Severe Weather and Flash Flooding Potential for the Center of the Nation

An upper level trough coinciding with surface frontal boundaries will focus showers and thunderstorms from the Great Lakes region into the Ohio and Tennessee Valley's, central and southern Plains. Instances of flash flooding, damaging winds and large hail are possible. Meanwhile, increasing waves and rip currents for portions of the eastern seaboard this week as tropical Atlantic is active. Read More >

Overview

A strong, slow-moving low pressure system drifted southeast across the upper Midwest over a 3-day period from Sunday May 17 through early Tuesday May 19. This system interacted with copious moisture streaming north from the Gulf of America that resulted in several rounds of moderate to heavy rainfall from Wisconsin, northern Illinois and Lower Michigan. Widespread rainfall amounts of 3-5 inches fell across much of east-central and northeast Wisconsin with a few locations breaking daily rainfall totals. The heavy rainfall was also accompanied by strong northeast winds gusting to 40 to 50 mph. The combination of heavy rainfall, high Lake Michigan water levels and northeast winds, led to widespread flooding and beach erosion at shoreline areas along the Bay of Green Bay and Lake Michigan. The strong northeast winds hindered the drainage of water from the Fox and East Rivers into the mouth of the bay, which contributed to flooding in parts of downtown Green Bay and further inland along the East River. Significant flooding was also observed in the city of Oconto along the Oconto River.

With Lake Michigan remaining near record levels, eastern Wisconsin will continue to be vulnerable to flooding as we move into the summer months.

Preliminary 3-Day Storm Total Rainfall

Please see tabs below for more information.

Rainfall Totals
Wind Reports
Surface Pattern/Radar/Satellite
Flooding

Precipitation Summary:

Here is a listing of rainfall reports:

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE GREEN BAY WI
944 AM CDT TUE MAY 19 2020

...PRECIPITATION TOTALS SINCE SATURDAY NIGHT...

LOCATION                     AMOUNT    TIME/DATE       LAT/LON              
TWO RIVERS 0.9 SE            5.10 IN   0700 AM 05/19   44.15N/87.57W        
MISHICOT 0.1 NNW             5.02 IN   0700 AM 05/19   44.23N/87.64W        
TWO RIVERS 4.1 WNW           4.36 IN   0700 AM 05/19   44.19N/87.65W        
TWO RIVERS                   4.09 IN   0700 AM 05/19   44.14N/87.57W        
MANITOWOC AIRPORT            4.02 IN   0915 AM 05/19   44.12N/87.67W        
GREEN BAY NWS                3.81 IN   0600 AM 05/19   44.50N/88.11W        
OSHKOSH 2.0 W                3.36 IN   0700 AM 05/19   44.02N/88.59W        
BRUSSELS 3 N                 3.27 IN   0700 AM 05/19   44.78N/87.62W        
OCONTO AIRPORT               3.19 IN   0915 AM 05/19   44.87N/87.92W        
KEWAUNEE                     3.12 IN   0700 AM 05/19   44.46N/87.50W        
OSHKOSH 1.5 SSE              3.07 IN   0700 AM 05/19   44.00N/88.54W        
OSHKOSH AIRPORT              3.04 IN   0853 AM 05/19   43.97N/88.55W        
DENMARK WWTP                 2.86 IN   0800 AM 05/19   44.35N/87.81W        
BRILLION                     2.74 IN   0658 AM 05/19   44.18N/88.07W        
APPLETON 0.9 W               2.70 IN   0700 AM 05/19   44.27N/88.42W        
WILD ROSE 0.5 E              2.65 IN   0700 AM 05/19   44.18N/89.24W        
APPLETON                     2.52 IN   0600 AM 05/19   44.28N/88.44W        
WAUTOMA 1 WSW                2.52 IN   0912 AM 05/19   44.06N/89.29W        
BREED 5 NE                   2.51 IN   0903 AM 05/19   45.12N/88.37W        
ALMOND 6.7 ENE               2.51 IN   0700 AM 05/19   44.29N/89.28W        
OMRO 1 WSW                   2.41 IN   0700 AM 05/19   44.02N/88.78W        
BONDUEL 3.3 NW               2.38 IN   0700 AM 05/19   44.78N/88.49W        
WRIGHTSTOWN 0.4 ENE          2.31 IN   0700 AM 05/19   44.33N/88.17W        
APPLETON                     2.30 IN   0907 AM 05/19   44.29N/88.46W        
ZITTAU                       2.30 IN   0600 AM 05/19   44.22N/88.78W        
KESHENA 2 WNW                2.28 IN   0905 AM 05/19   44.89N/88.66W        
NEW LONDON 2 SE              2.19 IN   0630 AM 05/19   44.36N/88.72W        
SHAWANO 2 SSW                2.19 IN   0800 AM 05/19   44.76N/88.62W        
MENASHA 2.4 E                2.19 IN   0700 AM 05/19   44.21N/88.39W           
NEENAH 1.1 ENE               2.13 IN   0700 AM 05/19   44.17N/88.45W        
AMHERST 3 SE                 1.92 IN   0700 AM 05/19   44.41N/89.26W        
WAUTOMA AIRPORT              1.90 IN   0856 AM 05/19   44.03N/89.30W        
PULASKI 3.7 W                1.88 IN   0700 AM 05/19   44.67N/88.31W        
BRILLION 2 SSE               1.86 IN   0800 AM 05/19   44.14N/88.04W        
SPLIT ROCK 1 NNW             1.79 IN   0800 AM 05/19   44.72N/89.02W        
SHIOCTON 0.6 NW              1.71 IN   0730 AM 05/19   44.44N/88.58W        
SHAWANO AIRPORT              1.69 IN   0935 AM 05/19   44.78N/88.57W        
BLACK CREEK 3 NW             1.59 IN   0700 AM 05/19   44.50N/88.47W        
1.5 W MENASHA                1.53 IN   0900 AM 05/19   44.20N/88.47W        
CLINTONVILLE AIRPORT         1.52 IN   0915 AM 05/19   44.62N/88.73W        
WAUPACA                      1.50 IN   0935 AM 05/19   44.33N/89.02W            

