Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 092108

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
308 PM CST Mon Jan 9 2017

.TONIGHT AND TUESDAY...Forecast Confidence Is High.

An area of light snow, associated with warm advection wing, will
continue to lift northeast through the forecast area this
afternoon into the evening. Light snow will probably persist most
places into the night, as low pressure approaches. Temps at the
surface and aloft will warm overnight into Tuesday, under
southerly low level flow.

Thus, still expecting precip to transition south to north from
snow to rain later tonight into early Tuesday morning. Left
mention of mix with or changeover to freezing rain and sleet for a
brief time during the transition to rain. Thinking this will have
minimal impact, given the short window for the mix and snow
already on the ground most places by then. Not out of the question
that this could cause some slick roads through early morning on
untreated surfaces.

Total snow is forecast to range from around a trace far southwest
forecast around 3 inches in the far northeast.

Decent looking wave for tomorrow, with models coming up in precip
amounts. Have thus raised pops and rain amounts. The associated
cold front will move through tomorrow afternoon, bringing colder
temps, but also an end to the precip. Doesn`t look like much of
an opportunity for rain to change back over to snow, as colder
air moves in. Should just see the precip end as rain most places.

.TUESDAY NIGHT THROUGH THURSDAY...Forecast Confidence Is Medium.

Strong cold air advection should bring in drier air for Tuesday
evening, ending any lingering precipitation. Warm air advection
then develops later Tuesday night into early Wednesday morning.
This period should be dry across the area.

The NAM is further to the north with the low track for Wednesday
afternoon and night than the GFS/ECMWF/Canadian models. Leaned
toward the GFS/ECMWF/Canadian solution for now, as they have been
fairly consistent with a low track from the central Plains
Wednesday afternoon into northern Indiana/southern lower Michigan
Wednesday night. In addition, there is upper divergence from
possible jet streak coupling Wednesday afternoon and evening.
There is a good push of warm air advection at 600 mb as well
during this time.

Inverted trough slides southeast through the area Wednesday
afternoon into northeast Illinois Wednesday night. Low to mid
level frontogenesis response also slides southeast through the
area. North to northeast winds allow for cold air to undercut the
warm air at 850 mb across the southeastern portions of the area
during this time. Forecast soundings from the GFS suggest that
there will be a risk for freezing rain Wednesday afternoon into
Wednesday night/early Thursday morning across the southeast
counties. Further to the north and west, colder air through the
column would support more of a mix of sleet and snow, or all snow.

For now, have likely PoPs continuing for mainly light freezing
rain in the southeast counties, with a mix to snow further to the
north and west. Ice accumulations around 0.10 inches are possible
in the southeast mainly Wednesday night, lower to the north and
west. Could see up to an inch in the north and west parts of the
area Wednesday night into Thursday as well. May need headlines for
freezing rain eventually in later forecasts for Wednesday night in
the southeast counties.

.THURSDAY NIGHT THROUGH MONDAY...Forecast Confidence Is Medium.

ECMWF/GFS are showing strong cold air advection into Thursday
night, with Arctic high pressure moving east across the region
Friday into Friday night. This will bring quiet weather but very
cold temperatures once again. Wind chills will be below zero
Thursday night but should not reach advisory levels.

These models show low pressure trying to slide northeast toward
and into the region Sunday into Monday. There are significant
timing and placement differences with the low and 500 mb
features during this period, so went with consensus blend of
models with PoPs and temperatures during this time.



Snow will continue to lift northeast through late afternoon into
the evening. Some light precipitation will then linger tonight,
with better development again late tonight into Tuesday. Precip
should remain mainly snow through much of the night, but milder
air will move in later tonight into Tue morning. Still think there
could be a brief mix with or changeover to sleet and freezing
rain, before the precip becomes all rain early Tue morning.

Total snow is forecast to range from around a trace far southwest
forecast area, to around 3 inches in the far northeast. Colder
temps will return later Tuesday and Tuesday night, though most of
the precip will have ended by then. Lower ceilings and
visibilities are likely at times with the precipitation through



Southerly winds will be gusty tonight into Tuesday ahead of
approaching low pressure, remaining gusty and becoming westerly
later Tuesday after the cold front moves through.

A Small Craft Advisory goes into effect this evening, lasting
into Tuesday night. The timing of this advisory still looks good
based on latest forecast winds.


LM...SMALL CRAFT ADVISORY from 6 PM this evening to 3 AM CST
     Wednesday for LMZ643>646.



TUESDAY NIGHT THROUGH MONDAY...Wood is the U.S. government's official web portal to all federal, state and local government web resources and services.