Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 231650
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
950 AM MST Sun Nov 23 2014

.UPDATE...
Mostly quiet today. Lowered POP through the day with weak high
pressure moving over. Expect a chance for precipitation to linger
over Southwest Montana, increasing from the west this evening.

&&

.AVIATION...
UPDATED 1157Z. VFR conditions will prevail for the majority of the
TAF period. Brief intrusions into MVFR due to lowered cloud
ceilings will be possible especially over KBZN and KHLN due to
some instability associated with a weak Pacific Cold front. Winds
will remain breezy today especially near the frontal passage. Suk

&&

.PREV DISCUSSION...
/ISSUED 457 AM MST Sun Nov 23 2014/

Today through Tuesday...Unsettled weather conditions will continue
through the short term period as an active northwesterly flow
aloft remains over the region. Scattered rain and snow showers
over the region will diminish over the next few hours as shortwave
energy pushes through the forecast area. The current batch of
Winter Weather Advisories will be dropped with this mornings
package. However, another push of Pacific moisture will bring
precipitation to the western and central Montana mountains this
afternoon and overnight. Latest models suggest that Marias Pass
and Kings Hill Pass could see 3 to 6 inches of snow during this
period so am issuing another batch of Winter Weather Advisories
for these areas. Precipitation diminishes to scattered showers
again for Monday afternoon and evening but another surge of
moisture coupled with increasing mid and high level winds and a
strengthening down-slope pressure gradient develops early Tuesday
morning. Strong westerly winds can once more be expected along the
Rocky Mountain Front from Glacier Park southward to MacDonald Pass
so have issued a High Wind Watch for these locations from late
Monday evening through early Tuesday afternoon. A surface low
pressure system in southern Alberta will sweep southeastward
through the day on Tuesday allowing northerly winds to develop
across north central Montana during the afternoon. This will
result in a significant surface convergence zone across central
Montana with uplift causing a good likelihood of precipitation.
Precipitation could start off in rain in some locations but
temperatures will likely fall during the afternoon with widespread
snow expected across much of the region by late afternoon. Am
expecting that highlights could be required before all is said and
done with this developing storm system. mpj

Tuesday night through Sunday...Unsettled weather continues into
the long term forecast as a potentially significant precipitation
producing system looks to impact the Thanksgiving weekend.
Unfortunately model confidence remains low due to a high variation
in model solutions. Have once again gone with a blend of model
consensus and then skewed it towards the ECMWF. This solution
keeps temperatures near seasonal values ahead of Thanksgiving, but
with a reinforcing push of cold air temperatures could drop down
below averages and possibly near zero. This solution also has a
potentially significant amount of moisture stream across the
divide and then produce snow showers over much of the region in a
multiple day event. Again there is low confidence in the amount of
or timing of snow over a particular area. Winter weather highlights
may become necessary if models begin to come into agreement about
this solution. Suk

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  40  26  39  28 /   0  20  10  20
CTB  37  25  37  26 /   0  10  10  20
HLN  39  27  38  25 /  10  30  20  30
BZN  34  18  33  15 /  10  40  30  30
WEY  27  10  26   5 /  40  70  40  40
DLN  32  17  31  17 /  10  30  10  20
HVR  37  24  39  24 /   0  30  10  20
LWT  38  26  38  25 /  20  40  30  20

&&

.TFX WATCHES/WARNINGS/ADVISORIES...

HIGH WIND WATCH from Monday evening through Tuesday afternoon
Central and Southern Lewis and Clark...Northern Rocky Mountain
Front...Southern Rocky Mountain Front.

WINTER WEATHER ADVISORY from 4 PM this afternoon to 6 AM MST
Monday For US 89 over Kings Hill Pass.

WINTER WEATHER ADVISORY until 6 AM MST Monday Northern Rocky
Mountain Front.

&&

$$

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