Scientific Forecaster Discussion
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Area forecast discussion
National Weather Service Milwaukee/Sullivan WI
345 PM CDT Tue Jul 23 2019
tonight through Wednesday night...forecast confidence is medium
There is a subtle upper trough moving through WI today within
cyclonic flow. Isolated showers and thunderstorms are developing
over central WI and these should roll through southern WI between
now and 7 PM. The stronger area of storms produced a wind gust to
40 kt (46 mph) in Marshfield. There is decent instability and
marginal shear to support these higher wind gusts. Small hail is a
possibility as well.
Patchy fog is possible tonight, especially in low lying areas and
Expect a similar setup for tomorrow with high pressure lingering
overhead and another subtle upper trough moving through. Winds
will be lighter, but we will have afternoon/evening chances for
Thursday through Saturday...forecast confidence medium.
High pressure will shift to the east bringing southwest flow. It
will remain weak enough to allow for a lake breeze on Thursday. A
shortwave will move through overnight. The GFS is showing some
precip on Thursday but soundings are pretty dry. There is a few
hundred j of possibly surface based cape but no forcing overnight
other than the lake breeze so thinking it will be dry.
For Friday and Saturday, the pressure gradient will strengthen
due to high pressure over the East Coast and low pressure over
Canada. This southwest flow will bring warmer temperatures for the
end of the week and increasing humidity. Broad cyclonic flow will
dominate the mid levels with little jet activity. The best
moisture transport is over northern and western Wisconsin. Right
now it looks like any precip and thunderstorm chances are more
toward central Wisconsin.
Sunday through Tuesday...forecast confidence medium.
There is a chance of showers and thunderstorms during this time
as shortwave activity looks to increase Saturday night into
Monday. A cold front will move through Monday or Monday night so
it is looking dry later than night and Tuesday. Temperatures will
be much cooler, but the humidity could stick around.
A mid level ridge is setting up in the southwest U.S. And heights
increase over US as it shifts eastward during the middle of the
week. This could mean warmer temperatures later in the week.
isolated thunderstorms are possible through early evening. Patchy
fog may develop well inland late tonight, especially in low spots
and river valleys. A similar setup is expected tomorrow, with
isolated thunderstorms Wed afternoon. Winds will be a little
lighter, and expect a lake breeze once again.
high pressure will slowly move from the northern Great Plains
into Illinois by late Wednesday. Northerly winds will prevail
during this time. The high pressure area will then move across the
Ohio River valley into the mid Atlantic states for Wednesday
night through Friday. Meanwhile, low pressure will move east
across southern Canada. Light to modest southwest winds will
develop for Wednesday afternoon and Thursday and become breezy for
Friday and Saturday. A few gale force gusts are possible over the
north half Friday.