Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 011657
AFDBYZ

Area Forecast Discussion...Updated
National Weather Service Billings MT
957 AM MST Wed Mar 1 2017

.UPDATE...

Increased pops across central and eastern areas this morning and
into the afternoon as weak energy slides through the area and some
instability produces isolated to scattered convective showers
ahead of an approaching cold front. Latest IR satellite shows
cooling cloud tops, and hi-res models seem to be picking up on
the shower development as well. A windy day is expected across
much of the area as strong 700 mb jet works over the region and
good lapse rates promotes mixing with strong pressure gradients
at the surface. Have continued the wind highlites. The rest of the
forecast remains on track and the previous forecast discussion
and an updated aviation discussion are below. STP

&&

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

Winds already on the increase over the western zones with Big
Timber and Harlowton weather stations showing gusts between 40 and
50 mph over the last few hours. Extended the High Wind Warning
into Wheatland county on this package. 700 mb jet is punching
into the Beartooth/Absaroka foothills at this hour as an upper-
low transitions eastward across the state. Soundings show steep
lapse rates from Livingston northward to Lewistown which should
allow those strong winds aloft to spread over most of south
central Montana by early afternoon. Wind gusts 40 to 60 mph will
be widespread across most of the foothills and central Plains this
afternoon with the strongest winds expected in the Livingston,
Big Timber, Nye, and Harlowton areas. Temperatures will warm into
the low 40s and given the steep lapse rates cannot rule out
isolated convective showers over the central and eastern Plains
during the afternoon ahead of an approaching cold front.

By, this evening a cold front sags into south central Montana
bringing a narrow band of rain/snow along the frontal axis. Where
exactly this band stalls overnight is uncertain, but 1 to 2
inches of snow looks likely given the qpf amounts in the models.
Held of on issuing any winter highlights this package given the
uncertainty of the frontal position. By late Thursday morning,
snow chances diminish and temperatures warm back into the low 40s
by afternoon. Walsh

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

Models continue to be in very good agreement with regard to the
overall synoptic pattern through about Sunday night before
solutions show some divergence. So confidence is relatively high
through the weekend for temps. However, timing of short wave
impulses in the strong flow aloft may be tricky, and reduces our
confidence in timing periods of precipitation and strong wind
impacts somewhat.

That said, we are looking for some weak ridging Friday with the
potential for strong winds in the usual gap flow locations
(Livingston, Big Timber and Nye). As a matter of fact, we may see
periodic gusts over 50 mph in the gap locations through much of
the weekend. Flow aloft will gradually back to the southwest as
an upper trof takes a position off the W/Pacific NW coast as we
head into the weekend. By Saturday night some Pacific moisture and
weak impulses are progged to track into our region. This should
produce mountain snow showers, but probably mostly just virga over
the plains. However, a stronger short wave ejects across our
region late Sunday and is strong enough to produce widespread
rain/snow showers over our CWA. Once again though, this is where
the models begin to diverge on their solutions. Thus, timing/strength
and exact track of this feature are a bit in question. Will weight
the ECMWF heavier at this point which shows a stronger
progressive wave move through.

We will take a basic blend of solutions past Sunday night as the
ECMWF wants to build a ridge over us, while the GFS has a
persistent NW flow over us which could lead to some fast moving
clippers or instability showers. At any rate, the chance of snow
showers in the high country looks like a good bet through the end
of the extended period. BT

&&

.AVIATION...

VFR conditions will prevail through the morning and afternoon,
though mountain obscurations will increase as snow showers develop
over the high country. We expect areas of snow showers/MVFR to
develop in the eastern sections of our forecast area in the
afternoon as a back door cold front slides westward into the
region. Conditions will deteriorate from east to west then by
evening affecting KBHK, KMLS and KBIL. Strongest wind gusts at all
terminals will be this afternoon followed by a steady weakening
trend through tonight. BT/Dobbs

&&

.PRELIMINARY POINT TEMP/POPS...

    Tdy Thu     Fri     Sat     Sun     Mon     Tue
-------------------------------------------------------
BIL 042 024/041 028/048 033/052 032/049 027/045 031/053
    2/W 54/J    10/B    01/B    12/W    30/B    00/B
LVM 038 025/041 030/047 033/049 031/044 021/037 029/047
    3/W 33/J    20/N    13/W    34/W    32/J    21/N
HDN 043 023/041 026/052 029/054 029/052 025/047 028/055
    3/W 54/W    10/B    01/B    12/W    20/B    00/B
MLS 041 023/038 026/051 030/055 031/052 030/046 028/052
    4/W 32/W    20/B    01/B    11/B    20/N    00/B
4BQ 040 023/039 024/053 029/058 032/057 028/047 028/053
    3/W 52/W    10/B    00/B    11/B    20/B    00/B
BHK 035 017/034 021/048 028/053 030/052 028/043 025/047
    3/J 21/B    20/B    01/B    11/B    30/N    00/B
SHR 040 020/040 021/050 027/053 031/053 025/046 025/054
    2/W 43/J    10/U    00/B    11/B    20/N    00/B

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...High Wind Warning in effect until midnight MST tonight FOR
      ZONES 28-41-63.
     Wind Advisory in effect until midnight MST tonight FOR ZONES
      65-66.
WY...None.

&&

$$
weather.gov/billings



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