Severe Thunderstorm Warning 7, NWS Glasgow, MT

Area Forecast Discussion
National Weather Service Glasgow MT
747 PM MDT Wed May 20 2020

.DISCUSSION...
Evening update...
Adjusted POPs to follow the line that's approaching from the
south, and now beginning to cross the southern border of the CWA,
across the area this evening into the early overnight hours.

97

Previous discussion...
Just at this forecast issuance time, the Storm Prediction Center
has coordinated with us, and a severe weather watch has just been
issued for most of northeast Montana.

All ingredients for strong to severe thunderstorms are location
over the region. Moist SE surface wind. Upper-level flow from the
west and southwest. Low surface pressure axis through the area.
Unstable atmosphere.

Although some disagreement between models still exist regarding
timing and placement of the strongest storms, a general idea of
where the risk of severe thunderstorms is set across the area.

Storms will move from south to north. Multiple waves will spread
through the CWA. Best guess places the strongest storms with the
heaviest QPF 0.50 to 1.00 inch in a band from Prairie County, up
through Valley County.

This activity is expected to persist through the evening hours,
then begin to diminish away toward the north during the overnight
hours tonight and early morning hours tomorrow.

Precipitation chances for the remainder of the week drop off
significantly, but another system set up for more rain showers
across southern and eastern portions of the region through the
weekend.

&&

.AVIATION...
FLIGHT CONDITION: mostly VFR, but periods of MVFR or IFR with
thunderstorms this evening. After 9z, all TAF sites should be VFR
through Thursday afternoon.

WINDS: from the south 5-15 kts overnight, except stronger and
gusty near storms. On Thursday, winds should be from the southwest
10-20 kts.

SYNOPSIS: A line of thunderstorms will move northward through the
area this evening and out during the overnight hours. This line of
storms will bring strong winds and hail, along with frequent
lightning. The intensity of the storms should decrease after
about 5 or 6z. Another round of showers cannot be ruled out late
in the day on Thursday.

97

&&

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

&&

weather.gov/glasgow

Special Weather Statement
National Weather Service Glasgow MT
554 PM MDT Wed May 20 2020

MTZ021-210100-
Petroleum MT-
554 PM MDT Wed May 20 2020

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHERN PETROLEUM COUNTY UNTIL
700 PM MDT...

At 553 PM MDT, Doppler radar was tracking a strong thunderstorm 10
miles southwest of Flatwillow, or 18 miles north of Roundup, moving
north at 30 mph.

Penny size hail and wind gusts up to 50 mph will be possible with
this storm.

Locations impacted include...
Winnett, Flatwillow, Petrolia Lake and Tiegen.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with this storm, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

A Severe Thunderstorm Watch remains in effect until 1100 PM MDT for
northeastern Montana.

LAT...LON 4684 10863 4684 10862 4690 10861 4710 10861
      4710 10862 4716 10855 4707 10802 4675 10831
      4675 10863
TIME...MOT...LOC 2353Z 201DEG 27KT 4672 10853

NWS Glasgow

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GLASGOW MT
820 PM MDT WED MAY 20 2020

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

0718 PM     HAIL             10 WNW MCCLOUD          46.95N 105.80W
05/20/2020  M1.00 INCH       PRAIRIE            MT   TRAINED SPOTTER

&&

TOMC

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GLASGOW MT
822 PM MDT WED MAY 20 2020

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

0750 PM     TSTM WND GST     10 WNW MCCLOUD          46.95N 105.80W
05/20/2020  E60 MPH          PRAIRIE            MT   TRAINED SPOTTER

            BLEW WELL HOUSE OVER.

&&

TOMC