High Wind in Montana, March 11, 2019

Area Forecast Discussion
National Weather Service Great Falls MT
814 AM MDT Mon Mar 11 2019

.UPDATE...

Wind gusts at Two Medicine Bridge and Browning have already
exceeded 50 kts this morning. Web cams reveal blowing snow in this
area. The High Wind Warning start time was moved up to present to
bring it into effect with this update. There is evidence of
drifting snow occurring at MacDonald pass, and at other isolated
locations across North-central Montana. Although the snow is
crusted over following the last few days of sunshine, the wind may
be strong enough in some areas to break the crust and get the
snow moving. Clear and calm conditions prevail over Southwest
Montana, which has allowed some very cold temperatures once again.
Most of these valleys will recover well as the shallow
temperature inversions mix out. Forecast grids for winds and
temperatures were updated to better match observed trends.

&&

.SYNOPSIS...

Increasing southwest winds will create areas of blowing and
drifting snow for portions of North-central Montana. Winds will
become strong and gusty along the Rocky Mountain Front and in the
Cut Bank area this afternoon and overnight. Another round of
light snow is expected around midweek.

&&

.AVIATION...
Updated 525 AM MST Mon Mar 11 2019

West-northwest flow aloft will prevail across the region today
through Tuesday morning. Strong downslope winds will prevail along
the Rocky Mountain Front through the forecast period and over the
adjacent plains of north-central Montana. Areas of blowing snow
could reduce visibility at the KCTB terminal at times. However,
widespread VFR conditions are expected to prevail with only
scattered to broken high level clouds anticipated. mpj

&&

.PREV DISCUSSION...
/ISSUED 525 AM MDT Mon Mar 11 2019/

Today through Tuesday morning...Westerly winds along the Rocky
Mountain Front will increase this morning, becoming strong and
gusty, then spreading out over the adjacent plains by early
afternoon. Areas of blowing and drifting snow could cause travel
difficulties so a Winter Weather Advisory will continue into
tonight. Have also issued a High Wind Warning for the Rocky
Mountain Front and the Cut Bank area for this afternoon through
early Tuesday morning. Strong downslope pressure gradients will
fuel these winds so the strongest gusts, possibly as high as 75
mph, will be confined to the immediate Rocky Mountain Front. Gusts
up to 65 are possible in the Cut Bank area, especially overnight
as time-height profiles show 60 knot winds just off the surface.

Tuesday afternoon through Thursday morning...An upper level trough
and associated surface cold front will sweep through the region
with widespread snow expected over the mountains of the
Continental Divide. Periods of light snow will also spread out
over the plains with generally 1 to 3 inches of accumulation
expected, mainly late Tuesday night through early Wednesday
afternoon. Areas of light snow will persist across portions of the
forecast area into Wednesday evening with skies clearing out by
early Thursday.

Thursday afternoon through Monday...The GFS and Canadian model
forecast models are backing off from the dry and warmer solutions
that they were showing for the upcoming weekend into early next
week. However, the (more reliable) ECMWF model continues to show a
strong ridge building along the West Coast and then progressing
inland over the Rocky Mountains by Monday. For now, I have kept
the forecast package for this time period pretty much in-line with
the ECMWF but confidence is no longer as high as it was just 24
hours ago. mpj

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  37  23  37  21 /   0   0  20  40
CTB  36  24  35  19 /   0   0  30  70
HLN  26   9  30  15 /   0   0  20  30
BZN  25 -12  28  11 /   0   0  10  50
WEY  31   0  32  10 /   0   0  10  60
DLN  25   4  26  10 /   0   0  20  60
HVR  33  19  34  19 /   0   0  10  40
LWT  39  18  40  18 /   0   0  10  30

&&

.TFX WATCHES/WARNINGS/ADVISORIES...

High Wind Warning until 6 AM MDT Tuesday Eastern Glacier...
Northern Rocky Mountain Front...Southern Rocky Mountain Front.

Winter Weather Advisory until midnight MDT tonight Cascade...
Eastern Pondera...Eastern Teton...Judith Basin...Southern Rocky
Mountain Front.

Winter Weather Advisory until 6 AM MDT Tuesday Eastern Glacier...
Northern Rocky Mountain Front.

Flood Warning until further notice for the Madison River near Ennis
in Madison County.

Flood Advisory until further notice for the Missouri River in
southwestern Cascade County.

&&

http://www.weather.gov/greatfalls