Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 211008
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
408 AM MDT Tue Mar 21 2017

.DISCUSSION...

Today through Thursday...The main challenges over the next few days
are the potential for a light wintry mix tonight along the Hiline,
the potential of accumulating snow along the MT/ID border, and
flooding concerns. For the latest flooding information, see the
Hydrology section below.

Showers this morning associated with the stationary front draped
across SW MT will gradually diminish as the best lift/moisture
shifts east of the local area. In the wake of the showers, patchy
fog (dense in a few spots) is likely this morning across parts of
SW MT where most of the precip fell yesterday and where low level
moisture lingers. The front will begin to move north as a warm
front later today as another shortwave approaches from the SW.
Lift with the wave isn`t overly impressive, but should be enough
to allow areas of light precip to develop from SW to NE later
today through tonight. Along the Hiline, temperatures may fall
near/just below freezing late tonight allowing a brief window of
opportunity for a wintry mix. The amount of warm air aloft moving
in makes the temp forecast tonight tricky and the models vary
quite a bit on just how cold it will get. Overall, confidence is
low to moderate on wintry precip from Cut Bank to Havre tonight.
Regardless, impacts look very minimal, if any at all, given the
short duration and ground/road temps only hovering around 32
degrees.

A dry and breezy westerly flow develops in the wake of tonight`s
system with precip decreasing at lower elevations (but still
lingering in the mountains). Late Wednesday night into Thursday,
there is the potential that parts of far SW MT (ie. in and around
the W. Yellowstone area) will get clipped by a strong storm system
moving through the central Rockies. I upped pops during this time
given the better model agreement. However, the highest
precip/snow amounts looks to stay east of the local area, but it
bears watching. Right now, only thinking light accumulations of
snow in that area with only minor impacts. Martin

Thursday night through Tuesday...An upper level ridge of high
pressure will build over the region for Thursday night and Friday.
Thus expect mostly dry conditions away from the Rocky Mountain
Front, along with comfortable spring time temperatures on Friday.
For the rest of the extended, the GFS/EC models differ on
timing/location of precipitation events. The GFS is wetter Saturday
afternoon through Sunday, while the EC is wetter Monday
afternoon/night. Thus confidence is low for now in terms of how wet
this weekend will be, especially across Southwest MT. By early next
week, both models bring in enough cold air, that snow could mix in
at all elevations from time to time, but especially at night/early
in the morning. Overall temperatures will be the warmest/well above
normal on Friday, then gradually cool to near/slightly above
seasonal normals over the weekend and into early next week. Brusda

&&

.AVIATION...
Updated 0452z.

-SHRA activity over southwest MT will keep cigs VFR to MVFR with
occasional IFR in sheltered valleys overnight. Expect mountain
obscuration during this time as well. Cigs rise to VFR by 18z
Tuesday most locations. However, upslope easterly flow on the
Plains will help reduce cigs mainly after 00z as the next system
approaches. Cassell

&&

.HYDROLOGY...
400 AM Update.

We will continue with the point flood warnings across Beaverhead,
Hill and Blaine counties this morning. The point forecast
warnings in Blaine county should be able to cover the flooding
impacts, as most problems are occurring on the Lodge and Battle
Creeks, along with the Milk River. River levels in Blaine County
have all shown a slow decrease over the past 24 hours, but it will
take a little more time to get all the water through the system.

In Beaverhead County, an ice jam is causing flooding problems on the
Big Hole River between Dewey and Wise River. This is a very
unpredictable problem/impact, and additional highlights might be
needed for this river later today.

A side from the potential of additional ice jams on rivers, no other
flooding impacts are expected at this time. Brusda

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  53  37  64  36 /  20  50  30  10
CTB  46  31  56  32 /  40  70  30   0
HLN  54  37  62  36 /  30  40  30  10
BZN  51  37  61  34 /  30  40  30  10
WEY  45  32  45  28 /  30  70  60  40
DLN  54  35  57  33 /  30  50  30  10
HVR  46  32  61  34 /  20  40  30  10
LWT  45  35  61  35 /  20  40  20  10

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Flood Warning until further notice for the Milk River near Harlem.

Flood Warning until further notice for the Big Hole River in the
vicinity of Wise River in northern Beaverhead County.

Flood Warning until further notice for Lodge Creek near Havre.

Flood Warning until further notice for Battle Creek near Chinook.

&&

$$

weather.gov/greatfalls



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