Alert archive / Montana / Special Weather Statements in 2021

Special Weather Statement, NWS Glasgow, MT

August 4, 2021Petroleum County, Montana

NWS Glasgow, MT issued this special weather statement at Aug 4, 2021, 10:48 PM MDT for Petroleum County, Montana. It was in force for 57 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
Aug 4, 2021, 10:48 PM MDT (04:48 UTC)
Expired
Aug 4, 2021, 11:45 PM MDT
In force
57 min
Issued by
NWS Glasgow, MT
Hail
0.88 in
Wind
30

County Petroleum County, MT

The radar

The Glasgow radar (KGGW), 147 km from the middle of the area, began a volume at 04:52 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Glasgow Intl Airport, MT (KGGW), launched 00:00Z, 4.8 hours before the alert went out and 149 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-pSkew-T log-p diagram, Glasgow Intl Airport, MT at 00:00Z on 2021-08-05Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 133 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Glasgow Intl Airport, MT at 00:00Z on 2021-08-05The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -18 square meters per square second.1939Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
133 J/kg
Mixed-layer CIN
-88 J/kg
Mixed-layer LCL
2787 m above ground
0-6 km bulk shear
15 kt
0-1 km storm-relative helicity
-18 m²/s²
0-3 km storm-relative helicity
13 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

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What forecasters said that day

The local office's own words before this special weather statement went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Glasgow, MT wrote its last area forecast discussion before this special weather statement went out at Aug 4, 2:57 PM MDT, 7 hours 51 minutes earlier.

Area forecast discussion, Aug 4, 2:57 PM MDT, 7 hours 51 minutes before
Area Forecast Discussion
National Weather Service Glasgow MT
257 PM MDT Wed Aug 4 2021

.DISCUSSION...

An embedded short-wave disturbance riding around the top of the
larger-scale high pressure ridge to our west is setting of some
small isolated thunderstorms across eastern Montana. Most of the
them are pulsing up, then diminishing 10 minutes later, but a few
others are maintaining their strength. Again, their spatial
coverage is so small, that some locations will get no
precipitation at all while small tracts of land here and their
will get a brief beneficial downpour. A few of the stronger cells
may include small hail this afternoon.

Tonight, a few of the models are hinting at enough leftover energy
to allow for a few nocturnal thunderstorms across our central and
northern zones. Otherwise, Thursday will shape up to generally be
a dry and hot day with less chances for precipitation as this
ridge of high pressure briefly rebounds.

Friday seems to be the beginning of a change in the weather
pattern. A stronger, more pronounced low pressure disturbance digs
into the Snake River Valley and Yellowstone National Park by
Friday mid day. During the afternoon and evening hours, when this
storm system lifts northeastward through eastern Montana, models
are showing better chances for accumulating rainfall through
Saturday morning. I tried to increase PoPs accordingly to account
for this recent increase in forecast confidence.

By Sunday night, another stronger storm system from British
Columbia looks to cut temperatures back to near or below normal
for the first time in many weeks and more chances for accumulating
rainfall.

&&

.AVIATION...

PATTERN: The otherwise benign NW flow aloft hides a small-scale
embedded disturbance with many models showing some scattered
precipitation today. Radar reflectivity confirms this with
multiple isolated thunderstorm across the area. This activity
should continue into this evening.

FLIGHT CONDITIONS: Mainly VFR, but borderline IFR if an afternoon
thunderstorm happens to pass directly over a TAF site. VFR
conditions are expected to return after the storms clear the area
later tonight.

WINDS: From the NW at 10 to 15 kts, with thunderstorm wind gusts
up to 30 kts from 21Z to 02Z. After 03Z tonight, expect light and
variable winds, if not calm.

&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.

&&

weather.gov/glasgow

In the hours before

Special weather statement, Aug 4, 5:15 PM MDT, 5 hours 33 minutes before
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  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
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      <h1 id="headline">This service is currently unavailable.</h1>
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        The site you requested is temporarily down for maintenance or an unexpected outage.
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        Please try again in a few minutes.
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        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
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Nearby

Special Weather Statements in Montana, 2021Every special weather statement in 2021

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.