Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
FXUS63 KMKX 300258
Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
958 PM CDT FRI JUL 29 2016
.UPDATE...Showers continue to dissipate and develop across srn WI
with the most concentration near Lake WI and from ern Lafayette
County to wrn Rock County. These areas of showers should mostly
dissipate by midnight. The shortwave trough over nrn IL and the
associated sfc trough from IL to IN will continue to move slowly
ewd tnt-Sat. Thus isold to sct showers will continue to be
possible tnt into Sat although shower coverage on Sat should be
less than the prior two days as the main upper trough has moved to
.AVIATION/06Z TAFS/...The nely winds may lower enough tnt to allow
patchy fog and/or a low stratus deck to develop over south
central WI, especially where rain has already fallen. If low
stratus does form it likely will be around 1 kft or possibly
lower. Vsby reductions would be in the mvfr range on average. Cloud
bases will lift through Sat AM to 3.5-4.0 kft for the afternoon.
Sky coverage will be sct-bkn for the afternoon with slight
chances of showers and tstorms.
.MARINE...A persistent nely fetch will continue on Sat with waves
of 2-4 feet. The winds and waves will lower for Sun.
.PREV DISCUSSION... /Issued 328 PM CDT FRI JUL 29 2016/
TONIGHT AND SATURDAY...Forecast Confidence Is Medium.
Scattered showers continue across portions of the area this
afternoon, in association with slow moving 500 mb shortwave
trough and inverted surface troughs. There is some divergence at
250 mb as well from left front quadrant of jet streak.
The 500 mb shortwave trough is expected to slowly move east across
far southern Wisconsin and northern Illinois into tonight, before
sliding to the east on Saturday. The inverted surface troughs 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 a few 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 into early evening, though think any storms
that develop will remain below severe levels in this area.
Most of the risk for short lived funnel clouds, with storms along
inverted trough from far north central Illinois southeastward, should
remain in that 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
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 a bit cooler near Lake
Michigan on Saturday. Highs into the upper 70s to around 80 inland
Saturday night and Sunday...Forecast Confidence...Medium
The upper level shortwave exits eastern Wisconsin Sunday night
and moves to the eastern Great Lakes sunday. Little in the way of
upper divergence or 700 mb upward motion. 700 mb RH gradually
lowers saturday night. 700 and 850 winds are weak. 925 mb RH
remains rather high. surface high pressure will become centered
over the great lakes with the light surface winds becoming east.
SUNDAY night AND MONDAY...Forecast Confidence...Medium
An upper ridge builds across the northern plains before moving
into the upper Mississippi Valley. Weak upper divergence begins
monday afternoon. 700 mb upward motion is weak. 700 mb RH is low.
850 mb winds are weak but gradually become south across south
central Wisconsin. surface dewpoints begin to rise to near 70,
especially over south central Wisconsin. High pressure remains
over the Great Lakes with the light surface winds becoming more
Monday night and Tuesday...Forecast Confidence...Medium
The upper flow becomes zonal with a shortwave moving across south
Deeper moisture will return but the main warm front will still be
to our south as low pressure exits the nebraska area. The 00Z
ecmwf has an area of moderate rainfall Tuesday, with little
precipitation on the GFS.
Tuesday night THROUGH Friday...Forecast Confidence...Medium
Deeper moisture persists across the region with the GFS showing a
more pronounced warm front that lifts to the north by Wednesday. The
best chance for storms is expected to be on Thursday night as a
cold front approaches.
Scattered showers and a few thunderstorms are expected from time
to time tonight into Saturday at TAF sites. MVFR ceilings should
gradually rise to VFR levels by early evening. They should remain at
VFR levels tonight into Saturday across TAF sites.
Visibilities should remain at VFR levels 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, but clouds hanging around should limit fog to low lying
areas. Northeast winds should persist tonight and Saturday.
Northeast winds of 10 to 20 knots are expected 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 into
early evening, with 2 to 4 foot waves to the north. 2 to 4 foot waves
should linger through tonight into early Saturday, before
slowly subsiding into Saturday night.
Persistent northeast winds and 2 to 4 foot waves should continue
to bring a Moderate Swim Risk to the beaches along Lake Michigan
into early this evening, 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.
TONIGHT/Saturday AND AVIATION/MARINE...Wood
Saturday NIGHT THROUGH Friday...Hentz