Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
FXUS63 KMKX 232034
Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
234 PM CST Mon Jan 23 2017
.TONIGHT - Confidence...Medium
A ridge of high pressure will dominate. Stratus is widespread though
still expect at least some fog development but SREF and MOS
suggesting less in the way of dense fog of the last few nights.
However could still see some pockets of locally dense fog. With the
cloud cover 3 hrly mos temps look better/warmer than the 12 hour min
.TUESDAY - Confidence...Medium
The influence of the surface high will dominate the first half of
the day. All indications are that the widespread cloud cover will
still be in place but no precip is expected until the afternoon
hours as some waa increases. Would expect some initially dry air to
chew away at some of the evolving precip. MOS pops are in the single
digits though QPF suggesting on average that the southwest half of
the area could get in on some measurable precip before 00z. A warm
nose starts to work into sw Wi with the increasing 850/925 flow and
the sfc temps should be well into the 30s so expect the predominant
precip type to be rain though evap cooling considerations may
result in at least some snow mixed at the very outset.
TUESDAY night and WEDNESDAY... Forecast confidence is medium.
An approaching trough and mid level low pushes into the central
plains and flattens as it reaches Wisconsin Wednesday morning.
Low pressure will track across Iowa and southeast WI. There is
fair agreement between the models on the track, but the axis of
highest qpf is still a little uncertain, but indications are that
it will be across our far north areas toward central Wiscosnin.
The overall synoptic forcing is quite strong, and forecast
sounding show 50 to 75 Joules/kg of elevated CAPE Tuesday night,
so can`t rule out a rumble of thunder.
Precipitation will begin as mainly rain in south central WI Tue
afternoon, but quickly transition to a rain snow mix with mainly
snow towards the Dells. Temperatures aloft will warm a little
across south central and southeast WI as the surface low tracks
through southeast WI. Expect snow to mix with or change over to
rain in Milwaukee and Janesville and southeast late Tue night.
Because of the mild boundary layer temperatures, there will not be
as much snow south areas as the mid levels suggest. Snowfall
rates should be high enough for 2-4 inches of a wet snow Tue night
for areas north of Madison to Sheboygan. This would impact the
Wedesday morning commute.
We are expecting snowfall totals for the 24-hr period from Tue
evening through Wed afternoon in the 2 to 5 inch range northwest
of a line from Madison to Sheboygan, with the highest snow totals
north and west of the Dells, so a winter weather advisory is
looking likely. An inch or less is expected in southeast WI
THURSDAY THROUGH SUNDAY... Forecast confidence is medium.
The upper trough still extends across southern Wisconsin Thursday
before extending across the eastern great lakes Friday. Another
shortwave drops southeast into southern Wisconsin in the northwest
flow Friday night, with a stronger one Saturday night.
Cooler cyclonic flow will continue overhead through the weekend.
This will keep clouds in place and the chance for light snow
showers and flurries across southern WI at times.
Temperature`s will drop to seasonal normals.
MONDAY THROUGH TUESDAY... Forecast confidence is medium.
A weak upper ridge drops southeast with a northern stream
shortwave moving across the Lake Superior region Monday evening.
A surface low is expected to drop down from south central Canada
and move across the northern Great Lakes.
Surface ridging continues to build into WI
with plenty of lingering low level moisture. Cigs are mostly IFR in
and trending into MVFR in others. Surface high settles across
tonight with overall light wind regime. With no real airmass
modification expect the ceilings to lower and for some fog to form.
SREF and MOS suggest dense fog less likely than the last few nights.
But given these low cigs it doesn`t take much to get some thicker
fog here and there with the overnight cooling. Not expecting any
precip through at least 18z Tuesday. Then srn WI likely to see pcpn
develop during 18-21z time frame esp in sc WI Tuesday afternoon as
waa regime sets up ahead of next low. Boundary layer looks warm
enough for rain though some flakes possible too with evap cooling
Small craft conditions are possible Tuesday night
through Thursday as low pressure approaches and then shifts east of
the area. Winds and waves will approach small craft advisory
conditions Tuesday night and Wednesday morning, as low pressure
moves into the Wisconsin/Illinois border area. Northwest winds may
approach small craft advisory levels late Wednesday into Thursday
in the wake of the low.
TONIGHT/Tuesday AND AVIATION/MARINE...Collar
Tuesday NIGHT THROUGH Monday...Hentz