131
FXUS65 KGJT 231139
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
539 AM MDT Sun Jun 23 2024

.KEY MESSAGES...

- Another round of isolated to scattered showers and
  thunderstorms will initiate around noon, build through the
  afternoon and diminish through the evening. A few stronger to
  severe storms may still form on the terrain across the north.

- High pressure moves in today, warming the region to about five
  degrees above normal.

- Expect afternoon convection to form daily over the higher
  terrain as trapped moisture is recycled.

&&

.SHORT TERM /THROUGH MONDAY/...
Issued at 318 AM MDT Sun Jun 23 2024

The weather pattern struggles to let go of the more Spring-like
pattern of deep troughs descending into the Pacific Northwest and
transiting east across the northern states with cool boundaries
reaching south to brush the northern areas of the region, and
grabbing onto the more Summer-like pattern of high pressure to the
south over Texas and New Mexico drawing subtropical moisture from
the Gulf of Mexico, northern Mexico and the Gulf of California into
the Desert Southwest and north into the eastern Utah and Western
Colorado. Tonight there is finally some activity over Sonora looking
somewhat MCS-ish that is typically seen much earlier in May, but
this is only one. It has been an interesting transition this year.

Currently dominated by high pressure across the south from the
Desert Southwest to the Lower Mississippi Valley, eastern Utah and
Western Colorado will see temperatures generally warm about five
degrees above yesterday as high pressure builds north over the
region. Moisture continues to be trapped under the high to get
recycled into showers and thunderstorms each afternoon with the
diurnal heating. Such is the forecast again today with again a
slight down-tick in convection over what we saw yesterday. With
afternoon CAPE running 200-500 J/kg and shear at 20-25 kts, isolated
stronger thunderstorms are still possible over the higher terrain
with strong gusty winds and small hail being more the norm for these
storms. Expect convection to initiate around noon following the
diurnal heating cycle, and increase through the afternoon before
dropping off going into the evening. We`ll see scattered showers and
thunderstorms over the higher terrain with denser activity over the
San Juans to the south becoming more isolated as you go north. Skies
will clear out overnight under the subsidence, readying the
atmosphere for another round of heating Monday and similar
convective activity with temperatures about the same as today.
Guidance continues to try to dry out the region, but without a
significant system to sweep the moisture out of the area, the
pattern of afternoon showers will continue. Additionally, as the
high to the south wobbles slightly east, more over Texas Sunday
night as an inverted trough rotates around the west flank, the
circulation will allow some supplemental moisture to slip north
into the Desert Southwest and into the region to further
strengthen the diurnal cycle.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Issued at 318 AM MDT Sun Jun 23 2024

The broad east-west oriented mid-level high across the southern tier
of the U.S. begins to consolidate over New Mexico Monday night into
Tuesday as a low pressure system approaches the Pacific Northwest.
As the trough approaches the West Coast Wednesday, it impinges on
the the western flanks of the ridge causing moisture from the
Mexican Plateau that had been kept west of the region to begin
drifting northward over the forecast area. As a result,
afternoon/evening showers and thunderstorms will increase from
isolated coverage on Tuesday to scattered Wednesday. By Thursday,
moisture levels peak with precipitable water levels near an inch for
much of the forecast area and as a result, moist convection becomes
widespread and the potential for heavy rain increases. As the trough
moves across the Pacific Northwest to the northern Rockies on
Thursday night then to the northern High Plains on Friday, the
moisture tap from the south is shunted to the east allowing drier
air to infiltrate in the west flow behind the trough. Consequently,
the area should see a downturn in moist convection on Friday with
even less shower/thunderstorm activity Saturday as drying continues.

Temperatures are expected to remain 5 to 10 degrees above normal
Tuesday and Wednesday with readings in the low 100`s forecast for
the Grand Valley and the lower elevations of southeast Utah.
However, increased clouds and shower coverage is expected to bring
temperatures to near normal levels Thursday with a slow rise
coinciding with drying Friday and Saturday.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 524 AM MDT Sun Jun 23 2024

Expect mostly VFR conditions and light winds through the TAF
period. The exception will be convection starting around 18Z
over the higher terrain, drifting into adjacent valleys and
winding down after 00Z. Look for scattered showers and storms
over the southern mountains with more isolated coverage as you
go north. Included VCTS in KTEX and KDRO, but not enough
certainty to include it in any other TAF`s, though most mountain
sites have some minimal risk through the afternoon.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

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