Area Forecast Discussion
Issued by NWS Glasgow, MT

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FXUS65 KGGW 260852

Area Forecast Discussion
National Weather Service GLASGOW MT
252 AM MDT THU MAY 26 2016

.SHORT TERM...for northeast through Sat...

Closed upper low currently over eastern Montana is producing
isolated showers over the area. This low will drift east today and
will be in North Dakota by evening. Air mass across the forecast
area today will become more unstable with daytime heating which
will allow showers and thunderstorms to increase over the area
during that day. Look for scattered to numerous showers and
thunderstorms. Most areas should see precipitation at some point
today but all day rain is not expected at any one location.

With the upper low over North Dakota tonight and weak high
pressure and shortwave ridge over Eastern Montana, the chances for
showers will diminish. The northeast corner of the state will stay
within the upper low circulation and a chance of showers could
linger all night.

The upper low retrogrades somewhat back towards Northeast Montana
on Friday before it dissipates. This will allow a chance of
showers to return to the eastern half of the forecast area in the
morning. Meanwhile, the next upper trough moves into Western
Montana during the day with a frontal system that moves into
Central Montana during the afternoon. This could bring showers and
thunderstorms to the western zones.

The upper trough and frontal system moves through Eastern Montana
Friday Night and Saturday with a good chance of showers and
thunderstorms. Forrester

.LONG TERM...Sat night through Thu...

As the next major Rocky Mountain low pressure trough emerges
eastward over the northern High Plains region, there is some hint
of a brief short-wave ridge in-between embedded disturbances.
Indeed, model precip consensus shows high confidence in keeping
most of our CWA dry Saturday night through Sunday.

Beginning Sunday night and lasting through the remainder of the
forecast period, significant model differences emerge regarding
precipitation chances. This lack of forecast confidence for next
week is based primarily on the evolution of another major low
pressure trough set to descend through our northern Rocky
Mountains and northern High Plains regions.

The most glaring difference is with the GFS bringing down a much
stronger closed low much earlier than that EC which brings a much
weaker open trough and does not mature it until it moves well to
our east. The GFS solution is similar to the DGEX and is very wet
with some strong and efficient rain makers late Monday night
through Wednesday.

Overall, I chose to lean toward the wetter solution when models
disagreed with some average to less-than-average confidence. Found
highest confidence with best model consensus early in the forecast
period, even if it shows dry. BMickelson



Isolated to widely scattered showers and thunderstorms will
be possible as the low pressure system spins over northeast
Montana. VFR conditions will mainly prevail, but would reduce to
IFR to MVFR if a storm passes directly over a TAF site.

Early morning light and variable winds will set up from the
northwest up to 15 mph with peak heating, then diminish again by
tonight. BMickelson




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