Area Forecast Discussion
Issued by NWS Great Falls, MT

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FXUS65 KTFX 160531

Area Forecast Discussion
National Weather Service Great Falls MT
1130 PM MDT Sun Oct 15 2017

Updated Aviation Discussion


Only update this evening was to decrease winds over the plains to
better reflect current trends. Post-midnight increase in winds is
still on track. Best chance for widespread strong winds still
appears to be on Tuesday, so will leave High Wind Watch as is.



High pressure at the surface and aloft over the western United
States will maintain windy, warm, and mostly dry conditions
through mid-week before a series of Pacific weather systems move
rapidly east across the region later this week. High winds capable
of producing minor property damage will be possible Tuesday along
the Rocky Mountain Front and adjacent High Plains, with strong
winds across the remainder of the north-central plains of Montana.


Updated 0600Z.

Area remains under a dry and stable westerly flow aloft with VFR
conditions prevailing and just some scattered to to occasionally
broken high level cloud-cover streaming over the Northern Rockies.
Breezy west winds on the plains will increase again Monday afternoon
with gusts 25-35kts across most n-central MT terminals while gusts
35-45 kts continue along and adjacent to the Rocky Mtn Front. Wind
speeds will increase Monday evening across n-central MT with gusts
in excess of 50kts possible along and adjacent to the Rocky Mtn
front by 06z Tuesday. Hoenisch


/ISSUED 600 PM MDT Sun Oct 15 2017/

Tonight through Monday Night...Fast westerly flow with a low-
amplitude wave pattern will persist into mid-week. The result in
sensible weather for north-central and southwest Montana will be
windy and seasonably warm conditions.

Low-amplitude ridging moves through by late this evening,
immediately followed by a low-amplitude disturbance which will push
a weak front across the plains. Nevertheless, this disturbance will
allow for an increase in winds through the night over much of the
plains. Additional low-amplitude ridging again moves across the
region Monday, but with a strong jet streak just to the north and a
critical layer near the top of the Rocky Mountains, expect continued
very strong to low-end high winds with mountain wave activity along
the Rocky Mountain Front.

Tuesday and Tuesday Night...A strong jet stream will accompany a
stronger disturbance in continued low-amplitude flow across the
Pacific Northwest and southwest Canada late Monday through Tuesday.
Meanwhile, a second weaker jet streak will push into central Montana
in association with a weakening upper ridge over the Great Basin.
The two jet streaks will phase over our area Tuesday, with high
winds of 60 to 90 mph capable of producing minor property damage
along the Rocky Mountain Front and possibly out onto the adjacent
plains, mainly west of Interstate 15. Strong wind gusts of 50 to 60
mph may extend across much of the rest of north-central Montana as
well. The bottom line is that Tuesday will be a very windy day
across the region, especially the plains, with potential for some
property damage near and along the Rocky Mountain Front. CC

Wednesday through Sunday...Overall pattern will continue to
suggest well above-normal temperatures to persist through mid-week
with a progressive zonal pattern set up aloft across the state.
Expect a quick moving shortwave trough and surface cold front to
swing through early Wednesday which will likely bump temperatures
down a tad, but not by much with temperatures still generally
remaining above normal during the day on Wednesday. Additionally,
the big story will be continued widespread strong winds which will
likely last even into the overnight hours on Wednesday and into
Thursday. We begin to see a slight transition in the upper air
pattern beginning on Thursday as a stronger longwave trough sets
up across the west coast. With southwesterly unidirectional flow
aloft downstream of the trough, expect downsloping to aid in much
warmer temperatures, as hinted by the latest model trends the past
few days. Otherwise, it will remain dry for most areas through
late Thursday. By Friday, another quick moving, yet stronger cold
front is forecast to push across the state followed by cooler
temperatures. Latest model guidance still suggests showers
increasing in coverage following the frontal passage across the
area late Friday and into early Saturday. Timing on any cooler air
and associated precipitation will need to be watched as we get
into Saturday morning, with the potential for rain and/or snow,
especially across higher elevations of southern Montana. By the
weekend, expect any lingering precipitation to quickly exit
leaving behind periods of sun and clouds with temperatures slowly
moderating into Sunday. KLG


GTF  45  69  48  71 /   0   0   0   0
CTB  42  65  43  65 /   0   0   0   0
HLN  35  68  40  70 /   0   0   0   0
BZN  32  65  35  69 /   0   0   0   0
WEY  21  53  25  54 /   0   0   0   0
DLN  29  62  34  65 /   0   0   0   0
HVR  38  68  43  72 /   0   0   0   0
LWT  39  67  42  71 /   0   0   0   0


High Wind Watch from Tuesday morning through Tuesday evening
Central and Southern Lewis and Clark...Eastern Glacier...Eastern
Pondera...Eastern Teton...Northern Rocky Mountain Front...
Southern Rocky Mountain Front...Toole.


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