Area Forecast Discussion
Issued by NWS Great Falls, MT

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS65 KTFX 091744
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1044 AM MST Fri Dec 9 2016

.UPDATE AVIATION...


&&

.DISCUSSION...

Band of light snow in warm advection aloft continues to gradually
lift north across north central MT this morning with a gradual
diminishing trend expected to continue though early this afternoon
as the associated lifting mechanism weakens. Snow has already
diminished across southern portions of central and SW MT. Next
round of Pacific moisture to overrun the cold airmass is already
seen in satellite imagery this morning moving into ID with radar
showing widespread precip over SW ID and SE Oregon in association
with this feature. Next period of more widespread light snow is
still on track to move into SW MT late this afternoon and
gradually spread to the North and East tonight through Saturday
morning. Hoenisch

&&

.AVIATION...Updated 1800Z.

An initial band of light snow will begin to diminish across north
central MT this afternoon...however...could still bring light snow
and brief MVFR/IFR to site in a line from KCTB to KGTF to KLWT and
north. Elsewhere will see the return of VFR conditions this
afternoon...with some MVFR cloud decks possible at times. A second
disturbance will bring snow across the south this evening...then
spread north and eastward overnight tonight into Saturday morning.
Snow from this disturbance could also provide prevailing MVFR to
IFR conditions at times during this time frame. Surface winds
remaining generally less than 10 kts across the region through
tonight and tomorrow. With low clouds and light snow...mountain
obscuration is also expected for much of the forecast period. Anglin

&&

.PREV DISCUSSION...
/ISSUED 436 AM MST Fri Dec 9 2016/

Today through Sunday...Gentle lift associated with weak warm
advection over southwest/central Montana has produced a band of
light snowfall across the middle portion of our forecast area.
This area of snow is expected to dissipate while moving north
into at least southern portions of North-central MT. In general
only a trace to 0.01 inches of liquid equivalent precipitation is
expected, but with high snow ratios could produce a few tenths to
one-half inch of new snow today. Temperatures are expected to
warm into the upper 20s today for southwest valleys, but the
Arctic airmass remains locked in place for north-central MT.
Shortwave ridging aloft moves quickly through the region this
afternoon. A stronger shortwave arrives later tonight. Light snow
is expected once again, developing from southwest to northeast
across the area. The winter weather advisory over SW MT remains in
effect even as snow tapers somewhat this afternoon and then
resumes tonight. A second segment to the winter weather advisory
begins 00Z tonight as snowfall spreads north into central Montana.
Snowfall amounts tonight into Saturday will generally be around 1
inch at lower elevations with 2-4 inches in the mountains. Areas
of snow continue through Saturday before ending Saturday night. A
new surge of Arctic air pushes into Montana Sunday morning as
mountain snowfall continues. PN

Sunday night through Friday...Northwest flow aloft over the Northern
Rockies will bring a continuing chance for snow Sunday night.
Another Canadian cold front pushes southward through North Central
Montana by Monday morning with high temperatures expected to drop
back into the single digits above zero while Southwest Montana
remains in the 20s. By Tuesday, a deep upper level closed low is
expected to be centered over central Manitoba with continued
northerly flow aloft continuing to push the surface cold front
through Southwest Montana along with areas of light snow and gusty
northerly winds. The closed low gradually drifts eastward across
Canada with flow over Montana becoming northwesterly once again and
allowing a very slight moderation in temperatures and slightly drier
conditions for Wednesday and Thursday. Medium range model consensus
falls apart late in the week but indications point toward another
surge of colder air and snow so have trended the forecast in this
direction. mpj

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  -1  -3  15  10 / 100  50  40  10
CTB  -3  -8   6  -2 / 100  40  20  10
HLN  12   9  34  15 /  70  70  20  10
BZN  23  18  35  15 /  50  70  20  30
WEY  25  18  31   7 /  80 100  40  40
DLN  29  21  36  15 /  50  50  20  30
HVR   1  -4   5  -5 /  80  50  40  20
LWT   5   0  23   8 / 100  60  40  20

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from 5 PM this afternoon to 5 PM MST
Saturday Broadwater...Cascade...Central and Southern Lewis and
Clark...Fergus...Jefferson...Judith Basin...Meagher.

Winter Weather Advisory until 5 PM MST Saturday Beaverhead...
Gallatin...Madison.

&&

$$

weather.gov/greatfalls



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.