FXUS63 KGRB 041642

AFDGRB



Area Forecast Discussion

National Weather Service Green Bay WI

1142 AM CDT Mon May 4 2026



Updated aviation portion for 18Z TAF issuance



.KEY MESSAGES...



- Warm and breezy today with lower RH values. 60-90% chance of 

  wind gusts 35 to 40 mph central to eastern WI. Elevated fire 

  weather conditions where fine fuels have dried out and green up 

  is not as advanced.



- Band of showers and storms (20-40% chance) develops mid to late

  afternoon, especially southern Fox Valley to the lakeshore. 

  Stronger storms could produce wind gusts 40-50 mph.  



- Temperatures fall below normal for the rest of the week. Risk

  for Frost/Freeze Headlines ramps up beginning Tuesday night.



&&



.DISCUSSION...

Issued at 204 AM CDT Mon May 4 2026



Breezy and warm today with elevated fire weather conditions. Also,

still a small chance of some showers and storms, especially later

in the afternoon. Cooler for the rest of the week, with frost/freeze

headlines likely needed multiple nights. 



Elevated fire weather conditions today: Cold front over northern

MN arrives late today. Ahead of the front, another warm and breezy

day is expected today. Highs will reach the lower to middle 70s

where clouds will not be as prevalent early on (north-central).

That will have to be monitored though as it will be gusty there as

well with low RH values. Based on deep mixing, wind gusts should

reach 35 to 40 mph, with even isolated higher gusts late morning

through mid afternoon. Strongest winds will be from central to 

eastern WI (60-90% chance of gusts over 35 mph). Conditions will

be most favorable for fire spread where green up is not quite as

advanced, but with the gusty winds and warm temps (10-15 above

climo), have issued an SPS for all areas except north-central.  



Shower and storm potential this afternoon: Dry airmass will impact

potential for showers and storms mid to late afternoon. Upstream

soundings at Omaha, Davenport are quite dry, so even with the

front moving in during peak heating, dry air and some evidence of

capping up to H7 looks to limit convective potential. Used gradient

of MLCAPE (up to 400J/kg) as guide and placed narrow ribbon of 

chance pops from southern Fox Valley to the lakeshore. A few 

showers could occur northwest of this area, but this is where 

thunder is most favored. Given winds aloft and inverted-V look to

soundings, if a storm develops, gusty winds 40-50 mph would be in

play. Honestly, given the winds aloft, even a more developed

shower could pull down similar wind gusts this afternoon. Will be

a near term forecast item for dayshift to keep tabs on. Any

showers quickly end early this evening and it will be a bit 

breezy behind the front as well as cooler air begins to arrive. 



Cooler with frost/freeze potential rest of the week: Small chances

for a few showers or sprinkles cannot be ruled out Tue or Wed over

northern WI. Better chances still in forecast for Thursday all

areas as stronger wave crosses the region. May be just cold enough

for some graupel or snowflakes to mix with the showers that day,

at least during the morning. Frost/Freeze potential highest Tuesday

night through Thursday night, and maybe on Friday night as well. 

Right now, appears that greater frost potential is setting up 

more west of the Fox Valley and lakeshore. Daytime temperatures 

will mainly be in the 50s, though highs likely stay in the 40s

over the far north. Temperatures will begin to rebound to around 

climo starting next weekend.



&&



.AVIATION...for 18Z TAF Issuance

Issued at 1142 AM CDT Mon May 4 2026



A cold front will continue tracking through the area this 

afternoon, accompanied by gusty winds of 25-35 knots. The front 

will bring an increase in mid and high clouds, with bases 

remaining at VFR. CAMs continue to indicate there may be some 

showers and perhaps a thunderstorm (20-30% chance) that pops up 

with the front this afternoon across east-central Wisconsin. While

most TAF sites will remain dry with this FROPA, the best chance 

of seeing rain will be at KMTW with a PROB30 group this afternoon.

If a stronger storm occurs this afternoon, wind gusts over 40 kts

would be possible given strong winds aloft and an inverted-V type

sounding profile. 



For tonight, as winds shift to the west-northwest expect gusty

winds of 20-25 knots to persist in the this evening. Winds will 

gradually subside overnight to 10-15 knots. Conditions will 

remain VFR as skies clear from northwest to southeast behind the

departing cold front.



&&



.GRB WATCHES/WARNINGS/ADVISORIES...

None.



&&



$$



DISCUSSION.....JLA

AVIATION.......Kurimski