Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Milwaukee/Sullivan WI
issued by National Weather Service Chicago Illinois
227 PM CST Tuesday Feb 9 2016
Short term...through Wednesday...
111 PM CST
Focus is on additional snow showers this evening...followed by
cold temperatures/wind chills.
This afternoon and tonight...forecast confidence medium-high.
Slightly more organized snow shower activity is working its way
southward through central Wisconsin...ahead of a sharp upper trough
in northern Minnesota. Shortwave energy associated with this
trough will rotate through eastern Wisconsin through tonight.
This will be the best chance for more organized snow showers as
lower level lapse rates increase through a fairly deep dendritic
growth layer...indicating some light accumulations remain
possible. The trough shifts east after midnight which should
wind shower activity down fairly quickly from west to east. There
could still be some lingering flurries overnight as well.
Continued cold advection coupled with some clearing skies will
promote temperatures dropping to near or just below zero in the
west...single digits closer to the lake. Winds remain elevated
tonight between the surface high to the east and low pressure
which will have moved to Lake Ontario. Wind chill values at
daybreak will fall to the teens below zero area wide...close to 20
below in the northwest.
Wednesday - confidence...medium-high.
The theme on Wednesday is cold. 850 temperature advection becomes
more neutral through the day. Surface high pressure will inch
eastward as well. 500 mb heights will be rising through the day
which will weaken the cyclonic flow. Forecast soundings suggest
only scattered clouds...though the pattern suggests scattered to
occasional broken clouds...thus a partly cloudy to partly sunny
forecast. Highs in the teens coupled with northwest winds 10-15 miles per hour
resulting in wind chills maxing out close to zero.
227 PM CST
Wednesday night and Thursday...confidence high.
A ridge of high pressure will spread southeast across western WI
and Iowa Wednesday night into Thursday. Dry weather is expected but
very cold temperatures are expected with lows Thursday morning
likely in the low single digits east to single digits below zero
in the west. These temperatures combined with northwesterly winds up to
10 miles per hour will push wind chills into the 10 below to 15 below zero
Thursday through Friday...confidence medium.
A weak upper wave will move across part of the Midwest late
thurdsay night into Friday morning ahead of the strong high
building south from Canada. A period of light snow or snow showers
is possible with this wave...but it may remain southwest of the
County Warning Area. For now have just slight chance probability of precipitation in the far south.
Friday night through Saturday night...confidence medium...high.
Very cold temperatures are expected with lows generally in the low
single digits below zero both nights along with wind chills values
of 15 below to 25 below zero possible. If these wind chills do
materialize...an advisory may be needed.
Sunday through Tuesday...confidence medium.
A clipper system is expected to move across the Great Lakes
region Sunday into Monday but there remains timing/track and
location differences. However...temperatures will be cold enough
that any precipitation that does occur should be all snow. With a fairly
dry/fluffy snow expected...even light quantitative precipitation forecast could fluff up a few
inches of snow from Sunday afternoon through Monday morning.
Terminals are in a relative lull in snow shower activity early
this afternoon. While snow showers will not completely fill back
in this afternoon and evening...do expect some uptick in coverage
middle afternoon through early evening...especially east of kmsn...as
a shortwave in northern Minnesota rotates southeastward. Ceilings
will hover in the MVFR to low VFR range through the
afternoon...trending toward MVFR. Visibility reductions in snow should
also be MVFR...with infrequent IFR possible. Expect coverage to
diminish significantly middle to late evening as high pressure moves
in from the west. Skies look to scatter from west to east
overnight...with broken clouds possible again Wednesday afternoon
that look to largely remain VFR. Gusty northwest winds continue through
tonight...easing some during the day Wednesday.
Marine...offshore winds will be on the increase out of the northwest
into Wednesday as a low pressure system drifts east through the Great
Lakes and a ridge of high pressure sets up across the eastern High
Plains. With gusts in the 20 to 30 knots range through Wednesday...a
Small Craft Advisory is in effect for this period. Waves will be
the highest toward the open waters of the lake as well given the
227 PM CST...gusty northwest winds will continue tonight into
Wednesday morning and begin to diminish Wednesday afternoon and
especially Wednesday night as a ridge of high pressure slowly
moves just southwest of southeast WI. A much stronger high will
build across the western lakes Friday night into Saturday and
ahead of this high...another period of strong/gusty northwest
winds is expected with perhaps some gusts to 30 kts and a Small
Craft Advisory will probably be needed.
Lm...Small Craft Advisory until midnight CST Wednesday night for
Tonight/Wednesday and aviation...kmd
Wednesday night through Tuesday and marine...cms