Area Forecast Discussion
Issued by NWS Glasgow, MT

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FXUS65 KGGW 241635 AAA
AFDGGW

Area Forecast Discussion...UPDATED
National Weather Service Glasgow MT
1035 AM MDT Mon Jul 24 2017

.SHORT TERM...for northeast Montana...today through Wed...
Update: Radar is currently showing some weak echoes over far
northeast Montana. Am pretty sure rain is not reaching the ground
but have not detected any lightning as of yet from this either.
Adjusted pops slightly and also bumped up some of the fire
weather parameters over the area, just in case the area does see a
lightning strike or two over the next couple of hours.

One major concern today continues to be the gusty northwest winds
as the front passes through. Although these will be short lived,
locations where the front has already passed have seen gusts in
excess of 30 mph. Adjusted the winds upwards a little to better
reflect some of this, but the winds were already in pretty good
shape. Another concern is the potential for dry thunderstorms this
evening, bringing further fire weather concerns to the area.

AEH
Synoptic Setup: A hot high pressure ridge has formed over the
western half of the CONUS. A ridge spur runs out of this from
southeastern Montana through North Dakota and into Manitoba. An
open trough over Alberta is rapidly closing off as the surface
and has latched onto the lee side mountain trough over the
frontrange moving it forward. Behind this a new ridge is forming
over British Columbia. Farther west another closed low is forming
over the Gulf of Alaska.

Today into tonight: as the lee side trough gets dragged along the
upper level trough it will quickly form into a dry cold front this
morning. Winds will be at their strongest directly behind the
front around Noon about should begin tampering down through the
afternoon hours as the gradient begins to slacken. Flow aloft will
transition in the afternoon to zonal and last that way overnight
stalling the front to the south. The slope of his developed front
will be a focal mechanism for lift and thunderstorms moving across
the southern zones overnight. A weak shortwave upstream int he
flow will also help to spark off these thunderstorms. As moisture
is lack luster near the surface, any thunderstorms that do develop
will be most likely be dry leading to further fire weather
concerns.

Tuesday: Front will move back to the north as a very diffuse and
dry warm front which should stabilize the atmosphere and lead to
a dry day with partly cloudy to clear skies.

GAH


.LONG TERM...Wed night through Mon...

Tuesday night into Wednesday night: Ridge will redevelop and
strengthen to the west stabilizing the profile and creating clear
to partly cloudy skies and dry conditions.

Thursday through Friday: Ridge will further strengthen and move
across northeast Montana. Temperates could begin pushing the
upper 90s to 100s with very low RH and surprisingly gusty winds.
This will be a group of periods to monitor for critical fire
weather conditions.

Friday night through Sunday night: Canadian breaks away from the
rest of the ensembled models leading to decreased confidence from
here onward. While the ridge axis crests over Montana, a shortwave
is expected to to move across the canadian prairies which will
blunt the ridge over northern Montana and may bring a light dry
cold front or at least partially cooler conditions initially. By
the end of these periods the ridge could easily rebound.

Monday onward: Chaos takes hold here onward with GFS/EC suggesting
another light frontal passage to the north blunting the ridge yet
again, yet these two models are also beginning to lose phase as
well. GAH



&&

.AVIATION...UPDATED

Flight Category: VFR today, tonight and Tuesday morning, although
smoke from the Lodgepole Complex fires may cause unpredictable
visibilities.

Today, GOES satellite imagery shows a stacked up low pressure
system in central Alberta moving into the middle of Saskatchewan
at noon today. By 6 AM Tuesday the center of the storm will have
moved into central Manitoba. A cold front associated with this
storm system kicked off a few thunderstorms this morning, which
are expected to move east out of the area this afternoon. The
other main effect will be the associated gusty northwest wind of
15-25G35KT. This wind is expected to diminish to less than 20KT
late this afternoon.

Tonight, another disturbance is expected to focus along the
frontal boundary and initiate thunderstorms south of the Missouri
River. Some of these thunderstorms may move through the
Yellowstone River area, affecting KGDV, and possibly KSDY for
temporary reductions to the flight category. Wind overall will be
northeasterly at less than 10 KT.

Tuesday morning, mild conditions with FEW to SCT clouds return
with a light northerly breeze of around 10 KT.

Templer


&&

.FIRE WEATHER...
...A Red Flag Warning remains in effect today until 9 AM Tuesday
morning for Fire Weather Zones 122, 135, 136, and 137...

...A Red Flag Warning is in effect for Fire Weather Zone 120 and
134 on Monday from 9 AM through 9 PM...

A cold frontal passage this morning will switch winds around to
the northwest early this morning. The strongest winds are
expected across the region today through 3 PM before gradually
diminishing thereafter. Winds will then become light out of the
north to northeast this evening. The potential also exists for
very isolated dry thunderstorms late this afternoon into tonight,
which would be accompanied by lightning as well as gusty and
erratic winds should they occur. An upper ridge will become firmly
established into the second half of the week with a continuation
of very warm and dry weather conditions.


&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until 9 AM MDT Tuesday for MTZ122-135>137.

Dense Smoke Advisory until 9 PM MDT Tuesday for Garfield.

Lake Wind Advisory until 9 PM MDT this evening For Fort Peck
Lake for Central and Southeast Phillips...Central and Southern
Valley...Garfield...McCone...Petroleum.

Red Flag Warning until 9 PM MDT this evening for MTZ120-134.

&&

$$

weather.gov/glasgow



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