Severe Thunderstorm Warning 23, NWS Salt Lake City, UT

Area Forecast Discussion
National Weather Service Salt Lake City UT
434 PM MDT Wed Jul 2 2025

.UPDATE...Aviation section updated to reflect developing outflow
winds in the Salt Lake Valley.

&&

.SYNOPSIS...A monsoon surge will bring the threat of
thunderstorms to much of the region through Thursday. Drier air
will work into the area for Friday and continue into next weekend.

&&

.DISCUSSION...Scattered showers and isolated thunderstorms have
developed across much of Utah and southwest Wyoming this
afternoon, just ahead of a weakening closed low currently crossing
California. Earlier morning cloud cover across southwestern Utah
has limited convection in this area, though with several more
hours of daylight and the current mesoanalysis suggesting around
300-600 J/kg of surface-based CAPE, still expecting more showers
and thunderstorms with gusty outflow winds up to 40-50 mph to
develop. That said, storms over southern NV have not been as
limited, and may produce stronger outflows that move into
southern/western Utah this evening.

Flash flooding will remain a threat heading into the evening hours
as synoptic lift starts to increase ahead of the aforementioned
closed low. Showers will become a bit more stratiform overnight,
but are likely to persist in some fashion, aided by the closed
low weakening into an open wave as it crosses the southern Great
Basin and into our area. Some high-res guidance is more limited in
areal coverage than others, but the flash flood threat should be
less given limited overnight instability.

Behind the trough, drier air will begin to filter into the area
from the southwest. There is still some question with how quickly
this occurs, which might affect thunderstorm coverage, particularly
further southwest. While the flash flood threat will be less
across western Utah, guidance is actually suggestive of a stronger
flash flood threat across eastern Utah, thanks to improved
moisture through the column (better precipitation efficiency)
combined with more shear (more organized, longer-lasting storms).

Dry, southwesterly flow will develop on Friday, resulting in
enhanced fire weather conditions across southern Utah (see Fire
Weather section). Please check with local officials regarding firework/fire
bans and restrictions to reduce the threat of wildfire ignitions
Friday afternoon and evening. While areas Salt Lake City and north
have the highest potential for afternoon showers and thunderstorms,
isolated showers and thunderstorms may extend further south into
central Utah during the afternoon. These storms may also be a bit
more organized thanks to a grazing shortwave trough.

High pressure is expected to develop this weekend and into early
next week, producing hot and dry conditions across the area.

&&

.AVIATION...KSLC...UPDATED...Developing thunderstorms are expected
to impact the terminal around 23z-01z with lightning and outflow
winds of 30-40kts likely. Vicinity showers may keep winds gusty and
erratic before the diurnal southeasterly flow becomes dominant
around 02z, with a 30% chance of being delayed until about 04z due
to persisting weather.

.REST OF UTAH AND SOUTHWEST WYOMING...Increasing monsoonal moisture
across the region has produced widespread thunderstorm coverage this
afternoon. Impacts to flight categories for regional terminals
remain very slight, but can't rule out brief CIG/VIS reductions to
MVFR/IFR conditions through about 03z across southern Utah terminals
where better shear and instability may produce heavier precipitation
cores. Otherwise, storms will be capable of producing gusty and
erratic outflow winds between 30-40 kts if they move into the
vicinity of any regional terminals before sunset.

&&

.FIRE WEATHER...A slow moving low pressure system will shift
eastward across Utah tonight and tomorrow, weakening as it does
so. This will likely result in continued shower activity overnight
tonight across southern and eastern Utah in particular, though
lightning activity will be much more isolated overnight. Drier air
will just begin to filter into the area from the west by Thursday
afternoon, resulting in higher wetting rain chances over eastern
Utah. Overnight RH recoveries will be excellent through at least
Friday morning statewide.

Friday will feature increasing dry, southwesterly flow up to 30-35
mph across southwestern and south-central Utah within an air mass
where RH becomes critical, thus a Fire Weather Watch has been
issued. Additionally, as an upper-level disturbance grazes
northwestern Utah, northern Utah may experience afternoon
thunderstorms and gusty outflow winds, with higher chances further
northwest. High pressure will build into the area for the
weekend.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Fire Weather Watch from Friday afternoon through Friday evening
     for UTZ492-495-497-498.

WY...None.
&&

Cunningham/Verzella

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

<!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>