Alert archive / Idaho / Special Weather Statements in 2019

Special Weather Statement, NWS Missoula, MT

August 7, 2019Lewis County, Idaho

NWS Missoula, MT issued this special weather statement at Aug 7, 2019, 4:06 PM PDT for Lewis County, Idaho. It was in force for 24 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 7, 2019, 4:06 PM PDT (23:06 UTC)
Expired
Aug 7, 2019, 4:30 PM PDT
In force
24 min
Issued by
NWS Missoula, MT

County Lewis County, ID

The radar

The Pendleton radar (KPDT), 193 km from the middle of the area, began a volume at 23:08 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 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 Missoula, MT wrote its last area forecast discussion before this special weather statement went out at Aug 7, 2:25 PM PDT, 1 hour 41 minutes earlier.

Area forecast discussion, Aug 7, 2:25 PM PDT, 1 hour 41 minutes before
Area Forecast Discussion
National Weather Service Missoula MT
325 PM MDT Wed Aug 7 2019

...SIGNIFICANT RAIN ACROSS NORTHERN ROCKIES FRIDAY, SATURDAY...

.DISCUSSION...

Showers and thunderstorms will be developing at times across the
Northern Rockies (both day and night) through Thursday night.
Waves of moisture and instability from south and west of the
region will result in highly variable conditions throughout the
area. There are significant disagreements between convective
allowing models (such as the HRRR, NAMNest) and global models
(such as GFS, ECMWF, Canadian) during the near-term forecast.
Considering that convection is already underway and the favorable
elements of convection are only just beginning to present, our
current forecast reflects much greater weight upon convective
allowing models than global models. Also, tonight and Thursday
night appear to have the sufficient ingredients for thunderstorms
to develop even in the absence of daytime heating. The next 36
hours will be just the beginning of an extended active weather
period.

Friday morning, a upper level disturbance tracking northward
across the Great Basin into the Northern Rockies will transport an
abnormally moist air mass into the area. A mid level circulation
associated with this disturbance will wrap additional mid to upper
level moisture into the Northern Rockies from the Midwest. The
presence of near record levels of atmospheric moisture, slow storm
motions, and high freezing levels will create an environment
favorable for thunderstorms to produce heavy rainfall. Flash
flooding is a concern, especially for urban areas and recent
wildfire burn scar areas.

On Saturday, a large area of low pressure will move onshore into
the Pacific Northwest and move northeastwards into the Northern
Rockies. This will help initiate another round of widespread
showers and thunderstorms across the area Saturday. Atmospheric
moisture will remain uncharacteristically high; therefore, another
round of flash flooding will be possible. A few strong to
potentially severe thunderstorms will also be possible across
north central Idaho and west central Montana, including the
Bitterroot and Missoula valleys, during the late afternoon and
early evening hours. These storms could produce large hail along
with heavy rainfall.

Sunday and Sunday night, the low pressure circulation is
anticipated to move to the north and east of the Northern Rockies,
leaving very cool daytime temperatures (up to 20 degrees below
seasonal average) and widespread precipitation across the region.
Thunderstorms remain a possibility during this time, however the
intensity will be trending downward.

Monday through middle of next week, zonal (west to east) flow
aloft will be present over the Northern Rockies. The airmass
overhead will remain relatively cool for mid August, with daytime
temperatures staying slightly below the seasonal average.
Conditions will be mostly drying, however that drying may be
short-lived, with global models suggesting another widespread
precipitation event late next week through the weekend.

&&

.AVIATION...

Showers and thunderstorms are anticipated to develop throughout
the next 24 hours across north central Idaho and southwest
Montana. Among area terminals, KSMN will be most favorable for a
thunderstorm nearby in the 08/0000Z through 08/0300Z period. There
is a bit more uncertainty about thunderstorms near KBTM, with the
target period of 07/2300Z through 08/0200Z, and then again
08/0600Z through 08/1000Z. KMSO has a relatively low chance of
thunderstorms in the 08/0400Z through 08/1000Z period. Isolated
terrain obscurations will be present KMSO and areas south, mainly
due to the nocturnal thunderstorm development. Thunderstorms will
become widespread south of KMSO after 08/1800Z. Terrain
obscurations will become more widespread KMSO southward after
08/1800Z.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...&&

In the hours before

Special weather statement, Aug 7, 4:06 PM PDT, 0 minutes before
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</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>
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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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The office that day

Everything else NWS Missoula, MT issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 7, 1:29 PM PDTFire Weather WatchMSOBeaverhead, Deer Lodge, Granite, Jefferson, Lewis and Clark, Madison and 4 more13 hr

Nearby

Special Weather Statements in Idaho, 2019Every special weather statement in 2019

Sources

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