Severe Thunderstorm Warning 13, NWS Grand Junction, CO

Area Forecast Discussion
National Weather Service Grand Junction CO
1135 AM MDT Thu Jun 20 2024

.KEY MESSAGES...

- Scattered to widespread showers and storms are expected today
  through tomorrow night.

- Significant moisture supports the potential for heavy rain and
  flash flooding especially across far western Colorado and
  southeast Utah. Those chances exist today, but are higher
  tomorrow.

- Strong storms capable of producing wind gusts in excess of 60
  mph are possible each afternoon/evening. Hail is also
  possible with the stronger cells.

- More general thunderstorms are possible Saturday afternoon
  with drier conditions for Sunday.

&&

.SHORT TERM /THROUGH FRIDAY/...
Issued at 218 AM MDT Thu Jun 20 2024

The next 48 hours are going to be fairly active across the forecast
area. The pattern will be driven by an expansive ridge over the
central US and a trough over the Great Basin. The ridge to our
east is already advecting moisture into the region and that
continues through tomorrow. This moisture is rich with PWAT
values 200-300 percent of normal, mixing ratios around 10 g/kg
and surface dew points above 45F more typical of late July. That
moisture is colliding with steep lapse rates due to the trough
out west. This combo will produce instability on the order of
500-1000 j/kg with daytime heating. Convection is expected to
develop around noon and will be mainly driven by the terrain.
After that outflows will dictate where storms propagate, which
is just anywhere in the forecast area. Given this very anamolous
moisture there is a chance for high rainfall rates. Due to the
trough...steering flow should keep storms moving toward the
northeast at a modest clip. This may limit the heavy rain
potential. Although high-res models show that storm cells could
train over the same areas. Given the instability hail is
certainly possible with the stronger storms. Even though
moisture is working into the area surface RH values across the
southwest half of the area will be in the 20-30 percent range,
which means DCAPE will be high. This will support efficient cold
pools and wind gusts upwards of 60 mph. As the evening progresses
a mix of stratiform and scattered convection is expected.
Models do show a decreases in cape especially for the higher
elevations. This should lead to an overall decrease in storm
intensity and rainfall rates. None the less chances for
scattered showers and some storms continue through the night
for a good portion of the area given the moisture advection does
not stop.

Tomorrow morning there could still be pockets of clouds and
showers across the area. The moisture values will peak tomorrow,
which increases the chances for heavy rainfall. Despite the
potential for clouds in the late morning the models are still
indicating cape values around 500-1000 j/kg. One uncertainty is
will this cape be realized if clouds do not clear out. As of
now models show weaker instability closer to the Divide and the
highest cape across the western half. In addition to all of this
a weak shortwave is projected to break away from the base of
the trough and pass just to our north. This wave should provide
some lift to help initiate convection during the afternoon.
Either way development on the higher terrain is still likely.
The wave will also supply decent flow and therefore the chance
for more organized convection. The HREF does show a slight
chance for rotating storms capable of producing large hail
across the western half of the area in the afternoon. Gusty
winds remain a threat especially with any storm clusters or
complexes. The models show that as the afternoon progresses
storms could congeal into these complexes or lines and move into
the eastern half of the forecast area in the evening. How much
they maintain intensity is uncertain. In general everything
should transition to more stratiform in the late evening and
eventually clear the area after midnight.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
Issued at 218 AM MDT Thu Jun 20 2024

Residual moisture will likely lead to additional storms Saturday,
especially in the high terrain. Mixed layer CAPE upwards of 1000
J/kg is currently present in the models early Saturday afternoon,
but with dew points gradually decreasing throughout the day so will
the CAPE. Because of this the heavy rain threat is not expected to
continue into Saturday. Mositure continues its downward trend on
Sunday and into the new week with an upper-level ridge building in
overhead. This will generally lead to warm and dry conditions with
periodic afternoon precipitation developing in the higher
elevations. High temperatures will likely be 5 to 10 degrees
above normal Tuesday through Thursday before the ridge slides
off to the east for the latter half of the week.

&&

.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1133 AM MDT Thu Jun 20 2024

Widespread showers and thunderstorms are expected this
afternoon, with some terminals already seeing impacts. These
storms will be capable of producing lightning, strong and gusty
winds, heavy rain, and even some small hail. Look for occasional
reductions in visibility and ceilings lowering below breakpoints
with passing showers. Outside of shower activity, look for
relatively strong and gusty southerly winds. VFR conditions will
prevail, but drops to MVFR are likely with passing showers or
storms.

