textproduct: Milwaukee/Sullivan

KEY MESSAGES

- Periodic shower and thunderstorm chances are forecast from Wednesday evening through Saturday, though there will be some dry periods. Cannot rule out a few stronger storms during this period.

- Conditions look a bit drier by later this weekend.

SHORT TERM

Issued 413 AM CDT Wed Jun 11 2025

Today and Tonight:

WAA is underway across southwestern Wisconsin and will expand across the entire forecast area through this morning. Temperatures have maintained or increased with many locations having temps in the mid to upper 60s. Despite clear skies early this morning, the overnight lows will remain warm due to this WAA. The pressure gradient will also tighten slightly across the state which will lead to some breezy southwest winds.

Aloft there is mostly zonal flow across the Great Lakes Region with a trough to our northeast in the Hudson Bay area and a weak ridge to our west. There will be multiple little upper level disturbances moving through this zonal flow, but many will be largely uneventful until moisture increases. Which thanks to the WAA kicking in this morning, moisture will gradually be climbing throughout the day. Dewpoints are lower this morning, so we can largely expect cloud cover to increase and maybe a shower or two. Chances for any showers are much better to the west, but that's still not saying a lot with a 10 to 15% chance POPs to our west. Therefore dry conditions should win out here. Heading into this afternoon dewpoints are likely to climb into the 60s with highs in the 80s leading to a more typical hot, humid summer day.

This evening, a cold front will move south down the state and eventually stall out along the WI/IL border Thursday. As this cold front moves south, a shortwave will move through bringing some upper level support. With both upper level and sfc lift/forcing, showers and storms will be likely (60-70%) especially for southwest and west central Wisconsin. Portions of far southeastern Wisconsin may see little in the way of rain until Thursday. This is in part due to a lack of instability and the low level jet will be to our west which leaves us with mostly decaying showers/storms. That being said, the best of our instability will be across our far southern counties and shear is good around 40 kts. Therefore a stronger storm or two can't be ruled out. The main hazards with any stronger storm will be brief gusty winds and hail. Instability will fall off quickly as the cold front passes so timing will be limited to the early evening hours.

Shower and storm chances continue into Thursday across the forecast area. Chances for rain and storms fluctuates wildly from model to model and run to run. A lot of this is dependent on just where the frontal boundary will stall and if it wiggles slightly north or south at any given time. What we can be sure of is that showers/storms are likely to linger into the morning hours from the day prior. There will be periods of dry weather throughout the day. Now moving onto the big ifs here, there does look to be more movement of the mid level frontal boundary than the sfc. Guidance is trying to push the mid level boundary further north out our area with help from a LLJ and shortwave. There are two scenarios here that would play out depending on the movement of this mid level boundary. One is if the mid level front stays put, it will likely be overhead leading to more rain and storms developing through the afternoon and evening. The second is the mid level front moves north and with it the better forcing and lift does too. This leads to more dry conditions for southern Wisconsin and more rain for central Wisconsin. Currently among guidance there is more support for a northward shift of the mid level frontal boundary and drier conditions. Its not enough to erase POPs but kept them lower in the 30s to 40s. Stay up to date with the forecast through Thursday.

Patterson

LONG TERM

Issued 413 AM CDT Wed Jun 11 2025

Thursday night through Tuesday:

There is a lot of uncertainty with how showers and thunderstorms will trend Thursday night into Saturday. Operational models have been trending northward with the focused 850 mb warm air advection and subsequent showers and storms for Thursday night into Friday. Ensembles have trended north of the area as well with the highest probabilities for at least 0.50 inches of rainfall. However, the warm/stationary front remains over or near the area, so cannot totally rule out some shower and thunderstorm activity occurring.

There may be a better chance for showers and storms Friday night, as the weakening low pressure system slides southeast through the area and may be accompanied by some differential CVA aloft. If the area can get into the warm sector and see some sunshine, then it can get more unstable and lead to better chances for thunderstorms.

Ensembles are generally showing around 40 to 60 percent chances for at least 0.10 inches of rainfall Friday night, but are much lower (less than 30 percent) with at least 0.50 inches of rainfall occurring. So, this may indicate lighter showers and weaker storms during this time.

It will all depend on what happens Thursday night into Friday for any impacts on Friday night shower and storm chances. There may be a few showers or storms that linger into Saturday, though anything here will be behind the exiting system and be scattered and weaker.

For now, will leave NBM PoPs in place through Saturday, perhaps with some adjustments, given the large amount of uncertainty with what may occur during this time. Temperatures will also be impacted by the amount of cloud cover and showers and storms that occur, so will leave those from the NBM as well.

High pressure to the northeast Saturday night into Monday morning may keep the area dry with cooler temperatures. There is more uncertainty later Monday into next week with shower and storm potential, so kept PoPs and temperatures from the NBM. Ensembles suggest a warmup may occur into next week, which may be reflected in NBM temperatures during this time.

Wood

AVIATION

Issued 413 AM CDT Wed Jun 11 2025

Southwest winds are expected to increase as warm air advection kicks in this morning. Some gusts to around 20 knots are possible. LLWS remain possible through this morning until roughly 15z. If LLWS does occur it should be brief and near the top of the column around 2000 feet AGL around 45 kts.

WAA ahead of an approaching cold front will lead to some increased cloud cover and maybe a showers or two this morning. Shower chances are very low. The cold front should move south into the area and stall in southern portions of the area by this evening. There may be weakening showers and storms that move east into the area during this time. Winds will weaken as the front moves in. Since showers and storms are weakening as they move in, kept mentions of thunder limited in the TAFs. Ceilings through out the day should largely stay VFR. The best chance for a few MVFR ceilings to move in with any storms will be across west central Wisconsin and should stay north and west of MSN. Periods of showers and storms will continue through Wednesday night.

Patterson

MARINE

Issued 413 AM CDT Wed Jun 11 2025

Low pressure in Ontario will slowly move out of the northern Great Lakes Region to the east, while high pressure in the Ohio Valley region is near stagnant. Light to moderate southwest to west winds are expected across the lake between these two systems today. Moderate winds will approach Small Craft Criteria late this morning into the afternoon. Winds should stay below with gusts of 21 kts possible.

This evening, a cold front will drop south down the lake and become stationary across the far southern end Thursday. This frontal boundary will remain draped across the far southern lake until Friday, when a low pressure system moves into central Wisconsin from the Rockies. Multiple rounds of showers and thunderstorms will be possible from Wednesday evening through Friday, with better chances remaining to the west.

Light north to northeast winds are expected behind the cold front this evening. When the front stalls, areas north of the boundary will have light northeast winds and areas to the south will have light southeast winds. While winds remain light, waves will slowly build into the weekend. Winds across the lake will increase slightly Thursday night into Friday and become easterly, as the low approaches. No gales expected at this time.

Patterson

MKX WATCHES/WARNINGS/ADVISORIES

WI...None. LM...None.