FXUS63 KMKX 171705
Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1205 PM CDT Tue Jul 17 2018
.UPDATE...The forecast is on track for today and tonight.
.AVIATION(18Z TAFS)...SCT050 cumulus for the afternoon with brief
periods of broken cumulus expected along the lake breeze front.
Clear skies for tonight with fog only expected in some low lying
areas including the WI River Valley. More SCT050 cumulus for Wed.
.PREV DISCUSSION... (Issued 1002 AM CDT Tue Jul 17 2018)
UPDATE...Expect scattered cumulus to develop for the afternoon
hours given 850 mb temps of 10-13C. Still looking at high temps
of 77-81F but several degrees cooler at the Lake MI shoreline via
MARINE...Modest nely flow will prevail today and tonight. Waves
will build to 2-3 feet for the afternoon and evening hours.
Lighter onshore flow and lesser wave heights for Wed.
PREV DISCUSSION... (Issued 535 AM CDT Tue Jul 17 2018)
Quiet conditions out there. The forecast is on track.
VFR conditions are expected through most of the TAF period. There
should be some areas of fog late tonight, mainly after 09z Wed,
burning off quickly after sunrise. This would mainly impact the
KMSN and KENW airports. Look for the northwest winds near Lake
Michigan to veer northeast then east beginning later this
PREV DISCUSSION... (Issued 239 AM CDT Tue Jul 17 2018)
Today And Tonight...Forecast Confidence Is High.
Expect quiet conditions with temperatures near or slightly below
normal for this time of year. Winds will turn easterly along Lake
Michigan today, offering a little cooling close to the lake.
However, water temps across most of the lake are in the upper 60s
to mid 70s, so that cooling won't be too dramatic. Some fog is
possible tonight, especially in the favored low spots.
Wednesday Through Wednesday Night...Forecast Confidence Is High.
Models are in good agreement with high pressure sliding southeast
across the region during this period. This will result in quiet
weather continuing. Temperatures will be near seasonal normals,
with onshore winds keeping lakeshore areas a little cooler. Middle
to high clouds will start to move east into the area later
Wednesday night, as the 500 mb shortwave trough approaches from
Thursday Through Friday Night...Forecast Confidence Is Medium.
Models seem to be in a little better agreement with trends during
this period. They bring a negatively tilted 500 mb shortwave
trough into the area Thursday and lingers into Thursday night. A
500 mb low develops during this period in central Minnesota,
before shifting east into central or northern Wisconsin on Friday.
The GFS and ECMWF seem to show similar trends with this feature,
and followed those models for this forecast.
This system in nearly vertically stacked, with the corresponding
surface low taking a similar track as the 500 mb low. Rounds of
differential cyclonic vorticity advection during this period, with
some warm air and moisture advection Thursday and Thursday night,
should bring good chances for showers and some thunderstorms
later Thursday into Friday. Kept highest PoPs during this period.
GFS forecast soundings continue to show rather weak and skinny
mean layer CAPE, with weak to modest deep layer bulk shear. Slow
storm motions may lead to locally heavy rainfall with any storms.
Any rainfall will be welcome, given how dry it has been over the
area lately. Temperatures should be in the middle 70s to around 80
Thursday and Friday, held down a bit by the cloud cover.
Saturday Through Monday...Forecast Confidence Is Medium.
It looks like the GFS has trended a bit slower with taking the
weakening 500 mb low to the southeast of the area Saturday into
Sunday. The ECMWF has been consistently a slower model with taking
the low out of the region. Thus, kept PoPs going for Saturday into
Saturday night. Things may dry out later in the weekend into
Monday, as the low pulls further away from the region.
Temperatures look to remain near seasonal normals into early next
AVIATION(09Z TAF UPDATES)...
There could be some fog early this morning and again Wednesday
morning, especially in the favored low spots across southern
Wisconsin. Otherwise, expect VFR conditions through the TAF period
with light winds continuing. Winds will turn to the northeast
then east along the Lake Michigan shoreline later this morning.
Winds and waves will remain below Small Craft Advisory levels
through Thursday. Increasing southeast winds and waves Thursday
night and Friday will approach Small Craft Advisory levels,
especially north of Port Washington.
Today/Tonight and Aviation/Marine...Davis
Wednesday THROUGH Monday...Wood
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