Area Forecast Discussion
Issued by NWS Glasgow, MT

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FXUS65 KGGW 242011
AFDGGW

Area Forecast Discussion
National Weather Service Glasgow MT
211 PM MDT Sat Oct 24 2020

.DISCUSSION...

AFTERNOON DISCUSSION:
Synoptic Setup: Trough of cold air runs from northern Montana up
into the Canadian Prairie Provinces. Farther west a large warm
pacific ridge is butting up against the trough over the Pac NW
coast. This is constantly pressing on the cold trough to move
out.

This afternoon through tonight: Bulk of the snow is over allowing
the northern tier of counties to cancel their advisories with only
a few stragglers left down south where snow has yet to cease on
MDOT web cams.

Sunday and Sunday night: Ridge to the West will topple over the
front Range over Northern British Columbia and ALberta forming a
chinook to the far northeast. The ridge should kick out the cold
core trough aloft and start shallowing out the surface cold with a
massive inversion forming. However surface cold air will remain in
place and therefore limited low stratus will form and maybe a
little fog for higher elevation.

Monday to Tuesday: Chinook ridge will make its way down the front
Range into northern Montana during these periods. Some melt may be
possible with the current snow pack but inversion will likely hold
if only lessen in intensity.

Tuesday night to Friday: A cold front will arrive Wednesday
morning followed by a ridge and massive warm up Thursday and
Friday. Significant melt is expected across the region with 850 mb
temps reaching up into the upper teens Celsius.

Friday night onward: Models disagree from here on with what looks
like and out-of-phase ensemble of a progressive series of troughs
and ridges training along our latitude. GAH


MORNING DISCUSSION:
Winter storm moving across southern Montana this morning with
snow across the southwest zones. Left winter storm warning and
advisory in place as snow is expected to continue through the day.

As the storm moves out of the area tonight the arctic high will
be reinforced helping to keep record cold temperatures around into
early next week. Sunday night / Monday morning looks to see the
coldest temperatures with widespread sub-zero readings expected.

Pacific upper ridge will gradually push across the west coast
through next week. This will result in slowly warming temperatures,
which will be slowed by the lingering snow cover. RAE


&&

.AVIATION...
FLIGHT CAT: VFR - MVFR.

DISCUSSION: Low ceilings will hang in low VFR dipping in and out
of high MVFR above fuel loading in short stints. Most snow should
exit northeast montana by mid evening with maybe an exception due
to Lake Effect showers south of Fort Peck Lake.

WIND: Northeast to 10 to 15 kts this afternoon. Backing to the
north and calming to less than 10 kts tonight. Backing further to
the northwest mid-morning Sunday.

GAH


&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning until 9 PM MDT this evening for Petroleum.

Winter Weather Advisory until 9 PM MDT this evening for
Prairie...Wibaux.


&&

$$

weather.gov/glasgow



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