High Wind in Montana, December 11 to 12, 2018

Area Forecast Discussion
National Weather Service Billings MT
315 PM MST Tue Dec 11 2018

.SHORT TERM...valid for Wed and Thu...

Beginning of a very windy multi day period begins tonight as the
leading edge of an energetic jet across the Pacific moves into
western Montana. With cold air already in place over northern
Wyoming and southeast Idaho pressure gradients will tighten as the
Pacific energy causes strong pressure falls over Alberta.
Orientation of the pressure gradient favorable for gap flow winds
tonight through early Wednesday before a cold front causes a
shift in the surface pressure orientation. This cold front will
bring the winds into the plains mainly west of Billings Wednesday
morning which will be augmented by some momentum transfer as 50KT
700mb winds move across the area. This will bring very strong
winds to the US191 corridor from Big Timber through Judith Gap and
have expanded the High Wind Warning to cover this area.

Ahead of the cold front and as a shortwave crosses the area the
mountains will see a period of snowfall as the energy stream
brings increased mid level moisture to the atmosphere. As this
moves across the plains Wednesday shower activity should be more
scattered and downslope will limit some of the moisture from
reaching the ground. Expect mountains to see 4 to 8 inches of snow
tonight and Wednesday especially areas north of Cooke City and
west facing aspects along the Paradise Valley but temperatures are
on the warm side which may limit accumulations.

Wednesday night is a quieter period but reestablishment of high
pressure over southeast Idaho tightens pressure gradients again
with another surge of shortwave energy crossing Canada inducing
leeside pressure falls. Expect gap area winds to again become very
strong Thursday and staying elevated into Friday. Plains winds do
not respond quite as strongly in this period because multiple
pulses of energy keep the leeside trough more anchored than the
Wednesday signature. Main moisture stream is shifted a bit north
so Thursday looks to be drier. Temperatures will continue to run 5
to 10 degrees above normal. borsum

.LONG TERM...valid for Fri...Sat...Sun...Mon...Tue...

Wind pattern continues into the weekend with Great Basin high
pressure trying to become a bit more dominant in the extended
period. One strong piece of energy slides from SW BC into northern
Alberta on Friday and this supports strong winds during the day
but the tail end of this energy may disrupt pressure gradients a
bit Friday night. A very powerful Gulf of Alaska low shifts
towards the coast for Saturday and slowly weakens which causes the
leeside trough to become a developing low pressure system across
Saskatchewan and Manitoba so winds lull Saturday night. Pressure
gradients become a bit better established Sunday into Monday but
energy stream is so active that the leeside trough is more
variable so while it will be a windy period...may not be very
windy. Transition of the jet stream early next week to lay across
the area will maintain the winds for gap flow areas but give more
support for plains to see some windy days.

Otherwise will be a dry pattern with above normal temperatures
with models hinting at some powerful downslope middle of next week
bringing some well above normal temperatures. borsum
&&

.AVIATION...

Southwesterly surface winds will increase through the morning,
with gusts up to 25-30 kts at KLVM by late morning. Winds will
continue to increase, with gusts to 40-55 kts by late this
evening. Areas of rain and snow showers will move into the areas
south of KLVM this evening with mountain obscurations likely.
borsum
&&

.PRELIMINARY POINT TEMP/POPS...

    Wed     Thu     Fri     Sat     Sun     Mon     Tue
-----------------------------------------------------------
BIL 030/044 024/043 028/048 031/048 027/048 030/049 030/049
    22/J    10/N    00/B    11/B    00/U    00/B    00/B
LVM 029/039 023/037 023/045 029/043 024/045 028/045 029/044
    57/W    00/N    00/N    10/N    00/N    01/N    03/W
HDN 025/045 021/044 022/050 026/048 022/048 023/050 024/050
    23/W    10/N    00/U    11/B    00/U    00/B    01/U
MLS 021/041 021/039 023/042 024/043 020/040 020/042 024/043
    24/J    10/U    10/U    11/B    00/U    00/B    00/U
4BQ 021/041 021/039 023/043 026/044 022/042 023/044 024/045
    14/W    10/N    00/U    11/B    00/U    00/B    00/U
BHK 021/040 022/039 024/044 027/043 022/041 023/042 025/043
    14/W    20/N    00/U    00/B    00/U    00/B    00/U
SHR 022/043 017/043 020/050 024/045 021/047 024/049 024/048
    25/W    20/N    00/U    00/B    00/U    00/B    00/U

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...High Wind Warning in effect from 3 AM to 9 PM MST Wednesday
      FOR ZONES 28-41-63.
     High Wind Warning in effect until 5 PM MST Thursday FOR ZONES
      65-66.
WY...None.

&&

weather.gov/billings

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BILLINGS MT
225 PM MST TUE DEC 11 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1120 AM     NON-TSTM WND GST 2 SSW BIG TIMBER        45.81N 109.98W
12/11/2018  M54.00 MPH       SWEET GRASS        MT   AWOS

1250 PM     NON-TSTM WND GST 6 ENE LIVINGSTON        45.70N 110.45W
12/11/2018  M60.00 MPH       PARK               MT   ASOS

&&

CARROTHERS

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE BILLINGS MT
456 PM MST TUE DEC 11 2018

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0200 PM     NON-TSTM WND GST 3 ENE LIVINGSTON        45.69N 110.50W
12/11/2018  M63.00 MPH       PARK               MT   DEPT OF HIGHWAYS

0230 PM     NON-TSTM WND GST 3 ENE LIVINGSTON        45.69N 110.50W
12/11/2018  M62.00 MPH       PARK               MT   DEPT OF HIGHWAYS

&&

VERTZ