906
FXUS63 KGRB 142309
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
609 PM CDT Fri Jun 14 2024

Updated aviation portion for 00Z TAF 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 305 PM CDT Fri Jun 14 2024

Short Term...Tonight and Saturday

High base cumulus clouds across northern and central
Wisconsin should dissipate early this evening as the sun sets, with
mostly clear skies overnight. The dry air will allow for another
cool and pleasant night with lows a degree or two below normal.

Saturday will start out sunny, but middle and high clouds will
increase during the afternoon in the warm advection ahead of a
warm front. Showers are possible west of highway 51/39 in the
afternoon. The showers will be falling into dry air, so rainfall
amounts will be minimal. Highs will be close to normal for this
time of the year.

Long Term...Saturday Night Through Friday

Forecast into next week continues to be volatile regarding
potential for some strong to severe storms with a ring of fire
pattern expected to build in across the CONUS. The SPC has
highlighted north-central and northwest Wisconsin under a
marginal risk for receiving severe weather on Sunday, although
there are still some questions about timing and airmass recovery.
Heavy rainfall will likely be a concern given abundant moisture
and an open Gulf. Hence, the WPC has put most of northeast
Wisconsin under a marginal/slight risk of receiving excessive
rainfall Saturday and Sunday.

Saturday night through Sunday precip chances... Saturday
night/Sunday morning convection remains a source of uncertainty
regarding storm potential later Sunday afternoon and evening. Some
storms will be possible out ahead of the warm front Saturday
evening through Sunday morning, especially as the nocturnal LLJ
ramps up to 50+ knots and moisture convergence results in modest
elevated instability. However, convective activity early Sunday
morning may act to shunt the northward movement of the warm front
later in the day. This scenario would affect how warm temperatures
are able to get Sunday afternoon, and in turn the possibility of
storm re-development, due to the effect of lingering cloud cover
and departing precip. Model soundings are quite aggressive with
instability (3000 to 4000+ J/kg of CAPE) Sunday afternoon,
although current thinking is that this will largely depend on how
the warm front behaves. Additionally, some models are suggesting
that any thunderstorm activity would be capped due to stable flow
off of Lake Michigan.

Rest of the extended... Attention then turns to storm chances on
Monday as a trailing cold front moves across the upper Midwest.
With an open Gulf and temperatures possibly surging into the low
90s across the warm sector, strong storms with locally heavy
rainfall will be possible across portions of central to north-
central Wisconsin Monday afternoon. Will continue to monitor
severe potential as we get closer to the event. As the cold front
departs to the southeast Monday evening, a robust trough west of
the Rockies will carve out a high amplitude ridge over the eastern
US, placing much of the Midwest under a warm and moist
southwesterly flow regime through mid-week. This ring of fire
pattern will bring about the first heatwave of the summer, with
heat indices early in the week potentially climbing into the low
to mid 90s.

&&

.AVIATION...for 00Z TAF Issuance
Issued at 609 PM CDT Fri Jun 14 2024

Scattered to broken high based cumulus clouds will
dissipate this evening, with mostly clear skies overnight. Saturday
will start out clear, but middle clouds will increase during the
afternoon. There is a chance of showers towards evening west of
a IMT to STE line as a warm front approaches. There is a good
chance of showers and thunderstorms Saturday night and Sunday
morning as the front lifts north across the region.

&&

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

&&

$$

DISCUSSION.....RDM/Goodin
AVIATION.......RDM