277
FXUS63 KGRB 090350
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1050 PM CDT Sat Jun 8 2024

Updated aviation portion for 06Z TAF issuance

.KEY MESSAGES...

- Isolated thunderstorms possible rest of this afternoon north-
  central to northeast Wisconsin. Severe weather is not expected
  but stronger storms could produce gusty winds and small hail.
  Next chance for thunder is late Tuesday with greater chances on
  Thursday.

- Chilly with potential for patchy frost over north-central
  Wisconsin late Sunday night.

- Below normal temperatures through Tuesday with warm up following
  mid to late week.

&&

.DISCUSSION...
Issued at 254 PM CDT Sat Jun 8 2024

Short Term...Tonight and Sunday

Main concern is extent and strength of storms into early this
evening.

Widespread showers from earlier have shifted east. Majority of
forcing was tied to upper level jet, so rain amounts were generally
less than 0.25 inch. Just as these showers are ending, approaching
shortwave trough, steep low-level lapse rates and sfc trough
working across Upper Michigan into northern Wisconsin is triggering
a line of scattered showers and isolated storms. Report of half
inch hail in western Upper Michigan and though the radar trends
point to stronger convection only grazing far northeast WI, will
have to watch if any stronger cells can shift into our area next
few hours. After this band of showers and storms drops across, may
see another shortwave pivot across northern WI bringing another
round of isolated showers into early this evening. By late evening,
convection will diminish as instability diminishes. A few light
showers or sprinkles could make it to central and east-central WI
late evening or early overnight. Otherwise, expect decreasing
clouds and lows similar to what occurred this morning (40s north
to mid 50s south and east).

Sunday starts off partly sunny but it will quickly become cloudy
from north to south. This as strong shortwave trough rotates just
to the northeast and swath of H925-H7 moisture drops across the
area. Soundings show some lift in this moist and weakly cyclonic
flow, so kept small mention of showers but still no thunder over
higher terrain of north-central. Some sprinkles may sneak south of
that, but will be isolated. Temps will be the main story may only
struggle into the lower 60s north before falling off some in the
afternoon as cold air advection aloft shifts across from the
north. Enough early day sunshine to boost readings into the upper
60s or near 70 elsewhere. Northwest winds will become breezy with
gusts of 25 to 30 mph.

Long Term...Sunday Night Through Saturday

Temps and frost potential Sunday night and thunderstorm chances
for the rest of the extended are main concerns.

Clouds to begin early Sunday evening, but these will diminish
through the night as high pressure and very dry airmass settles
across (PWATs down to less than 0.25 inch). Winds likely go calm
after midnight over northern WI which should allow temps to fall
and open the door to frost potential. Lowered mins toward MOS
guidance, though didn`t go as extreme as MET MOS at LNL which
showed 32. Certainly possible if trends continue parts of the
north may eventually need frost advisory. High pressure will then
bring dry conditions Monday into Monday night.

Dry trend will be short lived as approaching shortwave trough and
cold front will result in next period of showers across the area
on Tuesday. There is a narrow ribbon of return moisture surging
ahead of the front, but instability looks minimal overall (MLCAPES
well under 500J/kg) as the airmass only slowly recovers in wake
of the early week high pressure/dry air. Only chances for thunder
over the far west late aftn into the evening.

Looks like we`ll have a dry day on Wednesday in this on again off
again weather pattern, but Thursday holds a better chance for showers
and some storms as another shortwave trough and stronger cold front
arrive during peak heating. Timing differences in the guidance keeps
pops at chance right now but eventually could see higher pops. If
timing locks in more for the afternoon, possible that stronger
storms could occur as stronger mid level winds arrive as
instability builds up the best it is supposed to this week. Too
early to start messaging this though given the uncertainty. During
this time it appears temps rise to or even above normal with
highs in the upper 70s to lower 80s.

Beyond this, next better chance for showers and some storms would
be late Friday into Saturday as this active pattern marches on.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1049 PM CDT Sat Jun 8 2024

Skies are expected to become mostly clear overnight and start
that way on Sunday before broken to overcast cloud cover spreads
in by afternoon from the north with arrival of cooler air aloft. A
light shower with brief MVFR conditions could form over north-
central Wisconsin on Sunday afternoon, with MVFR conditions
across central Wisconsin as well minus the showers, and VFR
conditions elsewhere. VFR conditions will then return Sunday
evening as skies clear. Northwest winds will become gusty later
Sunday as well with gusts to 20 knots, then diminish by Sunday
evening.

&&

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

&&

$$

DISCUSSION.....JLA
AVIATION.......Kurimski