Wisconsin, 2001

Dense Fog in Wisconsin, December 2, 2001

December 2, 2001 · NWS MKX · 4 events in 4 counties and zones

Light winds, abundant low-level moisture, and clear skies led to the formation of dense fog which reduced visibilities to 1/8 to 1/4 mile. Several vehicle accidents were noted in local newspapers, and airplane traffic was delayed.

Where it happened

Every event with a place to put it; 4 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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The toll

Deaths
0
Injuries
0
Property damage
None recorded
Crop damage
None recorded
Events
4

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.

Light winds, abundant low-level moisture, and clear skies led to the formation of dense fog which reduced visibilities to 1/8 to 1/4 mile. Several vehicle accidents were noted in local newspapers, and airplane 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 Dec 2, 3:00 AM CST, 1 hour earlier.

Area forecast discussion, Dec 2, 3:00 AM CST, 1 hour before
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
300 AM CST SUN DEC 2 2001

FCST FOCUS ON LO CLDS/FOG THIS MORNING...MILDER TEMPS INTO TUES...
PRECIP CHC XTNDED.

AREA OF LO CLDS FORMED SAT EVENING OVR CWA. APPEARS TO BE A RESULT
OF WEAK WAA AND MOIST BOUNDARY LAYER UNDER NIGHTTIME INVERSION.
INVERSION ALSO PREVENTING MIXING OF WINDS ALOFT TO DISPERSE/ADVECT
CLDS OUT OF CWA. ALSO...FOG GETTING DENSE ACROSS CWA. SMALL
TEMP/DEWPT SPREADS COMBINED WITH FAIRLY WEAK SFC WNDS AND INVERSION
SHOULD YIELD FAIRLY WIDESPREAD DENSE FOG. WILL ISSUE DENSE FOG
ADVISORY FOR THIS MORNING FOR ALL OF THE CWA. DAYTIME HEATING
SHOULD HELP MIX OUT LO CLDS/FOG BY LATE MORNING.

TODAY AND MON LOOK NICE...WITH A GRADUAL WARMING TREND. 850MB TEMPS
RISE FROM 2C TO 4C TODAY AND 4C TO 8C MON IN GRADUAL WAA. ATMOSPHERE
LACKING SUSTAINED LIFT AND MOISTURE IN ZONAL FLOW ALOFT.

UPPER LEVELS TURN SWLY MON NGT IN RESPONSE TO DIGGING TROUGH IN SWRN
US. 850MB MOISTURE BEGINS TO ADVECT INTO CWA...COMBINING WITH WAA TO
ALLOW FOR CLDS TO INCREASE INTO TUES MORNING. TEMPS WILL REMAIN MILD
AS WAA REGIME CONTINUES. ENOUGH MOISTURE AND LIFT FROM WAA FOR
MENTION OF SHOWERS TUES AFTERNOON.

XTENDED LOOKS MORE ACTIVE...AS SFC LO FORMS IN SRN PLAINS AND MOVES
TOWARD CWA TUES NIGHT. AVN MODEL AGGRESSIVE WITH SYNOPTIC LIFT...
WHICH PROGS 850MB WAA...NOSE OF 50KT PLUS LLJ...AND RRQ OF 140KT
PLUS 250MB JET OVR CWA AT 06Z WED. STRONG RESPONSE IN 700MB OMEGA
NOTED AS A RESULT. AVN PROBABLY OVER DOING LIFT...BUT STILL FEEL
LIKELY POPS ARE GOOD FOR TUES NIGHT INTO WED. SFC LO MOVES OVER AND
NE OF CWA WED. 500MB SHORTWAVES IN SWLY FLOW WILL KEEP WED NIGHT
THROUGH FRI UNSETTLED.

.MKX...DENSE FOG ADVISORY UNTIL 10AM...ZONES 46..47..51..52..56>60..
                                             62>72.
0...0...0...0...0...0

WOOD

The radar

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

Open the radar archive at this moment

Event by event

4 dense fog. Local standard time, as filed.

Dense Fog, Milwaukee

When
December 2, 4:00 AM CST to 9:00 AM CST
Where
Milwaukee forecast zone
Reported by
AWOS,ASOS,MESONET,ETC
Coordinates
43.022, -87.929 (the zone’s center; the record gives no point)

Dense Fog, Walworth

When
December 2, 4:00 AM CST to 9:00 AM CST
Where
Walworth forecast zone
Reported by
AWOS,ASOS,MESONET,ETC
Coordinates
42.669, -88.542 (the zone’s center; the record gives no point)

Dense Fog, Racine

When
December 2, 4:00 AM CST to 9:00 AM CST
Where
Racine forecast zone
Reported by
AWOS,ASOS,MESONET,ETC
Coordinates
42.730, -87.812 (the zone’s center; the record gives no point)

Dense Fog, Kenosha

When
December 2, 4:00 AM CST to 9:00 AM CST
Where
Kenosha forecast zone
Reported by
AWOS,ASOS,MESONET,ETC
Coordinates
42.573, -87.840 (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

More

Every storm in Wisconsin in 2001Every state in 2001This day in weather historyWarnings in Wisconsin, December 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: 5275603, 5275604, 5275605, 5275606.