Dense Fog in Wisconsin, March 10, 2009

Name: Dense Fog in Wisconsin, March 10, 2009
Start: 2009-03-10T09:00
End: 2009-03-10T18:00
Location: Wisconsin

March 10, 2009 · NWS MKX · 12 events in 12 counties and zones

Abundant low level moisture from earlier rains and light winds with a weak pressure gradient as a surface low tracked across the region combined to produce dense fog during the afternoon of March 10th. Visibilities fell to 1/4 mile.

Where it happened

Every event with a place to put it; 12 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.

Tornadoes
Tropical storms and surge
Floods
Wind
Hail
Winter weather
Heat and drought
Cold
Fire, smoke and dust
Marine and coastal
Other

Open the live radar over this ground

The toll

Deaths: 0
Injuries: 0
Property damage: None recorded
Crop damage: None recorded
Events: 12

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.

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 Mar 10, 3:25 AM CST, 5 hours 35 minutes earlier.

Area forecast discussion, Mar 10, 3:25 AM CST, 5 hours 35 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
425 AM CDT TUE MAR 10 2009

.SHORT TERM...LIGHT TO MODERATE RAIN MOVED INTO SOUTHERN WISCONSIN
LAST EVENING AND CONTINUES EARLY THIS MORNING. TEMPERATURES HAVE
REMAINED ABOVE FREEZING ACROSS THE CWA AND EVEN WARMED A DEGREE OR
TWO OVERNIGHT...SO MIXED PRECIP WAS NOT A CONCERN. AREA OF DEEPEST
MOISTURE AND BEST LIFT WILL BE MOVING OUT OF THE AREA THIS
MORNING...WITH A FEW SCATTERED SHOWERS AND SOME DRIZZLE LEFT
BEHIND.

MAIN CONCERN AFTER CURRENT PRECIP MOVES OUT APPEARS TO BE WINDS
LATER THIS EVENING AND OVERNIGHT. FURTHER ORGANIZED PRECIP SEEMS
LESS LIKELY THAN PREVIOUSLY THOUGHT. MODELS HAVE TRENDED FURTHER
SOUTH WITH THIS SYSTEM...LEAVING THE WARM SECTOR AND BEST
ASSOCIATED MOISTURE/DYNAMICS SOUTH OF THE CWA. AT THIS POINT...IT
APPEARS THAT SOUTHERN WI WILL STAY SOCKED IN WITH LOW CLOUDS AND
DRIZZLE/LIGHT SHOWERS THROUGH THE BETTER PART OF THE DAY...AS A
DEEPENING SFC LOW TRACKS NE ACROSS THE STATE.

GOING BACK TO THE WIND CONCERN...A TIGHTENING PRESSURE GRADIENT
WILL SET UP ACROSS SOUTHERN WI BEHIND THE LOW THIS EVENING. EXPECT
SOME MIXING OVERNIGHT...BUT NOT TOO DEEP. NOT EXPECTING TO TAP 50
KT WINDS AT 850 MB...BUT COULD SEE SUSTAINED WEST WINDS UP TO 30
KT WITH HIGHER GUSTS AT THE SURFACE. CURRENTLY HAVE A WIND
ADVISORY FOR THE ENTIRE CWA FOR THIS EVENING THROUGH EARLY
WEDNESDAY MORNING.

FOR WEDNESDAY AND THURSDAY...SFC HIGH BUILDS INTO THE AREA WITH
THE HIGH SITTING RIGHT OVER WI ON THU. NW WINDS WILL KEEP
TEMPERATURES ON THE COLD SIDE...THOUGH SUNSHINE SHOULD BE
ABUNDANT.

FRIDAY AND SATURDAY...THE FLOW TURNS MORE SOUTHERLY AS THE HIGH
GETS PUSHED EASTWARD AHEAD OF AN APPROACHING SYSTEM. EXPECT
TEMPERATURES TO WARM BACK ABOVE NORMAL.

MODELS ARE IN FAIRLY GOOD AGREEMENT IN ADVERTISING A RETURN TO
UNSETTLED CONDITIONS BY SUNDAY OR MONDAY..WITH PRECIP POSSIBLY
RETURNING TO SOUTHERN WISCONSIN.

&&

.AVIATION...EXPECT IFR CONDITIONS THROUGH THE DAY WITH WARM CONVEYOR
BELT RAIN AHEAD OF APPROACHING LOW PRESSURE SHIFTING EAST LATE THIS
MORNING. UPSTREAM OBS INDICATING LOW CIGS AND PERIODS OF DRIZZLE
KEEPING VSBYS BETWEEN MVFR AND IFR LEVELS. AS LOW DEEPENS TONIGHT
LOOK FOR STRONG WEST WINDS TO DEVELOP...WITH GUSTS OF 35 TO 40 KNOTS
AFTER 03Z THROUGH THE END OF THE FORECAST PERIOD.