OBSERVATIONS ARE COLLECTED FROM A VARIETY OF SOURCES WITH VARYING
EQUIPMENT AND EXPOSURES. WE THANK ALL VOLUNTEER WEATHER OBSERVERS 
FOR THEIR DEDICATION. NOT ALL DATA LISTED ARE CONSIDERED OFFICIAL.

Image – This is a forecast average accumulated precipitation over the Great Lakes over a 48 hour period ending on Monday evening May 19. Note the area of 4-6 inches over east-central Wisconsin and another area over lower Michigan. Lower Michigan received even more rainfall than northeast Wisconsin, which led to two dam failures near the city of Midland, MI that resulted in historic and catastrophic flooding late Tuesday May 19 and Wednesday May 20.

Wind Reports:

Surface Pattern/Radar/Satellite:

	Image - Surface Pressure Animation. Associated with the upper-level circulation, a slow-moving surface low meandered over eastern Iowa and northern Illinois before finally drifting southeast and weakening. Note that there was also a strengthening area of high pressure (brown shaded area) that was parked just north of Wisconsin. The combination of these pressure systems created very strong and persistent northeast winds across much of Wisconsin on Sunday May 17th and Monday May 18^th. The strong winds caused water levels to rise significantly along lake shore areas.
	Image – Radar Composite Animation. An extensive area of moderate to heavy precipitation surged northward into the upper-Midwest and Great Lakes region. Note the precipitation echoes being wrapped back toward the west into east-central Wisconsin. This extended the duration of heavy rainfall over Lower Michigan and eastern Wisconsin, leading to significant 2-3 day rainfall totals and flooding.
	Image - GOES-16 water vapor satellite image animation. This animation shows a strong and slow moving upper-level circulation heading southeast across the upper Midwest from May 17^th through May 19^th. The upper-level system passed to the south of Wisconsin.

Flooding

 
Reports of flooding across Green Bay:

	Downtown Green Bay
	Downtown Green Bay - South Broadway
	Green Bay Boat Landing and Coast Guard Station
	East River Green Bay
	East River Green Bay
	East River Green Bay
	Oconto, WI
	Menominee, MI

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Severe Weather and Flash Flooding Potential for the Center of the Nation

May 17-19 Heavy Rain and Flooding Across Northeast Wisconsin