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fxus65 kbyz 260936 
afdbyz

Area forecast discussion
National Weather Service Billings Montana
336 am MDT Wed Apr 26 2017

Short term...valid for tdy and Thu...

One strong system has exited the area to the east and today will
be a much quieter day of weather. Things will turn active again
Thursday and Friday as the next system moves in.

For today, flow gradually backs as strong jet energy invades the
West Coast and dives toward the Great Basin. Will see scattered
showers form this morning over the west and then become more
numerous this afternoon as stronger energy works in along with
increasing upper divergence. Have raised pops for western zones a
bit for this afternoon and evening. The beartooth/absarokas will
get another shot of precipitation, but does not look as heavy as
the last event.

Energy continues to dive south tonight and a trough carves out
for Thursday and Thursday night over the central and southern
rockies. Models were taking a northern piece of energy and cutting
it off over northern Wyoming Thursday and Thursday night for
dynamic forcing. An inverted surface trough works through Sheridan
County and up in south central zones of southern Montana for
convergence. Will see showers increase in coverage and intensity
Thursday afternoon and night over western and central zones,
working into northern Wyoming. Models were hitting the bighorns
hard again with over an inch of quantitative precipitation forecast beginning Thursday afternoon.
Will issue a Winter Storm Watch for the bighorns for Thursday
afternoon through Friday evening.

This system does look warmer than the last one, but 850mb
temperatures were inching colder with each passing model run.
Current progs have 850mb temperatures falling to around 1c
Thursday night. Quantitative precipitation forecast over southern Big Horn County and Sheridan
County Wyoming was close to an inch for Thursday afternoon through
Friday night. Some of this may turn to snow late Thursday night
and continue early Friday. Have raised pops and included some snow
accumulation in Sheridan County, to get The Ball rolling. Will
have to monitor closely for another potential highlight there.

Sheridan County picked up upwards of 2 inches of reported rain
from this last event. That amount does not include the water that
remains in snow cover on the ground which will be melting off
today and Thursday. The ground was quite saturated as the water
year for rainfall at Sheridan was around 6 inches above normal.
Runoff seems to be more likely rather than widespread soaking in
of melting snow and additional quantitative precipitation forecast. Would not be surprised to see
a lot of standing water issues given the amount of precipitation
coming in over the next couple of days. Some of the rivers and
streams were already going up and should continue to do so given
the snow melt and added rainfall. May have some flood concerns,
especially along the foothills with smaller streams and ditches,
over the next several days. Will issue a flood outlook to talk
about that and stress in the severe weather potential statement. Twh

Long term...valid for Fri...Sat...sun...Mon...Tue...

Upper low drops south on Friday, which should help turn winds more
northeasterly and produce upslope flow. This continues a
precipitation event that begins Thursday with favored areas for
precipitation in an inverted surface trough that lays across the
central zones. Models are beginning to increase the precipitation
on the east side of the bighorns and trending with cooler surface
temperatures. Expect another significant amount of precipitation
to fall especially for Sheridan County and possibly could see some
snowfall. Will have to watch for another winter event but like
the event at the beginning of this week expect the area of impact
to be highly focused. Precipitation should taper to more scattered
showers from north to south Friday afternoon into the evening as
system moves southward. Will continue to be very cold for late
April.

Rest of the extended forecast will feature northwesterly flow
aloft as the Friday system ejects but looks drier with slightly
warmer temperatures. Do not expect more significant precipitation
under this regime but showers will be present during diurnal
heating and breezy afternoons. Somewhat greater chance of showers
late Monday as models bring shortwave trough southeast over the
area. More typical of an April weather pattern than the previous
heavy precipitation events. Rms/twh

&&

Aviation...

Low clouds and MVFR will persist through about 16z today. Areas
of fog and freezing fog are possible this morning along and south
of an Ekalaka-Broadus-Hardin line and west of a Roundup-Billings
line. IFR conditions and lower will be possible with any fog. VFR
will then prevail for the rest of today. Scattered showers are
possible over south central Montana (with thunderstorms also possible
west of kbil) during the afternoon hours with temporary MVFR
conditions. Mountains will be obscured today. Rms/twh

&&

Preliminary point temp/pops...

Tdy Thu Fri Sat sun Mon Tue
-------------------------------------------------------
bil 055 037/047 034/047 035/053 036/060 041/057 039/056
3/west 57/r 76/west 42/west 11/b 33/west 33/west
lvm 054 033/048 030/046 028/053 032/057 036/055 034/055
6/T 76/o 57/west 42/west 13/west 33/west 33/west
hdn 056 037/047 036/048 035/054 035/061 040/059 038/058
2/west 37/r 76/west 32/west 11/b 33/west 34/west
mls 052 033/054 034/052 036/056 036/061 041/060 040/057
1/b 12/o 43/west 22/west 11/u 33/west 33/west
4bq 049 029/050 033/047 032/052 031/058 039/058 038/055
1/b 13/o 54/west 32/west 11/u 33/west 24/west
bhk 049 026/053 028/051 031/054 031/059 037/057 035/055
1/b 11/b 22/west 11/east 11/u 33/west 13/west
shr 049 032/043 031/042 030/045 028/054 036/054 036/052
2/west 48/o 87/west 42/west 11/b 34/west 34/west

&&

Byz watches/warnings/advisories...
Montana...none.
Wyoming...Winter Storm Watch in effect from Thursday morning through
Friday evening for zone 98.

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