Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 140448
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1148 PM CDT Wed Sep 13 2017

.UPDATE...


&&

.AVIATION(06Z TAFS)...

An area of IFR stratus was over the far southeast.

Expect another night of fog developing, peaking in area coverage
around sunrise, then mixing out by mid to late morning. Peak time
for the IFR/LIFR fog will be around 08-14z. The fog should be
most widespread across the southeast. After the fog dissipates,
look for VFR conditions across the area with winds less than
10kts by Thursday afternoon.

Winds will be higher Thursday night, so not as much fog expected
then.

&&

.PREV DISCUSSION... (Issued 855 PM CDT Wed Sep 13 2017)

UPDATE...

Considered a dense fog advisory, as model/MOS consensus grids
still develop dense fog late tonight over the southeast. However
there is a bit more of a pressure gradient, and prefer to hold off
on any headlines at this time, as the 18Z GFS MOS only has dense
fog in the river valley and the usual low locations.

MARINE...

The fog has dissipated, but a repeat of conditions is expected
overnight. Therefore, the marine dense fog advisory is continued
through the night into the mid morning hours on Thursday. This
advisory may have to be extended south toward Kenosha if the fog
expands farther south. However there is a little more of a
pressure gradient, so will not change headlines attm.

PREV DISCUSSION... (Issued 659 PM CDT Wed Sep 13 2017)

UPDATE...

AVIATION(00Z TAFS)...

An area of MVFR stratus was over the far southeast tip near
kenosha, but mainly to the south and east. This may spread back
into the far southeast.

Expect another night of fog developing, peaking around sunrise,
then mixing out by mid to late morning. Peak time for the IFR?LIFR
fog will be around 07-15z Thursday. The fog should be most
widespread across the southeast. Prior to fog development and
after it dissipates, look for VFR conditions across the area with
winds less than 10kts.

PREV DISCUSSION... (Issued 252 PM CDT Wed Sep 13 2017)

DISCUSSION...

Tonight...Forecast confidence is high.

The upper circulation over the Ohio Valley...the remains of
Irma...will continue to slide off to the east. Conditions across
southern Wisconsin will be similar to the past few nights. A good
radiational cooling setup, so temps a bit below guidance with the
threat of dense fog looking even better tonight, especially
across the southeast. Pesky fog over Lake Michigan north of
Milwaukee may clear for a time later this afternoon or evening,
but will likely come right back. So, be prepared for some areas of
dense fog. We`ll issue headlines for the fog as needed, once we
get a handle on trends.

Thursday through Saturday...Forecast Confidence is high.

With old Irma heading into New England by Friday, we get into a
warmer southwest flow. Temps on Thursday will be a touch above
today, with Friday and Saturday looking very warm for mid
September. Look for highs as we head into the weekend in the lower
to mid 80s. Plenty of sun to go along with that.

Saturday night and Sunday...Forecast confidence is medium.

A low pressure system and associated cold front will push into the
area later Saturday night, exiting southeast Wisconsin Sunday
afternoon. We should see showers and a few thunderstorms accompany
the front. In classic fall fashion, the CAPE values aren`t very
impressive and it`s all rather elevated, so nothing of concern at
this time. We won`t be able to recover much on Sunday before the
front exits to the east. Hopefully, we can get a little needed
rainfall for the area.

Monday and Tuesday...Forecast confidence is medium.

The front that comes through on Sunday will stall to the south of
Wisconsin, then begin to head back north on Monday as a warm
front as the low level jet strengthens to the west. Some of the
guidance is generating a bigger complex of showers/storms across
southeast MN into central/nrn WI on Monday, closer to the nose of
the jet. We could see some activity across southern Wisconsin with
the warm front Monday afternoon into Monday night. We then stay in
a warm/moist southerly flow into Tuesday, but given the lack of
any forcing mechanism, Tuesday looks dry at this time. Same for
Wednesday.

AVIATION(18Z TAFS)...

We remain in a persistent pattern and that means another night of
fog developing, peaking around sunrise, then mixing out by mid to
late morning. Peak time for the fog will be around 07-15z
Thursday. The fog should be most widespread across the southeast.
Prior to fog development and after it dissipates, look for VFR
conditions across the area with winds less than 10kts.

MARINE...

The marine fog has been pesky and rather unpredictable today.
There is a stubborn marine later that obviously has some pooling
dew points trapped under a cooler inversion. The fog may
dissipate for a time later this afternoon and evening, but a
repeat of conditions is expected overnight. Therefore, the marine
dense fog advisory has been extended through the night into the
mid morning hours on Thursday. This advisory may have to be
extended south toward Kenosha if the fog expands farther south.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Dense Fog Advisory until 10 AM CDT Thursday for LMZ643-644.

&&

$$

Update...Hentz
Tonight/Thursday and Aviation/Marine...Davis
Thursday Night through Wednesday...Davis



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