Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 250538
AFDTFX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
1045 PM MST Sat Jan 24 2015

Aviation Section Updated

.UPDATE...Have issued an early update to overnight lows since
temperatures had already fallen below forecast MinT in
northeastern portions of my CWA. However, models continue to
indicate that temperatures will begin to warm towards morning as
gusty west winds pick up once again. mpj

&&

.AVIATION...
UPDATED 0545Z.
A weak upper level disturbance will move southward through the
region during the period. Expect mainly mountain showers over the
Rocky Mountain Front and Southwest MT. The Bozeman/Helena areas are
the best locations at seeing a small chance for a passing shower
thru 10z Sunday. Otherwise...it will mainly be windy...especially
after 15z Sunday over North Central MT. Overall...VFR conditions are
expected over the plains thru the period...with IFR conditions and
mountains obscured over the mountains thru 18z Sunday. Brusda

&&

.PREV DISCUSSION...
/ISSUED 450 PM MST Sat Jan 24 2015/

Tonight through Monday...A strong NW flow aloft persists over the
region tonight through Sunday as an upper level ridge, currently
along the US west coast, gradually moves back onshore then into
the Northern Rockies Sunday night and Monday. Embedded shortwave
and upper level jet energy continues move SE across the region
tonight, producing scattered precipitation mainly in the
mountains, but a few isolated showers cannot be ruled out further
east as well, particularly across central and SW Mt later this
evening. Snow levels will remain around 7500 feet or higher so
little or no snowfall is anticipated at or below pass levels. The
next stronger wave of energy to move over the top of the upper
level ridge moves onto BC tonight and northern AB Sunday. This
system will cause surface pressure gradients and winds aloft to
strengthen again later tonight with strong winds re-developing
along the Rocky Mtn Front by early Sunday morning and persisting
through Sunday afternoon. Very windy conditions are also expected
over much of the North-Central MT plains Sunday afternoon. As the
upper level ridge pushes inland Sunday afternoon any lingering
shower activity over the mtns will end with dry conditions
thereafter through Monday. Temperatures also continue to warm
Sunday and Monday with record max temperatures likely at many
locations Monday afternoon. Hoenisch

Monday Night through Saturday...Not too much change from previous
models runs in the overall pattern shift through this period. An
upper level ridge of high pressure will keep the area dry and warm
through Tuesday, with temperatures on Tuesday reaching near record
highs in the 50s at lower elevations. A shortwave trough from off
the California coast will then move through the central Rockies
Tuesday night, which will drag the jet stream back south out of
Canada and into Montana on Wednesday. The resulting moist westerly
then northwesterly flow aloft will bring an increasing chance of
mainly mountain precipitation to the area for Wednesday through
Thursday. Temperatures will also cool down closer to normal through
this period. The upper level ridge will shift west of the area
during this time as well. The Hudson Bay low will also eject a
shortwave and move it south over central Canada and into the Great
Lakes region, which will shift the flow aloft more northerly over
Montana. This will usher a cold Canadian airmass into the area to
begin the weekend, as highs will mostly be in the teens for Friday
night and highs on Saturday will be in the 20s. The northerly
upslope flow will also bring a good chance of snow to much of the
area. Although there is significant uncertainty on how much snow
could fall during this time and how cold temperatures could get
(leading to possibly very cold wind chills), the situation will be
monitored over the next several days for possible winter weather
highlights.
Coulston

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  40  60  45  63 /  10  10   0   0
CTB  36  57  39  58 /  10  10   0   0
HLN  36  52  34  53 /  40  10   0   0
BZN  29  48  34  54 /  50  10   0   0
WEY  19  38  18  47 /  40  10   0   0
DLN  34  52  37  57 /  20   0   0   0
HVR  30  52  39  55 /  10  10   0   0
LWT  31  57  40  63 /  10  10   0   0

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
HIGH WIND WARNING until 11 PM MST Sunday Eastern Glacier...
Northern Rocky Mountain Front...Southern Rocky Mountain Front...
Toole.

&&

$$

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