Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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910
FXUS63 KMKX 222018
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
318 PM CDT Tue Oct 22 2019

.SHORT TERM...

Tonight and Wednesday...Forecast confidence is medium.

The very large closed, mid level circulation north of Lake
Superior will continue to lift north and weaken this evening.
On Wednesday, a fast moving short wave will dive into the
southwest periphery of the upper trough and push across southern
Wisconsin and northern Illinois.

For tonight, any lingering showers/sprinkles will lift north of
the area early this evening with clearing spreading south to north
late this evening and into the early morning hours on Wednesday.
Will let the wind advisory go at 3 pm since we`re not meeting
criteria any longer. It`s still windy, but not meeting advisory
levels.

We should have a period of clear skies/sunshine Wednesday morning.
But, the fast moving short wave mentioned above will spread
clouds back into the area by mid day. An associated weak low level
circulation should generate enough isentropic lift/saturation to
squeeze out some rain Wednesday afternoon across southern
Wisconsin. This rain will lay out in an east/west band. It will be
fairly narrow, so a few local areas could see some focused
rainfall, other areas will be dry. It`s hard to determine at this
point just where that band will set up. The NAM and ECMWF look
quite dry with the low levels looking dry. The GFS and GEM-NH
look too wet. The blend is our friend then. Will keep POPs in the
Chance category for now and allow subsequent shifts to up chances
if necessary.

.LONG TERM...

Wednesday Night through Friday... Forecast Confidence is Medium.

Any light precip lingering with the brief round of isentropic lift
will exit to our east in the evening. Skies should thin out or
scatter overnight and winds will become light. This will allow
temperatures to drop into the mid 30s. Frost is possible. We no
longer issue headlines for frost potential since we are past the
median date of the first frost.

Temperatures will be below average on Thursday and Friday with a
cold upper trough over the region. Winds will be light. Clouds
may linger over southeast Wisconsin for much of the period due to
a front stationed over IL and IN, but no precip is expected for
southern WI. Temperatures are expected to drop below freezing for
most areas inland from the lake Thursday night. Friday night
should be slightly warmer with min temps around freezing.

Saturday through Sunday... Forecast Confidence is Medium.

Models start to diverge with the upper level patterns for the
weekend. The GFS keeps the whole upper trough progressive into the
eastern U.S. while the ECWMF and Canadian models leave a cutoff
low over the Texas Panhandle. If the cutoff low scenario happens,
it would lift into IL and potentially brush southern WI with
precip Saturday night into Sunday morning.

Temperatures this weekend will return to around normal for this
time of year, with highs in the lower to mid 50s.

Monday and Beyond... Forecast Confidence is Low.

The next amplified upper trough will slide into the western part
of the country early next week. This will be one to watch as there
are many differences between the models regarding the speed that
the trough moves across the country.

The only thing that all the models agree on is that much colder
air will drop into the Upper Midwest and Great Lakes region by the
middle of next week. 850mb temperatures might get down to around
-12C (and -7 to -9C at 925mb) for a time. That translates to highs
in the 30s and lows in the 20s. Temperatures are expected to
rebound later in the week.

&&

.AVIATION(21Z TAFS)...

MVFR CIGS will continue across the area through early evening.
Clearing is then expected to overspread southern Wisconsin from
south to north later this evening, into the overnight hours. Most
TAF sites should be VFR by 03-04z Wed with clearing reaching the
TAF sites by 07-09z Wed. VFR conditions should then hold through
the rest of the TAF period. Look for the winds to peak early in
the TAF period this afternoon, then diminishing late this
afternoon and continuing to diminish tonight. Winds will veer to
the west by evening.

&&

.MARINE...

A very strong low pressure system just north of Lake Superior
late this afternoon will continue to move northeast across
Ontario tonight. Southwest to west gales will will continue into
the early morning hours on Wednesday, but steadily decrease
through this evening. Once the gale warning expires for the
nearshore waters, a small craft advisory will be issued, running
through about mid morning on Wednesday.

Winds will be a bit lighter Wednesday, but will remain gusty out
of the west. Lighter winds are then expected for Thursday into
Friday as high pressure moves through the region.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Gale Warning until 1 AM CDT Wednesday for LMZ080-261-362-364-366-
     563-565-567-643>646-669-671-673-675-777-779-868-870-872-874-
     876-878.

&&

$$

Tonight/Wednesday and Aviation/Marine...Davis
Wednesday Night through Tuesday...Cronce



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