Scientific Forecaster Discussion
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Area forecast discussion
National Weather Service Milwaukee/Sullivan WI
523 am CST sun Dec 15 2019
no updates to the previous discussion.
VFR conditions are expected through the forecast period with
northwest winds decreasing through the day. Clouds will increase
tonight with ceilings around 5,000 to 8,000 feet late tonight.
Areas along the WI/Illinois border may briefly see MVFR ceilings
between 06-10z Monday.
Previous discussion... (issued 336 am CST sun Dec 15 2019)
Today through Monday...forecast confidence is high...
quiet conditions are expected for today and tomorrow as high
pressure sits over the area. Mostly sunny skies will give way to
more clouds tonight as a low pressure system passes to the south.
The dry air associated with the high pressure is expected to keep
precipitation south of the area, but flurries can't be completely
ruled out along the state line as 850mb convergence may briefly
overcome the dry air. Clouds will linger into Monday, but
temperatures will be warmer with highs in the mid 20s to low 30s.
Monday night through Tuesday night...forecast confidence high.
A large upper low and associated sfc low will track from south
central Canada to New England during this period. The sfc low
will gradually deepen as it does so. Ahead of this feature, a west
to east sfc ridge will shift south across srn WI Mon nt-Tue am.
Modest wly winds will prevail on Tue shifting nwly for Tue nt with
a dry cold frontal passage. A cold night, mostly in the single
digits, is forecast for Tue nt.
Long term...Wednesday through Saturday...forecast confidence
Will continue to use the European model (ecmwf) and nbm as guidance in the extended
fcst. Polar high pressure will arrive for Wed with a cold day
expected. Milder temps are then expected the remainder of the week
as sly flow and warm advection develops ahead of an approaching
shortwave trough from the wrn USA. A weak cold frontal passage
will eventually occur on Sat. The airmass may remain dry enough
for no precipitation.
MVFR ceilings are clearing this morning with VFR conditions
expected for the remainder of the day. Winds will be from the
northwest and decrease through the day becoming light and
variable this evening. Clouds will move back in from the south
tonight with ceilings around 7,000 to 10,000 feet.
northwest winds will decrease today as high pressure builds in.
Light winds will then continue until Tuesday as deepening low
pressure system develops over southern Ontario. Winds will
increase from the northwest through Tuesday with gusts up to 30
knots Tuesday night into Wednesday morning. A Small Craft Advisory
may be needed for the nearshore waters Tuesday night.