Flash Flood Watch 4, NWS Grand Junction, CO

686 
WGUS65 KGJT 010114
FFAGJT

Flood Watch
National Weather Service Grand Junction CO
714 PM MDT Wed Jun 30 2021

COZ008-010-013-010215-
/O.CAN.KGJT.FF.A.0004.000000T0000Z-210701T0300Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Central Colorado River Basin-Gore and Elk Mountains/Central Mountain
Valleys-Flat Tops-
714 PM MDT Wed Jun 30 2021

...FLASH FLOOD WATCH FOR THE GRIZZLY CREEK FIRE BURN AREA IS 
CANCELLED...

The Flash Flood Watch for portions of northwest Colorado and west 
central Colorado, including the following areas, in northwest 
Colorado, Flat Tops. In west central Colorado, Central Colorado 
River Basin and Gore and Elk Mountains/Central Mountain Valleys has 
been cancelled.

The Flood Watch is cancelled. Flooding is no longer expected to pose 
a threat. Please continue to heed remaining road closures.

$$

NL

Area Forecast Discussion
National Weather Service Grand Junction CO
1110 AM MDT Wed Jun 30 2021

.SHORT TERM...(Today through Thursday)
Issued at 443 AM MDT Wed Jun 30 2021

Convection has lingered well into the early morning hours but not
entirely where I expected 24 hours ago. There are light showers
rotating westward toward the main upper low over N.Utah which CAMs
suggested. More activity is lifting northward over NW
Colorado...a result of another spoke of energy and an embedded
weak MCV which a distinct spin on radar imagery. Showers seem to
be attracted to the Grizzly Creek burn scar but so far
precipitation rates and likely amounts have been light enough to
limit runoff hazards. Unfortunately this area will remain under a
threat of additional moderate to heavy rainfall rates today.
Forecasting this rainfall to actually occur on the scar is another
story however as forcing for ascent is not focused over this part
of the CWA. The eastern San Juans to the central divide mountains
again appear favored for the better storm coverage this
afternoon...again in vicinity of the upper wind maxima. The upper
low will remain stalled over northern Utah tonight then slowly
lift northeast as it gets undercut by high pressure expanding out
of the S.Plains into the Desert Southwest on Thursday. The
atmosphere remains unstable with both low level and mid level
moisture lingering in the profile. Unorganized elevated convection
will be around again tonight as a wave rotates through the base
of the low and ejects eastward across our CWA. The upper low will
weaken as it lifts into SW Wyoming on Thursday with a more
Westerly flow pattern setting up across our CWA. PWAT remains
unchanged...hovering just above 3/4 of an inch. There is some
focus for ascent near the periphery of the low circulation which
could force better coverage over N.Utah in the afternoon.
Otherwise looks like mainly storms will favor orographics and form
on the ridges early in the afternoon before shifting east and
moving over the valleys through the late afternoon hours.
Temperatures will gradually warm over the next few days and hover
closer to normal.

.LONG TERM...(Thursday night through Tuesday)
Issued at 443 AM MDT Wed Jun 30 2021

The Desert Southwest looks to remain unsettled going into the long
term period. PWAT values will remain well above the climatological
average of 0.6 inches. All that moisture combining with the
unsettled conditions, daytime heating, and the orographic lift will
lead to afternoon showers and storms nearly every afternoon. This is
great news as far as fire weather and drought conditions are
concerned, but not so great for burn scars or areas that see
training storms or continued rainfall.

Taking a look at the bigger picture, the ridge of high pressure that
brought record-breaking heat to the Pacific Northwest will be
centered over the Canadian Prairie Provinces Wednesday and is
forecasted to continue slowly shifting eastward. An elongated trough
of low pressure draped from New England to northeast New Mexico
Wednesday will also drift slowly east. A strong Bermuda high will
centered over the Mid-Atlantic will extend to Texas. This extension
of the Bermuda high is forecasted to cut off over Texas and
retrograde slowly to the west, reaching the Great Basin late
Saturday. Up to that point, moisture will continue to pump into
eastern Utah and western Colorado. Once the high pressure settles
over the Great Basin any lingering moisture over the Western Slope
will be recycled in the afternoons. Clouds and precipitation this
week will keep temperatures below average, but as high pressure
builds in over the weekend temperatures will rise to around.

&&

.AVIATION...(For the 18Z TAFS through 18Z Thursday afternoon)
Issued at 1107 AM MDT Wed Jun 30 2021

Thunderstorms are developing on the higher terrain, and may pass
over some of the sites this afternoon. Moderate to heavy rainfall
rates are possible with storms and this would likely drop
conditions to MVFR as it passes over an airfield. Gusty winds will
also be a threat near storms. The storms will decrease in
coverage overnight and not likely to impact TAF sites after
01/04Z.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...
CO...None.
UT...None.
&&

SHORT TERM...15
LONG TERM...BGB
AVIATION...TGJT

Hazardous Weather Outlook
National Weather Service Grand Junction CO
451 AM MDT Wed Jun 30 2021

COZ001>014-017>023-UTZ022>025-027>029-011100-
Lower Yampa River Basin-Central Yampa River Basin-
Roan and Tavaputs Plateaus-Elkhead and Park Mountains-
Upper Yampa River Basin-Grand Valley-Debeque to Silt Corridor-
Central Colorado River Basin-Grand and Battlement Mesas-
Gore and Elk Mountains/Central Mountain Valleys-
Central Gunnison and Uncompahgre River Basin-
West Elk and Sawatch Mountains-Flat Tops-
Upper Gunnison River Valley-Uncompahgre Plateau and Dallas Divide-
Northwest San Juan Mountains-Southwest San Juan Mountains-
Paradox Valley/Lower Dolores River-
Four Corners/Upper Dolores River-Animas River Basin-
San Juan River Basin-Southeast Utah-Eastern Uinta Mountains-
Eastern Uinta Basin-Tavaputs Plateau-Arches/Grand Flat-
La Sal and Abajo Mountains-Canyonlands/Natural Bridges-
451 AM MDT Wed Jun 30 2021

This hazardous weather outlook is for eastern Utah and western
Colorado.

.DAY ONE...Today and Tonight

Thunderstorm development will be possible again over a large part
of eastern Utah and Western Colorado today. A low probability
threat of flash flooding on recent burn scars remains in place
today due to slow moving storms. Lightning and gusty outflow
winds near storms will also be threats to monitor.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday

Thunderstorm development will be possible through the remainder
of the week though a slow downturn in coverage is forecast each
day. Expect isolated gusty winds and heavy downpours with the
strongest cells.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected today or tonight, however
spotters are encouraged to relay rainfall amounts or any observed
flooding to the National Weather Service in Grand Junction.