Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 191732 AAA
AFDMKX

Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
1232 PM CDT Sat May 19 2018

.UPDATE...

The fog over Milwaukee and other lakeshore areas is gradually
shifting toward the shoreline. Elsewhere, visibilities improved as
a light northwest breeze kicked in. Expect more breaks in the
clouds to develop from Madison to Janesville and west this
afternoon. There`s a much lower chance for sunshine east of there.

&&

.AVIATION(18Z TAFS)...

Fog over Milwaukee shifted toward the shoreline around noon.
There`s another chance for the fog and low clouds to move back in
early this evening until the northeast winds develop.

Low clouds will gradually lift to MVFR and possibly VFR this
afternoon. Expect breaks in the clouds with possible VFR bases from
MSN to JVL and west, less of a chance east.

Showers and a few storms will spread into central/southwest WI
late this afternoon and across southeast WI late this evening.
Showers, MVFR/IFR ceilings, and 2 to 4SM visibilities are expected
at times through Monday.

&&

.PREV DISCUSSION... (Issued 946 AM CDT Sat May 19 2018)

UPDATE...

Dense fog developed over the nearshore waters this morning due to
light wind flow and dewpoints around 50 degrees when the water
temperatures are only in the lower 40s at best. The fog is
impacting shoreline areas including Mitchell Airport. Farther
inland, visibility is in the 3 to 6 mile range with patchy
drizzle. Visibility will gradually improve through late morning.
Inland fog will clear out for early afternoon as a mid level
trough clears the region. Near the lakeshore, fog is expected to
remain in place until steadier northeast winds scour it out later
this evening. There is uncertainty about lakeshore visibilities
later today since we will continue to have an onshore wind
component.

There is a batch of showers and thunderstorms over northern
Missouri/southern Iowa that will make its way up to southwest WI
early this evening. The timing is delayed from the previous
forecast. This is associated with a mid level upper low drifting
over the Plains. Showers and any storms over southern WI will be
weakening as they reach us, so the main threat is lightning
through the evening hours.

Light showers will linger over southern WI all the way through
Sunday afternoon and potentially Monday.

MARINE...

Dense fog developed over the nearshore waters this morning. This
is due to light wind flow and dewpoints around 50 degrees when
the water temperatures are only in the lower 40s at best. Winds
will remain light until this evening when northeast winds increase
from north to south. The winds and a drier air mass will help to
scour out the fog during the evening hours. A marine dense fog
advisory is in effect.

AVIATION(15Z TAFS)...

Dense fog developed over the nearshore waters this morning and
light onshore winds are advecting it inland and impacting
lakeshore areas including Mitchell Airport. I expect the 1/4 to
1/2SM visibility to come and go through late morning and begin to
improve through early afternoon. There is uncertainty to how much
the visibilities will improve, given that we should have an
onshore wind component through the afternoon. Ceilings should
generally improve through the afternoon, but with the same
uncertainty.

Inland areas will see improving visibilities through late morning
and clear conditions this afternoon. There is still a small chance
for thunder with the showers moving in from the Plains this
evening. Timing is delayed from previous forecast. Showers and low
ceilings will persist through Sunday morning but may return at
times through Monday.

PREV DISCUSSION... (Issued 606 AM CDT Sat May 19 2018)

UPDATE...

Areas of drizzle through mid morning.

AVIATION(12Z TAFS)...

LIFR/IFR is expected until late morning.

Conditions should improve during the late morning to mid day
hours, though ceilings may be slow to lift, especially across the
east. Right now it looks like several hours of VFR should occur
Saturday afternoon, especially south central, before ceilings fall
back to MVFR Saturday night.

PREV DISCUSSION... (Issued 203 AM CDT Sat May 19 2018)

SHORT TERM...

Today and Tonight...Forecast Confidence - Medium.

Mid level low over Illinois will continue to move slowly
east/northeast in response to upstream western CONUS trof, along
with a lead shortwave moving into the central plains. Meanwhile a
northern stream shortwave moves across the lake Superior area.

Fairly moist sounding this morning with some mid level drying
during the afternoon.  low level into southern WI through the
evening. Precipitable water values around 1.5" in the southeast,
lowers to around 1.0 inch by evening. As the mid level low moves
off to the east this morning, the light rain will end.  As the
low level winds turn northwest this afternoon, a cold front
associated with the northern stream shortwave will move across
southern WI into the evening. This will bring showers and a few
thunderstorms late this afternoon and evening. Forecast sounding
show a little less than 500 joules/kg. lapse rates around 6 C/km
with zero to 3 km shear around 20-25 knots. Therefore severe
threat is minimal.

Sunday through MONDAY...Forecast Confidence - Medium.

A Central Plains low will then move along a nearly stationary
frontal boundary draped across the central Mississippi and Upper
ohio River valleys.  Secondary weak area of low pressure may pass
close to southern WI later Sunday Night into Monday, so wl keep
shower and small thunder chances. Passing systems will be weak so
QPF will be fairly light, which will allow current rivers in
Minor Flood stage to continue to slowly subside.

LONG TERM...

MONDAY NIGHT THROUGH FRIDAY...Forecast Confidence - Medium.

Weak zonal steering flow aloft transitioning to weak long-wave
ridging across the central CONUS later in the period. Temperatures
look to remain near or above seasonal normal for much of the
period with weak east to southeast surface winds resulting in
cooler by the lake conditions most days. A weak frontal boundary
wavering across the central MS Valley region may occasionally
trigger a few showers that may brush southern, and especially
south central Wisconsin, but nothing organized or widespread
anticipated, as surface high pressure moves slowly across the
Great Lakes region.

AVIATION(06Z TAFS)...

IFR/LIFR is expected until mid morning. The highest potential for
LIFR will be at KMKE and KENW.

Conditions should improve during the mid morning to mid day hours,
though ceilings may be slow to lift, especially across the east.
Right now it looks like several hours of VFR will occur Saturday
afternoon, especially south central, before ceilings fall back to
MVFR Saturday night.

MARINE...

Easterly winds will continue before becoming more northerly
tomorrow. Waves tonight should remain in the 2-3 foot range.

Stronger north winds will then push down the lake Saturday night
into Sunday. Winds/Waves during this time may become high enough
to require a Small Craft Advisory.

Monday and Tuesday look to be fairly calm, before multiple
chances for thunderstorms develop by mid week.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Dense Fog Advisory until midnight CDT tonight for LMZ645-646.

     Dense Fog Advisory until 9 PM CDT this evening for LMZ643-644.

&&

$$

Update...Cronce
Today/Tonight and Aviation/Marine...Hentz
Sunday THROUGH Friday...Hentz



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