Flash Flood Warning 73, NWS Salt Lake City, UT

823 
WGUS75 KSLC 182246
FFSSLC

Flash Flood Statement
National Weather Service Salt Lake City UT
446 PM MDT Mon Sep 18 2023

UTC013-051-182345-
/O.CON.KSLC.FF.W.0073.000000T0000Z-230918T2345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Duchesne UT-Wasatch UT-
446 PM MDT Mon Sep 18 2023

...FLASH FLOOD WARNING FOR THE DOLLAR RIDGE BURN SCAR REMAINS IN 
EFFECT UNTIL 545 PM MDT THIS AFTERNOON FOR WEST CENTRAL DUCHESNE AND 
SOUTHEASTERN WASATCH COUNTIES...

At 446 PM MDT, Doppler radar indicated thunderstorms producing heavy 
rain over the Dollar Ridge Burn Scar. Between 0.5 and 0.75 inches of 
rain have fallen. Flash flooding is ongoing or expected to begin 
shortly.

Excessive rainfall over the burn scar will result in debris flow 
moving through the Dollar Ridge burn scar. The debris flow can 
consist of rock, mud, vegetation and other loose materials.

HAZARD...Life threatening flash flooding. Thunderstorms producing
         flash flooding in and around the Dollar Ridge Burn Scar.

SOURCE...Radar.

IMPACT...Life threatening flash flooding of areas in and around
         the Dollar Ridge Burn Scar.

Some locations that will experience flash flooding include...
  Starvation Reservoir and Strawberry Reservoir.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A debris flow is expected to impact the Strawberry River corridor 
from Strawberry Reservoir to Starvation Reservoir. People living in 
this area should take action to ensure their safety!

&&

LAT...LON 4018 11090 4018 11089 4014 11073 4017 11053
      4015 11053 4005 11089 4003 11098 4015 11105

FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

Webber

659 
WGUS75 KSLC 182341
FFSSLC

Flash Flood Statement
National Weather Service Salt Lake City UT
541 PM MDT Mon Sep 18 2023

UTC013-051-182351-
/O.EXP.KSLC.FF.W.0073.000000T0000Z-230918T2345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Duchesne UT-Wasatch UT-
541 PM MDT Mon Sep 18 2023

...FLASH FLOOD WARNING FOR THE DOLLAR RIDGE BURN SCAR WILL EXPIRE AT 
545 PM MDT THIS AFTERNOON FOR WEST CENTRAL DUCHESNE AND SOUTHEASTERN 
WASATCH COUNTIES...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat. Please continue to heed remaining road closures.

LAT...LON 4018 11090 4018 11089 4014 11073 4017 11053
      4015 11053 4005 11089 4003 11098 4015 11105

$$

Webber

Area Forecast Discussion
National Weather Service Salt Lake City UT
405 AM MDT Mon Sep 18 2023

.SYNOPSIS...A more unsettled pattern will shift into Utah this
afternoon and evening. A cold, more significant system will impact
the state Thursday into Friday, bringing some of the coldest
temperatures of the fall into portions of Utah by late in the
week.

&&

.SHORT TERM (Through 12Z Wednesday)...The main weather impact for
today will be the threat of high-based convection especially
across east central Utah, the western Uinta Basin, and portions of
the Great Salt Lake Desert. Early morning upper air and satellite
analysis indicates a weak shortwave trough ejecting ahead of a
relatively weak upper level low camped off the central California
coast. Meanwhile an active northern jet is noted around the
periphery of a relatively strong eastern Pacific ridge.

Looking at radar/satellite trends this morning, high-based
convection is already ongoing across a broad section of the
Beehive State. Occasional wind gusts to 40 mph have been reported
near more robust convection.

Looking at the HREF ensemble mean SBCAPE this afternoon and
evening, the most significant instability is expected to be across
east central Utah, northward into the western Uinta Basin and
western Uinta Mountains, with perhaps another maxima near the
Utah/Nevada border into the Great Salt Lake Desert. Model
soundings support high-based convection, with the requisite
microburst threat. 00 and 06Z CAMS also support this area of
enhanced convection. Expect at least occasional microbursts with
wind gusts to 50-55 mph across these areas this afternoon and
evening.

The most significant threat of convection will shift into the
western Uinta Mountains and western Uinta Basin Tuesday afternoon
and evening.

.LONG TERM (After 12Z Wednesday)....A trough will be digging down
the PNW coast Wednesday morning. Ahead of the trough, strong
southwesterly flow aloft will mix down to the surface during the
afternoon Wednesday and Thursday producing gusty southwesterly
winds across the western half of Utah. Current guidance keeps max
gusts <40 mph, but there are several ensemble members that do
produce gusts above advisory criteria across west central and
southwestern Utah so this will need to be monitored as the trough
gets closer. Temperatures ahead of the trough will be near or
slightly above seasonal normals and conditions will stay primarily
dry with the exception of some terrain driven showers during the
afternoon.

As the trough pushes into the Great Basin it will cutoff from the
main flow and linger across the northern Great Basin through the
end of the week before ejecting eastward on Saturday. The greatest
chances for precipitation will be on Friday as the main
baroclinic zone pushes through northern Utah. The southern half of
Utah will remain mostly dry throughout the duration of the event
as dry westerly flow will inhibit rain chances. But across
northern Utah and southwest Wyoming anomalous PWATs on the order
of 75th-90th percentiles for this time of year will allow for
widespread precipitation to develop. Total valley precipitation
across northern Utah will generally be between .3"-.8" (25th-75th
guidance percentiles), but the ceiling and floor are widely
variable with 90th percentile totals near 1.5" and 10th percentile
totals ~.1". Given that we are transitioning into fall the
precipitation will be more stratiform and less convective,
particularly behind the front.

