508
FXUS65 KGJT 120540
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
1140 PM MDT Thu Jul 11 2024

.KEY MESSAGES...

- Temperatures will continue to climb into the weekend. Near
  record highs are expected Friday and Saturday.

- Afternoon showers and thunderstorms will develop over higher
  terrain each day throughout the next 7 days with an increase
  in coverage expected early next week.

- Temperatures remain elevated beyond the weekend, but some
  relief is expected from cloud cover and shower activity, as
  monsoonal moisture is forecast to return early next week.

&&

.SHORT TERM /THROUGH FRIDAY NIGHT/...
Issued at 205 PM MDT Thu Jul 11 2024

The forecast is still on track with little change as the high
pressure has currently inched up into southwestern Utah and will
continue its slow eastward progression over eastern Utah and
Western Colorado by Saturday. With the high moving in
temperatures will run five to ten degrees above normal for mid
July with lower valleys closer to the ten degrees above normal
mark and the mountains and higher elevations a bit cooler nearer
the five degrees above normal. Look for the temperatures to
warm yet another couple degrees to near record highs tomorrow as
the high pressure moves into the region. A Heat Advisory is in
effect for the lower valleys of eastern Utah and the Grand
Valley in Colorado beginning tomorrow at 10 AM and running
through 9 PM Saturday. With the daytime heating, isolated to
scattered showers and thunderstorms are beginning to fire again
as they have the past few days over the Park and Gore Ranges
west to the Flat Tops and south into the central Colorado
Mountains with scattered to widespread storms in the San Juans.
Convection will quiet down as the sun sets this evening. Models
are consistent with a drier airmass pushing into the northern
areas Friday to squelch convection along and north of the I-70
corridor. Expect showers and thunderstorms to be more isolated
to scattered tomorrow over the southern mountains with the dry
push of air. Again, these storms will end around sunset. The
primary threats from these showers and thunderstorms will be
lightning and outflow gusts of 40-50 mph.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
Issued at 205 PM MDT Thu Jul 11 2024

High pressure will be directly overhead by Saturday with a slight
nudge eastward by Sunday. This will result in well above normal heat
continuing with triple digits easily reached in the lower valleys of
eastern Utah and west-central Colorado. The high pressure nudging
eastward will allow for a return of sub-tropical moisture to work in
from the southwest around the high pressure as mixing ratios take a
good bump upwards over the high terrain. This will result in a bit
more coverage of showers and thunderstorms over the high terrain.
Given the dry low levels, gusty outflow winds look to be the primary
concern with any storm activity. The moisture return is not as
robust though as the high meanders and doesn`t quite stay east of
the region as shortwaves tracking across the Intermountain West and
down into the northern Rockies and Plains, this should allow the
high pressure area to shift back westward by Wednesday, allowing
drier air to infiltrate back in from the northwest. Our best period
of increased storm activity appears to be Monday and Tuesday as the
forcing from the shortwaves interacts with the moisture in place to
result in more coverage of storms and better potential for the lower
valleys to see some late in the day. Confidence in this pattern
shift as well as coverage of storms is low as models are still
trying to figure this out. So, while the details are a bit fuzzy,
the overall trend remains the same. Temperatures still look to
remain above normal heading into next week, but not quite as hot as
lower desert valleys look more like upper 90s to low 100s rather
than mid 100s.

&&

.AVIATION /06Z TAFS THROUGH 06Z SATURDAY/...
Issued at 1134 PM MDT Thu Jul 11 2024

VFR conditions are forecast through the TAF period. Very
similar conditions to what we saw yesterday are expected again
today with the most notable feature being isolated to scattered
showers and storms in the southern mountains this afternoon.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

CO...Heat Advisory from 10 AM Friday to 9 PM MDT Saturday for
     COZ006.
UT...Heat Advisory from 10 AM Friday to 9 PM MDT Saturday for
     UTZ024-027-029.

&&

$$

SHORT TERM...DB
LONG TERM...MDA
AVIATION...KAA