Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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773
FXUS63 KMKX 180240
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
940 PM CDT SUN JUL 17 2016

.UPDATE...A dry and weak cold frontal passage will occur tonight.
High pressure will then build into srn WI for Monday afternoon and
night. High temps in the mid 80s for Monday with lower humidity
values.


&&

.AVIATION/06Z TAFS/...Sct035-040 with a weak cool frontal passage
this evening into the early morning hours of Monday but no
showers or tstorms are expected. High pressure and VFR conditions
to then prevail for Monday afternoon and night.


&&

.MARINE...Cancelled the SCA for the nearshore waters as the gusty
swly winds have decreased with sunset. Wave heights have also been
diminishing and will continue to do so through the night. Light
winds and low wave heights are expected for the early portion of
the week.


&&

.PREV DISCUSSION... /Issued 338 PM CDT SUN JUL 17 2016/

TONIGHT... Forecast confidence is medium.

Shower and thunderstorm chances are dwindling quickly across
southern WI. The latest Convective Outlook from SPC cut the whole
area of Slight Risk out of WI and kept only the south half of the
MKX forecast area in a Marginal Risk. We continue to decrease shower
and thunderstorm chances across southern WI with each update. There
is warm air at 700mb that is spreading northward through WI this
afternoon and this will act as a lid on convection, even with the
surface frontal forcing.

High dewpoint temperatures around 70 are pooling up along and ahead
of the front this afternoon, so it will be a muggy evening as mixing
decreases and winds die down.

Low temperatures tonight should drop into the lower to mid 60s
inland from the lake as drier air works into the region behind the
front. Expect clearing skies overnight behind the front. There could
be some patchy fog in low lying areas and river valleys.

MONDAY... Forecast confidence is high.

High pressure will bring quiet weather and drier conditions to
southern WI on Monday. Plenty of sunshine will allow for highs in
the lower 80s. Winds will be fairly light out of the northwest.

MONDAY NIGHT AND TUESDAY...Forecast confidence is medium.

Right now this is a dry period. We see a building ridge across
Wisconsin and the western Great Lakes. However, on Tuesday, there
is some warm and moist air advection that could bring some showers
and storms to far western Wisconsin. We`ll have to keep an eye on
things to make sure they stay west of the forecast area. Right
now, that looks to be the case. We should see some increasing clouds
from the west.

TUESDAY NIGHT AND WEDNESDAY...Forecast confidence is medium.

The axis of the large ridge slides east a bit and the low level
jet increases upstream, allowing for some sustained deep warm and
moist air advection. At least for a time, we get under the right
entrance region of the upper jet and there is the potential for
some short wave energy to ride over/through the top of the mid
level ridge and into Wisconsin. We should see CAPE values climb to
about 2000j/kg but deep layer shear may only be on the order 25 to
30kts. This is enough to justify higher chances of thunderstorms,
especially by Wednesday.

THURSDAY AND FRIDAY...Forecast confidence is medium.

The building heat is the main concern this period. That warm air
advection Wednesday into Wed ngt will have pushed 925mb temps
into the upper 20s C and this should translate into sfc temps
pushing into the lower and mid 90s. There`s just a lingering small
chance of thunderstorms across the east on Thursday, but
confidence is pretty low that will happen. We`ll probably be too
capped off, but a few of the models try to develop some precip. On
Friday, a cold front will be dropping south through the state and
this could be a focus for some storms.

SATURDAY...Forecast confidence is medium.

We should be a little cooler in the wake of a passing cold front,
but that front will be lingering in the area, providing a
lingering small chance of showers and storms right into Sunday.

AVIATION/00Z TAFS/...

Gusty southwest winds will gradually diminish early this evening. A
cold front will move through southern WI late in the evening, so
expect a wind shift to the northwest by morning, although winds will
be light. Northwest winds will continue to be on the lighter side
Monday.

Drier air will work into southern WI behind the cold front, so I am
not expecting low clouds overnight. Low lying areas and river
valleys will be susceptible to some patchy fog early Monday morning.

MARINE...

Gusty southwest winds will persist through late afternoon due to a
tight pressure gradient ahead of an approaching cold front. A Small
Craft Advisory is in effect through mid evening.

Winds and waves will diminish tonight as the cold front moves
through and winds veer to the west and subside. There is a minimal
chance for showers and thunderstorms this afternoon.

BEACHES...

Winds became more southwest than anticipated this afternoon. Thus,
there is a lower risk of rip currents and other dangerous currents
through the evening due to the off shore flow. Therefore, I
cancelled the Beach Hazards Statement.

&&

.MKX Watches/Warnings/Advisories...
WI...None.
LM...None.
&&

$$

UPDATE...Gehring
TONIGHT/Monday AND AVIATION/MARINE...MRC
Monday NIGHT THROUGH Sunday...Davis



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