Wind Advisory 10, NWS Missoula, MT

737 
WWUS75 KMSO 030137
NPWMSO

URGENT - WEATHER MESSAGE
National Weather Service Missoula MT
737 PM MDT Wed Sep 2 2020

MTZ007-030245-
/O.EXP.KMSO.WI.Y.0010.000000T0000Z-200903T0200Z/
Butte/Blackfoot Region-
737 PM MDT Wed Sep 2 2020

...WIND ADVISORY WILL EXPIRE AT 8 PM MDT THIS EVENING...

Though still breezy, winds will continue to decrease over the next
hour.

$$

Area Forecast Discussion
National Weather Service Missoula MT
431 AM MDT Wed Sep 2 2020

.DISCUSSION...

A weak trough of low pressure moving out over the Canada plains
will graze the Continental Divide in northwest Montana today. In
addition to increased cloudiness over the Glacier Park Region,
the nearby trough will create gusty winds across much of the
Northern Rockies. Wind gusts in the 25-35 mph range will be common
across western Montana late this afternoon through early evening,
with slightly lower gust potential for north central Idaho during
this time. Afternoon temperatures today will be fairly similar to
Tuesday at lower elevations.

Warm and dry conditions will develop across the Northern Rockies
Thursday to Friday, as the Four Corners high pressure attempts to
redevelop one last time this season. Friday afternoon temperatures
will likely warm to the 85-100 degree range for most low
elevation locales.

A dry cold front is anticipated to sweep across the Northern
Rockies sometime on Saturday, however model guidances have been
delaying the cold frontal passage from Saturday afternoon to
Saturday late evening. One consequence of a delayed front is that
daytime temperatures will warm back to the 85-100 degree range
once again for low elevations. A tightening pressure gradient
ahead of the front may provide enough wind and instability for
area wildfire potential to increase during the afternoon and
evening hours.

Pretty much all available model guidances suggest that the Four
Corners high pressure will be quickly squashed in favor of a ridge
of over the Gulf of Alaska. This transition is expected to shift
flow aloft over the Northern Rockies to the relatively cool
northerly direction. Some of the global models and their ensembles
depict a trough of low pressure deepening within the northerly
flow aloft and intensifying along the Continental Divide. Light
snow accumulations down to at least 6000 feet appears quite
plausible over the Continental Divide (Glacier Park Region and
Bob Marshall Wilderness) late Monday evening. Also, the strong
surface pressure gradient over the Divide would likely introduce
gusty east and northeast winds across western Montana late Sunday
night through Monday.

The possibilities of what occurs over the Northern Rockies Tuesday
onward next week are quite vast. Some model guidances suggest that
very warm high pressure will redevelop and head back to the Four
Corners region by the end of next week. Other guidances depict a
slower progression of our cold trough southward, as well as some
intensification over the eastern Great Basin (which would keep the
high pressure ridge along the west US coast. Our current forecast
favors west coast ridge development, with daytime temperatures
quickly warming back to near or above seasonal averages by late
next week.

&&

.AVIATION...VFR conditions will be in store for all terminals
today. Strong west winds are also in the forecast for all
terminals today due to anomalously strong flow over west central
Montana at roughly 9 to 10K feet MSL. These winds will start late
morning, peak mid- afternoon, and dissipate after 03/0300z. KMSO
and KBTM will see the strongest gusts, with gusts up to 30 knots
possible at KBTM

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...ID...None.
&&