298 
FXUS63 KGRB 080346
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1046 PM CDT Thu Oct 7 2021

Updated aviation portion for 06Z TAF issuance

.SHORT TERM...Tonight and Friday
Issued at 251 PM CDT Thu Oct 7 2021

The upper trough over Southern Illinois is forecast to lift slowly
northeast to Lake Michigan by Friday afternoon and produce periods
of showers and isolated thunderstorms. Thunderstorms should be 
mainly during the afternoon and evening hours over the southern 
half of the forecast area.

BUFKIT forecast soundings have CAPE of 300 to 700 J/KG Friday afternoon
south of highway 29, so it wouldn't be impossible to get a storm with
gusty winds and small hail. 

Very little diurnal temperature change is expected with clouds and
high relative humidities.

.LONG TERM...Friday Night Through Thursday
Issued at 251 PM CDT Thu Oct 7 2021

Southwest flow aloft, between an upper trough over the west coast 
and a ridge east of the Mississippi River, will bring periodic rain 
chances to the region.  Timing of these precip chances is the focus 
in this part of the forecast.  In general, temperatures and precip 
will be above normal for the next week.

Friday night through Saturday night...A few showers will likely 
linger into Friday night, particularly over far northeast WI as the 
upper trough lifts across the central Great Lakes.  But as showers 
end, moist south or southeast winds will likely keep the boundary 
layer nearly saturated, which leads to the possibility of dense fog 
or widespread very low stratus.  Statistical guidance is already 
catching on to this and shows visibilities below 1sm over parts of 
the area.  Will increase fog coverage.  Once any fog burns off, 
Saturday still looks like the nicest day of the extended.  Between 
systems, temps should rise into the low to mid 70s on Saturday 
afternoon.  As low pressure moves northeast across the northern 
Plains on Saturday night, will see an influx of moisture and 
instability aloft, which will lead to an increasing chance of 
thunderstorms through the night, particularly over north-central WI. 
Severe weather looks unlikely as cape profiles look skinny.

Rest of the forecast...Low pressure will be tracking across northern 
Minnesota on Sunday and will push a cold front across the state of 
Wisconsin.  Strong dynamics will remain well northwest of the region 
and the front will be weakening as it moves east.  Forecast 
soundings indicate significant capping in place ahead of the front, 
which will make thunderstorm development difficult.  As a result, 
models are unenthusiastic about precip chances on Sunday.  While the 
low lifts into Ontario on Monday, a southern stream system remains 
forecast to lift into the region.  Instability is again lacking, but 
some indications that decent rainfall will be possible.  Then the 
next dynamic system is forecast to move into the center of the 
country by next Thursday.
&&

.AVIATION...for 06Z TAF Issuance
Issued at 1046 PM CDT Thu Oct 7 2021

Conditions were mainly IFR/LIFR across central and east-central
Wisconsin with MVFR/IFR across north-central Wisconsin. IFR/LIFR 
conditions are expected overnight and into Friday as a low
pressure system tracks through the region, bringing showers at
times. Although thunderstorms will be possible, the likelihood of
hitting the TAF sites is too low to include in the TAFs. 
Conditions could slowly improve to MVFR, with a few locations 
possibly hitting VFR, Friday afternoon and evening before settling
back down to MVFR/IFR later Friday night.
&&

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

$$

SHORT TERM.....RDM
LONG TERM......MPC
AVIATION.......Kurimski