122
FXUS63 KGRB 230853
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
353 AM CDT Sun Jun 23 2024

Forecast discussion for routine morning forecast issuance

.KEY MESSAGES...

- Scattered thunderstorms are possible this afternoon. A few could
  produce wind gusts to 40 mph and small hail.

- Runoff from recent rains will cause many rivers and streams to
  rise into the middle of the week. Minor flooding is possible.

- Strong to severe thunderstorms capable of producing large hail
  and damaging winds are possible Monday night and Tuesday, mainly
  across northern and central WI.

&&

.DISCUSSION...
Issued at 352 AM CDT Sun Jun 23 2024

Short Term...Today...Tonight...and Monday

Scattered light rain will end early this morning as a weak shortwave
exits northeast Wisconsin. Some clearing is expected by midday,
as drier air moves in on northwest winds. A stronger upper level
disturbance will move through during the afternoon, and produce
steeping lapse rates and scattered showers and low top thunderstorms.
An inverted V sounding wit colder air aloft suggests that a few
storms with gusty winds and small hail are possible. Highs today
will be near normal.

Any scattered showers will end during the evening hours, with
clearing skies overnight. Clear skies and dry air will allow for
low temperatures near or a couple degrees cooler than usual.

Monday will start out sunny, but middle and high clouds will
increase during the afternoon in warm advection ahead of a
frontal system approaching from Minnesota. Highs will be a couple
degrees above normal.

Many rivers and streams will continue to rise today from recent
rains. Minor flooding is possible at a few locations.

Long Term...Monday Night Through Saturday

Chance for strong to potentially severe storms, mainly across
northern WI, late Monday night into Tuesday morning is the main
focus of the extended forecast. Otherwise, mostly dry conditions
through the middle part of the up coming week before the next
weather makes arrives toward the end of the week.

Monday night through Tuesday...As a low-level jet intensifies
Monday nigh the chance for strong thunderstorms will increase in
an area of convergence along the noise of the LLJ. A strong cap
created by an elevated mixed layer will allow for increasing low-
level moisture and elevated instability (MUCAPE over
2000 J/kg).Strong effective layer shear (40-60kts) along the
noise of the LLJ should allow for storm organization and
sustained updrafts capable of producing large hail. As the night
progresses there is the potential for upscale growth that may
result in an MCS moving southeast across northeast WI and the UP
early Tuesday morning. In this case the threat for severe wind
gusts would increase. There are hindrances to the severe threat
during this time which are import to note. First the strongest
large scale ascent associated with the driving short-wave appears
to be well north of the region limiting the forcing available to
break the cap. Additionally, will have to monitor how upstream
convection earlier in the day over MN effects the low-level storm
environment. Should be able to get a better handle on the
expected environment over the next day as CAMs come into range.

It does look like once the trailing cold front is through the
region Tuesday morning the remainder of the day will be dry.
Temperatures do look warm on Tuesday with highs forecast to reach
the 80s across the region and a few locations in the fox Valley
possibly getting into the low 90s.

Wednesday through Thursday...A second shortwave propagating
across northern Wednesday may create scatter cloud cover, but
with forecast soundings showing a robust warm layer in the 800-
700 mb layer went with a dry forecast for Wednesday. A ridge of
high pressure is progged to take over the region for Thursday
keeping the conditions in place. Temperatures trend near or just
slightly below normal each day with highs in the upper 60s to
upper 70s.

Rest of the extended...Long range ensembles are showing early
indications the next chance for widespread moderate to heavy rain
may come Friday with a surge warm moist air out ahead of a low
pressure system progged to move east across the northern Plains.
It`s too early to get a handle on the severe potentially, but
this will be a time period to watch, especially if you have
outdoor plans next Friday.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1051 PM CDT Sat Jun 22 2024

A few VFR conditions will prevail late this evening where breaks
in the clouds are located. Otherwise, look for poor flying
conditions through Sunday morning as any breaks fill in, with
mainly IFR/MVFR ceilings/visibilities. Some LIFR conditions are
possible at times. Lingering showers are expected at times
overnight. While flying conditions will improve through the day on
Sunday, isolated to scattered showers are expected, especially
during the late morning and afternoon into the early evening
hours. A few storms will also be possible Some of the stronger
showers/storms could contain gusty winds to around 40 mph and
small hail.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

DISCUSSION.....RDM/GK
AVIATION.......Bersch