Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 261625
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
1025 AM MDT Wed Apr 26 2017

.UPDATE...

Areas of snow showers currently moving eastward through
Stillwater and northern Carbon counties this morning. Saw some
brief reduced visibility with these cells but no accumulations on
roadways as temperatures are already climbing into the upper 30s.
Could see a brief snow/rain shower in Billings before noon time.
Line of showers should develop from Big Timber to Harlowton this
afternoon and push east into the central Plains by early evening.
Isolated thunder is possible with these cells. Adjusted high
temperatures down a couple degrees to account for additional cloud
cover so far this morning, in general upper 40s to low 50s
expected today. Walsh

&&

.SHORT TERM...valid for Tdy and Thu...

One strong system has exited the area to the east and today will
be a much quieter day of weather. Things will turn active again
Thursday and Friday as the next system moves in.

For today, flow gradually backs as strong jet energy invades the
west coast and dives toward the Great Basin. Will see scattered
showers form this morning over the west and then become more
numerous this afternoon as stronger energy works in along with
increasing upper divergence. Have raised PoPs for western zones a
bit for this afternoon and evening. The Beartooth/Absarokas will
get another shot of precipitation, but does not look as heavy as
the last event.

Energy continues to dive south tonight and a trough carves out
for Thursday and Thursday night over the central and southern
Rockies. Models were taking a northern piece of energy and cutting
it off over northern Wyoming Thursday and Thursday night for
dynamic forcing. An inverted surface trough works through Sheridan
county and up in south central zones of southern Montana for
convergence. Will see showers increase in coverage and intensity
Thursday afternoon and night over western and central zones,
working into northern Wyoming. Models were hitting the Bighorns
hard again with over an inch of QPF beginning Thursday afternoon.
Will issue a Winter Storm Watch for the Bighorns for Thursday
afternoon through Friday evening.

This system does look warmer than the last one, but 850mb
temperatures were inching colder with each passing model run.
Current progs have 850mb temperatures falling to around 1c
Thursday night. QPF over southern Big Horn county and Sheridan
county Wyoming was close to an inch for Thursday afternoon through
Friday night. Some of this may turn to snow late Thursday night
and continue early Friday. Have raised PoPs and included some snow
accumulation in Sheridan county, to get the ball rolling. Will
have to monitor closely for another potential highlight there.

Sheridan county picked up upwards of 2 inches of reported rain
from this last event. That amount does not include the water that
remains in snow cover on the ground which will be melting off
today and Thursday. The ground was quite saturated as the water
year for rainfall at Sheridan was around 6 inches above normal.
Runoff seems to be more likely rather than widespread soaking in
of melting snow and additional QPF. Would not be surprised to see
a lot of standing water issues given the amount of precipitation
coming in over the next couple of days. Some of the rivers and
streams were already going up and should continue to do so given
the snow melt and added rainfall. May have some flood concerns,
especially along the foothills with smaller streams and ditches,
over the next several days. Will issue a flood outlook to talk
about that and stress in the HWO. TWH

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

Upper low drops south on Friday, which should help turn winds more
northeasterly and produce upslope flow. This continues a
precipitation event that begins Thursday with favored areas for
precipitation in an inverted surface trough that lays across the
central zones. Models are beginning to increase the precipitation
on the east side of the Bighorns and trending with cooler surface
temperatures. Expect another significant amount of precipitation
to fall especially for Sheridan County and possibly could see some
snowfall. Will have to watch for another winter event but like
the event at the beginning of this week expect the area of impact
to be highly focused. Precipitation should taper to more scattered
showers from north to south Friday afternoon into the evening as
system moves southward. Will continue to be very cold for late
April.

Rest of the extended forecast will feature northwesterly flow
aloft as the Friday system ejects but looks drier with slightly
warmer temperatures. Do not expect more significant precipitation
under this regime but showers will be present during diurnal
heating and breezy afternoons. Somewhat greater chance of showers
late Monday as models bring shortwave trough southeast over the
area. More typical of an April weather pattern than the previous
heavy precipitation events. RMS/TWH

&&

.AVIATION...

Most of the region will see MVFR conditions until early afternoon
when slight improvement is possible. Lower stratus will impact
KSHR where IFR is likely until mid afternoon. Snow shower
activity west of and including will decrease around noon with
shower activity redeveloping this afternoon. Expect decreasing
ceilings overnight. borsum

&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Thu     Fri     Sat     Sun     Mon     Tue
-------------------------------------------------------
BIL 052 037/047 034/047 035/053 036/060 041/057 039/056
    5/R 57/R    76/W    42/W    11/B    33/W    33/W
LVM 051 033/048 030/046 028/053 032/057 036/055 034/055
    6/T 76/O    57/W    42/W    13/W    33/W    33/W
HDN 054 037/047 036/048 035/054 035/061 040/059 038/058
    2/W 37/R    76/W    32/W    11/B    33/W    34/W
MLS 053 033/054 034/052 036/056 036/061 041/060 040/057
    1/B 12/O    43/W    22/W    11/U    33/W    33/W
4BQ 049 029/050 033/047 032/052 031/058 039/058 038/055
    1/B 13/O    54/W    32/W    11/U    33/W    24/W
BHK 048 026/053 028/051 031/054 031/059 037/057 035/055
    1/B 11/B    22/W    11/E    11/U    33/W    13/W
SHR 048 032/043 031/042 030/045 028/054 036/054 036/052
    2/W 48/O    87/W    42/W    11/B    34/W    34/W

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...None.
WY...Winter Storm Watch in effect from Thursday morning through
      Friday evening FOR ZONE 98.

&&

$$
weather.gov/billings


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