Area Forecast Discussion
Issued by NWS Billings, MT

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174
FXUS65 KBYZ 262111
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
311 PM MDT Wed Apr 26 2017

.SHORT TERM...valid for Thu and Fri...

Low clouds have been stubbornly hanging around over most of
northeastern Wyoming and eastern Montana. Had to adjust afternoon
high temperatures down several more degrees on this update given
the persistent cloud deck. A batch of rain/snow showers moved
through Billings late this morning bringing around 0.10 inches of
liquid.

A line of showers and isolated thunderstorms has developed from
Nye northward to Harlowton which is pushing into the central
Plains. Troughing begins to develop east of the Divide this
evening as an upper-level shortwave digs into Idaho.

Surface low begins to develop over southeastern Wyoming with a
trough axis northward through the Bighorns and into south central
Montana. Isentropic lift begins to generate the highest qpf area
from Sheridan County northwestward through Yellowstone county by
Thursday afternoon. This trough axis will remain quasi-stationary
through Friday morning. Then it will begin to push southwestward
toward the Beartooth/Absaroka foothills by Friday afternoon.

Models have trended cooler with this system particularly over
northern Wyoming with a rain to snow transition in Sheridan
expected some time on Thursday. This significantly increases the
expected snowfall accumulations for Sheridan and southern Big Horn
County. With this update, I have added those areas to the current
Winter Storm Watch for Thur-Fri. Expecting 6-10 inches of
snowfall for foothills and areas west of Interstate 90, with 4-6
inches in eastern portions of those counties. Still expecting
Bighorn Mountain locations to see 12 to 18 inches of snowfall
accumulation through Friday. Still some uncertainty whether enough
snow will occur in lower-elevations to warrant any advisories, so
I will let the next shifts take a look at that. Walsh


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

Building heights over the area on Saturday as energy near the 4
corners region begins to shift east. This will begin to dry out
the airmass and surface high pressure will be in place to limit
mixing but clearer skies will begin a warmup. Flow regime for
Sunday through Tuesday will be northwesterly with disturbances
bringing showers and temperatures closer to seasonal normals.
Tuesday disturbance is accompanied with a bit more upslope which
allows for better precipitation amounts but nothing significant
compared recent events.

Another pattern shift for Wednesday as a broader ridge shapes up
over the western US while northerly flow still keeps temperatures
cool over Montana and Wyoming, it does however trend drier with a
few diurnal showers due to high soil moistures. The ridge begins
to shift eastward towards the weekend which could bring a round of
above normal temperatures. borsum


&&

.AVIATION...

Areas of low clouds will persist over southeast Montana and for
northern Wyoming including KSHR producing MVFR conditions.
Scattered showers will move across the western and central
sections of the region this evening impacting KLVM and KBIL before
dissipating this evening. Another round of showers and increasing
cloud cover will move into the area later tonight increasing
coverage of MVFR ceilings and causing mountain obscurations.
borsum

&&

.PRELIMINARY POINT TEMP/POPS...

    Thu     Fri     Sat     Sun     Mon     Tue     Wed
-----------------------------------------------------------
BIL 036/047 033/045 034/053 036/059 040/056 039/055 038/060
    68/O    86/O    42/W    11/B    33/W    33/W    32/W
LVM 032/047 030/045 026/053 033/057 036/054 033/053 033/057
    76/O    47/O    42/W    13/W    33/W    33/W    32/W
HDN 035/048 034/049 033/056 035/061 039/058 039/057 038/061
    38/R    86/O    32/W    11/B    33/W    34/W    32/W
MLS 034/057 034/055 034/058 036/061 041/059 039/057 039/060
    12/R    33/O    21/B    11/U    33/W    13/W    22/W
4BQ 031/053 032/051 033/056 031/059 039/057 038/055 036/059
    12/O    44/O    21/E    11/U    33/W    24/W    22/W
BHK 025/054 028/052 030/056 030/059 037/056 035/054 035/057
    11/B    11/E    11/E    11/U    33/W    13/W    21/B
SHR 032/043 030/042 028/047 029/054 036/052 035/051 035/055
    38/O    87/O    42/W    11/B    33/W    34/W    32/W

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...Winter Storm Watch in effect from Thursday morning through
      Friday evening FOR ZONE 38.
WY...Winter Storm Watch in effect from Thursday morning through
      Friday evening FOR ZONES 98-99.

&&

$$
weather.gov/billings



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