Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 201048 AAA
AFDMKX

Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
548 AM CDT Sat Oct 20 2018

.UPDATE...

Clouds and showers are approaching from the northwest on schedule
early this morning. No significant updates to the forecast are
anticipated over the next few hours.

&&

.AVIATION(12Z TAFS)...

Quiet weather will persist through the early morning hours. The
only concern until daybreak remains some low level wind shear
from around the Watertown area westward. It will be a small window
for wind shear...until about 13Z, as winds at the surface will
pick up quickly after sunrise.

Attention then will turn to a trough and cold front that will drop
through the area this morning. This will bring showers to southern
Wisconsin along with gusty northwest winds and colder air. Could
see a mix with snow for a time...or maybe some graupel given the
convective nature of the precip. The precipitation will wind down
by mid-afternoon...with dry weather then expected through
tonight.

Ceilings could drop to near MVFR conditions for a short time as
the front and precip move through. Kept the forecast VFR for now
though given latest model soundings. Will keep an eye on upstream
obs.

&&

.PREV DISCUSSION... (Issued 251 AM CDT Sat Oct 20 2018)

SHORT TERM...

Today and tonight...Forecast confidence is medium to high:

A strong shortwave and cold front will drop through southern
Wisconsin this morning. This system will bring showers, colder
temps, and gusty northwest winds. The best chance for showers
will be after daybreak into early this afternoon. Model soundings
show it will be a close call with whether temps will be cold
enough for a mix with snow before the better moisture and lift
depart. Given lapse rates and the potential for the precip to be
of a convective nature...thinking at least graupel will be
possible...if not some snow. Left a rain/snow mix in the
forecast.

Wind gusts may approach advisory criteria late morning into mid-
afternoon, but thinking is that widespread gusts will remain just
below the 45 mph threshold.

Winds will ease this evening into tonight and skies will be mostly
clear. These conditions along with a colder airmass in place will
allow for below normal low temps in the mid to upper 20s.

Sunday through Monday night...Forecast confidence high.

A shortwave trough will move across Ontario Canada Sun-Sun nt
while a large high pressure area will move from the central
portion of the country to the east coast. Swly sfc winds and warm
advection will develop over srn WI with high temps near 50F on Sun
after a cold morning. Another larger upper trough and sfc low
will then track sewd across Ontario, Canada and into New York
State for Mon-Tue. It`s dry cold front will move across srn WI Mon
nt but not after a mild day on Mon.

LONG TERM...Tuesday through Friday...Forecast confidence medium.

Nwly sfc flow and cold advection will continue on Tue. Afterward,
impressive 500 mb height rises will occur with a large high
pressure area moving across the region for Wed-Thu. A slow moving
shortwave trough may then slowly approach from the Great Plains
for Thu-Fri but the evolution and timing is very uncertain.

AVIATION(09Z TAFS)...

Quiet weather will persist through the remainder of the night. The
only concern until daybreak will be some low level wind shear from
around the Watertown area westward. It will be a small window for
wind shear...from around 10-13Z, as winds at the surface will pick
up quickly after sunrise.

Attention then will turn to a trough and cold front that will drop
through the area this morning. This will bring showers to southern
Wisconsin along with gusty northwest winds and colder air. Could
see a mix with snow for a time...or maybe some graupel given the
convective nature of the precip. The precipitation will wind down
by mid-afternoon...with dry weather then expected through
tonight.

Ceilings could drop to near MVFR conditions for a short time as
the front and precip move through. Kept the forecast VFR for now
though given latest model soundings. Will keep an eye on upstream
obs.

MARINE...

Though winds are currently in a bit of a lull, will keep the Gale
Warning going for the open waters as winds will pick up through
the morning hours today. Highest gusts to 40 knots over the open
waters will be this afternoon.

The Gale Warning start time of 10 am this morning over the
nearshore waters still looks reasonable. The expiration time of 10
pm for the Gale Warning over the nearshore and open waters also
looks good based on the latest forecast winds.

The highest waves today will be across southeast portions of Lake
Michigan due to the northwest winds.

Left a mention of waterspout potential in the forecast for the
open waters today, particularly in the southern 2/3 of the lake.
May see some thunder there as well.

Could see gusts approach Small Craft Advisory levels over the
nearshore waters Sunday evening into Sunday night. Otherwise,
winds next week look generally lighter than this last week.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Gale Warning until 10 PM CDT this evening for LMZ080-669-671-673-
675-777-779-870-872-874-876-878-261-362-364-366-563-565-567-868.

     Small Craft Advisory until 10 AM CDT this morning for LMZ643>646.

     Gale Warning from 10 AM this morning to 10 PM CDT this evening
     for LMZ643>646.

&&

$$

Update...DDV
Today/Tonight and Aviation/Marine...DDV
Sunday THROUGH Friday...Gehring


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