073
FXUS65 KGJT 100547
AFDGJT

Area Forecast Discussion
National Weather Service Grand Junction CO
1147 PM MDT Fri Aug 9 2024

.KEY MESSAGES...

- Daily afternoon and evening thunderstorms with the threat of
  heavy rain rates, gusty outflow winds, frequent lightning, and
  small hail until further notice.

- This uptick in available moisture will bring an enhanced
  threat of flash flooding and debris flows through the weekend
  and into early next week.

- Temperatures will be cooling back toward normal with the
  increase in precipitation and cloud coverage through at least
  the middle of next week.

&&

.SHORT TERM /THROUGH SATURDAY NIGHT/...
Issued at 346 PM MDT Fri Aug 9 2024

There is high confidence in a wetter than normal forecast over
the next few days...along with more temperate conditions thanks
to the added moisture/clouds/precipitation. That is where the
confidence end however with models struggling with convective
feedback or their different schemes. Unfortunately the more
broad-brushed approach to PoPs continue which may not always
reflect reality on the radar. That said the latest CAMS have
reset better and the general trend looks like the more active
North shifts to the southern CWA through the evening and early
morning hours. This will likely be driven by the energy moving
across the NV/UT line attm where strong/severe storms have
popped up on the gradient of the main moisture plume. The threat
of heavy rainfall should taper off through the evening but
fairly deep warm core storms should still be able to produce
efficient rainers approaching an inch per hour in some areas.
Another active day expected tomorrow with moisture settling in
leading to CAPE values over 1500j/kg and around 35kts of shear.
Again heavy rainfall will be the main threat but a few organized
storms will likely be able to get some hail and stronger wind
gusts to the ground. A strong moisture plume and passing jet to
the North keeps a strong signal for nocturnal convection to
continue well into early Sunday morning. Temperatures remain
near to slightly cooler than normal until further notice.

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Issued at 346 PM MDT Fri Aug 9 2024

The active weather pattern prevails through much of the long term
period as a series of systems push across the area. These waves will
act on the continued abundance of moisture as precipitable water
values remain at least 150 to 180 percent of normal. As a result,
look for scattered to numerous showers and thunderstorms each day.
As has been the trend the last several days, gusty outflow winds,
frequent lightning and small hail will be possible with storms. On
days where shortwaves are present, locally stronger storms cannot be
ruled out. With a continued juicy atmosphere the potential for
excessive rainfall with thunderstorms will increase each day with
flash flooding subsequently being a threat as well. This will
especially be true over saturated soils, burn scars, and vulnerable
steep terrain. Storms are expected to drift into the valleys each
day, given surface dewpoints will remain in the 50s and 60s through
at least Tuesday. Finally, with the presence of mild support aloft
and plenty of moisture, nocturnal showers and storms are likely
through early next week. So, plenty to monitor as we finish the
weekend and head into the new work week.

Late Tuesday and into Wednesday will see flow aloft across eastern
Utah and western Colorado shift to the west as the subtropical high
flattens to our south. This will cut off our direct tap to the
monsoonal moisture and introduce some slightly drier air into the
region. As has been mentioned numerous times this summer, models
tend to be a bit aggressive with eroding deeper moisture in place in
the wake of these monsoonal surges, so will tread with caution as
guidance projects PWATs to drop back to 80 to 90 percent of normal.
Either way, daily showers and storms are expected from mid week
onwards as sufficient moisture will be in place to fire off at least
isolated to scattered convection over the mountains each afternoon.
Another trough of low pressure begins to elongate off the West Coast
as we head into the latter part of the work week, which could open
the door back to that subtropical moisture.

Daytime highs through the long term period will remain below normal
area-wide, thanks to the abundance of clouds and convection each
day. Monday looks to be the coolest day of the period as a stronger
wave passes through. Overnight lows each night will steadily remain
a few degrees above normal for early August.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1142 PM MDT Fri Aug 9 2024

Isolated to scattered showers and thunderstorms will continue
overnight, particularly across the southern portions of the area
with VCTS at KTEX and KDRO. Elsewhere, showers will be hit or
miss but expect periods of MVFR at times in rain with
occasional breezy winds. Storms will redevelop Saturday
afternoon with more widespread coverage late in the day and
potential for some storms to linger overnight as a wave moves
across the north. VFR should prevail for the most part with MVFR
and locally IFR at times in any heavier showers/storms.

&&

.HYDROLOGY...
Issued at 346 PM MDT Fri Aug 9 2024

Storms with heavy rainfall have gone to the left and right of
the Grizzly Creek burn scar today but so far the threat to
Glenwood Canyon has been minimal. There are still some active
storms upstream and will see how this plays out. The deeper
monsoonal moisture remains over the area well into next week
This will keep a persistent threat for flash flooding and
debris flows across the majority of the area with potential
rainfall rates in excess of 1-2" per hour. Be sure to stay
weather aware over the coming days, especially if recreating
outdoors and in locations prone to flash flooding and debris
flows. Stay tuned for forecast updates, as well as any Watches,
Warnings, and Advisories in the coming days.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

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

&&

$$

SHORT TERM...15
LONG TERM...MMS
AVIATION...MDA
HYDROLOGY...TGJT