Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 291651 AAA
AFDMKX

Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
1151 AM CDT FRI JUL 29 2016

.UPDATE...

Scattered showers continue across portions of the area this
morning, in association with slow moving 500 mb shortwave trough
and inverted surface trough. There may be some divergence at 250
mb as well from left front quadrant of jet streak.

Low cloud deck also lingering across the entire area, with
northeast winds. This is keeping temperatures in the mid/upper 60s
in the northwestern portions of the area, with lower to mid 70s in
the southeast. The southeast had some sunshine this morning,
resulting in the warmer temperatures.

The 500 mb shortwave trough is expected to slowly move east across
far southern Wisconsin and northern Illinois this afternoon and
tonight, before sliding to the east on Saturday. The inverted
surface trough may linger into tonight and perhaps Saturday across
the area as well. 12Z model runs seem to hang onto light QPF
across southern and eastern portions of the area into Saturday.
Thus, carrying at least small POPs for showers and storms into
Saturday should continue, especially in the south and east.

Area forecast soundings show moist adiabatic profiles with tall
skinny mean layer CAPE at times into Saturday. The Storm
Prediction Center put the far southeast in a Marginal Risk for
severe storms this afternoon and evening, though think any storms
that develop will remain below severe levels in this area.

Heavy rainfall parameters are favorable at times, with slow
propagation of any cells. May see locally heavy rainfall with any
of the showers/storms that move slowly, especially over the urban
areas.

Low clouds should gradually raise in height this afternoon into
tonight, until becoming partly cloudy later tonight into Saturday.
Persistent northeast winds should keep highs in the 70s in most
areas this afternoon, cooler at the lakeshore.

&&

.AVIATION/18Z TAFS/...

Scattered showers and a few thunderstorms are expected from time
to time this afternoon into Saturday at TAF sites. IFR/MVFR
ceilings should gradually rise to VFR levels by later this
afternoon. They should remain at VFR levels tonight into Saturday
across TAF sites.

Visibilities should remain at VFR levels this afternoon into this
evening. Brief lower visibilities are possible in any showers or
storms. May see MVFR category light fog later tonight into early
Saturday morning at TAF sites. Northeast winds should persist this
afternoon, tonight and Saturday.

&&

.MARINE...

East to northeast winds of 10 to 20 knots are expected this
afternoon into early this evening, before weakening somewhat
tonight into early Saturday. May see 20 knot gusts again by
Saturday afternoon. These winds should bring waves into the 3 to
4 foot range south of Wind Point this afternoon, with 2 to 4 foot
waves to the north. 2 to 4 foot waves should linger into tonight,
slowly subsiding Saturday into Saturday night.

No Small Craft Advisory will be issued at this time for this
afternoon and early evening, but small craft should exercise
caution south of Wind Point.

&&

.BEACHES...

Persistent northeast winds and 2 to 4 foot waves should continue
to bring a Moderate Swim Risk to the beaches along Lake Michigan
into this afternoon, and again Saturday. Do not anticipate a Beach
Hazards Statement at this time, as northeast winds should remain
in the 10 to 20 MPH range.

&&

.PREV DISCUSSION... /Issued 338 AM CDT FRI JUL 29 2016/

TODAY AND TONIGHT...Forecast Confidence Medium

Broad mid-upper level cyclonic flow remains anchored over the region
with models in good agreement with a fairly vigorous short wave,
currently moving into western Iowa on water vapor imagery as it runs
with a 250 mb speed max, slowing as it crosses the WI/IL border
region today into this evening.

Will focus precipitation chances in the sw half of the CWA with the
better 700 mb omega in the deformation zone on the northern flank of
weak 850 mb and 700 mb lows associated with this short wave, and low-
level convergence along weak surface troughs rotating east to west
around diffuse surface low wobbling around the IL/IN border that
eventually shifts east tonight.

Forecast most-unstable CAPE values climb to between 500 J/kg and
1000 J/kg, but northeast winds bringing lower 925 mb temperatures
into srn WI and early cloud cover will limit heating and resulting
amount of instability. Will go with chance showers/slight chance
thunderstorms.

Will slowly lower PoPS from nw to se tonight as drier air advects in
with lobe of surface high pressure nosing into southern Wisconsin as
the weak surface low shifts east and the axis of the short wave
trough reaches lower Michigan by 12Z Saturday. Lingering cloud cover
and onshore flow off now seasonably warm Lake Michigan water will
hold lows in the mid 60s in the southeast CWA, with the upper 50s in
the far northwest with potential of lowering cloud cover closer to
the axis of surface high lobe.

SATURDAY...Forecast Confidence...Medium

It looks mainly dry Saturday, as lower precipitable water values
arrive from the northeast. Deeper moisture and some instability
will linger toward the south and west, so did keep some low pops
there. Otherwise, it looks like a pleasant start to the weekend
with some sunshine and highs in the mid to upper 70s.

SUNDAY AND MONDAY...Forecast Confidence...Medium

It should be mainly dry Sunday and Monday with southern Wisconsin
sitting under the western portion of high pressure. Did put some
low pops in parts of the eastern forecast area Sunday afternoon
due to higher moisture advecting in from the east along with some
low level convergence. Temperatures should be within a couple
degrees of normal early next week.

MONDAY NIGHT THROUGH THURSDAY...Forecast Confidence...Medium

Deeper moisture is progged to return Monday night into Tuesday,
persisting across the region through Thursday. Some warm
advection aloft and a shortwave will provide lift for the first
round of showers and storms by later Monday night. The best
chance for storms is expected to be on Tuesday as the wave moves
through. The GFS is slower than the ECMWF and Canadian though, and
moves the wave through Tuesday night. Left some pops going then
through Thursday, as it will not take much lift to kick of more
showers/storms with deep moisture lingering.

Temps Tuesday through Thursday will be largely dependent on the
timing of clouds/precip. Overall though, will likely see highs a
few degrees above normal.

AVIATION/12Z TAFS/...

Tricky cloud cover early in the forecast as cigs bounce between
MVFR/IFR with high low-level RH with surface convergence over
southern WI. Guidance indicates rising northeast winds will bring in
slightly drier air to the northeast forecast area lifting cigs to
VFR by mid-morning while the southwest may see MVFR linger until mid-
afternoon. The southwest and south will also see the best chance of
showers and isolated thunderstorms today into tonight with passage
of a mid-level wave. Will keep mention of pcpn as vicinity or prob30
for now. SOme patchy fog is possible tonight, especially in the
southeast.

MARINE...

Northeast winds and wave heights are again marginal for a small
craft advisory today and remain just below criteria through Saturday
night. Will have a mention of caution for small craft in the
forecast for the southern zones today but no headline. Looking for
scattered showers and isolated thunderstorms through the day and into
tonight with passage of a mid-level wave.

&&

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

$$

UPDATE...Wood
TODAY/TONIGHT AND AVIATION/MARINE...REM
Saturday THROUGH Thursday...DDV



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