Severe Thunderstorm Warning 85, NWS Salt Lake City, UT

Area Forecast Discussion
National Weather Service Salt Lake City UT
336 PM MDT Wed Aug 23 2023

.SYNOPSIS...Monsoonal moisture potentially combining with the
remnants of Tropical Depression Harold will increase the flash
flood threat Thursday into Friday. Drier and warmer conditions are
in store for the weekend into early next week.

&&

.SHORT TERM (Through 12Z Friday)...Abundant moisture remains in
place across much of the forecast area this afternoon,
characterized by dew points in the 50s to low 60s and GOES-
derived precipitable water values in the 0.75-1 inch range.
Afternoon satellite imagery and objective analysis show the region
along the western periphery of an expansive mid level ridge, with
the remnants of Tropical Storm Harold quickly rotating around the
southwestern side of this ridge across AZ/NM. This wave is
inducing shortwave ridging across southern Utah currently, which
is acting to suppress convection to some degree despite the ample
moisture and instability. Nonetheless scattered convection is
firing mainly across central Utah, with somewhat better coverage
across northern Arizona getting primed to spread into southern
Utah late this afternoon and evening.

The wave crossing AZ/NM will slow its forward progress as it
begins to lift northward tonight through Thursday. Fairly
widespread precipitation associated with this wave will spread
across southern Utah mainly east of I-15 overnight through
Thursday morning, then spreading northward into central and
eventually northern Utah east of I-15. Despite the elevated PW
values, anticipate much of this precipitation will be stratiform
in nature with perhaps some embedded convection at times tonight
through Thursday morning, and with the widespread cloud cover
think its unlikely the airmass will be able to recover enough to
support another round of convection during the afternoon/evening
across much of the south. This is supported in much of the CAM
guidance, and as such have held off on the issuance of any Flood
Watches at this time for Thursday.

.LONG TERM (After 12Z Friday)...Remnants from a tropical system will
be weakening and pushing out of Utah Friday. Showers are likely for
portions of eastern Utah, including the Uinta Mountains, southward
to Lake Powell. For locations with clearing, isolated thunderstorms
are likely. Drier conditions will be advecting in from the west,
with PoPs decreasing in that direction.

A strong ridge that will have been in place to the east will
retrograde into the weekend. The same portion of Utah with showers
and thunderstorms Friday will have less coverage, with isolated to
scattered showers Saturday.

Drier conditions are forecast late in the weekend into the week as
ridging will retrograde into the southwest. Southwest Wyoming and
most of Utah will be dry, with isolated showers and thunderstorms
near terrain.

Temperatures will climb through the weekend into the week, with near
normal high temperatures through the weekend, then around 5-10F
warmer than normal into the week.&&

.AVIATION...KSLC...VFR conditions will prevail through the
remainder of the period for the KSLC terminal. Isolated storms
will diminish this evening. Variable and gusty winds created by
nearby storms will be possible. Otherwise, northwest lake breeze
will transition to a southerly drainage wind this evening.

.REST OF UTAH AND SOUTHWEST WYOMING...Mostly VFR conditions will
persist throughout the period. Brief category reductions are
possible across the area, except for far northern Utah, as
isolated storms impact the region and some CIGs could drop to near
ridgeline level creating mountain obscuration. Storms will
diminish across the area with showers lingering in south central
Utah as tropical remnants approach. Winds will remain relatively
light and variable.

&&

.FIRE WEATHER...An anomalously moist airmass will remain across
the region through Friday, resulting in several additional rounds
of showers and thunderstorms, along with elevated daytime humidity
and good to excellent overnight recovery. With this moisture in
place, wetting rains, and potentially heavy rainfall, can be
expected with any storms which develop. The combination of
precipitation and cloud cover will keep temperatures well below
normal across southern Utah through Friday, and slightly below
normal across the north.

A shift in the weather pattern will bring a warming and drying
trend this weekend into early next week, as high pressure
strengthens across the region. This pattern shift will push
the monsoon moisture out of the region, with any lingering
isolated shower and thunderstorm threat becoming confined to
the higher terrain. By early next week temperatures will be
slightly above normal, while afternoon humidity across the lower
elevations falls below 20 percent beginning Monday.

&&

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

Seaman/Wilson/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
418 PM MDT Wed Aug 23 2023

UTZ123-124-128-232300-
South Central Utah UT-Zion National Park UT-
Lower Washington County UT-
418 PM MDT Wed Aug 23 2023

...A strong thunderstorm will impact portions of south central
Washington County through 500 PM MDT...

At 418 PM MDT, Doppler radar was tracking a strong thunderstorm 11
miles southeast of St George, or 19 miles east of Virgin River Gorge,
moving north at 15 mph.

HAZARD...Wind gusts of 50 to 55 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...
St George, Washington, Hurricane, Santa Clara, Sand Hollow State
Park, Quail Creek State Park, Ivins, Virgin, Bloomington and Snow
Canyon State Park.

This includes the following highways...
 Interstate 15 between mile markers 2 and 18.
 Utah Route 18 between mile markers 0 and 8.

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.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 3719 11367 3719 11319 3700 11327 3700 11360
TIME...MOT...LOC 2218Z 183DEG 13KT 3693 11345

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...55 MPH

ND

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>