Area Forecast Discussion
Issued by NWS Great Falls, MT
FXUS65 KTFX 262345
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
545 PM MDT Thu Mar 26 2015
UPDATED AVIATION SECTION
Tonight through Saturday...The forecast area will be under the
influence of a strong upper ridge into Friday night. The upper ridge
which was over the Pacific Northwest Thursday afternoon will move to
western Montana Friday and then to eastern Montana Friday night. The
main weather feature to deal with during the forecast period will be
an upper trough which will move into central Montana Saturday
afternoon or possibly evening. The associated cold front is expected
to reach the continental divide late Friday night then move through
the plains and southwest Montana Saturday morning. Snow levels from
8000 to 9000 feet ahead of the front will fall to between 6000 and
7000 feet behind the front. Snow accumulations up to several inches
are expected in the mountains of the Rocky Mountain Front. For the
plains and valleys expect scattered showers Saturday. Would have
considered going with higher chances of showers but models differ
with details of the upper trough.
High wind watch...Gusty winds are expected with and behind the
cold front Saturday but am not too excited about a high wind
event. Winds aloft are not all that great. In addition winds aloft
could be diminishing when there is maximum daytime heating.
Actually more of a problem with high winds could be over Blaine
County where there will be strong pressure rises behind a Canadian
cold front Saturday afternoon which moves into that area and also
where winds aloft could be possibly as high as 50 knots. At this
time do not have enough confidence to issue a high wind watch but
the situation will need to be monitored. As for the current high
wind watch confidence level for a high wind event is only around
30 percent at this time. Can not rule out a stray wind gust
approaching 50 knots with afternoon showers on Saturday.
Record temperatures...Still expect widespread high temperatures
Friday to be near record levels. However a portion of southwest
Montana and also a few locations in Fergus and Blaine Counties
could also be near record levels Saturday afternoon. Blank
Saturday Night through Thursday...Period begins with high pressure
ridging redeveloping over the northern Rockies. Swaths of moisture
crossing through the top of the ridge will bring scattered cloud
cover, but no precipitation is expected from Sun thru Mon night.
Forecast models continue to indicate arrival of a quick-moving
shortwave trof on Tues that will produce areas of light valley
rain/mtn snow on Tue aftn/eve. Lower elevation sites along the
Rocky Mtn Front and parts of the Hi-Line and southwest MT could
see some rain/snow mix or light snow Tues night as colder air
mixes with waning moisture before the system moves off into
eastern MT. Central and Hi-Line counties could also see a period
of strong, gusty winds on Tues with the trof`s passage, resulting
from both mixing of 60 mph winds aloft and a sufficiently tight
surface pressure gradient. Models are in general agreement that
cool, moist northwest flow aloft will persist during the latter
half of the week with another Pacific shortwave trof coming into
the state on Thurs, accompanied by a mix of light rain/snow.
Mid and high level clouds will continue to move across the area but
as high pressure aloft builds, clouds should decrease after 18z Friday.
Gusty west winds will slowly decrease after 02z but will increase
again after 18z Friday with the strongest gusts along the Rocky
Mountain Front. VFR conditions prevail.
.PRELIMINARY POINT TEMPS/POPS...
GTF 42 72 46 63 / 0 0 0 30
CTB 41 70 45 60 / 0 0 10 50
HLN 40 72 43 61 / 0 0 10 20
BZN 33 71 36 63 / 10 0 0 30
WEY 27 56 33 57 / 10 0 0 40
DLN 38 70 41 61 / 0 0 0 20
HVR 36 73 41 66 / 0 0 0 50
LWT 42 71 46 63 / 10 0 0 40
HIGH WIND WATCH from late Friday night through Saturday evening
Eastern Glacier...Liberty...Northern Rocky Mountain Front...
Southern Rocky Mountain Front...Toole.