&&

.GJT WATCHES/WARNINGS/ADVISORIES...

CO...Flood Watch from Friday afternoon through Friday evening for
     COZ003-006-007-017-020-021.
UT...Flood Watch from Friday afternoon through Friday evening for
     UTZ022-025-027>029.

&&

SHORT TERM...KJS
LONG TERM...KAA
AVIATION...TGJT

Hazardous Weather Outlook
National Weather Service Grand Junction CO
307 AM MDT Thu Jun 20 2024

COZ001>014-017>023-UTZ022>025-027>029-210915-
Lower Yampa River Basin-Central Yampa River Basin-
Roan and Tavaputs Plateaus-Elkhead and Park Mountains-
Upper Yampa River Basin-Grand Valley-Debeque to Silt Corridor-
Central Colorado River Basin-Grand and Battlement Mesas-
Gore and Elk Mountains/Central Mountain Valleys-
Central Gunnison and Uncompahgre River Basin-
West Elk and Sawatch Mountains-Flat Tops-Upper Gunnison River Valley-
Uncompahgre Plateau and Dallas Divide-Northwest San Juan Mountains-
Southwest San Juan Mountains-Paradox Valley/Lower Dolores River-
Four Corners/Upper Dolores River-Animas River Basin-
San Juan River Basin-Southeast Utah-Eastern Uinta Mountains-
Eastern Uinta Basin-Tavaputs Plateau-Arches/Grand Flat-
La Sal and Abajo Mountains-Canyonlands/Natural Bridges-
307 AM MDT Thu Jun 20 2024

This Hazardous Weather Outlook is for northwest Colorado, southwest
Colorado, west central Colorado, east central Utah, northeast Utah
and southeast Utah.

.DAY ONE THROUGH DAY TWO...Today and tomorrow.

Scattered to widespread showers and storms are expected today and
tomorrow. Significant moisture supports the potential for heavy rain
and flash flooding especially across far western Colorado and
southeast Utah. Strong storms capable of producing wind gusts in
excess of 60 mph are possible each afternoon/evening. Hail is also
possible with the stronger cells.

.DAYS THREE THROUGH SEVEN...Saturday through Wednesday.

More general thunderstorms are possible Saturday afternoon with
drier conditions for Sunday.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

<!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>

Special Weather Statement
National Weather Service Grand Junction CO
223 PM MDT Thu Jun 20 2024

COZ002>005-007-009-013-202100-
Roan and Tavaputs Plateaus CO-Flat Tops CO-
Grand and Battlement Mesas CO-Debeque to Silt Corridor CO-
Upper Yampa River Basin CO-Elkhead and Park Mountains CO-
Central Yampa River Basin CO-
223 PM MDT Thu Jun 20 2024

...A STRONG THUNDERSTORM WILL IMPACT NORTHWESTERN EAGLE...
SOUTHWESTERN ROUTT...EASTERN GARFIELD AND EASTERN RIO BLANCO COUNTIES
THROUGH 300 PM MDT...

At 222 PM MDT, Doppler radar was tracking a strong thunderstorm 15
miles east of Meeker, or 30 miles south of Craig, moving northeast at
25 mph.

HAZARD...Wind gusts up to 50 mph and pea size hail. Heavy rain is
         also possible.

SOURCE...Radar indicated.

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

Locations impacted include...
Rifle, Parachute, Rio Blanco, Battlement Mesa, and Buford.

This includes the following highways...
 Interstate 70 in Colorado between mile markers 74 and 89.
 Colorado 13 between mile markers 1 and 26.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 3942 10804 3955 10824 4038 10746 4010 10697
      3984 10702
TIME...MOT...LOC 2022Z 218DEG 42KT 4008 10760

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

TGR

Preliminary Local Storm Report
National Weather Service Grand Junction CO
225 PM MDT Thu Jun 20 2024

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1115 AM     Hail             4 WSW Montrose          38.47N 107.94W
06/20/2024  M0.25 Inch       Montrose           CO   Public

            Pea sized hail lasted for roughly a minute.

&&

BGB

<!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>