-- Discussion containing changed information from previous version are highlighted. --
185
FXUS65 KGJT 230445
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
1045 PM MDT Sat Jun 22 2024

.KEY MESSAGES...

- Isolated to scattered showers and thunderstorms will continue
  for the next few hours, with a few strong to severe storms
  forming on the terrain across the north. These will diminish
  this evening.

- High pressure moves in tomorrow, bringing a drying and warming
  trend for the next several days. Highs will run 5-10 degrees
  above normal.

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

&&

.SHORT TERM /THROUGH SUNDAY/...
Issued at 155 PM MDT Sat Jun 22 2024

While conditions are nowhere near as impressive as at this time
yesterday, there`s still more than enough instability and shear to
spawn several strong to near-severe thunderstorms. Residual deep low-
level moisture is evident across the area in the form of dew points
in the 50s to low 60s all the way to the Wyoming border. CAPE values
analyzed on the SPC mesoanalysis are coming in line with earlier
forecast predictions at 1000-1500 J/kg. Bulk shear of around 40
knots is still present in the atmosphere, although low-level shear
is significantly reduced compared to yesterday...meaning there is
still a threat of large hail and strong, gusty winds, but that`s it.
This is all being helped along by the combination of lift from the
terrain and a passing shortwave over northeastern Utah and
northwestern Colorado. This activity will continue over the next few
hours before an expected downturn in strength and coverage. The
layer of dry air aloft, evident at around 450mb on this morning`s
12z GJT sounding, will be mixed down into the lower levels, diluting
that rich low level moisture and taking away fuel from this
afternoon`s convection. Shear will also be on the decrease, and
subsidence on the backside of the wave will make it much harder for
updrafts to not only sustain themselves, but to occur at all. So
look for showers and storms to begin dying off and skies clearing
out from 4PM onward.

Clear skies and drier overnight humidities will allow temperatures
to once again drop to near normal values tonight. Tomorrow,
temperatures will climb to around 5 degrees above normal as the
subtropical high slides in to our south and a ridge builds in aloft,
advecting warmer air in. Enough residual moisture will remain pooled
under the high that afternoon showers and thunderstorms are expected
over the higher terrain in the afternoon, but the threats will begin
transitioning to more gusty winds and small hail, compared to the
heavy rains and large hail we`ve seen the last few days. Another
passing wave in the afternoon may lend a little extra oomph to any
ongoing convection, leading to a few isolated stronger storms. Skies
are expected to clear after sunset with the loss of heating and the
passing of this shortwave. Continued warm air advection into the
night will keep overnight lows milder, running about 5 degrees above
normal tomorrow night.

&&

.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
Issued at 155 PM MDT Sat Jun 22 2024

Not much changes with the pattern into early next week with high
pressure staying anchored over New Mexico and Texas. The wave that
went through yesterday did pull in some dry air aloft and that will
eventually mix down to the surface. The best moisture has been pushed
just to our south, but there is still plenty lingering. Given the
high position weak southwest flow will allow some of that moisture
to sneak back into our area. This should translate into afternoon
showers and thunderstorms each day. Change comes around mid week
when a strong low pressure makes landfall in the Pacific Northwest.
That increased flow will tap into the rich moisture in the Desert
Southwest and bring back to our area. The low pressure system is
projected to track eastward over the Northern Rockies. Therefore we
should see an uptick in showers and storms perhaps as early as
Wednesday and lasting through Friday. We could be looking at another
round of severe hail, wind and heavy rainfall. The low pressure may
end up disrupting the moisture once again for a downtick by the
weekend. Temperatures warm up slightly before the moisture comes
back later in the week.

&&

.AVIATION /00Z TAFS THROUGH 00Z MONDAY/...
-- Changed Discussion --
Issued at 1042 PM MDT Sat Jun 22 2024

A few high clouds will move overhead this morning though most
areas will see SKC. Convection will start forming around 18Z
firing off the higher terrain and drifting into adjacent
valleys. Too early to put -TSRA or VCTS into TAFs but
possibility certainly exists Sunday afternoon. Widespread VFR
will be the rule though stronger convection may cause some brief
MVFR due to low ceilings or visibilities. Conditions will start
improving after 00Z.
-- End Changed Discussion --

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

SHORT TERM...BGB
LONG TERM...KJS
AVIATION...TGJT