817
FXUS63 KGRB 160902
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
402 AM CDT Mon Sep 16 2024

Forecast discussion for routine morning forecast issuance

.KEY MESSAGES...

- Summer-like temperatures continue through Thursday with highs in
  the 80s. Temperatures to stay in the 70s near Lake Michigan.
  Slightly cooler temperatures are expected next weekend.

- Other than a small chance (15 to 20%) of a thunderstorm over far
  north-central WI today, the next chances for rain arrive late
  this week and carry into the weekend.

&&

.DISCUSSION...
Issued at 402 AM CDT Mon Sep 16 2024

Short Term...Today...Tonight...and Tuesday

Fog this morning and the potential for a few showers and storms to
develop today in far north-central WI are the main highlights for
this forecast period. Additionally, the prevailing warm air mass
will keep temperatures above normal through Tuesday.

This morning`s satellite imagery highlighted areas of radiation fog
along the lakeshore counties, causing low visibilities of 1/4 to 1/2
mile. Model guidance indicates the fog sticking around in these
areas through early this morning, and lifting soon after sunrise.
Decided to issue a Special Weather Statement for the lakeshore
counties until 8 AM to account for the potentially hazardous driving
conditions. Otherwise, dry conditions under mostly clear skies
prevailed across the forecast area.

Today...Dry air from nearby upper-level ridging to the east will
keep the area precip-free for the day, with some high clouds passing
overhead from the south. The only exception could be in far north-
central WI, where diurnal cu is expected to develop in an area of
700 to 1200 J/kg of CAPE, potentially generating a few showers and
storms. Given the lack in upper-level forcing and light winds aloft,
if any showers or storms develop, they would be short-lived and very
isolated in coverage. Since the pattern is similar to yesterday,
anticipate today`s high temps to be around the same values in the
middle to upper 80s. However, it will not be as humid due to the
departure of the lingering moisture from Francine.

Tonight and Tuesday...The upper-level ridging to the east will
continue to feed dry air over the area tonight, resulting in dry
weather under some passing high clouds. Mild lows temps will
continue with values ranging from the middle 50s to low 60s. The dry
and warm weather continues on Tuesday as the upper-level ridge to
the east is gradually replaced with an amplifying ridge building
over the Central US. Tuesday`s highs to range from the low to middle
80s.

Long Term...Tuesday Night Through Sunday

Seasonably warm and dry weather into late week, then it turns
slightly cooler by this weekend. There will also be at least
small chances for some rain late this week into the weekend.

Pattern this week will be amplified, yet changeable. One of the
anchors in the pattern will be the system currently organizing
off the South Carolina coast. This may make landfall in the next
24 hrs as a tropical storm before meandering over the southeast
CONUS through midweek then lifting toward the Mid Atlantic at the
end of the week. Meanwhile, heights will remain high over the
Great Lakes to the north of this system, keeping our area dry.
Out west over western North America, deep trough keeps reloading
and now it appears that leading upper low that moves to south
central Canada by Thursday has trended stronger. Main impact for
weather in northeast WI is as this low moves east, heights will
fall quicker so that rain chances will arrive from the west late
Thursday or Friday. Models are showing tendency for QPF to fade
from west to east over the western Great Lakes, so could be
situation where western to central WI sees some rain while
eastern WI stays dry. Kind of early for those details though. By
next weekend, there will be opportunities for some showers all
areas, though there is disagreement on how frequent and widespread
these will be. At this point, sure doesn`t look like anything
significant enough to put dent into what has now turned into a
pretty dry 30 day stretch over much of our area.

Temps Wednesday through Friday will be seasonably warm, though
not hot, as highs persist in the lower to perhaps mid 80s (70s
lakeside) while lows drop mainly into the 50s. Temps this weekend
will drop into mainly the mid to upper 70s, with current forecast
only showing upper 60s over the far north on Sunday. Overall,
hazardous weather looks minimal with only a small chance for
thunder on Friday and winds/waves on the waters staying on the
light side. Tuesday night and Wednesday night will have a good
chance for patchy fog which will lead to localized reduced
visibility in the pre-dawn hours.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1059 PM CDT Sun Sep 15 2024

The main aviation impact for the TAF period will be fog tonight,
mainly along the lakeshore areas next to Lake Michigan. The fog
may impact MTW at times, but should remain out of GRB, ATW, and
areas further inland. outside of the fog, clear skies and quiet
conditions are expected across the region. Once fog dissipates in
the morning, good flying conditions are expected for Monday.

&&

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

&&

$$

DISCUSSION.....Kruk/JLA
AVIATION.......Uhlmann