Area Forecast Discussion
Issued by NWS Glasgow, MT

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FXUS65 KGGW 230126 AAA
AFDGGW

Area Forecast Discussion...UPDATED
National Weather Service GLASGOW MT
726 PM MDT Wed Mar 22 2017

.SHORT TERM...for northeast Montana...tonight through Fri...
Radar and lightning sensors have picked up thunderstorm activity
south of the CWA this evening. Therefore main update was to add
TS wording to the rain showers, which are not expect to spread
much beyond the southern borders of Petroleum and Garfield
Counties.

Templer

Previous update -
Synoptic Setup: short term begins with a large ridge over the
western half of the US running from the New Mexico through eastern
Montana and up into central Saskatchewan. To the east a highly
amplified trough of equal size runs from off the coast of British
Columbia to off the coast of southern California. These two large
airmasses have creates southern to southwestern flow running from
southern California to western Montana.

This afternoon and evening: Ridge will exit out of the area with a
warm front moving across at the surface. This will exit most of
the rain showers from the eastern side of the state by the late
afternoon.

Thursday morning through the afternoon: Flow will transition to
the southwest during this time. The base of the trough off the
coast of California will move inland and beginning transversing
the Desert Southwest. This will take the bulk of the energy for
lift and leave it well south of the CWA. However, just enough
Pacific moisture may be able to make it up to impact southern
Montana with rain showers. A few of these may be able to spill
into the far southeast corners of the CWA over the Yellowstone
Valley before dying off. Total should be minimal with maybe a
couple hundredths for those areas impacted. GAH

Thursday night and Friday: A return upper level ridge pattern
across the area will bring dry weather conditions to northeast
Montana along with mild to warm temperatures. Highs will reach the
50s for most places and some 60s in the southwest zones. Maliawco


.LONG TERM...Fri night through Wed...
The long term forecast as described below remains on track. The
only changes were to trend toward latest 12z consensus model
blends. Expect a shortwave trough to pass through the region over
the weekend with some scattered showers associated with that
system along a surface cold front. Models continue spread into
next week but overall expect continued chances for precipitation
with somewhat cooler temperatures. Maliawco

Previous Long Term Discussion...

The extended forecast begins Friday evening with Northeast Montana
located under an upper level ridge, with cut-off low spinning
across the Southern Plains. There will be a Pacific trough that
will come onshore and cross the Divide Saturday evening. Models
remain unclear with the timing. But after a mild Saturday morning,
the front should move across the area Sunday afternoon or evening.

The trough then moves across the area Sunday. Besides timing,
models are unclear about QPF amounts also. The GFS creates a more
structured storm with a surface low parked over eastern Montana.
The inverted trough in place when the cold front pushes through
could generate moderate rain through Sunday. The EC remains mostly
dry for this period.

The timing of the next trough is even more out of tune between the
GFS and the EC. The best that can be said is there is a cooler and
wetter trough pattern in store for next week.

Went with a broad brush blend of models until models align.

Templer


&&

.AVIATION...
FLIGHT CAT: VFR

SYNOPSIS: A warm front has rapidly moved across the northeast
Montana is about to exit for ND as of this evening. A few high
clouds are moving in behind it.

WIND: Calming to light and variable overnight. Then switching to
the west to northwest at around 10 to 15 kts Thursday.

GAH/Proton


&&

.HYDROLOGY...
The Big Muddy Creek in Sheridan County continues to drop further
below minor flood stage this afternoon. However, reports from law
enforcement indicate continued running water over area roadways.
In addition, there is concern with warmer temperatures that levels
could rise again. In order to gain additional confidence in the
downward trend, and to allow further time for running water to
continue to recede on local roadways, the flood warning was
extended for an additional day. The Milk River at Dodson also
continues to rise as a result of higher river levels upstream.
Expect this to lead to rises at Glasgow in the coming days. These
conditions will need further monitoring into next week. Maliawco


&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

weather.gov/glasgow



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