Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 260815

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
315 AM CDT Fri May 26 2017

Today and tonight...forecast confidence is medium.

The showers moving through early this morning should dissipate and
move off to the east by 12z this morning. Thereafter, the models
are coming into better agreement with the handling of the mid
level wave and associated weak surface trough moving through the
southern part of the region today. It now appears the better
precip amounts will be staying south of Wisconsin. The GFS is
clearly suffering some feedback issues, producing an unrealistically
intense short wave pushing into southwest Wisconsin early this
afternoon. This has ramifications in the low levels, spinning up a
strong low level jet and low pressure center, producing copious
precip amounts. That is being rejected. The NAM/Canadian/ECMWF/HRRR
keep the core of precip south. But, they all show a mid level
wave lifting up here and that should be able to pull a few showers
north into the area this afternoon, especially along the WI/IL
border area. Temps should be able to achieve the lower 70s most
places...except near Lake Michigan where it will be kept in the
60s. We dry out tonight, with a nice day on tap for Saturday.

.Saturday and Sunday...Forecast confidence is medium.

A mid level shortwave will approach from the southwest but models
differ on whether it will move across southern WI. Surface flow will
be weak across the region with low pressure well to the southwest
and north, so a lake breeze is possible. A weak frontal boundary
will be draped across the region providing the focus for some
showers and thunderstorms. There is some surface based cape. With
the exception of the GFS, models are showing a better chance for
precip Saturday night as an upper trough approaches and surface low
pressure tracks across Illinois and into Michigan. The GFS keeps us
much drier keeping this system further south.

On Sunday an upper low will drop from Canada to over the Upper Great
Lakes region. An upper trough will swing through on Sunday with
surface based instability yielding a chance for showers and
thunderstorms. A cooling trend will start with the influence of the
upper low. No severe weather is expected during this period.

.Memorial Day and Tuesday...Forecast confidence is medium

Several lobes of vorticity will rotate through the region as the
upper low lingers over Quebec. There are small chances for showers
each afternoon. No severe weather is expected. Thunder chances
diminish Tuesday as surface temperatures cool and warm air advection
at the mid levels reduces instability. Steep low level lapse rates
will promote mixing and breezy winds.

.Wednesday through Friday...Forecast confidence is low.

The upper low will slowly move east later in this period but won`t
entirely lose its grip on the region. Mid level flow will still be
out of the northwest. Models really diverge at this point. The GFS
is showing a low level jet nosing into the region Wednesday with a
frontal boundary moving through Wednesday night. This results in
precip through Thursday and is looking interesting for thunder
potential. The ECMWF, on the other hand, does not agree and is
quicker to bring high pressure over the region.



VFR conditions are expected through most of the TAF period. There
is some lower stratus moving south down the lake and there is
plenty of uncertainty with its behavior. It`s possible this could
make it south to the Milwaukee and Kenosha areas by around
sunrise this morning. CIGS would likely be around 500ft. Will be
watching this closely. Some showers could push through southern
Wisconsin, mainly this afternoon, but the bulk of the showers and
lower CIGS will remain south of Wisconsin. Winds will be light
southeast, generally less than 10kts.



Marine conditions are expected to remain favorable, below small
craft advisory levels, through the holiday weekend.




Today/Tonight and Aviation/Marine...Davis
Saturday through Thursday...Marquardt is the U.S. government's official web portal to all federal, state and local government web resources and services.