Area Forecast Discussion
Issued by NWS Glasgow, MT

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FXUS65 KGGW 012042

Area Forecast Discussion
National Weather Service GLASGOW MT
242 PM MDT SAT OCT 1 2016

.SHORT TERM...for northeast Montana...tonight through Mon...
Moist upper level southwest flow aloft has set up across the
region as a Pacific trough deepens and translates east. This flow
regime has allowed surface dewpoints to rise into the 40s and 50s
across northeast Montana. Coupled with warm daytime heating with
high temperatures in the 70s and 80s, and an approaching
shortwave, the recipe for scattered evening and overnight showers
and thunderstorms is at hand.

The trough will gradually make eastward movement over the next
couple days and associated surface low will track north across
eastern Montana by Monday, bringing with it steadier rainfall and
perhaps some thunder as well. Total rainfall by Monday late
afternoon may exceed one half inch in and near where steadiest
showers and thunderstorms occur. Maliawco

.LONG TERM...Mon night through Sat...

The main focus of the extended remains the Monday night into
Wednesday period with the wet upper low moving overhead. Snow
remains a big challenge, with just a degree one way or another
making a big difference in snow accumulations. This set of model
runs looks just a bit warmer for Tuesday morning, thus snow
accumulation potential does not look as good. With that said there
remains a great deal of uncertainty during this time. Thus,
confidence is high in a wet period, but low regarding snow
accumulation. The remainder of the forecast stands. Gilchrist

Previous discussion...A stacked upper low
will be over Eastern Montana Monday Night and Tuesday. Most of the
forecast area will be in the deep moisture either in the vicinity
of this low or on the back side. Areas near the North Dakota
border will be on the western edges of a dry slot that will cover
most of the Dakotas during this period. Within the upper low,
there will be a trowal over Northeast Montana Monday Night which
will make the atmosphere unstable enough for thunderstorms mainly
in the eastern zones. This trowal will also enhance precip amounts
Monday Night and Tuesday especially over the western half of the
forecast area. Models are forecasting 2-3 inches of precip with
this event. Also, cold air wraps around the back side of this low
Monday Night and Tuesday and 850 mb temperatures are expected to
fall below zero celsius which will allow for either a mix with
snow or change to snow. At this point, the best chances for snow
will be in the Little Rocky Mountains and some higher elevation
areas of Phillips, Petroleum, Garfield, and Valley Counties. If
temperatures are cold enough, there could be accumulating snow
across these area. Most locations will have all rain Monday Night
and Tuesday.

As the low moves to the northeast and precip lifts north Tuesday
Night, the cold air filters into all of Northeast Montana. More
areas of the forecast area will see a change from rain to snow
with any lingering precip and temperatures falling below freezing
over most areas.

While the low moves into Manitoba on Wednesday, a wave in the
northwest flow aloft will allow for a chance of rain and snow
showers. Another wave on Thursday could bring a slight chance of
rain showers.

An upper ridge will allow for mainly dry weather on Friday. Then,
an upper trough moves in on Saturday with a chance of rain
showers. Forrester


Flight Category: VFR.

Synopsis: A low pressure system and its associated cold front will
begin impacting northeast Montana this evening, brining chances
for showers and thunderstorms west of KGGW. As it progresses
eastward, the four TAF terminals will be impacted with showers
late this evening and overnight tonight.

CIGS: Mid and high clouds will increase with the frontal passage
this evening. Some partial clearing is expected west of KOLF early
Sunday morning.

Wind: East to southeast 5 to 10 knots this afternoon. Winds will
turn to the northwest as the cold front passes tonight, but will
continue to be in the 5 to 10 knot range.





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