Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 191749 AAA
AFDMKX

Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
1249 PM CDT Mon Jun 19 2017

.UPDATE...
Thunderstorms are moving across southern WI. The stronger storms
north and west of Madison have brought some pea sized hail and
wind gusts of 30-40 mph in Columbia county. Storms will continue
to move east and additional scattered showers and storms are
expected through the afternoon.


&&

.AVIATION(18Z TAFS)...
Thunderstorms are moving across southern WI and will impact
southeast WI over the next couple hours. The stronger storms have
brought pea sized hail and wind gusts around 35 mph. Additional
scattered showers and storms may develop through the afternoon.
Expect visibilities of 2-3 miles and ceilings around 2500ft within
the thunderstorms. Activity will diminish this evening. Scattered
showers and storms are possible on Tuesday. VFR conditions are
expected, except within thunderstorms.

&&

.PREV DISCUSSION... (Issued 1011 AM CDT Mon Jun 19 2017)

UPDATE...
Can see a trough axis over southwest WI on water vapor imagery.
GOES LI values show a minimum over the region of -2 and cape will
increase to around 500-1000 J/KG today. A few cells have
developed upstream with some lightning and may hold together as
they get into our NW forecast area. Scattered showers and
thunderstorms are expected to develop later this morning with
small hail the main threat. Activity will wind down during evening
with the loss of daytime heating.

MARINE...
West winds will gust 15 to 20 knots. Otherwise low wave heights
and lighter winds are expected through Wednesday morning.
Scattered showers and thunderstorms are expected today.

PREV DISCUSSION... (Issued 328 AM CDT Mon Jun 19 2017)

SHORT TERM...

Today and Tonight...Forecast Confidence is High.

An upper trough will pass today and help cool 500 mb temps to
-18C. Thus, tall and skinny CAPE is noted on forecast soundings
with all models producing fairly widespread qpf. Thus expect
showers and sct tstorms from late morning through the afternoon.
Small hail will probably occur with the stronger cells. Clouds and
rain will keep high temps around 70F. The upper trough will
depart by this evening with another strong shortwave trough to
arrive for Tue. Some clearing will occur tnt with low temps in the
50s.

LONG TERM...

Tuesday...Forecast confidence is medium to high:

Another wave is expected to move through on Tuesday. Consensus of
models suggests this wave will be clear of the area by mid to late
afternoon, so have have peak pops from mid-morning through mid-
afternoon. Kept small chance of thunder given some instability in
models. Overall, models look a little stronger with this wave and
are showing a bit more moisture than they did 24 hours ago. Should
see highs a few degrees below normal given the expected clouds,
showers, and temps aloft.

Wednesday and Thursday...Forecast confidence is medium:

The flow will turn more zonal mid-week, allowing a return of
deeper moisture and warmer temps. Shower/storm chances will also
increase during this time as moisture/instability and forcing
increase with low pressure moving into the region.

Models have slowed a bit with the arrival of the deeper moisture
and better warm air advection, so Wednesday now looks mainly dry
through the afternoon. Showers/storms are then likely Wed evening
and overnight.

Seeing more agreement among models now that the low level boundary
could get hung up in the area, allowing further rounds of
showers/storms on Thursday, especially in the south toward the
boundary.

Friday through Sunday...Forecast confidence is medium:

It looks dry Friday as high pressure builds toward the area.
Models struggle beyond that, with various strengths of the next
approaching wave for the weekend and resultant surface low
development. Have slight chance to chance pops through the weekend
due to the uncertainty of timing and precip coverage. Overall
though, it does seem likely that there will be precip at some
point during the weekend.

Models do agree that near normal temps Friday should drop to below
normal values by Sunday.

AVIATION(09Z TAFS)...Bkn035-040 cumulus congestus will develop
by late morning and continue through the day with showers likely
and sct tstorms. Areas of MVFR Cigs will be possible throughout
the day. Reduced Cigs and Vsbys within any storms. Some clearing
for tnt.

MARINE...Modest wly winds will prevail today and Tue with wind
gusts up to 20 kts. High pressure and light and variable winds are
then expected for Tue nt-Wed AM.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...None.
&&

$$

Update...Marquardt
Today/Tonight and Aviation/Marine...Gehring
Tuesday THROUGH Sunday...DDV



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