Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 300317
AFDBYZ

Area Forecast Discussion...Updated
National Weather Service Billings MT
917 PM MDT SUN MAY 29 2016

.UPDATE...
Upper trough over the Pacific Northwest was dropping into Idaho
this evening. Montana has been void of any decent shortwave
activity  to try to trigger convection and was limited with
afternoon dewpoints dropping into the 30s. Dewpoints were
increasing this evening as readings have risen into the 40s. Some
mid level moisture was getting pulled into the southwest flow
ahead of the trough and will lead to an increasing chance of
showers. Surface instability was weak and the forecast area was
covered by quite a bit of cin at the moment. That being said,
there is some mid level instability present that could be enough
to trigger isolated thunder. Convection now getting going from
around Harlowton to Columbus. High resolution models increase
coverage and move the showers over areas just northwest of
Billings through the early overnight hours. The surface cold front
that will race into the area late tonight is just now entering
northwest Montana, so do not expect a frontal passage in Billings
until very late tonight or toward morning. The front will likely
be aided along by the showers to the north. Showers will develop
readily behind the front and have thus raised pops some overnight
for the northern half of the area. Lowered lightning wording some
based on little activity at the present time. TWH

&&

.SHORT TERM...valid for Mon and Tue...

Dry zonal flow across the region becoming more southwesterly as
height falls are beginning to move into the Pacific Northwest.
These falls shift into Montana tomorrow and amplify with a small
but intense upper level low pressure system forming over north
central Montana. This low continues to deepen as it moves into
western North Dakota on Tuesday with heights beginning to surge
upward across western Montana. A strong cold front crosses the
area late tonight into early Monday with below normal temperatures
to start the week. The cold advection associated with this upper
low and the ability to mix down mid level momentum will bring a
couple of blustery days making outdoor activities no fun.

Convection this evening looks to be limited over southeast Montana
as drier air has moved in so an isolated thunderstorm cannot be
ruled out but would only expect a weak storm or two at most. Some
development is possible over the western mountains early this
evening with a better chance towards midnight as a shortwave moves
not the area and downslope surface flows wane.

Cold front arrives around 2 a.m. for Harlowton...5 a.m. for
Billings and 8 a.m. for Sheridan and Miles City. This shifts the
threat for strong thunderstorms east of the area for the daytime
hours on Monday. Monday will see highs in the 60s with northwest
winds and scattered showers though suspect northwest winds will
bring a better chance of moisture for the foothills. Will be cold
enough for snow over Beartooth Highway but amounts will be light.

System progresses pretty fast eastward on Tuesday and have lowered
precipitation chances as dry air looks to slide in on the back
side of the low. Winds also will be strongest during the morning
to midday hours across the western zones with decreasing winds
during the afternoon. Better chance for moisture will be over
southeast Montana as wrap around hits the area with the strongest
winds coming during the mid afternoon as the vertical motion
shifts east and subsidence brings an increase to the winds.
Temperatures will be cool Tuesday and especially Tuesday night as
drier air moves into the area to bring clear skies on top of the
temperatures 15 degrees below normal. borsum

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

Latest runs of the models have continued the trend towards a
warmer and drier solution for the extended. By Wednesday the flow
will become more northwesterly aloft as the ridge begins to build
in. This will lead to downsloping and quickly warming
temperatures. Once the ridge builds into the area, it will remain
in place for the remainder of the forecast. This will lead to much
of the area remaining dry into next weekend, along with
temperatures 5 to 10 degrees above normal.

There will be some lingering trapped moisture underneath the
ridge. While most of the area will stay dry, the moisture and
daytime heating over the mountains will lead to a slight chance or
rain over the mountains. The activity should be confined to the
terrain. Reimer

&&

.AVIATION...

Showers will increase across the area overnight as a cold front
moves into the region. There is the outside chance of a
thunderstorm through 06Z. Expect showers in the KBIL area after
06Z and KMLS around 09Z. The TAFs reflect VCSH through the night
to cover any evening activity followed by the showers expected
with the front. MVFR will occur with the showers. The front should
pass through KLVM by 06Z, KBIL by 09Z and KMLS/KSHR between 12Z
and 15Z Monday. Surface winds will increase from the N and NW
behind the front late tonight through early Monday...with gusts to
30 to 35 kt possible through the day on Monday. Expect
thunderstorms around the KMLS area during Monday, with MVFR/IFR
conditions, otherwise there will be scattered showers. Areas of
mountain obscuration will become more widespread Mon. afternoon.
Arthur

&&

.PRELIMINARY POINT TEMP/POPS...

    Mon     Tue     Wed     Thu     Fri     Sat     Sun
-----------------------------------------------------------
BIL 050/066 044/063 044/073 050/081 054/083 054/083 054/082
    35/T    33/T    11/U    11/B    11/B    11/U    11/U
LVM 043/063 039/063 038/075 046/080 048/082 050/080 050/082
    44/T    22/W    10/U    11/B    11/B    11/U    11/U
HDN 049/068 043/062 041/074 048/083 053/086 055/085 055/084
    34/T    35/T    21/U    11/U    11/B    11/U    11/U
MLS 054/070 048/061 045/072 050/081 057/084 058/085 058/084
    35/T    55/T    21/B    11/U    11/B    11/U    11/U
4BQ 049/071 044/060 043/071 047/081 052/084 055/084 054/084
    24/T    44/T    21/B    11/U    11/B    11/U    11/U
BHK 049/070 043/058 040/068 044/077 051/081 052/081 052/081
    25/T    55/T    31/B    11/U    11/B    11/B    11/U
SHR 046/067 041/060 039/071 045/080 049/083 050/083 051/084
    25/T    34/T    11/U    11/U    11/B    11/U    11/U

&&

.BYZ WATCHES/WARNINGS/ADVISORIES...
MT...None.
WY...None.

&&

$$
weather.gov/billings



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