Area Forecast Discussion
Issued by NWS Glasgow, MT

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FXUS65 KGGW 230259 AAA

Area Forecast Discussion...UPDATED
National Weather Service Glasgow MT
859 PM MDT Fri Sep 22 2017

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

A thick cloud cover and light winds seem to be the highest
confidence and most dominant feature in the forecast through
tonight. With the upper-low pressure trough holding nearly steady
over the Rocky Mountain region, models are indicating that a bit
of light rain showers streaming up from the south could be
possible tonight through the overnight hours. Shouldn`t amount to
much. Sent an update tonight to fine tune update the forecast
grids with the latest near term model consensus data.


Previous short term discussion: A closed upper low over/near
Idaho this afternoon is expected to become squeezed a bit from the
west and east tonight and Saturday. Energy in the form of
vorticity maximums are expected to focus energy closer to south-
central Montana this evening then southeast Montana Saturday.

Current rain is diminishing, but should hold together enough to
give the NE zones likely pops for the next several hours. Then,
an area of rain from south-central Montana will move N-NE this
evening into the NW zones later tonight but weaken. The next batch
of rain will move north into the SE zones Saturday afternoon.

Generally used what the models gave me, but did cool temps a tad
for the SE zones with the clouds and afternoon rain expected.


.LONG TERM...Sat night through Fri...

The inherited long term forecast remains on track with a trough
over the Great Basin this weekend lifting north and east into next
week. This pattern will maintain below average temperatures with
occasional chances for rain showers. As the low slides downstream
of the CWA, a ridge will build across the western U.S. Large scale
subsidence and height rises should mean drier weather conditions
and gradually warmer temperatures late next week.


Previous Long Term Discussion:

Deep upper trof/low over the Great Basin over the weekend will
slowly lift northeast toward Ontario through next week. By the end
of the week a ridge is expected to return to the western states.

Upper trof over the region will keep temperatures below normal but
will see a slight warming trend through the period as the trof
translates eastward. Unstable airmass will result in occasional
showers, with temperature profiles suggesting rain even with
temperatures dipping into the 30s at night over the weekend.

Dry and warmer weather expected by the end of next week with upper
ridge building across the northern Rockies.





SYNOPSIS: Lingering sprinkles on a persistent southerly flow aloft
may materialize only a little bit more overnight and into Saturday
morning into some light rain showers, but coverage and amounts for
the TAF sites are expected to be spotty.

WIND: Expect winds to be light and variable.





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