Severe Thunderstorm Warning 32, NWS Salt Lake City, UT

Area Forecast Discussion
National Weather Service Salt Lake City UT
405 PM MDT Mon Jul 3 2023

.SYNOPSIS...Thunderstorms capable of producing strong gusty winds
are expected to continue across northern Utah and southwest Wyoming
through this evening. A cold front will bring a modest cooldown to
northern Utah Tuesday into Wednesday while hot, dry and windy
conditions will continue Tuesday across southern Utah.

&&

.SHORT TERM (THROUGH 12Z WEDNESDAY)...High pressure has given way to
a near zonal flow aloft this afternoon as a shortwave trough digs
into the northwestern CONUS. PWATs have risen to between 0.6 inches
across the southern half of Utah to around 0.7-0.8 inches across
northwestern Utah. Even within the pocket of higher PWAT, the
moisture is still mainly confined to the midlevels, with dewpoints
generally in the upper 30s to mid 40s at many northern Utah surface
obs. However, enough moisture and instability is present to generate
showers and thunderstorms across the area, with scattered coverage
across the north and more isolated coverage across the south.
Mesoscale analysis of SBCAPE shows values of ~1000 J/kg across
portions of northern Utah. Meanwhile, DCAPE of between 1500-2000
J/kg is common across northern and central Utah, which is consistent
with model soundings depicting a deep inverted-V profile at many
locations.

There remains some agreement in CAMS on the evolution of a cluster
of showers and thunderstorms currently over the west deserts into a
complex that will be capable of producing gusty outflow winds. The
12z HREF ensemble max depicts pockets of greater than 60 mph gusts,
especially over the Dugway area and in southwest Wyoming (HREF
members are in greatest agreement in southwest Wyoming, showing a
30% chance of greater than 50 mph winds). The timing of this complex
has it moving through SLC around 00z and through Uinta County, WT
around 02-03z.

While the stronger storms taper off late this evening, some models
continue to indicate nocturnal showers continuing to focus near the
cold front tonight. This precipitation band looks to center near the
Ogden area late this evening, then shift to near SLC towards the
morning hours and shifting only slightly southward tomorrow
afternoon. Showers will taper off tomorrow evening as high pressure
begins to build in from the west.

.LONG TERM (after 12z Wednesday)...Relatively cool air will remain
in place over northern Utah and southwest Wyoming on Wednesday. As
the shortwave trough moves out Wednesday, a low-amplitude ridge will
take up residence just to the east of the area and a trough to the
west from Thursday through at least Sunday. This set-up will bring
temperatures close to seasonal norms. With no good moisture tap in
this pattern, very dry conditions will be present area-wide. The
only area with higher than a 5% chance of precipitation on any given
afternoon is the High Uinta Mountains. And even that famously
thunderstorm-prone area barely gets to a 20% probability of
measurable rain at a given location on the wettest day (Wednesday
afternoon) and is below 10% thereafter.

The most consequential aspect of the pattern Thu-Sat will be
southwesterly winds in areas south of the latitude of Delta and
Price. The wind will not be strong enough to be damaging, although
it will make for uncomfortable tent camping. The main concern is for
fire weather. There is a high probability (70-90%) of relative
humidity below 15% and wind gusts of 30 mph or higher, the criteria
in the atmospheric part of the red flag warning equation. However
fuel dryness will still be the limiting factor on problematic fires
in all but far southern Utah. Friday looks to be the driest and
windiest day at this time.

Beyond the weekend, the global ensembles are in agreement on a ridge
building over the Intermountain West. This would bring an end to the
windy conditions but also hotter temperatures, low relative humidity
and continued very low probabilities for wetting rain.

&&

.AVIATION...KSLC...Chaotic winds continue as a well-defined sharp
boundary between northwest and southerly winds sits just over the
airfield. Expect northerly winds to creep into the northern half of
the airfield but for the prevailing winds to stay southerly with
punches of southwest flow. Northerly incursions should remain around
or under 12 kts. Thunderstorms will approach the terminal by 23Z and
persist as late as 01Z. Additional isolated storms may develop off
terrain beyond what is currently forecast. Overall VFR conditions
are expected to persist as cloud bases remain high, and rain and
visibility reductions should be light. The potential for blowing
dust reducing visibility exists if stronger winds materialize. A 20%
chance exists that light rain showers will continue in the vicinity
of the terminal overnight, though without the wind threat.

.REST OF UTAH AND SOUTHWEST WYOMING...Scattered thunderstorms
continue across the northern half of the forecast area this evening,
capable of producing sudden and strong microburst winds and semi-
organized outflow boundaries. Blowing dust is possible in the
vicinity of these strong winds, especially across the West Desert.
Storms will weaken after 01Z and dissipate after sunset, though
there is a 20% chance that showers continue overnight across
portions of northern Utah from ENV to EVW in SW Wyoming, with a much
lesser wind threat associated with these overnight showers.

