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315
FXUS65 KGGW 232337
AFDGGW

Area Forecast Discussion
National Weather Service Glasgow MT
537 PM MDT Mon Oct 23 2017

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

6pm Update:

A quick update to extend the lake wind advisory out to
9 pm with wind still gusting to 40-50 mph over the central and
eastern forecast areas. Otherwise forecast in fairly good shape
for the evening and overnight hours. Proton

Previous Discussion:

An upper level ridge positioned over the western U.S. will slowly
make its way into eastern Montana tonight. As the upper level
trough that impacted the area over the past couple of days continues
to deepen and shift toward the Great Lakes, the jet core that
brought the very strong winds to eastern Montana will finally
depart this evening. This being the case, winds will drop off
quickly not much after sunset tonight, with mostly clear skies,
dry conditions, and relatively light winds are expected into
Tuesday morning.

With the ridge moving into northeast Montana Tuesday, the area
will see warmer temperatures with the associated height rises,
with highs ranging from near 60 to near 70 degrees in the
southwest.  Hickford


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

The extended period begins with an upper level ridge departing
the region Wednesday. This will bring about the warmest
temperatures of the week, with highs from the 60s to the mid 70s
in the southwest zones. Afterward, confidence has increased
regarding a shortwave that will drop into northeast Montana from
Alberta/Saskatchewan on Wednesday, just ahead of a strengthening
cold front which will bring strong northwest winds Wednesday
afternoon. Several models capture this feature, but blended
primarily with ConsMOS for sake of collaboration. Winds will
increase quickly to 25 to 35 mph, with gusts up to 40 or even 50
mph. Relative humidities will be in the 20s Wednesday afternoon
and evening, and this along with the strong winds, will
potentially bring about critical fire weather conditions are a
concern for Wednesday night.

As the cold front passes, there is a brief chance of
precipitation, mainly snow, Wednesday night and into Thursday
morning. If so, amounts are expected to be very light, likely
only a trace.

Just behind the passage of the front, very cold temperatures will
occur, with low temperatures Friday morning in the teens and 20s.

Friday and into the weekend, another high pressure ridge will move
over the region, but model consensus has not really improved from
the previous forecast, with the GFS moving this feature over the
area more rapidly than the ECMWF. Kept the trend toward forecast
blends for now. Hickford
Previous Discussion...
The extended period will feature a shortwave dropping southeast
from Canada with a surface cold front making its way toward
northeast Montana by late Wednesday. This system will likely lead
to strong northwest winds late in the day and continuing into
Thursday. Isolated to widely scattered showers remain possible
with this system, especially Wednesday night. However, current
model solutions maintain the heaviest precipitation totals
northeast and southwest of the forecast area. Lastly, the
combination of strong winds as well as relative humidity readings
below 30 percent may lead to elevated fire weather concerns for a
time late Wednesday.

Following the cold frontal passage will also be some of the
coldest temperatures so far this fall. By late Thursday night, low
temperatures will reach around 20 degrees with some of the deeper
valley locations dropping well into the teens.

Friday and into next weekend an upper trough and closed low will
evolve toward the Great Lakes all while a new upper ridge makes
its way toward the Pacific Coast. This will drive northerly flow
aloft over the forecast area and dry weather conditions. Given
increasing model spread in the 500mb heights at these larger time
scales, the forecast was trended toward consensus model blends for
now. Maliawco


&&

.AVIATION...
Synopsis: High Pressure over the Pacific Northwest and Low
Pressure over the Great Lakes continues to keep a fairly tight
pressure gradient over Northeastern Montana this evening.

Flight Category: VFR.

Wind: Northwest wind gusting to 35 kts will diminish AFT 03Z and
will pick up again AFT 18Z.

Proton


&&

.FIRE WEATHER...

Issued a Fire Weather Watch on Wednesday from the afternoon
through late evening Fire Wx Zones 122, 135, 136, and 137 due to
strong wind and low RHs associated with an approaching cold front.

Late Wednesday afternoon a strong cold front is expected to sweep
through the area, which will bring northwest winds of 20 to 30 mph
with gusts up to 45 mph. These winds are expected to diminish
Thursday morning.

Hickford


&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...
Fire Weather Watch from Wednesday afternoon through Wednesday
evening for MTZ122-135>137.

Lake Wind Advisory until 9 PM MDT this evening For Fort Peck
Lake for Central and Southeast Phillips...Central and Southern
Valley...Garfield...McCone...Petroleum.

&&

$$

weather.gov/glasgow