Severe Thunderstorm Warning 80, NWS Salt Lake City, UT

462 
WWUS55 KSLC 011058
SVSSLC

Severe Weather Statement
National Weather Service Salt Lake City UT
458 AM MDT Sat Oct 1 2022

UTC007-015-011115-
/O.CON.KSLC.SV.W.0080.000000T0000Z-221001T1115Z/
Emery UT-Carbon UT-
458 AM MDT Sat Oct 1 2022

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 515 AM MDT
FOR NORTHEASTERN EMERY AND SOUTHEASTERN CARBON COUNTIES...

At 457 AM MDT, a severe thunderstorm was located 8 miles south of
Sunnyside, or 25 miles southeast of Price, moving east at 40 mph.

HAZARD...Ping pong ball size hail. 

SOURCE...Radar indicated. 

IMPACT...People and animals outdoors will be injured. Expect damage 
         to roofs, siding, windows, and vehicles. 

Locations impacted include...
East Carbon.

This includes US Route 6 between mile markers 264 and 273.
 
PRECAUTIONARY/PREPAREDNESS ACTIONS...

For your protection move to an interior room on the lowest floor of a
building.

&&

LAT...LON 3936 11002 3932 11006 3934 11046 3951 11048
      3959 11003 3954 11003 3953 11005 3950 11002
      3941 11001
TIME...MOT...LOC 1057Z 264DEG 33KT 3944 11038 

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.50 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...<50 MPH

$$

CRK

Area Forecast Discussion
National Weather Service Salt Lake City UT
406 AM MDT Sat Oct 1 2022

.SYNOPSIS...Unsettled weather will continue across portions of
southern and eastern Utah through the weekend. Upper level ridging
will build into the region early next week and persist through
much of the remainder of the week.

&&

.SHORT TERM (Through 12Z Monday)...Morning upper air and satellite
analysis indicates a ~570 dam upper level low is located near the
Bear Lake area. A shortwave trough is noted in water vapor
imagery rotating around this circulation associated with a ~80kt
speed max. Enhanced lift associated with this shortwave trough is
already aiding in the development of nocturnal convection across
portions of northern and central Utah. Mesoanalysis indicates a
diffuse boundary located across southern Utah.

As far as the forecast through early afternoon, CAMs continue to
indicate convection will further develop across portions of
northern and eastern Utah, primarily east of the Wasatch Front.
Notably, this convection is expected to develop near several of
the northern Utah burn scars including Bear, Trail Mountain, Pole
Creek and East Fork. Will monitor rates as this convection is well
forced and moisture remains somewhat elevated. Surface dewpoints
in these areas range from the 30s to the 40s...keeping in mind
that temperatures are running more like typical October values in
these locations.

Attention will then turn to the eastern portion of the
aforementioned boundary across southern Utah. HREF ensemble mean
SBCAPE ranges from around 750-1000 J/kg across eastern Kane,
eastern Garfield, Wayne and southern Emery Counties by early
afternoon. This combined with steep lapse rates and deep layer
shear at or above 30kts should be sufficient for the development
of strong convection across the previously mentioned area. The
Storm Prediction Center has outlined this area with a marginal
risk for severe thunderstorms and concur with this assessment.

Even with somewhat lower PWATs across southeastern Utah, the
threat of organized convection would also represent an increased
risk for flash flooding particularly from Capitol Reef to the San
Rafael Swell area over to Canyonlands. CAMs support this
conclusion as well, with discrete, strong convection developing in
this area by 19-20Z. Added a few "probable" areas of flash
flooding to Capitol Reef, San Rafael Swell and Canyonlands to
account for this with the morning package.

Model trends have shifted to show widespread convection across
southern and eastern Utah Sunday afternoon and evening as yet
another shortwave trough rotates around the parent trough and
provides more than sufficient lift for convection across much of
southern and eastern Utah. HREF ensemble mean SBCAPE near
1000-1250 J/kg combined with at or above 20kts of deep layer shear
should allow for another round of convection, starting perhaps in
the morning hours. Storm motions will support movement toward the
east to southeast, which is most conducive to flash flooding for
locations in the Escalante/Grand Staircase National Monument, Glen
Canyon National Recreation Area, portions of Capitol Reef and the
Swell and depending on storm morphology, Zion National Park. Most
of these areas will continue to see surface dewpoints near
45-50F, which will support heavy rainfall reaching the surface.

