583
FXUS63 KGRB 140835
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
335 AM CDT Fri Jun 14 2024

Forecast discussion for routine morning forecast issuance

.KEY MESSAGES...

- Well above average temperatures are expected from Sunday into
  the middle of next week. Heat indices may surpass 90 degrees at
  times.

- A round of showers and thunderstorms is expected across the area
  Saturday night into Sunday morning. Locally heavy rainfall is
  likely across northern Wisconsin, with amounts over an inch
  possible. High rainfall rates could result in localized street
  flooding and ponding of water on roads.

- There is a Marginal Risk of severe thunderstorms across much of
  the area Sunday afternoon and Sunday night. Some of the storms
  could produce damaging winds and large hail.

- On and off chances for thunderstorms will continue next week,
  although there is still some uncertainty with timing. Due to
  increasing heat and humidity, some stronger storms and locally
  heavy rainfall may be possible.

&&

.DISCUSSION...
Issued at 332 AM CDT Fri Jun 14 2024

Short Term...Today...Tonight...and Saturday

Quiet weather was observed across the region early this morning. A
band of mid-level clouds was gradually expanding south across the
region, in association with a short-wave trough and the LFQ of an
upper level jet streak. Just north of this cloud band, some
patchy fog had developed in Vilas County.

Cooler but seasonal temperatures and lower humidity can be
expected through Saturday, as Canadian high pressure dominates our
weather. Highs both days should be in the 70s, with lows tonight
ranging from the upper 40s to middle 50s.

For today, morning clouds should erode as the short-wave exits
this morning. A few models show scattered afternoon showers
developing near a weak inverted surface trough and convergence
zone in central WI. Have opted to keep any mention of these
showers out of the forecast, given the proximity of the Canadian
high and a drier air mass. Dry weather prevails through Saturday
morning, but developing WAA on the western periphery of the
departing high and the arrival of a short-wave trough may trigger
scattered showers in parts of C/NC WI later Saturday afternoon.

Long Term...Saturday Night Through Thursday

The 500mb pattern for next week will feature a ridge across
the eastern United States with a trough across the western United
States. This pattern will result in the area being in the ring of
fire with thunderstorm complexes moves across the area from time
to time through the middle of next week.

For Saturday night, an increasing low level jet approaching 50 knots
will be the focusing mechanism for the development of showers and
scattered thunderstorms during the evening across central and
north-central Wisconsin. The main difference tonight is the rain
may be a little bit slower to arrive/develop across east-central
Wisconsin. I lowered rain chances in this area during the evening
hours. The showers and storms will expand/move across the area
overnight. There will be likely be more activity around during the
morning across northeast Wisconsin. This activity could result in
a slower push of the warm front northward Sunday afternoon which
could impact high temperatures and the possibility of redevelopment
of storms along the warm front Sunday afternoon into Sunday night.
Bufkit soundings impressive with 3,000 to 4,000 J/KG of cape with
shear values around 30 knots. The big issues in the soundings is
the warm layer between five and seven thousand feet that would
inhibit thunderstorm development. More likely will need to watch
boundary across northeast Minnesota and northwest Wisconsin, or
along the lake breeze boundary near Lake Superior for focused
development of storms. The Storm Prediction Center Day 3 Outlook
has a marginal risk of severe storms, mainly for Sunday afternoon
into Sunday night.

For Monday and Tuesday, the GFS solution is further south with the
frontal boundary compared to the ECMWF/Canadian model, which
would support highs in the middle 80s to lower 90s with afternoon
heat index values from the upper 80s to middle 90s. Will need to
watch for thunderstorm complexes along the front that could make a
move into the forecast area both days. With the abundant heat and
humidity, there is the potential for stronger storms and locally
heavy rainfall. It appears Wednesday will be somewhat cooler as
the frontal boundary is expected to move across the area which
will result in additional chances for stronger storms and heavy
rain. Temperatures will likely be closer to normal Thursday.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1034 PM CDT Thu Jun 13 2024

VFR conditions are expected through the TAF period as high
pressure tracks through southern Canada. Other than a few mid and
high clouds and light winds not much in the way of aviation
impacts is expected through Friday evening.

&&

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

&&

$$

DISCUSSION.....Kieckbusch/Eckberg
AVIATION.......Kurimski