Dense Fog in Wisconsin, May 25, 2001

Name: Dense Fog in Wisconsin, May 25, 2001
Start: 2001-05-25T03:00
End: 2001-05-25T06:00
Location: Wisconsin

May 25, 2001 · NWS MKX · 5 events in 5 counties and zones

Dense fog developed over southeast and south-central Wisconsin after light winds off Lake Michigan pulled moist air into the region. Clear skies aided in the nighttime radiational cooling.

Where it happened

Every event with a place to put it; 5 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.

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Wind
Hail
Winter weather
Heat and drought
Cold
Fire, smoke and dust
Marine and coastal
Other

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The toll

Deaths: 0
Injuries: 0
Property damage: None recorded
Crop damage: None recorded
Events: 5

Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.

What happened

The episode as NWS MKX wrote it up.

Dense fog developed over southeast and south-central Wisconsin after light winds off Lake Michigan pulled moist air into the region. Clear skies aided in the nighttime radiational cooling. Visibilities were reduced to 1/8 to 1/4 mile. About a dozen vehicle accidents were noted and local airport traffic was delayed.

What forecasters said that day

The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Milwaukee, WI wrote its last area forecast discussion before the first event at May 25, 2:10 AM CST, 50 minutes earlier.

Area forecast discussion, May 25, 2:10 AM CST, 50 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
310 AM CDT FRI MAY 25 2001

FCST CHALLENGE...DENSE FOG SOUTHEAST...OTHERWISE SIMILAR TO LAST 3-4
DAYS.

LIGHT WINDS...DAMP BNDRY LEVEL AND COOL LAKE EFFECTED AIR HAS
BROUGHT DENSE FOG TO THE SOUTHEAST AND WILL CONTINUE THE DENSE FOG
ADVISORY THROUGH ABOUT 10 AM...FINAL CONFIGURATION WILL BE
DETERMINED AT PRESS TIME.

BIG WOBBLELY LOW WITH ITS CIRCULATION CENTER OVER KSPI EARLY
THIS MORNING...WILL SWING NORTH INTO MI TONIGHT THEN BACK SOUTH
ACROSS WI ON SAT...FINALLY EXITING SLOWLY EAST ON SUN.  MODELS
SUGGEST A SOMEWHAT QUIET DAY TODAY...PCPN WISE. SOUTHERN WISCONSIN
SITTING BETWEEN TWO MAIN VORT SPOKES ROTATING AROUND THE LOW.  THE
FIRST IS ROTATING ON THE WESTERN...BACKSIDE OF THE LOW TODAY...WHILE
THE NEXT BEGINS TO WRAP AROUND THE FRONT SIDE...COMING BACK DOWN INTO
THE CWA ON SATURDAY. HOWEVER...WITH COLD POOL IN PLACE AND STRONG
SUNSHINE...ANY BREAKS IN CLD COVER TODAY WILL LEAD TO MORE
DEVELOPMENT OF PCPN...JUST ABOUT ANYWHERE.  A LOOK BACK AT THE
DIURNALLY DRIVEN DEVELOPMENT AROUND THIS MONSTER CIRCULATION OF THE
LAST 3 OR SO DAYS IS EVIDENCE ENOUGH.  THUS...WILL KEEP POPS IN THE
LIKELY CATEGORY TODAY...DESPITE MODEL INDICATIONS OF LITTLE OR NO
QPF.  NEXT VORT SPOKE WITH ASSOCIATED INCREASE OF H7 OMEGA AND
OVERALL INSTABILITY SHOULD LEAD TO MORE FOCUSED PCPN ON SATURDAY.

WILL FINALLY TREND TO AN END OF THE PCPN FOR EARLY NEXT WEEK AS LOW
PULLS AWAY.

TEMPS NEAR PERSISTENCE TODAY AND GUID MOS LOOKS GOOD.  SOME WAA ON
SAT TO PUSH TEMPS UP A NOTCH...NOT MUCH THOUGH.

.MKX...DENSE FOG ADVISORY TIL 9AM SOUTHEAST ZNS...52..59..60..65..66
           :                                    71..72

DAVIS

The radar

The national radar mosaic for the moment the first event began.

Open the radar archive at this moment

Event by event

5 dense fog. Local standard time, as filed.

Dense Fog, Dodge

When: May 25, 3:00 AM CST to 6:00 AM CST
Where: Dodge forecast zone
Reported by: AWOS,ASOS,MESONET,ETC
Coordinates: 43.416, -88.707 (the zone’s center; the record gives no point)

Dense Fog, Dane

When: May 25, 3:00 AM CST to 6:00 AM CST
Where: Dane forecast zone
Reported by: AWOS,ASOS,MESONET,ETC
Coordinates: 43.067, -89.418 (the zone’s center; the record gives no point)

Dense Fog, Jefferson

When: May 25, 3:00 AM CST to 6:00 AM CST
Where: Jefferson forecast zone
Reported by: AWOS,ASOS,MESONET,ETC
Coordinates: 43.021, -88.776 (the zone’s center; the record gives no point)

Dense Fog, Green

When: May 25, 3:00 AM CST to 6:00 AM CST
Where: Green forecast zone
Reported by: AWOS,ASOS,MESONET,ETC
Coordinates: 42.680, -89.602 (the zone’s center; the record gives no point)

Dense Fog, Rock

When: May 25, 3:00 AM CST to 6:00 AM CST
Where: Rock forecast zone
Reported by: AWOS,ASOS,MESONET,ETC
Coordinates: 42.671, -89.072 (the zone’s center; the record gives no point)

What these are

Dense Fog: Fog reducing visibility to a quarter mile or less, filed where it caused accidents or disruption.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

Every storm in Wisconsin in 2001 Every state in 2001 This day in weather history Warnings in Wisconsin, May 2001

Sources

NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 5248227, 5248228, 5248300, 5248301, 5248302.