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000
FXUS65 KTFX 261135
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
435 AM MST Mon Jan 26 2015

UPDATED AVIATION DISCUSSION

...Near record high temperatures most areas through Tuesday...

.DISCUSSION...

Today through Wednesday...The upper level ridge of high pressure
currently just west of the spine of the Rocky Mountains will move
slowly east over the Rockies through the day on Tuesday. This will
keep the area dry with unseasonably warm temperatures. Today will
be the warmest of the two days, as temperatures will warm to
between 20 and 25 degrees above normal, despite a chinook arch
lingering over north central Montana. As the ridge axis shifts
just east of the area on Tuesday, temperatures will be about 5
degrees cooler than today. However, temperatures both days will be
near record highs. Westerly winds will also be breezy both days.
In fact, winds along the Rocky Mountain Front could reach the 30
to 35 mph range with possible gusts as high as 55 mph, which would
keep it just shy of High Wind criteria. Will therefore not be
issuing a High Wind Warning, but will monitor the situation
closely. A shortwave trough will move across the area Tuesday
night into Wednesday in the wake of the ridge. The greatest energy
and moisture associated with this disturbance will remain over the
Central Rockies, but there should be enough to bring at least
occasional rain and snow to the mountain areas of western and
southwest Montana. Snow levels will fall from around 7000 feet
Tuesday evening to around 6000 feet on Wednesday, which should
keep the best chance for light measurable snow in the mountains.
Am not anticipating a need for winter highlights from this, but
will keep an eye on the situation. This disturbance will generally
cool temperatures another 5 to 10 degrees from Tuesday to
Wednesday, allowing highs to only warm into the 40s on Wednesday
at most lower elevations.  Coulston

Wednesday night through Monday...The main message with the period is
the latest ECMWF model run has flip-flopped with their solution over
the weekend and now has a cooler and wetter pattern than what it
forecast yesterday. The evening run of the GFS sticks with a milder
and drier pattern. Both the ECMWF and GFS model runs bring in colder
air Friday and Friday night. The latest ECMWF model run holds on to
the cold air over the weekend but the evening run of the GFS moves
out the cold air over the weekend. This leads to big temperature
differences between the two models with the ECMWF forecasting
highs mostly in the 20s Saturday and Sunday while the GFS has
highs mostly in the mid 30s to mid 40s. Did not want to jump on
the ECMWF bandwagon due to their flip-flopping so have only gone a
little cooler with forecast highs on Saturday. Did add a slight
chance of snow to the plains for Friday night and Saturday. For
the Wednesday night through Friday time frame went with the
inherited forecast of mostly dry conditions with highs in the mid
30s to mid 40s range. Blank

&&

.AVIATION...
UPDATED 1135Z.
Expect VFR conditions and no precipitation. The only exception to
the VFR conditions is there will be IFR conditions in patchy
freezing fog over the far southwest valleys this morning and there
is a very small threat of MVFR/IFR conditions in freezing fog in the
southwest valleys late tonight. Otherwise expect ceilings at or
above 15000 ft to develop this morning with skies clearing during
the afternoon. Then tonight ceilings at or above 25000 ft will
spread east over the forecast area. Expect gusty southwest winds 25
to 35 kts over the Rocky Mountain Front today with local gusts 45 to
50 kts. These winds will gradually diminish tonight.

&&

.HYDROLOGY...
With warm temperatures expected to continue for at least the next
couple of days, increased snow melt could problems with ponding of
water and rises in smaller creeks and streams across southwest
Montana. In fact, there have already been some reports of snow
melt causing ponding of water in the Helena Valley. This situation
will continue to be monitored for possible flood statements and/or
highlights.

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  62  42  57  34 /   0   0   0  10
CTB  60  38  54  31 /   0   0   0   0
HLN  61  29  54  28 /   0   0   0  20
BZN  55  28  51  27 /   0   0   0  30
WEY  40  19  37  27 /   0   0   0  50
DLN  60  34  54  31 /   0   0   0  30
HVR  55  35  53  30 /   0   0   0  10
LWT  59  37  57  29 /   0   0   0  10

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

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