Area Forecast Discussion
Issued by NWS Billings, MT

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FXUS65 KBYZ 190929

Area Forecast Discussion
National Weather Service Billings MT
329 AM MDT Wed Oct 19 2016

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

A weak cold front is slowly oozing into the northeast portion of
the forecast area. The main impact of this cooler air will be some
patchy fog from northern Rosebud county southeast into Carter
county. This front will wash out mid day as an upper level
disturbance moves into the area. This upper level trof is moving
into western zones this morning with associated jet dynamics
working to generate scattered showers. Temperatures are cold
enough for a mix of rain and snow at this time in Livingston with
this activity. Will continue to see this area of showers work
slowly through the area today with a mix of rain and snow early
this morning, becoming all rain by mid morning. Best chance for
showers will be along and south of I-90 in the west and I-94 in
the east. With significant cloud cover and shower activity todays
temperatures will be a bit cooler than yesterday, in the 45 to 55
degree range. Expect clearing from the west late in the day.

Upper system shifts east of the area early this evening with
shortwave ridging building into the area for a mostly clear and
cool night.

Ridging is short lived as another strong zonal Pacific jet moves
into the area. This will increase cloud cover across the area as
well as bumping up winds along the east slopes of the Rockies.
Current model guidance suggests winds in the Livingston/Nye gap
wind areas will increas through the morning hours Thursday with
gust around 50 mph by afternoon...continuing Thursday night. Not
out of the question that we will need an wind advisory for these
areas at some point but for now guidance is just under this
threshold so will continue to highlite wind increase in HWO. With
increase in downslope winds temperatures will push toward 60
degrees Thursday afternoon. Given downslope westerly flow will
keep dry forecast for most locations Thursday with better chances
in the mountains on west facing slopes. As winds decouple Thursday
evening could see some light showers/sprinkles over northern zones
and over central areas in favored isentropic rebound area west of
Billings east into Rosebud county. Chambers

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

The GFS/GEFS and associated plumes suggested uncertainty in the
extended forecast details beginning on Saturday. The forecast
begins on Friday under an upper ridge and dry, warm airmass.
Temperatures will climb into the 60s. By Sat. morning, a shortwave
approaches from the W or NW depending on the model. Trimmed back
Fri. night PoPs to just the NW zones late at night. Most of the
wave energy passes N of the area on Saturday, and pushes a cold
front through the region while the airmass dries out. Went mostly
dry for Saturday. The model blend gave lower to mid 60s for
temperatures, but there was some spread in the plumes so
confidence was a bit low on high temperatures. The upper ridge
rebuilds through Sun. night with dry conditions. Highs will reach
the 60s on Sunday.

The flow aloft turns SW with energy moving through the flow for
Mon. through Tuesday. Moisture differed between the GFS and ECMWF
during the period. Kept mainly mountain PoPs Mon. and Mon. night.
Models brought another cold front through the area on Tuesday.
Kept the inherited PoPs W and E of KBIL due to downslope flow.
There was uncertainty with the temperatures, but expect Tuesday to
be cooler than Mon. due to the frontal passage. The model
forecasts differed quite a bit for Tue. night and Wednesday. Went
with blended PoPs for these periods with blended temperatures.



Scattered rain and snow showers will move through the
region this morning, accompanied by MVFR conditions. Patchy fog
will occur from Rosebud County E this morning. Scattered showers will
be focused over SE MT and the KSHR area this afternoon. There
will be areas of mountain obscuration through the day, with
widespread obscurations over the NE Bighorns. Precipitation will
end over the KBHK area this evening. There will be localized
obscurations over the NE Bighorns in the evening. Otherwise, VFR
will prevail tonight. Arthur



    Tdy Thu     Fri     Sat     Sun     Mon     Tue
BIL 055 034/059 043/065 042/063 040/061 042/063 044/059
    3/W 11/B    10/B    11/B    11/B    11/B    11/B
LVM 049 032/057 042/063 039/061 037/063 040/063 040/057
    3/W 01/N    10/N    21/B    11/U    12/W    22/W
HDN 055 033/061 040/067 040/064 039/063 040/066 042/060
    3/W 10/B    10/B    11/B    11/B    01/B    11/B
MLS 052 034/060 041/064 041/063 038/061 039/063 042/060
    2/W 10/B    21/B    11/B    11/U    01/B    12/W
4BQ 051 032/060 038/067 039/065 038/064 039/068 042/064
    4/W 10/U    11/B    00/U    11/U    01/B    12/W
BHK 049 031/057 037/063 038/062 036/058 036/061 040/060
    3/W 20/U    11/B    01/B    10/U    01/B    12/W
SHR 050 028/059 036/065 037/065 036/064 039/066 039/061
    3/W 20/B    10/B    00/U    11/B    01/B    11/B




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