437 
FXUS63 KGRB 220811
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
311 AM CDT Wed Jul 22 2020

Forecast discussion for routine morning forecast issuance

.SHORT TERM...Today...Tonight...and Thursday
Issued at 311 AM CDT Wed Jul 22 2020

A weak surface trough will linger across northeast Wisconsin today
and tonight as several weak shortwaves track through the region.
These features will bring isolated showers to the area, with a
boost during daytime heating during the afternoon and evening
hours with destabilization. Current model runs keep the activity
through tonight until the surface trough and shortwaves exit the
region. Rainfall amounts should be fairly light given the shallow
nature of the shower activity as models show an inversion around
700 mb. Highs this afternoon are expected to rise into the middle
to upper 60s across the north, with middle to upper 70s across
east-central Wisconsin. Lows tonight are expected to range from
the lower to middle 50s across the north, with lower 60s across
east-central Wisconsin.

High pressure across the western Great Lakes region should keep
things dry on Thursday as daytime highs into the middle to upper
70s.

.LONG TERM...Thursday Night Through Tuesday
Issued at 311 AM CDT Wed Jul 22 2020

The focus of the long term will be mainly on the weekend, as 
temperatures head above normal with highs around 90 degrees, and a
chance for storms and heavy rain by Saturday night through 
Sunday.

Thursday night through Saturday morning... An upper level ridge is
expected to move into the region for the beginning of the extended
period, bringing quiet and dry weather conditions. Return flow at
the surface will be increasing during this time, bringing back a 
warmer and more moist air mass. Any storms and rain should be 
fairly limited to far northern Wisconsin until Saturday afternoon.
High temperatures on Friday are expected to push into the lower 
to middle 80s while low temperatures rise into the upper 60s and 
lower 70s by Friday night.

Saturday afternoon into Sunday...By Saturday afternoon, boundary 
layer temperatures are expected to rise up to 24C-27C at 925mb and
19C-23C at 850mb, which mixed to surface will bring a strong 
warmup with highs in the into the middle 80s to lower 90s. With 
dewpoints also pressing into the lower 70s, a hot and humid 
afternoon can be expected to last through the evening. With ample 
CAPE at the surface, diurnally driven rain and storms are possible
during this time. Shear will be somewhat lacking during this 
time, so organization of storms may be somewhat limited. The main 
threat will be torrential rainfall, as PWAT values head into the 
2.00-2.50 range. And storms in the region will likely weaken 
overnight into Sunday.

Rest of the forecast... Sunday is still somewhat uncertain, as the
amount of instability available may be limited by any remaining
rain from the Saturday night event. A slow moving cold front is
expected to move through the region in the evening, and will serve
as the focal point for any more intense convection in the
afternoon to evening hours. Ample moisture and instability will
still be present in the region, so some stronger storms are not
out of the question, especially if the highs manage to push once
again into the upper 80s and lower 90s. Cooler air is expected to
follow the cold front for the beginning of next week, with highs 
headed back towards the 80s by the middle of the week.
&&

.AVIATION...for 06Z TAF Issuance
Issued at 1050 PM CDT Tue Jul 21 2020

Overall confidence in thunderstorm activity continues to be 
fairly low. There have been a few lightning strikes near CWA/AUW,
which may shift eastward through the night; however, instability
remain fairly low east of those locations. this should limit
thunder chances at GRB/ATW/MTW. Otherwise, there will be 
continued chances of showers at each of the TAF sites through late
tonight before ending from the west. Ceilings will lower to 
IFR/LIFR and patchy fog will develop, leading to poor flight 
conditions. Fog will mix out early Wednesday, and ceilings will 
slowly rise, but flight conditions will likely still be in the 
MVFR category into Thursday evening.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

SHORT TERM.....Kurimski
LONG TERM......Uhlmann
AVIATION.......Cooley