Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 161126
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
626 AM CDT Tue May 16 2017

.UPDATE...

Overnight convection still messing with the warm front boundary.
As the morning goes on south/southwest winds should become
established as the warm front lifts north, taking the isolated
showers/thunderstorms with it. Mainly south/southeast winds near
Lake Michigan due to a lake breeze.

&&

.AVIATION(12Z TAFS)...

Overnight convection still messing with the warm front boundary.
As the morning goes on south/southwest winds should become
established as the warm front lifts north, taking the isolated
showers/thunderstorms with it. Mainly south/southeast winds near
Lake Michigan due to a lake breeze. Some IFR fog along Lake
Michigan, north of Milwaukee. otherwise VFR conditions.

Wind shear is expected Tonight as winds at 2 thsd ft increase.

&&

.PREV DISCUSSION... (Issued 313 AM CDT Tue May 16 2017)

Today and Tonight...Forecast Confidence is Medium...

An upper level ridge extends north into the central great lakes
region, with upper divergence across southern Wisconsin lifting
north this morning.

A large upper tough across the central and southern Rockies will
begin to lift northeast into the central high plains tonight.
The strong 120 knot jet max at the base of the trough will lift
north into Iowa by sunrise Wednesday. This increases the upper
divergence across southern Wisconsin during the wednesday early
morning hours. This should lift the lingering thunderstorms in our
north areas into central Wisconsin.

The surface warm front should be north of the forecast area today
with southern Wisconsin well into the warm sector trough tonight.

Forecast soundings show a strong cap developing in the warm
sector. This cap weakens a little and rises tonight, but should
inhibit thunderstorm development despite the 2000 joules/kg of
CAPE. Will bring a chance of thunderstorms later this evening
mainly far west and northwest closer to the developing lift late
with the approaching upper trough.

Wednesday and Thursday...Forecast confidence is Medium.

South to southwesterly flow dominates as another low approaches
from the central plains. The chance for thunderstorms continues and
increases during the afternoon on Wednesday. Mid level shortwaves
move across the region ahead of the negatively tilted mid level low.
A broad low level jet redevelops and surges into southern WI during
the afternoon. Soundings show elevated CAPE rooted around 900-850mb
where there is warm air advection and good moisture transport. PWs
increase to 1.5. Model consensus yields about 800-1000 J/kg Cape
with 40 knots of shear. SPC has us in a Marginal Risk for Wednesday.

There is a small chance of thunderstorms through Thursday morning
until the upper low and shortwave activity moves off to the north.
Winds become northwest later Thursday morning behind a cold front
and drier air moves into the region. Mid level ridging dominates
through Friday morning before the next system arrives.

Friday through Monday...Forecast confidence is Medium.

Agreement is pretty good on the next low moving across the
state Saturday night. Precip chances increase on Friday with
widespread rain likely on Saturday. There is enough instability on
Saturday for some thunderstorms. A dry slot punches through
on Sunday, but a shortwave moves through on Sunday and cyclonic flow
lingers bringing a small chance for showers. Then high pressure
pushes in from the southwest bringing dry weather for Monday.

AVIATION(06Z TAFS)...

Convection in the La Crosse area is expanding east as it lifts
north with a warm front overnight. These storms could clip the
Dells and Montello areas for a short period of time.

Breezy southwest winds just above the lighter south to southeast
winds at the surface are causing wind shear overnight into early
Tuesday morning. Expect warm and breezy southwest winds on
Tuesday. Wind shear is expected again Tuesday night.

MARINE...

Winds will increase out of the southwest this morning. Wind gusts
up to 25 knots are expected this afternoon into tonight.
Brisk winds will continue into Thursday as strong low pressure
moves into Iowa Wednesday, then lifts northeast. A small craft
advisory is in effect from noon today until 3 pm cdt Thursday.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Small Craft Advisory from noon today to 4 PM CDT Thursday for
     LMZ643>646.

&&

$$

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



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