&&

.MARINE...RAPID DEEPENING OF LOW PRESSURE EXPECTED AS IT MOVES FROM
EASTERN IOWA THIS AFTERNOON TO THE UPPER PENINSULA OF MICHIGAN BY
MIDNIGHT. VERY STRONG WEST WINDS WILL DEVELOP IN THE WAKE OF
LOW...HOWEVER LATER DEEPENING THAN PREVIOUS FORECASTS BRINGS
TIGHTEST PRESSURE GRADIENT ACROSS NORTHEAST WISCONSIN. BUFKIT
SOUNDINGS INDICATE 30 KNOT SUSTAINED WINDS AND GALE FORCE GUSTS TO
40 KNOTS DEVELOP BY 02-03Z AND LAST INTO EARLY WEDNESDAY AFTERNOON.
HAVE ISSUED A GALE WARNING FOR 00Z TO 22Z WEDNESDAY TO ACCOUNT FOR
POSSIBLE TIMING DIFFERENCES.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...WIND ADVISORY FROM 10 PM THIS EVENING TO 9 AM CDT WEDNESDAY FOR
     WIZ046-047-051-052-056>060-062>072.

LM...GALE WARNING FROM 7 PM THIS EVENING TO 5 PM CDT WEDNESDAY FOR
     LMZ643>646.

&&

SHORT/LONG TERM...DDV
AVIATION/MARINE...REM

Hazardous weather outlook, Mar 10, 4:41 AM CST, 4 hours 19 minutes before

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The radar

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

Open the radar archive at this moment

Event by event

12 dense fog. Local standard time, as filed.

Dense Fog, Sauk

When: March 10, 9:00 AM CST to 5:00 PM CST
Where: Sauk forecast zone
Reported by: AWOS
Coordinates: 43.427, -89.948 (the zone’s center; the record gives no point)

Dense Fog, Columbia

When: March 10, 9:00 AM CST to 5:00 PM CST
Where: Columbia forecast zone
Reported by: Law Enforcement
Coordinates: 43.467, -89.334 (the zone’s center; the record gives no point)

Dense Fog, Iowa

When: March 10, 10:00 AM CST to 4:00 PM CST
Where: Iowa forecast zone
Reported by: ASOS
Coordinates: 43.001, -90.135 (the zone’s center; the record gives no point)

Dense Fog, Lafayette

When: March 10, 10:00 AM CST to 4:00 PM CST
Where: Lafayette forecast zone
Reported by: Law Enforcement
Coordinates: 42.661, -90.132 (the zone’s center; the record gives no point)

Dense Fog, Green

When: March 10, 10:00 AM CST to 4:00 PM CST
Where: Green forecast zone
Reported by: Law Enforcement
Coordinates: 42.680, -89.602 (the zone’s center; the record gives no point)

Dense Fog, Milwaukee

When: March 10, 10:00 AM CST to 5:00 PM CST
Where: Milwaukee forecast zone
Reported by: ASOS
Coordinates: 43.022, -87.929 (the zone’s center; the record gives no point)

Dense Fog, Waukesha

When: March 10, 11:00 AM CST to 2:00 PM CST
Where: Waukesha forecast zone
Reported by: AWOS
Coordinates: 43.018, -88.304 (the zone’s center; the record gives no point)

Dense Fog, Racine

When: March 10, 11:00 AM CST to 3:00 PM CST
Where: Racine forecast zone
Reported by: ASOS
Coordinates: 42.730, -87.812 (the zone’s center; the record gives no point)

Dense Fog, Walworth

When: March 10, 11:00 AM CST to 3:00 PM CST
Where: Walworth forecast zone
Reported by: Law Enforcement
Coordinates: 42.669, -88.542 (the zone’s center; the record gives no point)

Dense Fog, Washington

When: March 10, 12:00 PM CST to 3:00 PM CST
Where: Washington forecast zone
Reported by: AWOS
Coordinates: 43.369, -88.231 (the zone’s center; the record gives no point)

Dense Fog, Ozaukee

When: March 10, 12:00 PM CST to 3:00 PM CST
Where: Ozaukee forecast zone
Reported by: Law Enforcement
Coordinates: 43.403, -87.891 (the zone’s center; the record gives no point)

Dense Fog, Sheboygan

When: March 10, 12:27 PM CST to 6:00 PM CST
Where: Sheboygan forecast zone
Reported by: ASOS
Coordinates: 43.756, -87.800 (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 2009 Every state in 2009 This day in weather history Warnings in Wisconsin, March 2009

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: 164692, 164697, 164694, 164695, 164696, 164698, 164700, 164701, 164702, 164704, 164705, 164707.