textproduct: Milwaukee/Sullivan

KEY MESSAGES

- Significant severe weather event remains forecast this afternoon & evening (peak intensity 3-10 PM). All severe weather hazards, including very large hail greater than golf ball size and tornadoes, are possible. Seek immediate shelter if a warning is issued for your area later today.

- Additional severe storms possible Wednesday afternoon if a front remains stalled across the area. If the front sets up south of the area, severe potential will greatly decrease but flash flooding will remain possible due to training convection.

- Heavy rainfall could lead to additional periods of flooding this afternoon into Wednesday. Additional Flood Watches are possible especially tomorrow.

- Additional windows for heavy rainfall, flooding, and severe thunderstorms Friday into Saturday. All severe hazards will be possible later Tuesday afternoon into the evening.

SHORT TERM

Issued 309 PM CDT Tue Apr 14 2026

Tonight through Wednesday night:

Storms have begun to fire this afternoon over central to NW Iowa. This corroborates a westward shift in initiation trends in recent runs of the HRRR model. Current runs of the WoFS support two main areas of storms this afternoon with a cluster of storms over central WI through Sauk, Columbia, Green Lake, and Marquette Counties that will then track east to the lakeshore and a cluster that will move through southwest Wisconsin and east to the lake. These storms are projected to be supercells when they enter our area but may cluster into a line with eastward extent

An 18z sounding from Davenport supports a very unstable environment supportive of 4000 J/kg held by a cap at 800mb. With the cap eroding to our west, explosive supercell development is expected, leading to the corridors of storms in southern WI mentioned in the previous paragraph. All hazards will be possible during the supercell mode, as mid level lapse rates ~8 C/km and hodograph curvature will support large hail, and curvature in the low levels of the hodographs and 3CAPE >150J/kg will support 0-1 km SRH >200 m2/s2 and low level stretching for tornado formation. As we head into the evening, there may be some potential for these storms to become linear, leading to a damaging wind and QLCS tornado threat, especially as the LLJ increases near sunset and lengthens the low level hodographs. Todays severe weather hazards are expected to be high end and should not be taken lightly. Have multiple ways to receive warnings.

Storms are largely expected to be out of the area after 10PM, and may push a surface boundary through our area. If this happens, storms tomorrow will be less severe though flash flooding will still be a threat. Runs of the CAMs depict a west to east oriented line of storms that may set up along the WI/IL border during the late afternoon into the evening, capable of heavy rain. The wind, hail, and tornado threat with the storms tomorrow will be far less than today.

CMiller

LONG TERM

Issued 245 PM CDT Tue Apr 14 2026

Thursday through Tuesday:

A shortwave trough will track across southern WI Thursday morning. Scattered showers and a few thunderstorms are expected with this feature, especially in the morning with deeper moisture still in place over the region. The chance for showers and thunderstorms will linger into the afternoon. As the deeper moisture departs during this time and we heat up, the low level lapse rates will increase to allow for instability (up to 1000 j/kg) to develop. A lake breeze should push inland and help to trigger some of the showers/storms. Look for the precip chances to exit by sunset.

High pressure will pass through Thursday night and lows will dip into the 40s wherever the lake breeze hit, so bisecting southern WI from east to west. Friday morning and early afternoon look quiet, but we will be getting primed for the next system to arrive Friday late afternoon and night.

Low pressure tracking across the northern Plains on Friday, in response to a high-amplitude upper trough, will cross Lake Superior Friday night. A strong cold front will slide across WI from west to east late Friday night through Saturday morning. Showers are thunderstorms are expected within the warm sector Friday afternoon/evening and also along the cold front. Scattered showers are possible behind the front during the day Saturday. Strong cold air advection will follow, so low temps should dip down to around or below freezing Saturday night on brisk westerly winds. The models dry out the atmosphere quickly, but if there happens to be any lingering moisture, the precip type would chance to flurries/snow.

Brisk westerly winds will persist through Sunday. Finally, high pressure will dominate and give us dry weather through Monday or Tuesday. The weather pattern has a large degree of uncertainty beyond Monday between the models.

Cronce

AVIATION

Issued 236 PM CDT Tue Apr 14 2026

Severe storms are expected this evening across all of southern Wisconsin. These storms will be capable of all severe weather hazards. The storms should track from west to east across the area between 21Z and 03Z tonight. Higher surface moisture has supported low VFR to high MVFR BKN to SCT conditions and those cigs should largely continue into tonight. Ambient, background flow should be southerly to southwesterly with breezes from 15 to 20 knots. After storms move through tonight, winds should briefly become light and variable for a time before southerly winds return. Fog may also form over south central WI.

CMiller

MARINE

Issued 245 PM CDT Tue Apr 14 2026

A stationary front will remain parked over the middle third of the lake into tomorrow, slowly sinking south to the southern end of the lake by Thursday morning. Winds will remain southerly south of the front and modestly breezy, while winds north of the front will remain light and variable to northerly during this time. Today, severe storms are expected over the southern half to southern two thirds of the lake. Hail and gusty winds will be possible and waterspouts may occur with any tornadic storms from land that move over the waters. This will be most likely near the shoreline of Wisconsin and Illinois.

The front will clear the lake as a cold front Friday, before low pressure of 29.6 inches approaches from the west.

CMiller

MKX WATCHES/WARNINGS/ADVISORIES

WI...None. LM...Dense Fog Advisory...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ643-LMZ644-LMZ669-LMZ671-LMZ868-LMZ870-LMZ872 until 7 AM Wednesday.