Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Milwaukee/Sullivan WI
233 PM CST Monday Feb 8 2016
Tonight and Tuesday...forecast confidence...high
A surface front/trough is currently dropping south through the state
and will move through southern Wisconsin late afternoon and evening.
Snow showers continue to increase in coverage from the northeast
forecast area and northward early this afternoon. These snow showers
are expected to affect at least the eastern half of the forecast
area this afternoon and evening...with generally up to an inch of
Saturation and weak lift will linger through Tuesday as the upper
trough slowly heads eastward. This will likely result in persistent
snow showers...the best chance for light accumulations in the east.
Accumulation will be mainly under an inch tomorrow. May not see much
west of Madison tomorrow.
Temperatures tomorrow will be several degrees below normal behind the
Tuesday night and Wednesday...forecast confidence...high
A northwest upper level flow continues with a 140 knot upper jet
maximum dropping down across eastern Minnesota.
700 mb relative humidity remains saturated east into the evening...but then
finally dries. Weak 700 mb upward motion also continues Tuesday
night. Even with a deep moist layer through 700 mb during the
evening...the steeper lapse rates are below 925 mb. Strong 850 mb
cold air advection occurs Tuesday night with the low level
inversion lowering. Initially the low levels below 850 mb remain
rather saturated...but eventually dry Wednesday.
850 mb winds briefly become north. Low level winds remain
northwest keeping any lake snow out over the Waters. Lake snow
may get close to the shoreline area...but should not extend
Mainly dry weather is expected Wednesday as a surface high
pressure ridge moves into the upper Mississippi Valley.
Wind chills will approach 20 below over south central Wisconsin
with the colder surface temperatures and rather brisk winds near
Wednesday night and Thursday...forecast confidence...high
The upper flow remains out of the northwest behind the large
trough over southeast Canada and the eastern Great Lakes.
Both the GFS and European model (ecmwf) are dry with a surface ridge continuing
to build across the upper Mississippi River valley.
Even though lows will be colder...winds will not be as strong so wind
chills will approach 15 below near sunrise.
Thursday night and Friday...forecast confidence...medium
The upper level flow becomes just a little more zonal with another
upper low forming near and southeast of James Bay with a shortwave
dropping into the upper Great Lakes. This shortwave is more
pronounced on the 00z European model (ecmwf).
A weak surface trough forms across the Great Lakes region...and extends
more into southern Wisconsin on the 00z European model (ecmwf). The 00z European model (ecmwf) has a
band of light snow across southern Wisconsin Thursday night.
Saturday and Sunday...forecast confidence...medium
An upper level ridge builds across the northern rockies and moves
across the northern plains Saturday or Saturday night and into
Wisconsin Sunday ahead of an approaching shortwave.
A strong surface high extends across the western Great Lakes
Saturday. The GFS is a little quicker moving it across the eastern
Great Lakes Sunday. This results in the GFS spreading light
precipitation into northern portions of southern Wisconsin Sunday
The GFS takes the middle level shortwave through Wisconsin by Monday
morning...while the 00z European model (ecmwf) still has the trough axis across
eastern Wisconsin Monday afternoon.
The GFS brings a trough with light precipitation Sunday
night...while the European model (ecmwf) brings in the light precipitation Monday.
More snow showers upstream will continue to move in for the
afternoon and evening as a surface front/trough swings through.
Would not be surprised by another inch or so in some spots. Best
chance for additional accumulating snow will be in the eastern half
of the forecast area this into evening. Snow will continue to be
drier...with earlier accumulations suggesting a 20 to 1 snow to
Light snow is expected to persist through tonight and much of
Tuesday...especially in the east. Light accumulations generally less
than an inch are possible tomorrow.
Ceilings will mainly be MVFR through Tuesday. Visibilities will bounce around
as snow showers come and go...likely ranging from 1 to 6 miles.
Current timing of Small Craft Advisory from later this evening
through Wednesday evening still looks reasonable. Northwest winds
will be gusty...with gusts up to 30 knots possible at times. Waves
will be highest toward open waters due to the offshore nature of the
Lm...Small Craft Advisory from midnight tonight to midnight CST
Wednesday night for lmz644>646.
Small Craft Advisory from 9 PM this evening to midnight CST
Wednesday night for lmz643.
Tonight/Tuesday and aviation/marine...ddv
Tuesday night through Monday...hentz