textproduct: Milwaukee/Sullivan

KEY MESSAGES

- Strong to severe storms remain possible late tonight (mainly after 10 PM). Damaging winds and isolated tornadoes are the main hazards.

- Urban and small stream flooding will remain possible overnight as additional rounds of rain move across southern Wisconsin.

- Rain expected Tuesday into Tuesday night. An isolated thunderstorm cannot be ruled out. As rain exits late Tuesday night, some wintry mix is possible.

UPDATE

Issued 630 PM CST Fri Mar 6 2026

A lull in the active weather persists through around 10 PM CST this evening. Our attention now turns to the convection firing up off the cold front in southwestern IA (as of right now), which should gradually track northeastward into our region (likely arriving between 10 PM and 1 AM CST in a west to east manner), then gradually taper down from west to east through predawn Saturday morning, followed by the west to northwest surface wind shift (the cold front itself) after dawn Saturday morning.

Bottom line is that strong to severe storms remain possible with this last round of activity (specifically damaging wind gusts and isolated tornadoes), especially between 10 PM and 4 AM CST. The risk is somewhat 'conditional', in that it depends on the northward progress of the surface warm front draped across our region and the organization of the aforementioned southwest IA convection into a QLCS or other multicellular mode.

Sheppard

SHORT TERM

Issued 153 PM CST Fri Mar 6 2026

This afternoon through Saturday:

Watching an effective warm front wiggle northward through the Mississippi Valley this afternoon, with expectations of a brief period of peeks of sunlight and higher clouds this afternoon as a much warmer airmass arrives in the southern two tiers of Wisconsin counties. As temperatures rise, isolated to scattered thunderstorms may develop in the warm sector along the effective warm front. A few of these cells have already developed in northern Illinois, with expectations that as the front moves northward this isolated to scattered activity will develop across far southern Wisconsin. Within these cells, without much steering flow, expecting more pulse-tyle convection with primary hazards of hail and gusty winds. CAPE nearing 500 J/kg, bulk shear around 35 kt, and moderate mid level lapse rates of 6-7 degrees C/km along with freezing levels near convective cloud base will set the stage for isolated cells to be able to tap into all the dynamics and instability this afternoon. Significant turning in the lowest 5000 ft may allow for an isolated supercell to develop, but confidence is low. Expecting isolated storms with hail up to 1 inch and gusty winds.

A brief break in precipitation may develop around sunset into the early overnight hours as the surface warm front weakens with the lack of solar heating, and the developing low remains to the southwest. However, going into the 10 PM to 3 AM timeframe, expecting the low to rapidly lift northeastward, bringing convection through all of southern Wisconsin. With LLJ dynamics in play (nearing 60 kt nosing across far southern Wisconsin, nearing 50 kt in central Wisconsin), expecting this prefrontal convection to have plenty of lift (frontal boundary), shear (bulk shear values near 50 kt, 0-3 helicity 300-400 m2/s2), and moisture to work with (PWATs nearing 1.5 inches). MUCAPE will also continue to increase through the overnight hours, nearing 1000 J/kg by the time the prefrontal convection moves in. With all these ingredients in play, expecting a squall line type feature with low topped convection and potential for QLCS tornadoes along the leading edge where individual bowing segments turn northeastward (along the 0-3 shear vector). Even with a stable layer near the surface, strong enough cells embedded in the line are expected to punch through to the surface, resulting in damaging wind potential along with the low topped QLCS tornado threat. Hail is less likely for this round, but not out of the question.

Convection will sweep eastward into the early morning hours Saturday, with lighter rain and embedded lightning to continue after the main band of strong thunderstorms moves through. All activity will exit into Lake Michigan and northern Illinois by 4 AM based on current model guidance. The main cold front lags behind the convection by several hours, allowing for slight chances of additional showers (20-30%) through mid-morning Saturday along the cold frontal boundary. No additional severe storms are expected. Temperatures will remain in the 50s throughout the day, falling quickly into the 40s after sunset.

MH

LONG TERM

Issued 153 PM CST Fri Mar 6 2026

Saturday night through Friday:

Overall a mild pattern is expected for southern WI through the end of the weekend into the start of next week with well above normal temps. Temps regulate closer to normal through the middle of next week with a more active pattern. Next chance for precip across southern WI is looking to be later Tuesday into Wednesday. Additional chances are possible for the second half of the week, but more uncertainty and variance in solutions remains this far out.

