Area Forecast Discussion
Issued by NWS Glasgow, MT

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FXUS65 KGGW 170438
AFDGGW

Area Forecast Discussion
National Weather Service Glasgow MT
1038 PM MDT Mon Oct 16 2017

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

730PM UPDATE:
Changes to the forecast are very similar conditions to yesterday
at this time. Afternoon heat has held on a little bit longer than
anticipated. However, with a complete lack of cloud coverage this
evening low are expected to bottom out rapidly. So, timing of the
rapid bottoming out needed to be back up about 1 to 2 hours on the
diurnal curve in hourly temperatures. RH was also lower than
predicted at this time so a longer smooth time was needed to ease
it into the evening. Radar, satellite, and models show conditions
should remain dry throughout the night. GAH


PREVIOUS SHORT TERM DISCUSSION:
Winds continue to be the main forecast concern for this week.
Shortwave trof will be coming into Western Canada tonight, then
slide across the Rockies on Tuesday. Winds expected to increase on
Tuesday ahead of a cold front, along with warming temperatures
and lowering RH. Strongest winds expected over the higher terrain
in the northwest zones. Fire weather concerns are increasing with
recent dry conditions, so have issued a Red Flag Warning for the
Little Rockies. Ebert


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

AFTERNOON UPDATE:
Changes were made for mainly the winds on Tuesday night.
Shortwave sliding along the Canadian border and cold front passage
will bring very strong winds into northern Montana. Models
continue to increase the 850mb and 700mb winds, especially into
the northwest zones for the overnight hours. Given the caa and
pressure rises, even overnight, expect some very high wind gusts
around the Little Rockies especially. Have issued a High Wind
Watch for Southwest Phillips County for Tuesday night.


PREVIOUS LONG TERM DISCUSSION:
An upper level disturbance tracking well north of the area
Tuesday night will track close as a surface dry cold front passes
through the area. With this system will come a tight pressure
gradient leading to gusty winds, particularly before 06Z. Some
model guidance shows in excess of 40 kts at 850mb Tuesday evening.
The proximity of the shortwave to the region, CAA, and other
factors could allow enough boundary layer mixing to continue the
breezy conditions well into the evening and nighttime hours. Thus,
continuing the Lake Wind Advisory for the Fort Peck Lake area
makes sense.

Warmer temperatures and dry weather conditions will once again
arrive by Thursday and Friday as the upper ridge pattern over the
Western U.S. becomes established and advances toward northeast
Montana. Height rises are sufficient along with 850mb model
temperatures to trend this portion of the forecast a little above
the consensus model blends. This results in highs on Thursday well
into the 70s for a large portion of the area.

Although models indicate that a new trough will arrive near the
Pacific Coast by the end of the week, allowing the ridge to
gradually shift downstream of the area, there remains enough
spread int he model solutions to create some uncertainty here. As
a result, the forecast was trended close to consensus model blends
at the end of the period. Maliawco


&&

.AVIATION...

FLIGHT CAT: VFR.

SYNOPSIS: An upper level disturbance will bring fast winds above
the surface at night and then increase them over the day through the
cycle.

LLWS: Low level wind shear is anticipated between 06z to 15z as
strong winds set up above a surface inversion this morning. This
is anticipated again Tuesday night/Wednesday morning, but
possibly stronger.

WIND: Southwest at less than 10 kts tonight, increasing to 15 to
25 kts Tuesday afternoon, veering to west and further increasing
to 20 to 30 kts Tuesday night.

GAH


&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from 11 AM to 7 PM MDT Tuesday for MTZ135.

High Wind Watch from Tuesday evening through late Tuesday night
for Southwest Phillips.

Lake Wind Advisory until 8 AM MDT Wednesday For Fort Peck Lake
for Central and Southeast Phillips...Central and Southern
Valley...Garfield...McCone...Petroleum.


&&

$$

weather.gov/glasgow


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