Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 240235
AFDBYZ

Area Forecast Discussion...Updated
National Weather Service Billings MT
835 PM MDT Mon Oct 23 2017

.UPDATE...
No significant changes this evening, just tweaked the winds a bit.
Will turn out to be a bit of a chilly night as winds continue to
slacken allowing temps to fall. BT

&&

.SHORT TERM...valid for Tue and Wed...

Stiff northwest flow over the state this afternoon. This combined
with mixing was creating wind gusts to 45 mph over the east, with
30-40 mph winds over western and central zones. Winds will relax
this evening as the gradient weakens, and the strongest mid level
winds shift east.

Heights build tonight and Tuesday and this allows for warmer
temperatures. Winds will be much weaker, but still expecting some
afternoon mixing for breezes. A strong shortwave will drop down
into the northern Rockies/Plains Wednesday afternoon and evening.
This will drive a strong cold front through. This front will have
2+mb an hour surface pressure rises behind it as it moves through.
850mb winds ahead of the front increase to around 40kts.
Afternoon temperatures rise to the lower to mid 70s and humidities
will fall into the teens. All of this point to a critical fire
weather day. Will issue a Fire Weather Watch for Wednesday
afternoon and night.

Expect wind gusts of 40 mph ahead of the front, and 45 to 55 mph
behind it. Winds could be even stronger from Big Timber to
Harlowton to Judith Gap, where mid level winds and gradient were
favorable. Will issue a High Wind Watch for these locations for
Wednesday afternoon and night. May need a highlight for Livingston
and Nye ahead of the front, but this appears to be in the
Advisory category, so will hold off on a High Wind Watch for that
area at this time. TWH

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

Made relatively minor changes to the extended forecast period,
with mainly dry conditions prevailing through the bulk of the
period.

The extended period begins with weather system completing passage
through the region Thursday morning and early afternoon. The
system looks a little later than previously advertised, so POPs
expanded coverage area some, generally slowing exit of the system
out of the region. Expect to see mixed precip across the
region Thursday morning, but little snow accumulation other that
area mountains. An inch or two is possible in high terrain and
foothills regions, including Red Lodge and Story.Strong and gusty
winds will continue behind the front Thursday morning, but should
taper off through the afternoon as the system shifts out of the
area.

Dry northerly flow prevail over the region through Sunday on the
front side of a high amplitude ridge. Temperatures will warm up
again into the 60s on Saturday and Sunday.

Models diverge drastically to end the period. ECMWF continues with
dry northerly flow, while GFS favors fairly strong backdoor cold
front dropping into the area Monday morning. Have trended grids
toward the wetter GFS at this time, with scattered POPs across the
region. Timing of the front at this time points to highs being
reached by late morning, but should see a significant cool off
from the previous couple of days. AAG


&&

.AVIATION...

W to NW surface winds will continue to decrease this evening and
overnight for most locations with some passing high clouds
overhead. Winds will increase along the western foothills and at
KLVM late tonight with wind speeds up to 30 kt possible by
daybreak. VFR will prevail through the period. STP


&&

.PRELIMINARY POINT TEMP/POPS...

    Tue     Wed     Thu     Fri     Sat     Sun     Mon
-----------------------------------------------------------
BIL 035/067 046/073 037/046 028/056 039/065 043/064 037/055
    00/U    00/N    42/W    00/B    00/U    00/U    13/W
LVM 035/067 047/071 033/046 026/058 037/067 040/064 035/055
    00/N    00/N    52/W    00/U    00/U    00/U    12/W
HDN 030/069 038/076 035/047 025/056 032/066 037/065 034/057
    00/U    00/N    42/W    00/B    00/U    00/U    13/W
MLS 031/063 040/073 034/043 021/049 030/060 036/062 033/053
    00/U    00/N    22/J    00/B    01/B    00/U    12/W
4BQ 031/062 039/076 035/043 021/048 031/060 037/063 033/053
    00/U    00/N    23/W    00/B    01/B    00/U    12/W
BHK 029/059 038/070 034/038 020/044 027/055 033/058 032/050
    00/U    00/N    23/W    00/B    01/B    11/U    12/W
SHR 029/065 036/076 034/041 020/051 030/063 035/065 031/055
    00/U    00/U    53/W    00/B    00/U    01/U    12/W

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...High Wind Watch in effect from Wednesday afternoon through
      late Wednesday night FOR ZONES 28-41-63.
     Fire Weather Watch in effect from Wednesday morning through
      Wednesday evening FOR ZONE 117.
     Fire Weather Watch in effect from Wednesday afternoon through
      late Wednesday night FOR ZONES 124>133.
WY...Fire Weather Watch in effect from Wednesday afternoon through
      late Wednesday night FOR ZONE 274.

&&

$$
weather.gov/billings


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