Damaging Winds in Utah, August 7, 2024

Area Forecast Discussion
National Weather Service Grand Junction CO
1134 AM MDT Wed Aug 7 2024

.KEY MESSAGES...

- Daily afternoon showers and thunderstorms continue through the
  week and weekend. These storms will be capable of producing
  brief bouts of heavy rain, gusty winds, and small hail.

- Localized flash flooding and debris flows will be possible
  with these afternoon storms. The potential for flash flooding
  increases this weekend with a monsoonal moisture push on tap.

- Temperatures remain 5 to 10 degrees above normal for the next
  couple of days before we cool back to normal by the weekend.

&&

.SHORT TERM /THROUGH THURSDAY/...
Issued at 334 AM MDT Wed Aug 7 2024

The forecast remains on track for PWATs to gradually decrease over
the next 24 hours or so as drier air is advected into the region in
west/northwesterly flow aloft. Despite this trend CAMs guidance
continues to depict showers and storms developing across the
forecast area this afternoon. Today's environment will feature
better synoptic-scale support than we've seen in previous days with
the right entrance region of a jet streak passing over northeast
Utah and northern Colorado this afternoon. So while moisture
availability favors the Four Corners region, organized ascent along
and north of I-70 will also support convective development today. If
PWATs do indeed dry out throughout the day the threat for localized
flash flooding will decrease some. Other thunderstorm threats
include lightning, gusty outflow winds, and small hail.

Tomorrow's forecast hinges on the return time of moisture. Hi-res
guidance is holding onto drier PWATs into Thursday evening. Even so
isolated to scattered showers and storms are projected to develop
over the higher terrain Thursday afternoon. Coverage may vary across
the forecast area as the synoptic support will no longer be in place
to aide convective initiation.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Issued at 334 AM MDT Wed Aug 7 2024

By Friday morning the ridge of high pressure over the west will be
flattened with the center of the high over the southern Plains while
a quasi-stationary low sets up over the Baja Peninsula. This pattern
will persist from Friday, through the weekend, and into early next
week. This is a pretty classic set up for a monsoonal burst over
eastern Utah and western Colorado. Therefore, it should come as no
surprise that GFS and ECMWF ensembles were similar in depicting
precipitable water values from 1 to 1.25 inches over the forecast
area, or from 130 to 180 percent of normal on average throughout the
long range period. Consequently, expect showers and thunderstorms to
become numerous each afternoon with scattered nocturnal moist
convection each night. At these moisture levels, stronger cells will
be capable of producing excessive rainfall, potentially leading to
localized flash flooding. On the plus side, this pattern should
bring much needed moisture to the region while also driving
temperatures down to normal, or slightly below normal levels.

&&

.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 1134 AM MDT Wed Aug 7 2024

Most TAF sites will have some probability of seeing a passing
storm move in the vicinity of the airfield or at least get some
of the outflow winds through the evening. The mountain TAF sites
by default will be favored to see a storm roll nearby. Gusts of
35 to 45 mph will be the main threats besides lightning. There
is an very small probability (10%) that rainfall rates could
drop vsby to MVFR. Otherwise VFR will dominate the forecast over
the next 24 hours.

&&

.HYDROLOGY...
Issued at 334 AM MDT Wed Aug 7 2024

Monsoonal moisture is expected to persist across eastern Utah
and western Colorado through the week, with daily showers and
thunderstorms forming first over the higher terrain and then
spreading over adjacent valleys. Areas south of the I-70
corridor will see the most consistent activity. The threat for
heavy rainfall will increase Friday into the weekend as a deep
monsoonal moisture push will increase precipitable water values
towards 150-200% of normal (above 1"). This will lead to an
increasing threat of flash flooding across the majority of the
area, potentially lasting into early next week. 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...KAA
LONG TERM...NL
AVIATION...GJT
HYDROLOGY...GJT

Hazardous Weather Outlook
National Weather Service Grand Junction CO
354 AM MDT Wed Aug 7 2024

COZ001>014-017>023-UTZ022>025-027>029-081200-
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-
354 AM MDT Wed Aug 7 2024

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

.DAY ONE...Today and Tonight

Afternoon showers and storms are expected today. Storms will be
capable of producing gusty outflow winds, small hail, and brief
bouts of heavy rainfall. Localized flash flooding and debris flows
are possible.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday

Chances for daily showers and storms continue through the week.
The potential for heavy rainfall increases heading into the
weekend.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed.

Special Weather Statement
National Weather Service Grand Junction CO
125 PM MDT Wed Aug 7 2024

COZ008-010-013-072000-
Central Colorado River Basin CO-Flat Tops CO-
Gore and Elk Mountains/Central Mountain Valleys CO-
125 PM MDT Wed Aug 7 2024

...A STRONG THUNDERSTORM WILL IMPACT NORTHWESTERN EAGLE COUNTY
THROUGH 200 PM MDT...

At 124 PM MDT, Doppler radar was tracking a strong thunderstorm over
Eagle, or 25 miles east of Glenwood Springs, moving east at 25 mph.

HAZARD...Wind gusts up to 40 mph. Torrential rain may cause travel
         issues along the I-70 corridor.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects.

Locations impacted include...
Eagle, Gypsum, Edwards, Dotsero, Wolcott, State Bridge, and
Sweetwater.

This includes the following highways...
 Interstate 70 in Colorado between mile markers 133 and 161.
 Colorado 131 between mile markers 1 and 14.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

&&

LAT...LON 3963 10707 3973 10711 3988 10658 3958 10663
TIME...MOT...LOC 1924Z 258DEG 20KT 3966 10687

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...40 MPH

TGR