Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 262059

Area Forecast Discussion
National Weather Service Great Falls MT
259 PM MDT Wed Oct 26 2016


Tonight through Friday...The upper level high pressure ridge will
continue to build over Montana overnight, as a weak warm front
moves north through Southwest and North Central Montana. Clouds
will decrease somewhat over Southwest Montana, but breezy
southerly winds will help keep the area quite mild. Any
precipitation should remain over the Northwest Montana mountains.
Mid level winds will become fairly strong (45 to 55 kt) along the
Rocky Mountain Front as well later tonight into Thursday, which
could cause gusts in the 40 to 60 mph range there. Am not
expecting high wind criteria winds from this. Winds will also be
breezy over the plains. Overall, temperatures will warm to between
10 and 15 degrees above normal, with some areas possibly reaching
70 degrees for a high on Thursday. The upper level trough off the
Pacific Northwest coast will gradually move onshore Thursday into
Thursday night. Energy and Pacific moisture in the southwest flow
aloft will bring showers to the mountains of Western and Southwest
Montana during this time, and a few showers may move onto the
plains Thursday night. The focus of the moisture and energy will
shift mostly into Southwest Montana for Friday, as a passing
shortwave trough makes the flow aloft more westerly. A weak
Canadian cold front will also move south across North Central
Montana, shifting winds more northerly there. The combination of
the cooler air in the north and the showers in the south will cool
temperatures closer to normal.

Friday Night through Wednesday...A rather unusual pattern evolves
over the region Friday night and Saturday. While heights rise
with an amplifying ridge over the Canadian Rockies, a shortwave
trough lifts through the Great Basin and cuts under the ridge
through Southwest Montana. Model solutions have reached a general
consensus on this feature, so have raised to categorical POPs
Friday night for the southwest, with only slight-chance for the
North-central plains. Rainfall amounts range from around one-
quarter inch in the southwest valleys to near one inch over the
southwest mountains. Snow levels remain above around 8000 feet,
with a few inches of snow possible on the higher summits and no
snow-related impacts on area roads. This wave clears to the east
by Saturday afternoon, with mostly cloudy but generally dry and
mild conditions prevailing through Sunday. The next weather
system crosses Oregon and Idaho Sunday night, producing periods
or rain over our forecast area early Monday. This is a broad and
disorganized system, so will seek to refine timing and spatial
coverage of rainfall with subsequent forecast updates. Although
cooler with seasonal temperatures, the westerly flow pattern
remains relatively mild so do not anticipate winter weather
impacts. Weak ridging, or at least a confluent flow aloft
produces generally drier and mild conditions Tuesday and
Wednesday. PN


.AVIATION...Updated 1715Z.

Weak upper-level trough and accompanying scattered areas of -RA
that moved through central MT this morning are now east of
KHVR/KLWT. Moist westerly flow aloft continues through today,
with widespread mid-level ceilings (generally 7000-12000 ft)
expected through mid- evening, then gradually increasing above
15000 ft tonight. Can`t rule out a few very isolated -SHRA with
all the cloud cover, but probabilities of that at local terminals
too low to include in any local TAFs. Waranauskas


GTF  51  68  42  54 /  10  10  20  10
CTB  43  61  35  50 /  10  10  20  10
HLN  46  68  39  56 /  10  10  20  20
BZN  45  69  43  56 /  10  10  20  30
WEY  33  57  35  49 /  10  10  30  60
DLN  43  65  41  55 /  10  10  20  40
HVR  46  66  39  52 /  10  10  20  10
LWT  50  67  41  52 /  10  10  20  20



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