Area Forecast Discussion
Issued by NWS Glasgow, MT

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FXUS65 KGGW 180930

Area Forecast Discussion
National Weather Service Glasgow MT
330 AM MDT Fri Aug 18 2017

.SHORT TERM...for northeast through Sat... Flat
upper ridge pushing east from the northern Rockies today will pull
a hot and dry airmass out of the Great Basin. With warm
temperatures and low RH, near critical fire weather conditions are
possible but weak pressure gradient and waa will keep winds
generally light.

Shortwave pushes into the ridge on Saturday, deflecting the hot
airmass eastward. Fairly strong cold air advection behind frontal
passage will bring some gusty winds. Fire weather concerns remain
elevated, but morning timing of the frontal passage suggests
strongest winds will not match up with lowest RH. Ebert

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

The Northeast Montana forecast is picked up Saturday evening with
zonal flow aloft and a dry cold front having passed through the
area during the day. So, wind behind the front will be northerly,
but calmed down from the day. Weak disturbances along the frontal
boundary could generate a few showers and thunderstorms, but a
surface high should keep most of that south of our area Saturday
evening. However after midnight, a short-wave trough moves in from
the west to ride along the frontal boundary. This could initiate
rain showers and thunderstorms into Sunday, tapering off Sunday
evening through Monday morning. Near normal temperatures.

Monday morning a second, more energetic, quick-moving, trough
from the west could initiate another round of showers and thunder
Monday afternoon and evening. Near normal temperatures.

Tuesday and beyond, models show a broad upper ridge moving over
the Divide for warmer, quieter and dry conditions at least
through mid-week.

Beyond that, model differences in location and timing of the next
trough/storm system grow. But both the GFS and the EC bring in a
rather large system from the Gulf for the weekend with a return to
near normal temperatures.



VFR conditions through Friday evening.

High pressure move in behind the departing cold front this
morning. Satellite imagery is showing mid-to-high clouds upstream
in the northwest flow aloft.

WIND: east at 5 to 10 kts, becoming southwest today.



Locally critical fire weather conditions are expected over the
next few days.

Continued warm and dry weather is expected today but with less
wind. Temperatures will rise into the lower 90s with RH dropping
into the teens. Winds will be variable at less than 10 mph.

Another cold frontal passage is expected on Saturday with
low relative humidity and gusty northwest winds possible in the
afternoon behind it.



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