.LONG TERM (After 12Z Monday)...One last round of convective
activity is expected for southern and potentially central Utah on
Monday as the last shortwave of the series rotates through its
parent longwave trough that has been parked over the region for
some time. Some disagreement exists in the modeling suite at this
time, with the NAM12 and ECMWF holding on to the development of a
pronounced lee trough while the GFS and majority of ensemble
members from each system lack this feature. This lee trough has
trended further west into Nevada with today's forecast cycles, and
at this time does not appear to be of major concern given its
positioning.

While some degree of upper-level divergence will be present on
the tail end of the departing longwave trough and jet max west of
its axis, most of the forcing will come from mid-level cooling and
surface heating destabilizing the atmosphere, especially in the
presence of a moist low-level atmosphere left behind from the
prior days' precipitation. That said, the extent and intensity of
the precipitation will likely be limited, especially likely to
trigger off the high terrain, and may struggle to move off with
any vigor. Therefore, mostly mountain showers and a few isolated
thunderstorms are expected, and thus the flash flood potential at
this time is very low.

In a look at this morning's cluster analysis of the ensemble
membership, worth noting that confidence does not always increase
as lead time shortens. While the mean solution still represents a
high- amplitude ridge, each cluster shows some degree of the ridge
buckling at some point mid to late week, allowing for perhaps a
weak and progressive shortwave trough to barrel through. None of
the membership suggest any trough passage will be all that potent,
but it does reduce confidence in reaching temps well above
seasonal normals for more than just a day or two as the ridge
crests. Additionally, this is evident in the NBM PoP and WPC QPF
grids Thursday-Saturday as precip chances have crept up from their
previously bone dry outlook yesterday.

&&

.AVIATION...KSLC...VFR conditions expected through the valid TAF
period with periods of showers throughout the day. While some
showers or thunderstorms could produce gusty winds, these are
largely expected to be weak, topping out in the mid 20 knots.
Northerly flow is expected to hold on until a later-than-usual
transition back to light southeasterly drainage flows Saturday
night.

.REST OF UTAH AND SOUTHWEST WYOMING...Showers and thunderstorms
are expected today for central and southern Utah, especially east
of I- 15. Terminals west of I-15 could see some gusty winds as a
result of passing showers, though are likely far enough west to be
out of the main threat area. Expecting VFR conditions overall
with cloud decks around 8-10kft building in for central and
eastern portions of the forecast area, and high clouds elsewhere.

&&

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

Kruse/Wessler

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

For frequently asked questions about the Area Forecast Discussion
visit...
http://weather.gov/saltlakecity/general/afd_faqs.php

Special Weather Statement
National Weather Service Salt Lake City UT
437 AM MDT Sat Oct 1 2022

UTZ113-120-121-011115-
San Rafael Swell UT-Wasatch Plateau/Book Cliffs UT-Castle Country UT-
437 AM MDT Sat Oct 1 2022

...A strong thunderstorm will impact portions of northeastern
Emery...eastern Carbon and southeastern Duchesne Counties through 515
AM MDT...

At 436 AM MDT, Doppler radar was tracking a strong thunderstorm 9
miles southeast of Wellington, or 14 miles southeast of Price, moving
northeast at 40 mph.

HAZARD...Wind gusts of 50 to 55 mph and nickel size 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...
Sunnyside and East Carbon.

This includes US Route 6 between mile markers 250 and 269.

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 3972 10995 3974 10999 3967 10998 3964 11001
      3954 11003 3953 11005 3949 11002 3931 11067
      3948 11076 3985 11030 3986 10996 3981 10997
      3980 10993 3975 10993
TIME...MOT...LOC 1036Z 246DEG 34KT 3943 11063

MAX HAIL SIZE...0.88 IN
MAX WIND GUST...55 MPH

CRK