Scientific Forecaster Discussion
fxus65 kbyz 282118
Area forecast discussion
National Weather Service Billings Montana
318 PM MDT Tue Mar 28 2017
Short term...valid for Wed and Thu...
Upper convergent area shifting east over southeast Montana.
Lingering showers were decreasing over the forecast area. Trends
for the evening have been updated to reflect for decreasing pops.
A drying trend takes place for tonight and Wednesday. Will cancel
the Winter Weather Advisory for the Bighorn Mountains as snow was
quickly winding down there.
Temperatures will be warmer with highs reaching the 60s most
locations. The flow backs Wednesday night and Thursday as a
sharpening upper trough moves toward Nevada. Energy and moisture
and will stream out ahead of the main trough and therefore
increasing pops for the west looks valid for those periods.
The main period of potential forcing looks to be Thursday night
and Friday as the western trough moves out into the central and
southern rockies. The models continue to have large discrepancies
with each other. There are also large run to run variances within
the models too, and all this leads to low confidence on how the
pattern resolves itself. The GFS pushes a strong wave out of the
main trough and sends it across central and northern Montana
Thursday afternoon and night. The European model (ecmwf) was farther south with
this wave and produces stronger ascent over western zones, then
consolidates the forcing around the upper low dropping into
northern Arizona. Have kept pops mainly scattered for Thursday and
Thursday night. The mountains and foothills look to be the most
likely location for precipitation, so have low likelies there.
Will have to monitor this event closely as could be a heavy snow
event for area mountains, especially the bighorns. Twh
Long term...valid for Fri...Sat...sun...Mon...Tue...
The extended forecast, beginning on Friday, has not changed much
with this update. There is still plenty of uncertainty in regards
to how much rainfall and mountain snow will fall Thursday night
through Friday night. Precipitation will be ongoing across much of
the region on Friday morning but timing, and exactly how much
will fall over the day Friday, is uncertain. The GFS is still the
wetter of the two solutions, but even that solution has trended
down for precipitation amounts compared to yesterday while the
Euro solution has remained relatively steady. For this update, did
not change rainfall amounts very much. The biggest impacts for
this system will likely stay in the mountains, and more
specifically, the Bighorn Mountains where there is a better
consensus for heavy precipitation. The upper level low
responsible for the rainy weather will push out of the region by
Saturday morning, with drier conditions moving in for most of the
weekend. By the time the system has moved out, the mountains will
likely see precipitation amounts near an 1-1.5 inches (amounting
to 8-12 inches of snow). We're still forecasting near 0.75 inches
of rain along the foothill locations and around 0.25-0.50 inches
in the plains. Precipitation amounts will be further refined as
model agreement gets better.
The next system of interest moves in Sunday night into Monday.
This will give US another chance for rain and mountain snow.
Models differ in terms of timing, but all show some type of
system pushing through so increased rain chances on Monday and
Tuesday. Temps will be near to above normal through the period
and in the mid to upper 50s. Dobbs
While scattered shower activity is possible over extreme southeast
Montana late this afternoon and early this evening, with brief
MVFR restrictions in showers, VFR conditions will prevail. 30kt
wind gusts possible at klvm after 06z and through most of the day
tomorrow. Mountain obscurations will diminish overnight as well.
Preliminary point temp/pops...
Wed Thu Fri Sat sun Mon Tue
bil 036/063 043/061 042/052 034/061 041/058 038/054 034/053
01/b 23/west 56/r 20/b 11/b 34/west 32/west
lvm 029/060 040/052 035/051 030/060 036/056 033/052 030/052
11/north 46/west 54/o 10/b 13/west 33/west 33/west
hdn 032/064 038/064 040/053 034/061 036/060 036/057 032/055
00/b 13/west 56/r 40/b 01/b 34/west 32/west
mls 036/064 040/064 044/056 036/060 040/060 038/058 036/056
10/b 12/west 54/r 30/b 01/b 33/west 32/west
4bq 035/062 039/065 042/054 036/058 038/060 038/056 035/054
30/u 01/b 35/r 51/b 01/b 35/west 43/west
bhk 036/062 037/065 040/055 036/057 036/059 036/057 034/053
30/b 01/b 46/r 51/b 01/b 34/west 44/west
shr 030/059 034/060 038/050 032/056 034/057 035/054 032/052
20/u 12/west 57/r 61/b 11/b 35/west 43/west