Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 292029
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
329 PM CDT WED JUN 29 2016

.TONIGHT AND THURSDAY...Forecast Confidence - Moderate.

Quiet weather will prevail tonight as high pressure drifts out of
the region. The flow becomes southwest behind the departing high
bringing in a more moist airmass.

Precip and embedded thunderstorms looks like they won`t impact the
area until the afternoon in south-central to early evening in the
east. A deep 500mb trough approaches the region from northwest WI.
The best forcing is later in the afternoon into the evening when
moves across central/southern WI. During this time there is
additional forcing from the left entrance region of a 80kt 250mb jet
that develops west of the state. Meso models are in fairly good
agreement showing a line of precip along the surface cold front that
moves through during the late afternoon/evening. Subsidence behind
the mid level trough axis is quick to follow later in the evening.

There is decent model consensus for dewpoints around 60 resulting in
CAPE up to about 1000j/kg, though the gfs and nam are on the higher
side of these parameters. 0 to 6 km shear is 20 to 35 knots depending
on the model. As a result, SPC has us in a Marginal Severe Risk.

.THURSDAY NIGHT...FORECAST CONFIDENCE HIGH

Mid-upper trough axes do not reach the Lake Michigan shore until 06Z
Friday, with subsidence and mid-level drying spreading in behind.
Will keep chance of showers in the west with likely PoPs in the east
where stronger low-mid layer frontogenetic forcing and convergence
along the surface cold front and 850 mb trough axis lingers at 00Z,
then taper PoPs off from west to east through the evening as forcing
shifts east.

2-meter dew points appear too high on GFS/NAM that brings CAPE
values between 1100 to 1300 J/kg ahead of the front and keeps 500-
1000J/kg of CAPE post-frontal until late in the evening. Followed
lower MOS guidance numbers which are also reflected in consensus dew
points. Still produces enough instability to keep mention of
thunder going.

Will see lows dip into the mid 50s north and upper 50s near the
Illinois border by Friday morning as cold advection drops 850 mb
temps 4c to 5C and 925mb temps between 6C and 9C from 00Z to 12Z
Friday as surface high builds in.

.FRIDAY THROUGH SATURDAY NIGHT...FORECAST CONFIDENCE HIGH.

Great start to the holiday weekend as surface high pressure
remains in control. Upper jet in west-northwest flow settles over
the western Great Lakes region with southern Wisconsin between the
500 mb cyclonic circulation over eastern Canada and short wave
energy running to the south of the upper jet.

850 mb thermal trough centered over Wisconsin at 12Z Friday shifts
to the eastern Great Lakes by 00Z Saturday. The 850 mb baroclinic
zone drops south and then stalls, wavering between central IL to
southern IL with the passage of a short wave early Saturday and
another Saturday night. Precipitation will remain tied to this
baroclinic zone and the surface warm front well south of the region
through Saturday night.

Though no strong warm advection, 850-925 mb temperatures moderate
upward with weak return flow around the high as it slowly settles to
the southeast. Cool highs in the mid 70s Friday warm into the upper
70s for Saturday. Look for cool overnight lows in the lower to
middle 50s Friday night with mid to upper 50s Saturday night.

.LONG TERM...SUNDAY THROUGH WEDNESDAY...FORECAST CONFIDENCE
MEDIUM.

Models differ handling strength and position of short wave trough
and associated surface low passing south of the state Sunday night
and Monday. GFS brushes the far southeast with QPF Monday morning
while the Canadian GEMNH covers all but the far northern counties
with QPF through the day as both have a well-developed surface low
crossing central IL. ECMWF has a weaker short wave and surface
feature keeping the precipitation in IL. Will follow consensus blend
that brings slight chance PoPs into the far southeast Monday.

Short wave ridging keeps Monday night and Tuesday dry. More
differences with a short wave crossing the central U.S. and another,
stronger wave moving along the U.S. Canadian border Tuesday night
into Wednesday night leads to chance PoPs for the rest of the
extended. Temperatures warm from slightly below, to near-normal
levels Sunday and Monday, to above normal for Tuesday and Wednesday.

&&

.AVIATION/00Z TAFS/...

Some cirrus and light winds will prevail tonight. Winds will become
southwest around 10 to 15 knots on Thursday with gusts up to 20
knots. A cold front will bring a line of showers and thunderstorms
late Thursday afternoon into the evening with MVFR conditions
possible.

&&

.MARINE...

Lighter winds are expected over the near shore waters
tonight as weak high pressure departs the region. South winds around
10 knots are expected for Thursday. A passing cold front will bring
a period of showers and storms late Thursday afternoon into
the evening.

&&

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

$$

TONIGHT/Thursday AND AVIATION/MARINE...Marquardt
Thursday NIGHT THROUGH Wednesday...REM


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