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721 
FXUS63 KGRB 130345
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1045 PM CDT Thu Jun 12 2025

Updated aviation portion for 06Z TAF issuance

.UPDATE...
Issued at 953 PM CDT Thu Jun 12 2025

Waves of showers tied to mid-level fgen and warm air advection
continue to drift across central and northern WI this evening.
Outside of a few sprinkles, thus far most of the activity has 
remained northwest of the Fox Valley. Earlier models, including 
CAMs, struggled with look of upstream convection over IA/MN this 
evening. Generally, expect remnants of storms along MN/IA state 
line to phase with next batch of showers and storms currently 
shifting east across central MN. This activity will shift across 
central WI and eventually into northern WI late tonight. Isolated 
narrow areas of moderate to heavy rainfall could occur as has 
been observed this evening upstream. Flash Flood Guidance is on
the higher end, but some spots over central WI have seen nearly
0.75 inch of rain. So, there could be minor flooding issues if
additional rainfall falls across the same locations. Overall 
though, expect rainfall rates to be held down as higher MUCAPES, 
elevated instability remain well to the southwest of our area. 
Also, given limited instability, kept only mention of thunder 
central to north-central WI.

&&

.KEY MESSAGES...

- Rain and a few thunderstorms tonight into Friday. Low risk 
  for severe storms. Probability of 1 inch or more of rain 
  remains 20 to 40 percent mainly north of US-8.

- Drier Saturday, then additional chances for rain and storms
  Sunday into next week.

&&

.DISCUSSION...
Issued at 201 PM CDT Thu Jun 12 2025

Scattered showers are starting to redevelop to the west along an
axis of 700mb moisture and convergence. As we head into this
evening this area of convergence will gradually shift north with
850mb warm air advection and convergence adding to low level
lift. The environment will saturate from the top down as it
works through the drier air at the surface. This area of
convergence will linger over northern Wisconsin through Friday
and Friday night. With precipitable water values around an inch
some heavier rainfall is possible, especially where lift is the
strongest, which currently looks to be north of US-8 where 
probabilities of an inch or more is 20 to 40 percent.

The upper level flow remains quite westerly but a shortwave
trough moves through Saturday morning bringing some drier
conditions for the afternoon and evening. Moisture returns 
Sunday, but lift is marginal with limited positive vorticity 
advection, hence only 20 to 40 percent PoPs across most of the 
area. Slightly higher chances (40 to 50 percent) are expected 
Monday as another shortwave moves through. The flow becomes more
southwesterly for Tuesday ahead of a deeper shortwave 
Wednesday. This period will have our best chances for rain and
thunderstorms (50 to 70 percent) due to the better lift in 
place.

Cooler temperatures are expected over the next few days with 50s
and 60s in the north and 70s to the south. As we head through
the weekend into next week however highs warm into the mid 70s
to mid 80s. Overnight lows will largely be in the 40s and 50s
until next week when they'll be in the 50s and 60s.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1044 PM CDT Thu Jun 12 2025

Rain showers continue to spread across central and northern WI. 
Generally seeing VFR ceilings with MVFR visibility where rain is 
steadiest. Additional waves of showers will work across central
and northern WI overnight through Friday morning. A few showers 
may also impact the Fox Valley and east-central WI, though this 
chance is not as high as from central WI into northern WI 
(AUW/CWA/RHI). Easterly winds will remain elevated tonight around 
10 kts with gusts up to 20 kts. 

Friday into Friday evening, ceilings will deteriorate to MVFR and
IFR central to north-central, with MVFR to lower VFR elsewhere. 
MVFR or even IFR visibilities will occur at times over northern 
WI, including at RHI as showers prevail there. Easterly winds 
will remain gusty at times. Patchy fog may develop by Friday
evening over northern WI.  

The potential for thunder through the TAF period remains low.

&&

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

&&

$$

UPDATE.........JLA
DISCUSSION.....RAH
AVIATION.......JLA