Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Billings Montana
1048 am MDT Monday Mar 10 2014
the forecast remains on track...and thus updates this morning
have been fairly minor. Confidence is growing for southeast
Montana to switch to snow overnight...as models are coming into
better agreement about the rain to snow transition. While snow
amounts will be remain very elevation dependent...the combination
of high snowfall rates and blowing snow in the southeast part of
the state warrants a Winter Weather Advisory.
Short term...valid for today and Tuesday...
Forecast remains on track concerning the upcoming late winter
storm. Upper low and trough currently working their way across the
Pacific northwest coast this morning and will be situated across
the Great Basin area this afternoon. At the same time...a cold
front will move through the area this afternoon as a surface low
develops across north central Wyoming. A 700mb low will also
develop across northern Wyoming and both these lows will bring a
deep northeast upslope flow across south central Montana.
Time heights from Billings to Red Lodge and Livingston continue
to show very unstable conditions and lift for a 12 to 18 hour time
period beginning this afternoon and continuing into Tuesday
morning. Models do not bring too much cold air into the area with
this system so precipitation this morning should be in the form of rain
showers with a rain/snow mix during the afternoon.
However...dynamics are strong enough that evaporative cooling is
expected by late this afternoon resulting in rain to quickly
change to snow. Once the changeover to snow begins...a period of
heavy wet snow will be likely early this evening into the late
night hours tonight. Bulk of snow accumulations will come tonight
and little if any are expected during the daylight hours today.
Snow accumulations of 3 to 5 inches will be likely for the lower
elevations from Sheridan to Billings and Roundup and locations
westward with higher amounts along the beartooth/absaroka
foothills and mountain locations.
Liquid amounts from this storm look to be on the order of 0.50 to
1.00 inches so flooding concerns will continue especially for
areas that have already experienced flooding over the past few
days due to snow melt...as well as areas affected by ice jams. The
system is expected to quickly shift south out of the forecast area
by Tuesday afternoon. Hooley
Long term...valid for Wednesday...Thu...Fri...Sat...sun...
Models are in good agreement regarding the extended forecast
periods through Saturday...but their solutions tend to diverge
toward the latter half of next weekend. We will start out with a
ridge positioned over the northern rockies at midweek leading to
mild temperatures and mostly sunny skies. It may be needless to
say at this point...but this may very well lead to continued
flooding issues depending on how the snowstorm in the short term
period turns out. A mild air mass and sunny skies will reduce any
newly fallen snow quickly this time of year and there will likely
be quite a bit of liquid water involved in the coming snowstorm.
Flooding issues will thus likely continue to be a primary concern
into the extended periods.
We do have two notable short waves moving over the ridge. One is
prognosticated for Thursday...but the atmosphere appears rather dry with
this feature and we will keep probability of precipitation low or at zero for most
locations. The next short wave rounding the ridge is prognosticated for
Friday night/Saturday. This system looks more dynamic and has a
better supply of moisture. I generally kept a shotgun approach of
scattered probability of precipitation over the forecast area for this system.
The models then are out of sync on the timing of another stronger
trough moving out of the Canadian rockies early next week...with
the GFS bringing it through Sunday night and the European model (ecmwf) over the
latter part of Monday. At any rate it does seem like it will be an
active pattern...but there is not any indication of any cold
snaps taking place. Bt
Rain was falling from klvm to kbil to kbhk north this morning. The
rain will spread S across the whole area during the day into this
evening. Expect MVFR to LIFR conditions in the precipitation.
Rain will mix with and turn to snow this evening by 06z with IFR
to vlifr conditions. The snow will taper off from north to S overnight
through Tuesday morning bringing improving conditions. The
beartooth/absaroka and Crazy Mountains will be obscured today and
the NE big horns will become obscured this afternoon. The
mountains will remain obscured tonight and improve from north to S Tuesday
Preliminary point temp/pops...
Today Tuesday Wednesday Thursday Friday Sat sun
bil 047 028/038 027/048 031/054 031/053 034/049 031/053
+/o +3/o 10/u 00/u 00/b 22/west 20/u
lvm 046 022/036 021/049 027/051 027/051 030/045 024/050
+/o +4/o 10/u 01/north 00/b 32/west 10/u
hdn 046 027/039 028/048 028/055 030/054 034/049 028/053
+/o 93/o 10/u 00/u 00/b 23/west 20/u
mls 049 027/042 029/050 031/055 030/051 033/047 027/052
9/o 91/north 10/u 01/u 00/b 22/west 20/u
4bq 052 028/038 029/051 029/056 031/052 032/048 027/050
4/o +3/o 10/u 00/u 00/b 23/west 20/u
bhk 047 024/041 025/050 029/053 028/048 028/044 025/048
8/o 81/north 00/b 00/u 00/b 23/west 20/u
shr 050 029/034 020/048 024/055 025/052 029/046 024/051
5/o +6/o 10/u 00/u 00/u 23/west 10/u
Montana...Winter Weather Advisory in effect until noon MDT Tuesday for
Winter Weather Advisory in effect from 3 PM this afternoon to
noon MDT Tuesday for zones 34-35-39-57.
Winter Weather Advisory in effect from 6 PM this evening to
noon MDT Tuesday for zones 36>38-58.
Winter Storm Warning in effect until noon MDT Tuesday for
Winter Storm Warning in effect from 3 PM this afternoon to
noon MDT Tuesday for zones 56-66.
Wyoming...Winter Weather Advisory in effect from 6 PM this evening to
noon MDT Tuesday for zones 98-99.