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Area forecast discussion
National Weather Service Green Bay WI
243 PM CDT Wed Jun 28 2017

Forecast discussion for routine afternoon forecast issuance

issued at 240 PM CDT Wed Jun 28 2017

Periods of showers and thunderstorms will continue through this
evening, with severe storms still possible.

A seasonably strong band of relatively low-amplitude westerlies
is across the northern Continental U.S.. the large scale pattern will be
slowly progressive and gradually reamplify as an upper trough
passes through the Great Lakes region during the upcoming weekend.
Late in the period and beyond, the pattern is likely to
transition to a typical mid-Summer regime with a the main
westerlies across southern Canada, and a large broad anticyclone
centered over the intermountain west.

The large scale pattern should result in temperatures fairly
close to seasonal normals for most of the period, though there
will be day to day variations due to precipitation and
differences in cloud cover. Readings should warm to above normal
for the middle to latter part of next week. The pattern will still
be favorable for precipitation through the weekend, though it
does look drier after that. So although the precipitation will be
front loaded in the period, amounts will probably still end up
above normal.

Short term...tonight and Thursday
issued at 240 PM CDT Wed Jun 28 2017

It's still tough to get a firm grasp on the severe potential late
today and this evening. Rain persists across much of the area,
though it is diminishing from the west. Mid-level dry slot is
pushing into western Wisconsin, but convection continues to fire
at the nose of the dry slot. Will stick with convective scenario
set forth in the previous afd and mid-day severe weather potential statement. Storms are likely
to develop over west-central and northwest Wisconsin during the
middle to late this afternoon, and push across the forecast area
this evening. A separate band of storms developing over southeast
Minnesota and northeast Iowa may graze the southern part of the
forecast area earlier. The late-day/evening storms will pose a
risk of damaging winds and large hail. The risk of tornadoes will
also be present, mainly with any storms near the warm front
lifting into the area.

Tapered pops down later tonight, though isolated showers could
linger well past midnight. Gusty west winds are expected Thursday.
Stuck with dry forecast for most of the area, but went with a
chance of showers across the north.

Long term...Thursday night through Wednesday
issued at 240 PM CDT Wed Jun 28 2017

The weather pattern will remain busy at least through the weekend,
though there are indications that quieter conditions will finally
occur next week. Will use a multi-model blend for much of this

Thursday night through Saturday...conditions will start out quiet on
Thursday night as weak high pressure will initially be present. But
will then see clouds increase late when low pressure moves into
Iowa. With lift increasing ahead of the low, showers could push
into central and east-central WI by sunrise. The models are
trending weaker and further south with the system for Friday.
Scattered light showers will remain possible, but heavier rainfall
looks to occur south of the area. Will keep a slight chance of
thunderstorms across the southern 2 rows of counties, though not
confident that thunderstorms will reach this far north. Skies should
partially clear behind the system for late Friday night into
Saturday morning. However, upper troughing will remain overhead,
which should lead to scattered showers and isolated storms popping
up with heating on Saturday. No significant changes to temps.

Rest of the forecast...Sunday is looking like the better day of the
weekend. A shortwave trough will be dropping southeast across the
Lake Superior region and most likely will not have much impact on
our sensible weather. However, it could provide a few showers to
the region on Sunday night as it pushes a cold front south over the
state. As it stands now, early to middle of next week looks
relatively quiet with high pressure in control.

Aviation...for 18z taf issuance
issued at 1240 PM CDT Wed Jun 28 2017

Timing of rain showers/thunderstorms and rain and ceilings are the main aviation forecast
concerns. The initial band of rain showers should exit the area. There
will then likely be a second round of thunderstorms and rain during the late
aftn/evening. Timing/strength of those storms is very much in
question, so made a guess at most likely timing in the tafs with
the expectation that will probably need adjustment later. The
guidance is pretty aggressive with low ceilings overnight. There
are plenty of low clouds out there now, but wonder how many will
remain once the initial band of rain shifts off to the NE. Went
with a little more optimistic ceiling forecast in the tafs, though
confidence in that aspect of the forecast is also low.

Grb watches/warnings/advisories...
beach hazards statement through Thursday morning for wiz022-040-


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