Area Forecast Discussion
Issued by NWS Glasgow, MT

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FXUS65 KGGW 211806

Area Forecast Discussion
National Weather Service GLASGOW MT
1106 AM MST Sat Jan 21 2017

.SHORT TERM...for northeast through Mon...
11 AM Update...

Visibility is improving and dense freezing fog has become less
widespread across the advisory area late this morning. Therefore,
the advisory has been allowed to expire. However, patchy dense
freezing fog still exists out there and is maintained in the
forecast through tonight. Travelers are encouraged to allow extra
time on their commute and use caution as a result of these
occasional conditions. Maliawco

9 AM Update...

Included patches of dense freezing fog across the CWA in the
weather grids through this morning given recent observations and
satellite trends. Very light precipitation is expected at times
across the eastern zones. It may not be enough to evaporatively
cool the column and freezing drizzle and/or light freezing rain
may result. At this time amounts do not look high enough to
consider highlights, but will assess with the afternoon package
and provide latest thinking. Maliawco

Previous Discussion...
After a comfortable and welcome January thaw, temperatures across
northeast Montana now begin a gradual slide back down to more
normal levels for this time of year.

Overall, on a very large scale, a widespread upper-level trough
will dominate the weather pattern over our region throughout this
weekend, but most of the Pacific moisture, riding into the region
on these series of low pressure systems, gets rung out over the
Rocky Mountains and very little if any remaining precipitation
makes it out here on the northern high plains.

To begin with, later tonight, as the departing trough of low
pressure slowly slides away toward the east, a very slight,
lingering chance for some precipitation may occur over our
northeastern zones. The deterministic models all show a very dry
forecast for this time, but the reflectivity models indicate that
some scattered light precip may be possible, and in the cold
season amid a northwest flow regime, the reflectivity models can
often be more accurate than the deterministic models. If nothing
else, they seem to be more accurate at representing what appears
on the radar data, as has been the case recently. Given the fact
that our forecast neighbors to our east were quite liberal with
PoPs, felt it was best to compromise with more of a middle ground
and show PoPs diminishing through our CWA from east to west. The
ForecastBuilder tool painted the chance for some freezing rain
over those northeast zones this evening through tonight. Given
that precip amounts are expected to be very light and confidence
is low at best, do not feel any headlines or additional products
are necessary at this time for this chance of freezing rain

The next chance for additional precipitation comes beginning on
Monday, as southwest flow aloft sets up ahead of a large west
coast low pressure system. At this time, most of the moisture
again seems to steer around and away from our CWA.


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

Upper trof moves across the western states midweek with slight
chances of snow and cooler temperatures. Best energy will be to
the south, but snow could spread northward on Tuesday.

Upper ridge then pushes over the Rockies for drier weather through
the end of the week. Cooler temperatures should persist until the
weekend before another chinook begins to develop across Alberta.



Mainly VFR. Patchy dense fog across the region early this
morning. Additional flight restrictions are possible tonight with
a front pushing out of Saskatchewan pushing south and bringing a
return of light mixed precipitation. /TFJ




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