Area Forecast Discussion
Issued by NWS Glasgow, MT

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FXUS65 KGGW 210431
AFDGGW

Area Forecast Discussion
National Weather Service Glasgow MT
931 PM MST Mon Nov 20 2017

.SHORT TERM...for northeast Montana...tonight through Tue...

Evening Update: Main focus for the evening update was timing the
decrease in winds towards morning, as rapid pressure rises behind
the front are keeping winds strong into the overnight. The edge of
the cloud deck is still slowly creeping to the south across the
region, so the timing of the clearing was also a top priority. As
for morning low temperatures, currently in the northern zones
closer to the Canadian border, temperatures are already in the mid
single digits above zero, and with adequate clearing and no
resurgence from clouds currently in southern Saskatchewan, below
zero lows may yet be likely, but for now still went with a blend
of the short term models and NBM just to bring the collective lows
down and close to zero for pretty much all areas near the border.

Bigelbach

PREVIOUS DISCUSSION: Amid some scattered virga showers over the
northwestern and central zones of NE Montana, strong and gusty
winds, associated with a potent cold front have pushed through the
region today. The high temperature today was recorded during the
latter morning hours, after which, temperatures began to steadily
drop from north to south with the advance of this cold front.

This afternoon through tonight, most model solutions support
growing chances for snow developing near and south of a line from
the Little Rockies through Jordan. Accumulations are expected to
be light overall, although, upwards of 1/4 inch to 1/2 inch are
possible for portions of Petroleum and Garfield Counties tonight.

This cold spell, associated with a pronounced low pressure trough
from the Canadian prairie, will be relatively short-lived for NE
Montana. By Tuesday afternoon, although the coldest morning lows
we`ve seen for several days will have occurred across our northern
zones, a rebounding warm up already approaches from the west.

BMickelson

.LONG TERM...Tue night through Mon...

Wednesday through Thanksgiving Day, a strong high pressure ridge
from the west will bring temperatures into our region well above
normal. Afternoon winds might be breezy, but not too far out of
control. Only scattered chances of light precip seem possible,
especially for the NE corner of Montana.

Thursday night into Friday morning the next short-wave low
pressure trough will be quick-passing and short-lived. Some model
support shows a few rain and snow showers, especially near and
south of Highway 200.

The remainder of the forecast looks quiet.

BMickelson

Previous long term discussion: Tuesday through Thursday: Pacific
ridge off of the Pac Northwest will move inland and the heat over
California will quickly fill it in making it larger over these
periods. FLow will become northwest aloft over northeast montana
and temperatures should rapidly warm with the peak hitting
Thursday as the ridge axis moves by. Conditions should remain dry
through most of these periods.

Thursday night into Friday: Ridge axis will exit as the pacific
trough part of the couplet moves through. Thankfully, models,
while looking cooler, do not appear to bring in arctic air into
the passing trough making things more seasonal.

Friday night into Saturday night: Models begin to break down
here. Best guess is for another Pacific Ridge to move through the
region warming things up briefly again.

Sunday onward: Rapid model breakdown post ridge leads to a below
confidence forecast. Expect the forecast to change from about here
onward.

GAH

&&

.AVIATION...

EXPECTED FLIGHT CATEGORY: VFR

SYNOPSIS: Scattered light precipitation behind the cold front that
passed through the region today will continue to be possible
mainly at GDV for the next few hours. Skies clear out behind the
front tonight and flight category will remain VFR. As high
pressure begins to build back into the region tomorrow,
conditions are expected to remain dry for the period and continued
VFR ceilings will remain likely.

WINDS: Northwest winds of 10-15 kts with gusts to 25 will slowly
back down to generally light and variable winds around sunrise and
remain that way for the rest of the period.

Bigelbach

&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...
Lake Wind Advisory until 10 PM MST this evening For Fort Peck
Lake for Central and Southeast Phillips...Central and Southern
Valley...Garfield...McCone...Petroleum.

&&

$$

weather.gov/glasgow


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