Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 281228
AFDBYZ

Area Forecast Discussion
National Weather Service Billings MT
628 AM MDT Tue Mar 28 2017

.UPDATE...
Area of rain continues to shift east early this morning, and now
includes Sheridan, where pcpn began in the last hour. Billings
will see rain for a little longer, but drying is just to our west
in Stillwater and Golden Valley Counties. Have adjusted pops per
current trends. Antelope Butte web cam in the Bighorns has shown
snowfall for the past couple hours, and Dome Lake snotel shows a
couple inches of accumulation so far. Expect moderate snowfall
over the Bighorns thru the morning hours. JKL

&&

.SHORT TERM...valid for Tdy and Wed...

Water vapor imagery shows an elongated trof over the intermountain
west, with a low cut off over AZ, and a northern portion over
central MT associated with diffluent flow and pcpn over our
western cwa. Convergent mid level flow has allowed rainfall to
overachieve at Billings, with around a third of an inch as of 3
am. Temperatures at Red Lodge are in the low-mid 30s, so a mix
with wet snow is likely occurring, but with only a few hours of
precipitation left will not see much if any accumulation at that
elevation. Looking to the east, its been a dry night so far. The
combination of a mid level low lifting out of eastern WY, and
ascent from central MT trof shifting east, will result in an
eastward shift of the precipitation today especially for our
upslope areas and far southeast MT. The Bighorns have received
virtually no snow so far, but convergent mid level flow should
allow snow to develop and become moderate to heavy for a time
later this morning, keeping in mind mid level lapse rates remain
steep at about 7C/km. Will let the winter wx advisory for the
Bighorns continue, but have shaved snowfall totals a few inches,
to something on the order of 4-6 inches today. Travel on Hwy 14
thru Burgess Jct will be impacted. Drying can be expected from
west to east today as subsidence works in, and by this evening,
focus of precipitation will be along inverted trof over far SE MT.
Showers in our east will taper off late tonight as this slow-
moving system finally departs our region.

Flat upper level ridging along with downslope surface winds will
produce dry/mild conditions for Wednesday. Next approaching
Pacific trof will bring a chance of snow to our western mountains
by late Wednesday night.

Temps will be cooler today with highs in the upper 40s and 50s,
coolest down toward Sheridan. After a cool start, western areas
will warm to the 50s today with decreasing clouds and a little
west wind. Wednesday should see temps back to the lower/mid 60s
most areas.

JKL

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

The main forecast issue in the extended remains the period of rain
and snow Thursday into Friday. While the general pattern of a
trough moving across the western US with a cut-off low digging
into the Great Basin is the same in both the GFS and the ECMWF,
there continues to be significant differences in the weather for
Montana. The ECMWF is still offering a lower QPF solution with the
low farther to the southwest. This solution would not produce any
impacts for the area. The GFS solution is wetter, with the
ensemble mean remaining near a half inch for Billings. This
produces much high QPF, especially in the upslope areas.

Given the inter-model differences, have generally gone with the
previous PoPs. QPF remains just over a half inch over the plains
and three-quarter of an inch to near an inch in the foothills and
mountains. Temperatures will still be cold enough to get some
significant accumulations in the mountains.

Models are consistent with drying things out late Friday and
keeping things dry for Saturday. Models remain highly variable
with the timing of the next trough moving in early next week. For
now have gone with some broad brush chance PoPs for the end of the
extended. Reimer

&&

.AVIATION...

Showers will continue across southern Montana this morning. These
will produce MVFR conditions mainly around KBIL through 18z. A
rain snow mix is possible around KSHR this morning, along with
mountain obscurations. VFR conditions expected at the rest of the
terminals. Conditions will improve from west to east through the
afternoon. Reimer

&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Wed     Thu     Fri     Sat     Sun     Mon
-------------------------------------------------------
BIL 056 036/063 043/061 042/051 033/058 039/060 038/059
    8/W 00/B    13/R    55/R    21/U    11/B    12/W
LVM 054 029/060 040/052 035/049 029/058 035/059 034/058
    2/J 01/N    25/R    54/O    21/U    11/B    22/W
HDN 055 032/064 038/064 040/053 032/058 035/062 036/062
    9/W 10/B    12/R    55/R    31/B    11/B    12/W
MLS 056 036/064 040/064 044/054 035/058 039/062 039/064
    5/W 30/B    11/E    46/R    31/B    11/B    12/W
4BQ 050 035/062 039/065 042/052 035/056 037/061 038/063
    6/W 60/U    01/B    46/R    51/B    10/B    12/W
BHK 055 036/062 037/065 040/053 034/055 035/059 036/060
    5/W 60/B    01/E    46/R    41/B    10/B    12/W
SHR 047 030/059 034/060 038/049 032/054 034/059 035/060
    +/W 20/B    02/R    66/R    51/B    11/B    12/W

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...None.
WY...Winter Weather Advisory in effect until 9 PM MDT this evening
      FOR ZONE 98.

&&

$$
weather.gov/billings



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