Area Forecast Discussion
Issued by NWS Glasgow, MT

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FXUS65 KGGW 212114
AFDGGW

Area Forecast Discussion
National Weather Service Glasgow MT
314 PM MDT Fri Jul 21 2017

.SHORT TERM...for northeast Montana...tonight through Sun...
An upper level low is moving eastward across Alberta and
Saskatchewan today, and northwest flow has returned to most of
the area behind a shortwave trof that passed through this morning.
Gusty northwest winds will lead to continued critical fire
weather conditions through this evening.

High pressure builds over the area Saturday. RH values will have a
modest recovery, especially up north where high temperatures will
generally only be in the low to mid 80s, and a couple of
locations in the far northeast may struggle to reach 80 degrees.
Winds will continue to be an issue Saturday, especially in the
east as the Canadian upper low starts to turn southeast in the
general direction of the Great Lakes. As RH values will continue
to be low in the south and with the strong and gusty winds east,
critical fire weather conditions will persist through some areas
of northeast Montana Saturday. Stronger winds currently look to
remain slightly east of Fort Peck Lake Saturday, so will hold off
issuing any kind of advisory to see if that continues to be the
case with the later model output overnight. Hickford

.LONG TERM...Sun night through Fri...
Saturday night an upper level ridge axis will be positioned over
the Northern Rockies resulting in a dry northwest flow aloft over
Northeast Montana. The ridge will work its way over the local area
Sunday. Increased heights will warm temperatures into the upper
80s to mid 90s.

Sunday night/Monday a stacked, low moves east across the prairie
provinces sending a cold front through the local area. Although,
not certain, this may initiate rain showers and thunderstorms. Due
to continued low RHs, nw wind accompanying the front could bring
about critical fire wx conditions.

Tuesday, another ridge follows in advance of the next chance for a
storm system, which could arrive Tuesday night or Wednesday. The
southwest flow associated with this system taps into the ocean
waters off the coast of California. This additional moisture
could lead to wetting rains for the region through Wednesday
evening, along with thunder.

Models suggest another ridge for Thursday followed by another
front around Friday night for more precipitation.

Used Forecast Builder to update Saturday night through Monday
grids with 12Z Guidance.

Templer

Previous discussion -
Synoptic Setup: Long range begins with hot high pressure over the
western half of the CONUS and centered over central Nevada. A
ridge runs north out of this through eastern Wyoming, central
Montana, and southern Alberta. A closed low has moves over British
Columbia and begun to defuse. Farther west another low/trough is
forming south of the Aleutians.

Saturday night through Sunday: As the ridge moves across
conditions will be stable and dry. Meanwhile, the trough will step
off the front range over central Alberta.

Sunday night through Monday night: Trough will begin to spin up a
lo pressure center and latch onto some cooler air from northwest
territories and drag it through the area Sunday evening. The cold
front could spark up a few showers over northeast Montana as it
passes through on Monday morning/afternoon. Afterword max Highs
should be much cooler.

Tuesday through Wednesday night: These periods mark a rebound in
the ridge to the west and increase in temperatures. COnfidence
also begins to drop off from here onward.

Thursday onward: Models become out of phase from this point
onward. flow becomes zonal to southwestern which hints toward a
better chance for rain showers. Confidence is low however.

GAH


&&

.AVIATION...
FLIGHT CAT: VFR.

SYNOPSIS: Behind a cold front that passed through this morning,
stable and dry air will persist through the TAF period.
WIND: northwest at 15 to 20 kts sustained gusting to 30 kts into
this evening, calming to roughly 10 kts overnight. Northwest winds
will increase by 15Z Saturday morning to a sustained 10 to 20
kts, with gusts potentially up to 25 kts.

Hickford


&&

.FIRE WEATHER...

Critical fire weather conditions are expected across the region
through this evening, and across portions of northeast Montana
Saturday.

As an upper low moves across Canada, gusty northwest winds will be
an issue through this evening. Low temperatures tonight will be
in the mid 50s to mid 60s and modest recovery of RH is expected,
especially across the northern areas. Low relative humidity and
the gusty winds will keep fire weather conditions at critical
levels and a Red Flag Warning remains in effect through 9 PM MDT
this evening.

The dry northwesterly flow will continue into Saturday. Winds are
expected to be weaker, leading to potentially only locally
critical conditions. With the expected gusty winds across the east
and low relative humidities across the south, a Red Flag Warning
is in effect Saturday for southeastern portions of northeast
Montana, specifically Fire Weather Zone 122.


&&

.GLASGOW WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until 9 PM MDT this evening for MTZ120-134>137.

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 Saturday for MTZ122.

&&

$$

weather.gov/glasgow


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