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afdbyz

Area forecast discussion
National Weather Service Billings Montana
308 PM MDT Tue Apr 25 2017

Short term...valid for Wed and Thu...

Current satellite imagery depicts an occluded low over
northeastern Wyoming with associated bands of snow extending into
eastern Montana and the western Dakotas. This evening, 700 mb flow
becomes more northerly as this low moves east of our area, and
snow bands deteriorate from west to east. Hi-res models indicate
modest instability ahead of a weak front over central Montana
could pop up a few showers with some isolated thunder from
Livingston to Harlowton. Areas of fog will be a concern again
tonight and tomorrow morning from the foothills of the Bighorn
Mountains through southern Powder River and Carter counties.

A shortwave moves into Idaho by Wednesday afternoon carving an
upper trough down into the Central Plains. Associated height falls
east of the range will produce a slight chance of showers and
thunderstorms mainly from Billings westward into the central
mountains and foothills. As a second shortwave arrives on Thursday
night, the upper trough becomes negatively tilted with an area of
divergence setting up over most of central and eastern Montana.

This will bring more wet weather to the area through Friday.
Expecting most of the area to see rain or snow with this system,
but given the differences in the models it is too soon to
determine where the heaviest band will setup Thursday night
through Friday. 850 temperatures will hover near the freezing mark
on Friday which means rain/snow mix possible for low-land
locations. Bighorn Mountains will continue their recent trend of
snowy weather with several inches of snow expected each day from
thur-Sat. Walsh

Long term...valid for Fri...Sat...sun...Mon...Tue...

Troughiness over the region on Friday begins to see a broad
circulation spin up over eastern Wyoming which amplifies an
upslope flow into the area. This continues a precipitation event
that begins Thursday with favored areas for precipitation in an
inverted surface trough which lays across the central zones.
Models are beginning to increase the precipitation on the east
side of the big horns and trending with colder 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. 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. More typical of an April weather
pattern than the previous heavy precipitation events. Borsum
&&

Aviation...

Low clouds will persist overnight as precipitation decreases.
Patches of fog will develop along northeast Facing Hills and MVFR
conditions are likely most locations until daybreak with kshr
persisting with IFR through most of the night. Improving
conditions expected during the day on Wednesday. Borsum

&&

Preliminary point temp/pops...

Wed Thu Fri Sat sun Mon Tue
-----------------------------------------------------------
bil 032/056 036/048 035/046 034/052 036/059 041/058 039/054
22/r 56/r 66/west 42/west 11/b 33/r 33/r
lvm 030/055 034/048 030/046 027/052 031/056 036/055 033/054
46/T 66/o 57/west 42/west 12/r 33/r 33/r
hdn 030/058 035/050 035/049 034/054 034/061 040/060 039/057
12/r 36/r 65/west 42/west 11/b 33/r 34/r
mls 027/054 033/054 034/052 036/055 035/061 041/060 040/057
11/b 23/r 55/west 31/b 11/u 33/r 33/r
4bq 021/046 028/048 033/047 033/051 031/059 039/059 038/056
11/b 13/o 56/west 42/west 11/u 33/r 34/r
bhk 021/049 026/053 028/051 031/053 031/058 036/058 036/056
11/b 11/b 33/west 12/east 11/u 33/r 33/r
shr 020/049 032/044 031/042 030/047 029/055 036/054 036/052
22/r 46/o 77/west 52/west 11/b 34/r 34/r

&&

Byz watches/warnings/advisories...
Montana...none.
Wyoming...none.

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