Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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023
FXUS63 KMKX 170503
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1103 PM CST Wed Jan 16 2019

.UPDATE...No changes needed at this time.

PC

&&

.AVIATION(06Z TAFS)...MVFR cigs will be increasing later tonight
into Thursday. A low pressure tough will move through. there may
be some light snow showers here and there but not expecting any
impact or accumulation.

PC

&&

.PREV DISCUSSION... (Issued 931 PM CST Wed Jan 16 2019)

UPDATE...No changes of great consequence. Went with somewhat
cooler readings in the north where more breaks in clouds possible
there during the overnight hours.

PC

MARINE...High pressure across the center of the Lake tonight.
Some uptick in north winds Thursday night in wake of a trough.
Still looks like a stronger wind regime setting up for the weekend
as low pressure passes well south of state. There will be a tight
pressure gradient between this passing low and high pressure in
the northern Plains.

PC

PREV DISCUSSION... (Issued 549 PM CST Wed Jan 16 2019)

UPDATE...No changes needed to forecast at this time.

PC

AVIATION(00Z TAFS)...
Expect VFR conditions until MVFR ceilings move in late tonight
through tomorrow from west to east. These lower ceilings are due
to a low pressure system passing to our south. Some light snow is
possible, but the main area of snow remains south of Chicago. No
accumulations are expected for our area.

RAR

PREV DISCUSSION... (Issued 334 PM CST Wed Jan 16 2019)

DISCUSSION...

Tonight Through Thursday Night...Forecast Confidence Is Medium.

Lake effect clouds may hang on into tonight across areas near Lake
Michigan, with low level northeast flow becoming east with
favorable delta T values. Otherwise, expect mainly low clouds to
gradually push east northeast into the area this evening,
lingering overnight into Thursday. Went with lows in the middle
to upper teens north, to the lower 20s south.

Models continue to show a 500 mb vorticity maximum moving east
southeast through the area on Thursday. Cold front also moves
southeast through the region later Thursday into Thursday evening.
Forecast soundings are showing some deep saturation at times
later tonight into Thursday. There is some dry air between the
middle and low levels which will need to be overcome. Models still
bring very light QPF across parts of the area later tonight and
Thursday.

Main upward vertical motion and area of light snow will remain to
the south of the area during this time. Not a lot of confidence
that we will see much if any light snow, given the rather weak to
modest upward vertical motion and short duration of deep
saturation. May end up being flurries. For now, will continue to
mention just low PoPs for light snow for later tonight into
Thursday. No accumulations are expected. Highs should be in the
lower 30s.

Should see partial clearing, at least, for Thursday night, with
drier and slightly colder air moving into the area. Lows should be
in the middle to upper teens in most areas.

Friday through Saturday night...Forecast confidence is medium.

We continue to fine tune snowfall amounts, but no major model
swings are noted today.

A mid level short wave/low pressure system associated with a
major storm system hitting the Pacific Northwest tonight, will
dive into the Central and Southern Plains by Friday night. This
wave will be broadly connected to a large trough over Canada, but
not really phase until the southern system gets well south and
east of the Midwest. For those that track surface lows, this one
is still expected to move from OK, thru AR to the Mid Atlantic.
That is well south of a storm track that normally brings us big
snowfall. But, it is that broad troughing aloft that will allow
the moisture to spread farther north than is typical.

The models have been keying on some h8-h7 frontogenesis well north
of the surface low over IA/Srn MN into srn WI and IL later Friday
afternoon into Friday night. This would be the period when we
could see the majority of the snow accumulation awake from Lake
Michigan. The highest amounts would be limited to the WI/IL
border, less north of Milwaukee and Madison. If that frontogenesis
shifts a bit farther south, we could see a significant drop in
snow amounts to the south.

The other main concern will be a favorable wind fetch and delta T
over the lake bringing higher snowfall amounts across the far
southeast counties, especially Milwaukee/Racine/Kenosha, later
Friday night into Saturday night. Delta Ts will be approaching 20,
which is impressive. This will need to be watched closely as a
stationary snowband would be very productive in this setup.

Sunday...Forecast confidence is high.

High pressure and north winds will bring some of our coldest air
of the season, but certainly not unusual for mid January. Lows
Sunday morning and Monday morning will drop into the single
digits, maybe a few degrees below zero. We`ll recover to around
10 above Sunday afternoon.

Monday and Tuesday...Forecast confidence is medium.

The ECMWF and the GFS continue to show another system moving by to
our south during this period. It`s a bit farther south than the
past few storms, so this will bring us another chance for some
snow early next week.

Wednesday...Forecast confidence is medium.

We should dry out at mid week, if things progress as planned.

AVIATION(21Z TAF UPDATES)...

Lake effect clouds with ceilings around 3000 feet should linger at
Milwaukee and Kenosha into this evening. Gusty north to northeast
winds near the lakeshore should weaken by sunset.

Clouds with mainly VFR ceilings should move east northeast into
the area this evening, lowering to 1500 to 2500 feet later tonight
into Thursday morning. They should remain around 1500 feet for the
rest of Thursday. Winds will be rather light tonight into
Thursday, before a cold front moves through the area later
Thursday into Thursday evening. Winds should then become
northwest.

Any light snow chances later tonight into Thursday will be rather
low, with the main area remaining to the south of the area. It
could end up being mainly flurries. No accumulations are
expected.

MARINE...

Nearshore Waters...

Gusty north to northeast winds and waves of 3 to 4 feet will
subside by early this evening. Winds will become southeast tonight
into Thursday morning, weakening Thursday afternoon. Northwest
winds will increase after the cold front moves through Thursday
night, then weaken on Friday.

Northeast winds will become gusty Friday night into Saturday,
becoming north Saturday night into Sunday. Frequent gusts to 25
knots are likely during this time. Waves of 3 to 5 feet are
possible Friday night into Saturday, before slowly subsiding. A
Small Craft Advisory may be needed for Friday night into Sunday.

Open Waters...

Gusty northeast winds are expected Friday night into Saturday,
becoming north Saturday night into Sunday. Frequent gusts to 30
knots are likely during this period. Waves will build during this
time as well. As of now, it appears that gusts will remain below
gale force. Freezing spray is expected Friday into the weekend as
well.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...None.
&&

$$
Tonight/Thursday and Aviation/Marine...Wood
Thursday Night through Wednesday...Davis



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