Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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801
FXUS63 KMKX 292020
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
320 PM CDT Wed Mar 29 2017

.SHORT TERM...

TONIGHT AND THURSDAY - Confidence...Medium

An unsettled period with widespread rain gradually overtaking the
area tonight. The primary mid level circulation will stay to our
south as will the surface and 850 lows. 850 waa/moist advection
takes place tonight and lifts the 850 baroclinic zone northward. The
far northern cwa still looks thermally vulnerable for at least a
brief period of a snow or a mix. Amounts have continued a downward
trend with the 12z run and this has been reflected in the forecast
snow amounts with highest amounts of around an inch in the far
northern reaches of our northern tier of counties. Some decent lift
noted with one 250 millibar jet max providing right rear lift
tonight then a renewed southerly upper jet pivots northward around
low with left front positioning on Thursday. Even a hint of some
coupling at times between these 2 features. Throughout the event
both the RAP and NAM Bufkit soundings show enough elevated CAPE to
warrant at least a small chance of thunder in the southern cwa so
have included that potential.

Thursday night through Saturday...Forecast confidence medium.

The weakening low pressure area and upper low will track from wrn
IL to Lake Erie from Thu nt into Fri eve. The upper trough axis
extending north of the upper low will pass Thu nt into Fri AM.
Low to mid level frontogenesis may linger during this time. Thus
rain will continue to be likely over ern WI for Thu nt with areas
of light rain or drizzle elsewhere including on Fri. Gradual cold
and dry air advection Fri aft-eve will eventually lead to
clearing skies. High pressure will then prevail late Fri nt and
Sat. The cool temps on Fri will return to seasonal values on Sat.

.LONG TERM...Sunday through Wednesday...Forecast confidence low to
medium.

The passage of a weak shortwave trough and round of warm advection
will bring chances of light rain for late Sat nt-Sun nt. Chances
of rain will then continue for Mon-Wed. Low pressure over the
Lower MS River Valley will move newd into the Ohio River Valley
for Mon-Tue followed by another low moving from the central Great
Plains into possibly the Great Lakes for Wed-Thu.

&&

.AVIATION(UPDATE)...VFR ceilings will progressively lower this
period as rain overspreads TAF sites. Bufkit is showing the
process may take a while, with initially deep dry layer. Seeing
the upstream IFR conditions across IA and western IL. Will
gradually head this way especially after 06z. Increasing forcing
will lead to rain development. Already seeing some of this across
eastern Iowa with mid level returns into western WI. This precip
fighting off some dry air in the low levels. As low pressure
approaches tonight into Thursday morning we will see IFR ceilings
and vsbys develop. May even have an isolated thunderstorm or two
as soundings are implying some elevated instability. With low
pressure passing to our south later tonight into Thursday a
tightening pressure gradient will set up rather gusty east winds.

&&

.MARINE...Main focus shifts to increasing onshore and long duration
wind regime tonight which gets underway tonight. This will build
high waves near the shore and remain in place through late Friday
night.


&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Small Craft Advisory from 10 PM this evening to 4 AM CDT
     Saturday for LMZ645-646.

     Small Craft Advisory from 2 AM Thursday to 4 AM CDT Saturday for
     LMZ643-644.

&&

$$

Tonight/Thursday and Aviation/Marine...Collar
Thursday Night through Wednesday...Gehring



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