FXUS65 KGGW 212037
Area Forecast Discussion
National Weather Service Glasgow MT
237 PM MDT Mon Aug 21 2017
.SHORT TERM...for northeast Montana...tonight through Tue...
Upper ridge moves east into Montana late Tuesday, which takes the
area from a cyclonic NW flow to an anticyclonic NW/lighter flow
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 back in for tonight then exiting
Temperatures will average close or below normal tonight with
temperatures close to normal Tuesday. Winds will be light tonight,
increasing from the SE Tuesday. TFJ
.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
PREVIOUS LONG TERM DISCUSSION:
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. Ebert
VFR expected tonight and Tuesday.
Mainly clear skies this evening will become partially cloudy from
high and mid-level clouds, then return to mainly sunny conditions
by late Tuesday.
Wind: becoming light and variable tonight, then increase from the
SE Tuesday, but less than 15 kts.
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