Area Forecast Discussion
Issued by NWS Glasgow, MT

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FXUS65 KGGW 202008

Area Forecast Discussion
National Weather Service GLASGOW MT
208 PM MDT Thu Oct 20 2016

.SHORT TERM...for northeast Montana...tonight through Sat...
A broad upper level ridge over the region will persist tonight
through Saturday if only translating a bit to the east.
Meanwhile, a shortwave will slide over the northern periphery of
the ridge bringing with it enough upper level forcing for a few
showers, mainly across northern portions of the CWA tonight into

A second shortwave will track through the area on Saturday. This
system may be a bit more robust, but again, scattered showers will
likely remain confined to northern portions of the area. As a
whole, continued mild temperatures are generally expected thanks
to the proximity of the ridge. Maliawco

.LONG TERM...Sat night through Thu...

Changes to the forecast were focused mainly on the Tuesday period
onward where the broad ridge exits and a Pacific trough moves
through the region. Confidence with these periods onward is low.
as ensembles have a very high spread in height data. Overall view
is that the pacific trough will move through however, shortwave
features such as the passing cold front are different from run to
run. Currently models tackle the bulk if the lift for
precipitation and pass it to the south over southern Montana and
northern Wyoming, but this could change quickly with the QPF
moving farther south... or north over GGW territory. GAH

An upper ridge will be building over the northern plains through
the weekend, opening the region to southwest flow aloft. Warm and
generally dry condition are expected through Monday with high
pressure sliding from the northern plains into the upper midwest.

The upper trof digging off the Pacific Northwest will begin
ejecting shortwaves across the northern Rockies to break down the
ridge early in the week. Lee side low develops in southern Alberta
on Tuesday then pulls a cold front through Montana Tuesday night.
Precipitation chances increase behind the frontal passage on
Wednesday although timing and position of the moisture stream
decrease confidence for details.

A better chance for precipitation occurs by the end of the week
with the upper trof moving on shore. Ebert




SYNOPSIS: Boundary has lifted to the northwest clearing most of
the morning fog. High clouds associated with a pacific jet will
stream across the region through the remainder of the TAF cycle. A
second front will pass through the Terminals overnight.

LLWS: As the front passes through tonight it will move in over and
inversion and cause a couple hours of Low Level Wind Shear.
It should quickly scour out the inversion generating a wind shift
at the surface and end LLWS concerns from that point onward. Best
guess at timing is between 06 to 12Z.

WINDS: South to southwest at 5 to 15 kts, becoming west by the
between early to mid Friday morning.





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