305
FXUS65 KGJT 071131
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
531 AM MDT Sat Jun 7 2025

.KEY MESSAGES...

- Drier and warmer conditions return this weekend and continue
  into early next week with afternoon storms favoring the high
  terrain and more of a gusty wind threat than wetting rain.

- Isolated storms possible this afternoon over the San Juans and
  southern divide with potential for gusty winds, small hail and
  possibly a brief rain shower.

&&

.SHORT TERM /THROUGH SUNDAY/...
Issued at 336 AM MDT Sat Jun 7 2025

Mostly clear skies are seen across much of the region with some
high clouds moving into northeast Utah and extreme northwest
Colorado from Wyoming due to a shortwave dropping southward from
a low pressure trough over Sashatchewan and Manitoba in south-
central Canada. This shortwave drops southward across the Front
Range through the day today as high pressure ridge builds to our
west with what appears to be a Rex Block forming with the ridge
axis over the Pacific Northwest and a low trapped underneath
off the central California coast. This high pressure and Rex
Block does look to control our weather this weekend into at
least early next week with drier and warmer conditions and less
in the way of precipitation as yesterday`s cold front and trough
helped sweep out the deep tropical moisture that has been in
place since Monday of this past week. Most areas will see mostly
sunny skies and relatively quiet conditions today under this
drier air mass, with exception of the San Juans and southern
Divide mountains. The front from yesterday appears to have left
a boundary across the San Juans, as evident from the last of
yesterday`s convection before it ended. Models indicate some low
level convergence across the San Juans this afternoon and
frontogenesis fields appear to pick this up. Some of the hi-res
guidance is showing development of isolated showers and
thunderstorms over the San Juans along this boundary as the
shortwave drops southward and interacts with it, providing a
focus for convection. While the probabilities of precipitation
are not high by any means, there still exists a low end chance
that something could develop with daytime heating and this
boundary interaction. CAPE is around 200 J/kg with 20 kts of
shear in this area, so increased PoPs to include a mention of
thunderstorms here this afternoon, albiet a low end chance.
Anticipate more of a gusty wind threat than wetting rain
although a little bit of remnant moisture remains here with
mixing ratios around 4 g/kg, where they are much lower across
the rest of the area...reflecting a drier forecast.

The Rex Block and high pressure ridge moves further inland onto
the west coast by Sunday and maintains northwest flow across the
region with continued drier and warmer conditions. However, the
low pressure system over Manitoba deepens and drops into the
northern High Plains and Upper Midwest and kicks out another
shortwave that again drops north to south across the Divide and
down the Front Range. This is enough forcing to help kick off
more afternoon showers and storms mainly over the mountains,
favoring the Divide but a bit more coverage than today, so again
increased PoPs a bit more over the mountains for Sunday,
favoring the Divide which the NAMNest and HRRR appeared to pick
up on. Temperatures overall will take a 10 degree jump today
from yesterday given more sunshine and WAA with the high
pressure ridge. This might be a bit ambitious given the recent
cooler temperatures last few days so backed off a bit on the
warmup. We should see near normal highs today, give or take a
few degrees on either side, and highs on Sunday a bit warmer to
around 5 degrees above normal.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
Issued at 336 AM MDT Sat Jun 7 2025

Ridging aloft continues to build over the west and move towards
our region early in the coming week. With this pattern change
no major sources of upper-level support are expected to pass
through the area, which should generally limit PoPs outside of
afternoon heating. Through the long term atmospheric moisture
looks to remain elevated as moisture continuously advects into
our CWA. PWAT anomalies will not be as great as they have been
the past few days, but should fluctuate between moderately above
normal values (~125- 175% of normal). This consistent moisture
will support afternoon convection each day, primarily over the
high terrain. High temperatures, which have been below normal,
will be 5-10 degrees above normal through the coming week with
ridging aloft. The ridge looks to potentially break down by mid
week as a trough moves into the Pacific Northwest. This could
result in an uptick in afternoon storms but coverage appears to
favor the mountains with the best forcing and coverage moving
into Idaho, Wyoming and Montana as drier southwest flow moves
in late in the coming week.

&&

.AVIATION /12Z TAFS THROUGH 12Z SUNDAY/...
Issued at 529 AM MDT Sat Jun 7 2025

VFR conditions are expected to prevail over the next 24 hours
with mostly sunny skies. Some clouds will develop this afternoon
over the high terrain with afternoon wind gusts in the 20 to 30
mph range across most TAF sites. Isolated storms are possible
this afternoon over the San Juans and southern Divide mountains
but probability of impacts to TAF sites remains low. Clearing
skies and light, terrain driven winds return after sunset this
evening and overnight.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

SHORT TERM...MDA
LONG TERM...GF
AVIATION...TGJT