As the axis of the cutoff low moves to our east there will be a
brief window of northwest flow to establish on Friday afternoon
that will bring a transition from stratiform to more showery
activity. Additionally, mean 700 mb temperatures of 0-1C with mean
700mb heights ~10,000 feet Friday through Saturday morning will
bring snow to the higher elevations. Accumulating snow (<3") is
possible across the high Wasatch and Uinta mountains. Snow levels
could dip lower (~8500'), but accumulating snow is not expected at
these lower elevations. Temperatures across northern Utah Friday
and Saturday will be 10-15 degrees below normal with southern Utah
running 5-10 degrees below normal. There is a 50% chance of the
first freeze on Saturday morning across the higher valleys of Utah
and SW Wyoming, such as the Bear River Valley, Wasatch Back, and
Lower Sevier Valleys.

As this cutoff low exits the region late weekend, high pressure
will begin to build back into the area with a drying and warming
trend to accompany it.

&&

.AVIATION...KSLC...VFR conditions will prevail for the KSLC
terminal through the period. Isolated early morning and afternoon
scattered showers likely won't have any significant impacts to the
terminal with the exception of some sporadic wind shifts due to
outflow. Otherwise, winds will follow a typical southerly drainage
through the early morning before transitioning to northerly in
the afternoon.

.REST OF UTAH AND SOUTHWEST WYOMING...VFR conditions will prevail
for most terminals through the period. Isolated early morning and
afternoon showers across the northern half of the area likely
won't have any significant impacts to the terminals besides
sporadic wind shifts due to outflow. Otherwise, expect typical
diurnal wind patterns across the area. Conditions will be dry
across southern Utah.

&&

.FIRE WEATHER...High pressure will continue to shift away from
the region today. An area of increased mid-level moisture will
help to foster the development of high-based, dry thunderstorms.
The most significant threat will be across east central Utah
northward into the western Uinta Basin and across portions of the
Great Salt Lake Desert through this evening. This threat will
shift to mainly the western Uinta Mountains and western Uinta
Basin Tuesday afternoon and evening.

A cold, upper level low will impact the region Thursday into
Friday. Gusty winds can be expected Thursday ahead of the main
cold front, which will cross the region later Thursday into
Friday. Widespread precipitation is expected near and behind this
cold front Friday, with snow levels falling as low as 8500-9000
feet, with light snow accumulations possible above around 8500
feet.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...None.
WY...None.
&&

Kruse/Mahan

For more information from NOAA's National Weather Service visit...
http://weather.gov/saltlakecity

Special Weather Statement
National Weather Service Salt Lake City UT
1218 PM MDT Mon Sep 18 2023

UTZ125>127-181900-
Upper Sevier River Valleys UT-Bryce Canyon Country UT-
Southern Mountains UT-
1218 PM MDT Mon Sep 18 2023

...A strong thunderstorm will impact portions of west central
Garfield County through 100 PM MDT...

At 1218 PM MDT, Doppler radar was tracking a strong thunderstorm near
Panguitch, or 33 miles east of Cedar City. This storm was nearly
stationary.

HAZARD...Wind gusts up to 50 mph and half inch hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Panguitch, Red Canyon and Hillsdale.

This includes the following highways...
 US Route 89 between mile markers 120 and 133.
 Utah Route 12 between mile markers 0 and 5.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 3769 11255 3779 11260 3790 11234 3769 11227
TIME...MOT...LOC 1818Z 238DEG 2KT 3777 11248

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...50 MPH

Webber

Special Weather Statement
National Weather Service Salt Lake City UT
128 PM MDT Mon Sep 18 2023

UTZ125-128-129-182000-
Capitol Reef National Park and Vicinity UT-South Central Utah UT-
Southern Mountains UT-
128 PM MDT Mon Sep 18 2023

...A strong thunderstorm will impact portions of north central
Garfield and southwestern Wayne Counties through 200 PM MDT...

At 127 PM MDT, Doppler radar was tracking a strong thunderstorm 8
miles northwest of Boulder, or 18 miles north of Escalante, moving
east at 20 mph.

HAZARD...Wind gusts up to 50 mph and half inch hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Boulder.

This includes Utah Route 12 between mile markers 90 and 111.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 3794 11161 3805 11164 3820 11127 3797 11116
TIME...MOT...LOC 1927Z 251DEG 19KT 3802 11153

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...50 MPH

Webber

Special Weather Statement
National Weather Service Salt Lake City UT
200 PM MDT Mon Sep 18 2023

UTZ125-128-129-182030-
Capitol Reef National Park and Vicinity UT-South Central Utah UT-
Southern Mountains UT-
200 PM MDT Mon Sep 18 2023

...A strong thunderstorm will impact portions of north central
Garfield and southwestern Wayne Counties through 230 PM MDT...

At 200 PM MDT, Doppler radar was tracking a strong thunderstorm near
Boulder, or 17 miles southwest of Capitol Reef National Park, moving
east at 10 mph.

HAZARD...Wind gusts up to 50 mph and half inch hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor damage to outdoor objects is
         possible.

Locations impacted include...
Capitol Reef National Park and Boulder.

This includes Utah Route 12 between mile markers 91 and 110.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 3796 11149 3810 11152 3820 11120 3796 11116
TIME...MOT...LOC 2000Z 265DEG 10KT 3802 11142

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...50 MPH

Webber