Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 240005

Area Forecast Discussion
National Weather Service Great Falls MT
505 PM MST Thu Feb 23 2017

Aviation Section Updated


Tonight through Saturday...Disturbances to our south will continue
an unsettled weather pattern through much of the short term
period. A developing upper low in WY is currently bringing moist
easterly flow to the region...providing abundant cloud cover and
scattered snow showers through this evening. A sfc low then looks
to develop in southern ID sending an inverted trough across the
region...with more moisture...and scattered snow showers. This
setup lingers through Friday...continuing more periods of snow for
much of the CWA...with the best chances coming across the south.
Some periods of moderate snow will be possible in the
south...however...confidence is again low to moderate for exact
locations and impacts. Will hold off on advisories for now...but
portions of the south will have to be watched. Meanwhile isolated
to scattered snow showers...under cloudy skies...and below normal
conditions are expected for central and northern portions through
Friday. The mentioned sfc low in ID moves across southern MT
Friday night through Saturday...with a weak shortwave moving out
of Canada on Saturday. This will bring more scattered snow showers
to the region...especially across the south. Again light to
moderate snow looks possible with perhaps a few impacts to area
roads. Confidence is still only moderate as recent snowfall hasn`t
brought to many impacts. Advisories again will just need to be
monitored. Temperatures look to be below normal during the short
term. Most areas will see lows in the teens to single
digits...while highs get in the 20s and 30. Areas with lack of
fresh snow may not as cold as originally thought. Anglin

Saturday Night through Thursday...A series of weather systems will
move through Western Canada and the PacNW Sunday into early next
week. Most of the synoptic forcing with these systems skirts around
our forecast area to the west and south. Temperatures remain below
seasonal averages as we remain on the cold side of the mid-latitude
jet. Although moisture is limited through this period, a combination
of weak instability combined with orographic and minor shortwave
forcing will continue to produce widespread light snow showers
across much of the forecast area. Continued light snow accumulation
should be expected in mountain areas. Temperatures begin to moderate
by mid-week as the Pacific ridge axis flattens somewhat and moves
inland. The second half of the week is likely to be windy, with
temperatures near average and periods of snow continuing mainly
along and west of the Continental Divide. PN



A strong late winter storm system continues to move through the
central Plains at this time. In its wake, a SFC trough extended back
west into ID/WY. A moist, easterly flow to the north of this feature
will keep scattered -SHSN going into this evening, mainly
along/south of KGTF to KLWT line. The scattered nature of the SHSN,
though, makes it difficult to pinpoint the exact timing for most
sites. That said, confidence is higher at KGTF/KLWT over the next
few hours where snow has been reported recently and based on latest
radar imagery. MVFR/low VFR CIGS will likely continue through the
night at all central MT terminals, with slightly higher CIGS
expected across SW MT. However, any SHSN that impacts SW MT
terminals could lead to a brief period of MVFR CIGS. Lastly, some
BR/FG may develop tonight, especially central MT where low level
moisture is expected to be the highest. Given the current
cloudcover, though, confidence in FG development is somewhat lower
for now, but is something we will keep a close eye on through the
night. Martin


GTF  14  29   9  30 /  20  30  20  20
CTB   7  24   5  26 /  20  10  20  10
HLN  15  29  10  30 /  20  30  30  20
BZN  15  28  10  28 /  30  30  30  40
WEY   6  21   3  19 /  50  50  40  40
DLN  11  24   7  24 /  40  40  30  30
HVR  16  31  12  28 /  20  30  20  20
LWT  16  30  13  28 /  20  30  30  30



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