Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

909
FXUS63 KMKX 201442
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
942 AM CDT Tue Aug 20 2019

.UPDATE...

The higher humidity air nudging into the area this morning had
resulted in widespread low clouds and fog with some patchy dense
fog. Obs and webcams suggest some of the fog is lingering but
should begin to clear as we go through the morning. The MCS that
had developed over MN/IA overnight is now pushing S/SE into
central and northern IL. A MCV tied to this MCS will end up
passing just south of the area as it moves out of Iowa and into
northern IL. There is a decent instability gradient situated along
the WI/IL border and as the MCV moves into this higher instability
air, we expect a few stronger storms to develop just south of the
area. The cloud cover should keep temperatures in check for much
of the morning and thus limit our overall storm potential.

Looking off to the NW a shortwave moving across northern MN/WI has
generated another line of convection and this is heading S/SE.
We`ll need to watch this band of storms has it might have a better
shot of bringing us a rain. The only issue is that it might start
to take a more southerly track and follow the higher
theta-e/instability axis down into IA. That would lead to only the
western area getting clipped by the storms.

Needless to say we will be watching trends this morning closely
and trying to determine what impact the MCV/MCS will have on storm
potential this afternoon.

&&

.MARINE...

Patchy marine dense fog has developed this morning along the
Sheboygan nearshore waters and a Marine Dense Fog advisory is in
effect until 11 AM. Winds stay out of the south for much of the
day but begin to shift to the west as a front nears the area.
Expect showers and storms along the southern portions of the lake
through the evening hours.


&&

.PREV DISCUSSION... (Issued 622 AM CDT Tue Aug 20 2019)

UPDATE...
Showers and maybe few thunderstorms will likely clip southwest
Wisconsin this morning. The cells on the northern end of the
complex over Iowa are weakening as they move into lower cape
environment. Still expect the core of the activity to move
southeast where the environment is more favorable for storms.
Details in previous discussion.

AVIATION(12Z TAFS)...
High clouds are rapidly moving in ahead of storms in Iowa which
should erode the fog. Light south to southwest winds will be less
than 10 knots today. Thunderstorms may impact far southwest and
southern Wisconsin late this morning. MVFR ceilings are likely,
especially for far southwest Wisconsin.

Then there is a very small chance for thunderstorms
this afternoon. A cold front will move through early Wednesday
morning bringing north winds and MVFR or IFR ceilings. These lower
ceilings will likely continue through the morning or early
afternoon then improve.

PREV DISCUSSION... (Issued 252 AM CDT Tue Aug 20 2019)

SHORT TERM...

Today and Tonight...Forecast confidence medium.

Storms currently over northern Iowa could clip southwest Wisconsin
later this morning. Can`t rule out something strong to severe, but
the more favored area for this is southwest of Wisconsin. These
storms are expected to form into a line with the core of the
activity diving south as it approaches southern Wisconsin.

Storms over north-central Iowa developed on the nose of a developing
low level jet where there is 1500 J of MU cape. A shortwave is
moving through this region and it is expected to track just
southwest of Wisconsin. An instability gradient lies from northern
Iowa to northern Illinois, along with 925-850mb baroclinic zone, and
the mean wind is west southwest. This favors the core of the severe
activity to track to our southwest. Despite a cap this morning, cape
will be around 1500 J with 20 knots of shear so could see
thunderstorms on the strong side.

The RAP shows us becoming uncapped this afternoon so will have to
watch for any thunderstorms popping up. We will likely have
subsidence behind the shortwave and MCS so this is just a small
chance.

Another shortwave will be moving north to south across Wisconsin
later Tuesday, reaching us late evening. This brings a small
chance for thunderstorms. The instability and shear will still be
in place.

Wednesday...Forecast confidence high.

A cold front will move through early Wednesday morning bringing
north winds. It will be cloudy and dry.

LONG TERM...

Thursday through Saturday...Forecast Confidence High...

High pressure will be building into the area Wednesday night into
Thursday morning, and will remain anchored across the Great Lakes
through the rest of the week. This will set the stage for a few
cool days and nights, with highs in the low to mid 70s Thursday to
Saturday, and overnight lows in the low to mid 50s. It wouldn`t
be at all surprising to see a few of the usual cool spots across
central Wisconsin dip into the upper 40s Friday morning.

Sunday and Monday...Forecast Confidence Moderate.

Temps Sunday will likely warm back to around 80, with increasing
moisture as winds come around to the south. Another frontal
boundary should begin to approach from the west late Sunday into
Monday, which will be the next chance for showers/thunderstorms.

AVIATION(9Z TAFS)...Fog will impact the low lying areas early
this morning. Light south to southwest winds will be less than 10
knots. Thunderstorms may impact far southwest and southern
Wisconsin late this morning. MVFR ceilings are likely, especially
for far southwest Wisconsin.

Then there is a very small chance for thunderstorms
this afternoon. A cold front will move through early Wednesday
morning bringing north winds and MVFR or IFR ceilings.

MARINE...
South to southwest winds on Tuesday will be 10 to
20 knots. Waves will be 3 feet or less across the open waters.
Lighter winds are expected Tuesday night. A cold front will move
down the lake around sunrise Wednesday morning, reaching the
southern part late morning. North winds will gust around 20 knots on
Wednesday. Lighter winds are expected Wednesday night.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Dense Fog Advisory until 11 AM CDT this morning for LMZ643.

&&

$$

Update...Stumpf
Today/Tonight and Aviation/Marine...Marquardt
Wednesday THROUGH Monday...Boxell



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.