Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 160252

Area Forecast Discussion...Updated
National Weather Service Billings MT
852 PM MDT Thu Mar 15 2018

Made some PoP adjustments for the rest of the night based on radar
trends and the new NAM. Tried to combine GFS/NAM solutions.
Challenging forecast with models not in agreement with QPF, and
NAM trending a bit westward. Given the above, not enough
confidence to support changing the highlights. When 00Z GFS comes
in, perhaps agreement will be better. Kept slight chance of
freezing rain in the SE. As mentioned before, soundings were more
indicative of freezing drizzle, but the decent QPF amounts
supported leaving the slight chance of freezing rain. Any freezing
precipitation will change to all snow late tonight. Friday`s high
PoPs central and E fit the new NAM. No other changes. Arthur


.SHORT TERM...valid for Fri and Sat...

Mainly dry weather continues across the region this afternoon,
but showers are developing in the southwest zones as a shortwave
with upper jet support moves through the region. This will bring
shower potential across the west this evening, with isolated
thunder possible.

Jet shifts north and west, setting up a period of moist and deep
easterly flow across the east. Strong ascent in concert with a
developing deformation zone into southeast MT, will result in rain
and snow across much of the CWA, with greatest amounts in eastern
zones. Snow amounts continues to be a difficult question, as warm
initial temps resulting some snow being lost as rain as well as
sfc melting. That said, still expect a convergence zone,
developing east of Billings, that should see 7 to 9 inches of
fresh wet snow tonight through Friday afternoon. The higher passes
like Lame Deer Divide on 212 and the Hysham Hills on I-94 will
likely see very poor travel conditions on Friday.

Additionally, GFS/NAM and HREF members continue to support
freezing rain potential impacting the area including and east of a
line from Forsyth to Ashland this evening and into the overnight.
Rain will turn to snow later in the night. Furthermore, some
elevated instability is evident on the north side of the surface
low in northeast WY, resulting ina few embedded lightning strikes
this evening. Precip will taper off from south to north Friday
afternoon and evening as a shortwave lifts slowly through the cwa.

Dry conditions will persist into Saturday morning, but upper
level Pacific trof shifts toward the region, bringing southwest
flow into western zones by Saturday afternoon. Wave opens up as it
shifts across the region, through Saturday evening, bringing rain
and snow showers across the region. Best chances appear to be in
western mountains and near plains at this time, but lesser chances
across the plains. AAG

.LONG TERM...valid for Sun...Mon...Tue...Wed...Thu...

Broad upper low will continue to impact the area through Monday
with cool temperatures and a chance for precipitation. Main energy
focus is well away from the area so precipitation will be
generally light. Ridging builds into the area Tuesday through
Thursday with warmer temperatures and dry conditions. Next broad
upper low coming in off the Pacific begins to impact the area on
Friday, and this system could be pretty potent as currently
advertised for next weekend.

Hydrology...Snow melt should slow through the weekend and into
early next week. As temperatures begin to warm on Tuesday any snow
from the weekend will quickly melt bringing an increase in the
threat for overland flooding and ice jam development as the water
works into frozen creeks and streams. Keep up with the latest on
the hydrologic situation at our web site .


Flight conditions will deteriorate across the area later this
evening and overnight as another disturbance moves in from the
south. The poorest flight conditions will be east of Billings
where a mix of rain and freezing rain is expected late this
evening, turning to heavy snow overnight into Friday morning.
Expect IFR to local LIFR conditions by 06z in this area. From
Billings west rain/snow showers and some fog can be expected with
lowering ceilings resulting in MVRF to local IFR conditions.
Mountains will be obscured. Chambers/STP



    Fri     Sat     Sun     Mon     Tue     Wed     Thu
BIL 026/040 024/040 024/038 023/041 024/044 025/047 027/049
    37/O    22/O    52/W    32/W    21/B    11/B    11/B
LVM 027/047 023/045 025/041 024/043 025/046 026/051 027/054
    13/O    13/O    53/W    32/W    21/B    11/B    12/W
HDN 023/039 018/041 020/038 018/040 017/044 018/047 020/049
    79/O    31/B    42/W    32/W    21/B    11/B    01/B
MLS 022/033 017/036 019/034 018/034 015/036 015/040 017/040
    89/S    51/B    32/J    21/E    21/B    11/U    11/B
4BQ 023/034 018/043 023/038 021/037 019/041 019/046 019/050
    9+/S    31/B    22/W    31/E    21/B    11/B    01/B
BHK 021/030 017/038 022/034 020/033 016/035 015/041 018/041
    66/S    41/U    22/J    31/E    21/B    11/B    01/B
SHR 030/040 019/047 024/039 021/041 021/044 020/049 023/051
    87/O    22/R    33/W    22/W    21/B    11/U    01/B


MT...Winter Storm Warning in effect until midnight MDT Friday
      night FOR ZONES 30>32-36-37-58.
     Winter Weather Advisory in effect until midnight MDT Friday
      night FOR ZONE 33.
     Winter Weather Advisory in effect until 7 PM MDT Friday FOR
      ZONES 38-57.
WY...Winter Weather Advisory in effect until 7 PM MDT Friday FOR
      ZONES 98-99.


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