures will rise yet a few more degrees to near
record highs and may warrant heat advisories especially in the
lower valleys. Stay tune for more on these temperatures over the
next few day, but know that we are moving into the warmest
season of the year. Be sure to plan accordingly if you will be
out in the heat and intense sunshine.

&&

.AVIATION /00Z TAFS THROUGH 00Z TUESDAY/...
Issued at 515 PM MDT Mon Jul 8 2024

As high pressure continues to build in from the west, winds will
remain light and variable. Typical terrain driven wind patterns
will prevail. Skies will remain clear and VFR conditions will
prevail for the next 24 hours.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

SHORT TERM...NL
LONG TERM...DB
AVIATION...TGJT