&&

.FIRE WEATHER...A weather disturbance grazing northern Utah will
bring a cold front into northern Utah tonight into tomorrow. Ahead
of this front, scattered showers and thunderstorms, especially
across northern Utah, will continue this evening. A few of these
storms may produce wetting rain, but most will be dry. The cold
front will settle across central Utah tomorrow and serve as a focus
for showers and thunderstorms tomorrow. Breezy southwest winds will
continue across southern Utah tomorrow ahead of the cold front.
Thereafter, weak high pressure will bring a drying trend to the area
for the middle to latter part of the week. However, breezy southwest
winds and low humidity will develop again across southern and
portions of central Utah Thursday into the weekend.

&&

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

Cheng/Jeglum/Wessler

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

Special Weather Statement
National Weather Service Salt Lake City UT
231 PM MDT Mon Jul 3 2023

UTZ111>113-032100-
Wasatch Plateau/Book Cliffs UT-Western Uinta Mountains UT-
Wasatch Mountains South of I-80 UT-
231 PM MDT Mon Jul 3 2023

...A strong thunderstorm will impact portions of southeastern Wasatch
and central Utah Counties through 300 PM MDT...

At 231 PM MDT, Doppler radar was tracking a strong thunderstorm 14
miles east of Mapleton, or 20 miles southeast of Provo, moving east
at 30 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...
Strawberry Reservoir.

This includes US Route 40 between mile markers 38 and 57.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4002 11140 4020 11141 4036 11098 4006 11088
TIME...MOT...LOC 2031Z 252DEG 26KT 4011 11130

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

STW

Special Weather Statement
National Weather Service Salt Lake City UT
252 PM MDT Mon Jul 3 2023

WYZ021-032130-
Southwest Wyoming WY-
252 PM MDT Mon Jul 3 2023

...A strong thunderstorm will impact portions of southeastern Uinta
County through 330 PM MDT...

At 252 PM MDT, Doppler radar was tracking a strong thunderstorm over
Robertson, or 28 miles east of Evanston, moving east at 30 mph.

HAZARD...Wind gusts up to 50 mph and pea 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...
Lyman, Robertson, Mountain View, Millburne, Church Buttes and Fort
Bridger.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4110 11055 4132 11055 4147 11005 4110 11005
TIME...MOT...LOC 2052Z 252DEG 26KT 4122 11041

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...50 MPH

STW

Special Weather Statement
National Weather Service Salt Lake City UT
318 PM MDT Mon Jul 3 2023

UTZ101-103-032145-
Eastern Box Elder County UT-Great Salt Lake Desert and Mountains UT-
318 PM MDT Mon Jul 3 2023

...A strong thunderstorm will impact portions of north central Box
Elder County through 345 PM MDT...

At 318 PM MDT, Doppler radar was tracking a strong thunderstorm 15
miles southwest of Snowville, moving east at 40 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...
Snowville, Howell and Curlew Junction.

This includes the following highways...
 Interstate 84 between mile markers 0 and 22.
 Utah Route 30 between mile markers 67 and 90.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4177 11246 4177 11313 4200 11313 4200 11246
TIME...MOT...LOC 2118Z 260DEG 34KT 4185 11298

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

STW

Special Weather Statement
National Weather Service Salt Lake City UT
342 PM MDT Mon Jul 3 2023

UTZ101-032230-
Great Salt Lake Desert and Mountains UT-
342 PM MDT Mon Jul 3 2023

...Strong thunderstorms and outflow winds will impact portions of
south central Box Elder and central Tooele Counties through 430 PM
MDT...

At 342 PM MDT, Doppler radar was tracking strong thunderstorms and
outflow winds along a line extending from 14 miles northwest of Utah
Test and Training Range South to 14 miles southeast of Dugway
Proving Ground Test Range. Movement was northeast at 45 mph.

HAZARD...Wind gusts of 50 to 55 mph.

SOURCE...Radar indicated.

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

Locations impacted include...
Dugway English Village, Dugway Proving Ground Test Range, Utah Test
and Training Range South, Knolls, Utah Test and Training Range North,
Clive, Skull Valley and Bonneville Salt Flats.

This includes Interstate 80 in Utah between mile markers 10 and 61.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4111 11336 4100 11309 4072 11282 4039 11256
      4015 11255 3990 11321 4078 11390
TIME...MOT...LOC 2142Z 229DEG 38KT 4069 11368 4000 11310

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...55 MPH

STW

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