Area Forecast Discussion
Issued by NWS Glasgow, MT

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FXUS65 KGGW 210408

Area Forecast Discussion
National Weather Service Glasgow MT
908 PM MST Sat Jan 20 2018


Evening Update (9pm MST): Main focus for the update is on the
potential for freezing fog through the overnight, as that is the
main source of any potentially impactful weather expected until
tomorrow night. Models continue to back off on the extent of the
potential fog, though they keep some patchy to areas of freezing
fog mainly confined to the Missouri River Valley, and generally
between Wolf Point and Saco. Fog formation does seem to be more
likely tonight than last night due to generally weaker winds, clear
skies over a broader area than last night, and the reformation of
the low level inversion. However, some mechanical mixing to the
surface, a very dry atmosphere above the surface, and reduced
surface albedo of the dwindling snowpack across much of the region
may work to inhibit fog development. Otherwise, with such a benign
weather pattern underneath the building ridge, no further updates
were really necessary to the forecast at this time. Bigelbach

The upper trough works its way east through the Southwest tonight,
followed by a narrow ridge Sunday for another dry day. The
generally clear skies tonight will allow for cooling. With the
snow pack and the expected inversion developing tonight, and the
melting of snow today by the sunshine, could produce a fog layer.
Let the near term models produce the expected freezing fog, and
added to wx grids.

A narrow ridge will move through Sunday night, immediately
followed by a quick moving trough Monday afternoon, which should
bring little to no precipitation.

A broad ridge of high pressure will then dominate our weather
pattern through the middle of the week, allowing temperatures to
remain near normal through Thursday.

A strong low pressure system will move onto the northwest Pacific
coast Thursday, and while it is expected to weaken as it slams
into the Rockies, it currently looks that it will remain strong
enough to bring some snow to the area toward the end of the week.
There is the normal model guidance uncertainty regarding timing
and geographic area of any precipitation from this, but Thursday
night and Friday looks to be the most likely time frame for snow
across northeast Montana.

Overall, there are no temperature extremes expected with highs and
low generally close to seasonal norms.




Expected Flight Category: VFR

Synopsis: High pressure continues to build across the region,
which will keep flying conditions generally pleasant over the next
couple of days. Some patchy freezing fog is still possible
tonight, however, confidence currently is medium to low. Should
fog form, it is expected to mainly be confined to the Missouri
River Valley, and thus mainly affecting GGW and OLF. Otherwise,
generally clear to light cloud cover is expected for the period
with ceilings remaining at VFR levels.

Winds: Expect west to southwest at 5-10 kts.





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