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000
FXUS65 KTFX 110949
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
349 AM MDT Tue Mar 11 2014

.DISCUSSION...

Today through Thursday...Widespread precipitation across Central
and Southwest Montana is rapidly diminishing as the upper wave
digs southward into the central Rockies. Areas of light snow will
likely persist into the morning hours across portions of Southwest
Montana but additional accumulations are expected to be light so
have allowed the winter weather highlights to expire. Areas of fog
and patchy dense freezing fog have been added to central portions
of the forecast area for early this morning but with rapidly
clearing skies and a warming early spring sun, any fog should burn
off by mid-morning. Temperatures are expected to remain relatively
cool today, but Wednesday and Thursday should see afternoon highs
climb back above seasonal averages for most locations. Mostly dry
conditions are expected after areas of snow clear out of the
forecast area later on this morning until isolated mountain snow
showers return to the continental divide on Thursday. Breezy to
windy westerly winds will prevail through the period as well.
Models suggest that the strongest period of winds will be late
Wednesday night and early Thursday morning. However, at this time,
it does not appear that high wind criteria will be met. mpj

Thursday night through Tuesday...Medium range weather models remain
in fair agreement through this weekend with little change from
previous forecasts. However, confidence drops significantly early
next week as ECMWF and GFS models become out of phase and spread
among model ensembles increases. Upper level ridging along the west
coast shifts inland Thursday night and Friday for generally dry
conditions. Friday night and Saturday a more energetic shortwave
moves southeast across the region as the upper ridge retrogrades
back to the west coast and amplifies. This will shift upper level
from to the northwest and bring some cooling to area Saturday along
with  better chance for precipitation, especially Friday night. The
upper ridge then moves back inland and across the Northern Rockies
and MT Sunday for dry and warmer conditions. Model agreement then
degrades Sunday night with a breakdown of the upper level ridge
likely Sunday night into Monday as another Pacific trough moves into
the region. Have weighted pops and temps heavily toward climatology
for Monday and Tuesday due to high spread among models. Hoenisch

&&

.AVIATION...
UPDATED 0445Z.
A weather system will be moving through the area the for the rest of
tonight. Widespread snow will continue to bring visibilities down
throughout the first part of the overnight hours  with the bulk of
the precipitation finished by daybreak.  Clearing conditions and
eventual VFR categories prevailing towards the morning hours and
through the rest of the TAF period. Some lingering showers may
reduce visibilities and ceilings in the morning hours...however none
of these reductions to flight rules are expected to be long lasting.

&&

.HYDROLOGY...
Numerous hydrologic highlights remain in effect for portions of
North Central and Southwest Montana. Run off tonight will be
limited as snow levels fall to around 3500 feet. However...warmer
air will begin to move back into the region by mid week and into
the weekend...increasing the snow melt. Small stream flooding is
likely to continue over a portion of the region for the next
several days. Additionally...even though overnight lows are
expected to fall near/slightly below freezing over the next few
nights...the amount of time the actual temperature will be near/below
freezing will be short lived...and snow melt runoff is likely to
continue through much of the night. Brusda

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  43  27  50  31 /  10   0   0   0
CTB  43  25  48  29 /   0   0   0   0
HLN  44  24  47  25 /  20   0   0   0
BZN  40  17  44  20 /  20   0   0   0
WEY  37   4  39  11 /  50   0   0   0
DLN  39  19  45  21 /  30   0   0   0
HVR  47  24  51  27 /   0   0   0   0
LWT  41  25  48  30 /  10   0   0   0

&&

.TFX WATCHES/WARNINGS/ADVISORIES...

FLOOD WARNING until further notice for Clear Creek near Chinook in
Blaine County.

AREAL FLOOD WARNING until 345 PM MDT Tuesday for Lewis and Clark
County.

AREAL FLOOD ADVISORY until further notice for Fergus, Glacier,
Pondera, Beaverhead, Jefferson, Gallatin Counties.


&&

$$

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