Area Forecast Discussion
Issued by NWS Glasgow, MT

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FXUS65 KGGW 280202
AFDGGW

Area Forecast Discussion
National Weather Service Glasgow MT
802 PM MDT Sat May 27 2017

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


8PM UPDATE:
Changes to the forecast were to raise PoPs along the northwestern
zones with radar trends from Canada sending a showers and a few
isolated thunderstorms into this area. Water vapor imagery clearly
shows an upper level disturbance holding these showers from dying
immediately with sundown. Lake wind advisory was also extended
about two hours as pressure gradient remains tight and showers
embedded in it may be able to bring irregular gusts to the ground
for the next couple hours. GAH


PREVIOUS SHORT TERM DISCUSSION:
The upper-flow pattern for tonight and Sunday consists of an
amplified ridge, with its axis centered along the West Coast, and
a trough anchored by a closed, stacked low centered over central
Manitoba. Through Sunday afternoon the ridge drifts east slightly
and the low center plunges into southwest Ontario and northern
Minnesota. Northeast Montana will remain under the boundary
between the cooler air of the trough and the warmer air of the
ridge, resulting in near normal late May temperatures.

A short-wave trough rotating around the backside of the Canadian
low in Manitoba will continue to spread isolated to scattered
showers, thunderstorms and broken clouds across the area tonight
and Sunday. The short-wave kicking through our northeast zones
today increased northwest winds to around 15-25kt, which will
diminish by 02Z, allowing the NPW for Fort Peck Lake to end.

Sunday, models again point to a well mixed boundary layer with a
pressure gradient increasing across western zones as the closed
low to the northeast moves south and east. This will likely again
lead to windy enough conditions in the afternoon to necessitate an
NPW for Fort Peck Lake.

Templer


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

ATFERNOON UPDATE:
Nothing significant to change in the going forecast. Upper ridge
moves across the region through midweek then begins to break down.
Models have not quite resolved much for the end of the week but
expect a return of scattered showers. Ebert


PREVIOUS LONG TERM DISCUSSION:
Eastern Montana will remain in northwest flow aloft between
trough over the Great Lakes and ridge over the northern Rockies
Monday and Tuesday. Surface high pressure will build into the area
allowing for dry weather and lighter winds especially on Tuesday.

Upper ridge moves east into Western Montana on Tuesday and the
ridge axis reaches Eastern Montana on Thursday. This will allow
for warmer temperatures and continued dry weather.

Models begin to differ Thursday Night and Friday. ECMWF has a
progressive shortwave trough along the MT/Canada border Thursday
Night and Friday which is followed a ridge on Saturday. GFS takes
wave further south across the Central Rockies and maintains the
ridge over the Dakotas. Could see a few showers at times towards
next weekend. Forrester


&&

.AVIATION...

FLIGHT CAT: VFR.

SYNOPSIS: A closed low storm system centered over central
Manitoba will send a short-wave disturbance through Northeast
Montana this afternoon and tonight. Expect isolated rain showers
and a few thunderstorms, with the frequency low enough to not
include in the TAFs. Will amend as necessary.

WIND: This wave will energize northwest winds to around
15-25G35KT this evening and Sunday, but diminish to around 5-10kt
overnight.

Templer/GAH


&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...
Lake Wind Advisory until 10 PM MDT 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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