FXUS63 KGRB 031849

AFDGRB



Area Forecast Discussion

National Weather Service Green Bay WI

149 PM CDT Thu Jul 3 2025



Forecast discussion for routine afternoon forecast issuance



.KEY MESSAGES...



- Continued potential for showers and thunderstorms late tonight

  into Friday (July 4th). Marginal chance for severe weather

  tonight.



- Better chance for widespread rain and storms will occur Saturday

  and Saturday night. There is marginal chance for severe and the potential

  for heavy rainfall Saturday into Saturday night.



- Temperatures will be above normal through the holiday weekend,

  with very warm and humid conditions expected Friday (July 4th)

  and Saturday.



&&



.DISCUSSION...

Issued at 149 PM CDT Thu Jul 3 2025



Rain late tonight into Friday...

The weak frontal zone remains visible on satellite this afternoon

as an area of cumulus stretching from southwest Wisconsin to the

western portions of the state. As warm air advection kicks up

again late this afternoon and evening, this boundary will once

again lift into the region for the early overnight period.

Elevated showers and thunderstorms are then expected to develop

again, pushing into central Wisconsin from the southwest. Best

timing still remains from the overnight period around midnight

through the mid to late morning hours on Friday. Would expect the

best convective potential to be earlier in the overnight period, 

with just some weaker storms or even just showers around by the 

early morning period. Severe weather potential remains fairly 

marginal, with relatively little instability and shear in the 

region, but some brief wind gusts and small hail will be possible.

Any remaining convection will then slowly be suppressed through 

the afternoon on Friday as ridging works its way into the region. 

Maintained low pops further east as the ridging arrives, as some 

meso models do allow for weak instability late in the day. 

Regardless, mostly dry conditions are expected by firework time in

the early overnight.



Saturday...

The best chance for widespread rain and showers arrives on

Saturday as a cold front sweeps across the region from west to

east. Models have largely kept the slower arrival time, bringing

the front through mainly in the afternoon to evening period of

Saturday. As a result, 1-2 thousand J/kg CAPE will have a chance

to develop ahead of the front before storms arrive. Shear still

looks weaker but sufficient, around 20-30 knots, so some stronger

or a few severe storms will remain in the forecast. SPC currently

has most of northeast Wisconsin in the Marginal risk category for

severe weather, which makes sense. In addition to any severe

weather, ample moisture in the region will support a heavy rain

threat, with many areas seeing at least 40-60% of exceeding half

an inch of rain with the storms.



Rest of the Forecast...

Drier conditions then return behind the cold front Saturday, as

high pressure returns through early next week. The next hints of

some unsettled weather are not in the forecast until we get

towards the middle of next week.



Temperatures...

Above normal temperatures are expected through Saturday, followed

by near to a little below normal conditions through the middle of

next week. Very warm and muggy conditions arrive for Friday (July

4th) and linger over eastern WI into Saturday, with heat indices 

into the lower to middle 90s. The heat and humidity will impact 

outdoor activities for the 4th of July, but heat indices fall a 

little short of advisory criteria at this point.



&&



.AVIATION...for 18Z TAF Issuance

Issued at 1256 PM CDT Thu Jul 3 2025



Good flying conditions are expected to persist through the

afternoon and evening. Skies will see some scattered cu in the

afternoon, but ceilings should remain VFR.



Then, an area of rain and thunderstorms are expected to move in

from the west and affect portions of central and north-central

Wisconsin in the late evening to overnight timeframe. The line of

storms is expected to be oriented from northwest to southeast,

only getting to RHI later in the overnight period. Included a

PROB30 group for CWA and AUW for the earliest arrival, then a

later group for RHI. Forecast confidence isn't high enough to also

include rain reaching eastern TAF sites, so no mention as of now,

but there is the potential for a few showers to still pass over

the region sometime Friday morning. Any storms overnight could

bring some brief gusty winds and MVFR ceilings.



&&



.GRB WATCHES/WARNINGS/ADVISORIES...

None.



&&



$$



DISCUSSION.....Uhlmann

AVIATION.......Uhlmann