Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Great Falls Montana
427 am MDT Mon Mar 17 2014
this afternoon through Wednesday evening...upper-level trof
currently centered in eastern Washington/or continues to make steady
eastward progress this morning. Large swath of moisture ahead of
the trof axis is generating widespread mid- and high-level cloud
cover, along with snow in the high elevations along the rocky mtn
front and scattered light rainshowers over parts of the hiline
counties. Additional scattered areas of light rain will develop this
morning east of the Continental Divide as more moisture arrives
while temperatures remain above freezing. The surface cold front
with this weather system is forecast to cross The Divide later this
morning. As the colder airmass behind the front settles across the
region, there will be a brief period of rain/snow mix in some
locations, but most spots will change over to snow fairly quickly,
with snow spreading south and east through the day. Current winter
weather advisories for the lower elevations remain in effect and
have added a small-area Winter Storm Warning for the little belt
mtns from Monarch to Kings Hill Pass as snowfall totals there may
reach 8 to 10 inches by this evening. Primary short-term forecast
models are all in good agreement on the snow through this afternoon,
but seeing some differences on when the snow will end. Half the
models taper off the snow by early evening over the central and
hiline counties, while the remaining models have areas of light snow
continuing tonight into early tues morning. Current forecast leans
toward the slower solution with a chance of snow showers through
tonight across the region. Tuesday looks mostly dry, though isolated
snow showers may linger over the southwest mtns and parts of the
central mtn ranges. West-to-northwest flow pattern aloft will bring
mostly cloudy but dry conditions on Wed, except for snow developing
again along the rocky mtn front. Temperatures will reach low 40s
this morning ahead of the cold front, then decrease this afternoon.
But the airmass begins to moderate tomorrow with highs in the upper
30s, increasing to the upper 40s to low 50s on Wed.
Wednesday night through Monday...a return to cooler and wetter
conditions is expected as the next shortwave trough moves into the
area Wednesday night and Thursday morning. While the system does not
look too impressive right now it will usher in a pattern change to
wetter conditions and temperatures below seasonal averages. This
will likely produce rain snow mixtures over the lower elevations as
temperatures peak near freezing through the weekend and then drop
back into the 20s and teens overnight. There continues to be some
timing differences of subsequent shortwaves across the area through
the weekend, however a general northwest flow aloft will allow for
showers to develop under the moist flow aloft. This will create a
generally wet and cool outlook through the bulk of the long
term...however by Sunday afternoon and evening a shortwave ridge of
high pressure will begin to move into the area and could provide
some temporary drying.
Gusty winds have diminished along the Rocky Mountain front and
adjacent plains this evening. As a trough of low pressure and
associated surface cold front arrive tonight, conditions will
deteriorate from north to south beginning late tonight along the
Rocky Mountain front spreading into north-central and southwest
Montana through Monday. Precipitation will start as a mix of rain
and snow at taf sites before changing to all snow between 12z and
16z Monday. Winds will also become northerly with gusts up to 30kts,
which will create low visibility in snow and blowing snow. Periods
of MVFR and IFR ceilings/visible are likely in areas of snow and mountains
will become obscured. Mlv
Preliminary point temps/pops...
gtf 40 23 40 25 / 100 60 20 10
ctb 37 21 38 25 / 100 40 20 10
hln 42 25 41 25 / 100 60 10 10
bzn 41 23 38 19 / 100 70 30 10
wey 37 12 33 8 / 90 60 20 10
dln 37 18 35 18 / 80 60 10 10
hvr 45 27 43 26 / 100 50 30 10
lwt 41 23 37 23 / 100 80 30 10
Winter Weather Advisory until 6 am MDT Tuesday Blaine...
Broadwater...Cascade...central and southern Lewis And Clark...
Chouteau...eastern Glacier...eastern Pondera...eastern Teton...
Madison...Meagher...northern Rocky Mountain front...southern
Rocky Mountain front...Toole.
Winter Storm Warning until 6 am MDT Tuesday for Little Belt
Mountains in Cascade...Judith Basin...Meagher.
Winter Storm Warning until 6 am MDT Tuesday for elevations above
5000 feet for northern Rocky Mountain front...southern Rocky
Flood Advisory until Monday afternoon for Jefferson.