The upper-level trough bringing today's active pattern will exit the region overnight Saturday into Sunday. Light winds and dry conditions will linger as another weak dry cold front swings through early Sunday. Behind this weak front, winds turn more southwesterly through Sunday as another warm front begins to lift northward while another surface low develops across Manitoba overnight Sunday into Monday. This prevailing WAA pattern is looking to warm things up well above normal Sunday into Monday. Looking at 50s into the lower 60s for Sunday, but even milder temps for Monday with high chances (<80% from the NBM) to see highs exceed 65F for Monday and even a potential (20-40%) to even see temps approach and crack 70F. Global ensembles are not a enthusiastic about the milder temps exceeding 60F, but given the WAA pattern would hedge toward the milder stretch.

Milder temps are expected to tampered down by the Monday low pressure trekking across Ontario and dragging another dry cold front through the Upper Great Lakes. Will likely see temps fall for Tuesday closer to normal ranging from around 50F into the 40F. There are hints in the models of this cold front stalling somewhere across the region, so depending on where will ultimately impact overall temp trends Tuesday.

Meanwhile the next system to bring precip chances to southern WI will be taking shape across the Plains as an upper-level trough digs across the Central CONUS. This will be associated with a surface low developing across the plains and looks to ride up the stalled boundary into the Great Lakes Region later Tuesday into Wednesday. Again some uncertainty remains with this system as models hint at an upper-level cutoff low developing across the southern Plains at the same time as the main trough, thus if these two systems phase can alter the track of the surface low along with precip chances and types. So will have to monitor how trends evolve over the next few days as southern WI could see snow to wintry mix to rain all depending on the track of the midweek system.

Otherwise, the pattern becomes more uncertain through the second half of next week, which is not that uncommon during the spring here in the Midwest.

Wagner

AVIATION

Issued 620 PM CST Fri Mar 6 2026

A brief hole in the low stratus clouds has progressed northeastward into far southern WI early this evening, and should continue to make northward progress over the next few hours, resulting in a brief window of 3,500+ ft cloud ceilings (VFR) for much of the region. Some IFR clouds and thin fog may linger further north towards central WI. Breezy southwesterly winds (40-50kt) have arrived aloft (2,000 ft AGL) resulting in some low level wind shear, with the surface winds in our region remaining relatively light at the surface (~10kt). A warm front draped south of the region may make some northward progress (allowing the south to southwesterly surface winds to increase), though the winds aloft will continue to accelerate and outpace surface winds (hence, LLWS remains in the TAFs through much of the overnight hours).

A lull in the active weather (mostly dry conditions aside from some patches of drizzle and fog) continues through much of this evening. From 10 PM to 4 AM CST (overnight) the next round of thunderstorms is expected to track eastward across the region, with potential for some strong to severe storms (damaging winds and isolated tornadoes possible). Cloud ceilings are likely to decline to IFR levels with this activity. Rain showers decrease in coverage towards daybreak Saturday, with PROB30 for rain lingering through much of the morning hours. Surface winds veer west and eventually northwest through Saturday morning as a cold front crosses the region.

Sheppard

MARINE

Issued 153 PM CST Fri Mar 6 2026

Low pressure in the central Great Plains will continue to track northwards into the Upper Mississippi River Valley by this evening. Southwesterly winds will prevail ahead of this low through the evening along with widespread rain and embedded thunderstorms will accompany the approaching low today. Light to modest winds and milder temps will also create conditions favorable for marine fog to develop at times through this evening into Saturday morning. Thus a Marine Dense Fog Advisory is in effect for periodic drops in visibilities to less than 1 nm at times. Then the low will move near or just north of Lake Michigan tonight into Saturday morning and drag a cold front across the Upper Great Lakes into Saturday morning. Will see breezy west to northwesterly winds behind the front and usher out the marine fog by late Saturday morning. Westerly winds will prevail through Saturday night before increasing and turning more southwesterly for Sunday into Monday as a series of two low pressure systems develop and track north of Lake Michigan through this time frame.

Wagner

MKX WATCHES/WARNINGS/ADVISORIES

WI...None. LM...Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646...midnight Saturday to noon Saturday.

Dense Fog Advisory...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563- LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779- LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 until 9 AM Saturday.