Area Forecast Discussion
Issued by NWS Glasgow, MT

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FXUS65 KGGW 250153

Area Forecast Discussion
National Weather Service GLASGOW MT
753 PM MDT TUE MAY 24 2016

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

Update: Adjusted chances of precipitation up a little bit in the
lower Yellowstone River Valley through tomorrow morning. Also
added a slight chance of thunder to the forecast in the same area
with some convective activity east of Billings moving towards the
region. Otherwise very few adjustments made to the ongoing
forecast for the overnight hours.      Proton

Synopsis: A pair of upper lows under a broad upper trough will
make for unsettled conditions over northeast Montana, with the
lower Yellowstone valley and adjacent areas seeing significant
rainfall into Wednesday.

A vertically stacked low continues to rotate across southern
Saskatchewan. This evening said low will retrograde southeastward
toward the Montana, Saskatchewan, Alberta triple point. as it
does so, it will begin advecting in weak circulations out of
wyoming, and into eastern Montana. this weak circulation has a
good moisture source, and will rapidly deepen in the mid and low
levels, driving widespread rainfall mainly targeted over the lower
Yellowstone valley late tonight into Wednesday.

Wednesday afternoon and evening the low will slowly drift into
North Dakota sending the best precipitation band northward along
the Montana/North Dakota border.

Late Wednesday night the North Dakota low will push far enough
east that precipitation will begin to taper off over eastern
Montana. At the same time, the first low over southern
Alberta/Saskatchewan will begin to push through northeast Montana.

Thursday the Sask. low will begin to grab moisture provided by
the North Dakota low...bringing another round of widespread shower
activity to northeast Montana. Gilchrist

.LONG TERM...Thu night through Tue...
The 12z model guidance maintains the overall persistent pattern
described by the previous shift. Upper trough will persist over
the region with chances for showers and thundersorms continuing
each day. Activity will be scattered in nature and difficult to
predict any specific periods in which it may be dry given
uncertainty and predictability issues out at larger time scales.
Inherited forecast handled this by broad-brushing pops and agree
with the idea that they captured in doing so. Maliawco

Previous discussion...

A shortwave trough over eastern Montana Thursday Night will bring
a chance of showers and thunderstorms to the area. Then, a longwave
trough will be over the western US and Canada starting on Friday
and remaining there into early next week. Eastern Montana will be
in a south to sw flow aloft for most of the period. Shortwaves
will combine with unstable air mass for a chance of showers and
thunderstorms for most of the period. Models are timing the waves
differently. Will generally broadbrush the chances of showers and

On Monday and Tuesday, the GFS keeps the trough to the west of
Montana while the ECMWF wants bring the trough east across the
forecast area. Either way, it looks like unsettled weather
continues. Forrester



VFR Conditions will prevail into tonight with isolated showers
possible through the overnight hours. West winds around 10 kts
will become light overnight and switch north.

By early Wednesday morning, a better chance of more widespread
rain will impact KGDV and KSDY from the south with MVFR/IFR
conditions possible. Maliawco/BMickelson




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