Area Forecast Discussion
Issued by NWS Glasgow, MT

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FXUS65 KGGW 220254 AAA

Area Forecast Discussion...UPDATED
National Weather Service Glasgow MT
854 PM MDT Mon Aug 21 2017

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

Sent an update this evening merely to freshen up the immediate
short term forecast mainly to represent the cloud cover more
accurately. Expecting no rain for a while, and temperatures
becoming progressively warmer through mid-week in advance of the
next low pressure system beginning Thursday evening.


Previous short term discussion: Upper ridge moves east into
Montana late Tuesday, which takes the area from a cyclonic NW flow
to an anticyclonic NW/lighter flow Tuesday.

Clouds across the area this afternoon that blocked some of the
viewing of the eclipse will move out with some warm-advection mid
and high level clouds moving in for tonight then exiting Tuesday.

Temperatures will average close or below normal tonight with
temperatures close to normal Tuesday. Winds will be light tonight,
increasing from the SE Tuesday.


.LONG TERM...Tue night through Mon...


Changes to the forecast were focused on Thursday through Friday
night were a collection of models agree that ridge breakdown is
expected and southwest flow with an embedded shortwave takes hold.
PoPs were already averaged between 20 to 40 percent during these
times. But with confidence be higher decided to move models over
to N-PoPs which raised totals to near 40 to 70 percent near the


Upper ridge builds over Montana midweek with temperatures warming
into the upper 80s to lower 90s. Upper flow amplifies as an upper
trof pushes into western Canada, with low level lee trof
developing across central Montana. A pressure gradient tightens
with strengthening lee trof, will see increasing southeast winds
Wednesday into Thursday. Fire weather concerns due to the gusty
winds are expected to partially mitigated by dew point rises with
the southeast low level jet across the plains.

As the western Canadian upper trof moves across the Rockies, lee
trof will push through eastern Montana Thursday night into Friday.
Showers and thunderstorms possible with the frontal passage.
Depending on the timing, elevated fire weather concerns are also
possible on Friday with drying airmass with gusty northwest winds
as high pressure pushes out of Alberta.

Cooler and mostly dry conditions expected for the weekend as the
upper ridge begins to rebound to the west.




Synopsis: A dry NW flow aloft will keep NE Montana TAF sites dry
through mid-week as another ridge of high pressure builds in from
the west.

Flight Conditions: VFR.

Winds: NE winds overnight around 5 kts will increase to around 10
kts from the SE and S during the day on Tuesday.





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