625
FXUS65 KGJT 021741
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
1141 AM MDT Tue Jul 2 2024

.KEY MESSAGES...

- Much drier air infiltrates the area today leaving only
  isolated terrain based showers and thunderstorms along the
  Continental Divide and our southern mountains.

- This drier regime brings the return of critical fire weather
  conditions...very localized today but becoming more widespread
  across northern portions of Colorado and Utah on Wednesday.

- Dry and warm conditions persist through the Holiday weekend
  and likely into early next week.

&&

.SHORT TERM /THROUGH WEDNESDAY/...
Issued at 325 AM MDT Tue Jul 2 2024

It was a fairly exciting end to this monsoonal moisture push
with a few robust storms likely dropping some hail and rainfall
rates in excess of 1.5 inches/hour. With the arrival of the
northern stream trough to the Rockies much drier air will be
ushered into the CWA along with slightly cooler temperatures.
Dew points have already dropped into the 30s behind the pseudo
cool front...which has made it through northeast Utah and
northwest Colorado as of 3 am. There are some high based showers
developing in the upglide area behind the front but with the
drier air infiltrating below haven`t seen any reports of this
making it to the ground. Farther to the South with the moisture
still in place some rainfall is still being reported but the
rates have dropped significantly over the past several hours. A
few showers linger this morning as the front`s progress stalls
over the central CWA and the main trough axis swings through.
Behind this there will likely be some very isolated mountain
convection that forms with steep lapse rates aloft over
lingering residual moisture. Temperatures will be noticeable
cooler behind the front up north and in parts of the western
CWA. Farther south the drier air and sunnier conditions look to
bring warmer temperatures today than those from 24 hours
ago...but most will be 4 to 8 degrees below normal for early
July. With drier air and clearer skies in place low temperatures
will be allowed to fall to more normal level and bring a
welcome relief to the muggy overnights of the past few days.
Temperatures on Wednesday will gain a few degrees under this
drier atmospheric regime. Gone will be the threat of heavy
rainfall...replaced by the return of fire weather concerns. Deep
mixing means afternoon winds will on the increase and when
combined with the lower humidity...critical fire weather
conditions look to be possible over portions of the northern CWA
where fuels could be ready to burn. More details below.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
Issued at 325 AM MDT Tue Jul 2 2024

High pressure will dominate the long term period resulting in mostly
dry weather. The ridge will remain situated off the West Coast on
Wednesday night before slowly nudging inland on Thursday. Flow aloft
will be out of the northwest across western Colorado and eastern
Utah as we remain on the outer periphery of the ridge while the
large trough pushing into the Northern Great Plains heads towards
the Upper Midwest on Thursday. This synoptic shift will close off
our tap to the monsoonal moisture with our precipitable water values
gradually trending down a bit each day as the deeper moisture begins
to erode in that drier northwest flow. It`s always a bit of a gamble
to say there won`t be any chance for shower and thunderstorm
activity through the end of the week given daytime heating,
orographics, and residual moisture. But, for the most part, guidance
knocks those PWATs down to well below normal area-wide as surface
dewpoints drop back into the 20s and 30s.

The ridge axis will continue to amplify on Friday but especially
this weekend, though its center will remain over the West Coast.
This will only further enhance the dry northwest flow overhead and
see temperatures rebound back to normal. As troughing continues to
impact the central CONUS some weak waves on the backside of the low
may brush the Divide and bring some increased clouds to those areas.
Otherwise, quiet weather prevails going into the new work week. One
area to monitor will be potential fire weather concerns as mixing
under the ridge brings breezy conditions most afternoons. We did
just receive a bunch of rain over the last couple of weeks but there
are some areas where fuels remain critical. Something to be mindful
of regardless as humidities drop back into the teens.

&&

.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/...
Issued at 1137 AM MDT Tue Jul 2 2024

VFR conditions are expected at terminals through the TAF period.
Winds will pick up this afternoon from the west to northwest at
around 15-20 mph and then subside towards sunset. A few
scattered mid level clouds will clear out eventually this
evening. There is a small chance for some showers to form on the
Continental Divide this afternoon, but they should be short
lived in this drier airmass.

&&

.FIRE WEATHER...
Issued at 325 AM MDT Tue Jul 2 2024

.A system moving across the Rockies today will sweep out the
monsoonal moisture and replace it with much drier air. Localized
areas of critical fire weather conditions are possible across
the far northern fire zones today...but this becomes more
widespread on Wednesday and a Fire Weather Watch has been issued
as afternoon humidity and breezy conditions combine. Dry
conditions look to persist into the near future as ridging
anchored to our West keeps us in a northwest flow
pattern...inhibiting the return of subtropical moisture.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

CO...Fire Weather Watch from Wednesday afternoon through Wednesday
     evening for COZ200-202.
UT...Fire Weather Watch from Wednesday afternoon through Wednesday
     evening for UTZ486-487.

&&

$$

SHORT TERM...15
LONG TERM...MMS
AVIATION...TGJT
FIRE WEATHER...15