Cristobal - The First of its Kind in Wisconsin

Earlier this week, Wisconsin had an unfamiliar visitor in the form of a tropical system named Cristobal. Cristobal's appearance on Tuesday, June 9, marked the first time a tropical depression had ever crossed into the state. Other tropical systems had clipped the southeast corner of the state before; an unnamed storm in 1900, another one in 1949, and then the remnants of Gilbert in 1988, but these storms weakened to extratropical cyclones (another name for our run of the mill, "Low pressure systems," around here) before doing so. Not only was Cristobal Wisconsin's first tropical depression, but its path was the furthest northwest ever taken by a tropical system since the beginning of records. Below is a quick summary concerning Cristobal.

Cristobal began moving into Wisconsin during the afternoon hours on Tuesday, June 9. It was fairly progressive in nature, quickly clearing the state by 6 am on Wednesday, June 10, but in that time it managed to dump a considerable amount of rain over parts of Iowa, Minnesota, and western and north-central Wisconsin. This was owed to Cristobal's surplus of tropical moisture, as precipitable water values were observed to be close to 225% of normal for this time of year in Wisconsin. Cristobal's moisture lingered into the day on Wednesday, when a second low pressure system and frontal boundary gave much of the southern half of the state a second shot of rain. Details on the heavy rain and flooding in western Wisconsin from the NWS La Crosse.

Radar imagery (above, top image) showing Cristobal move across the state Tuesday into Tuesday night and then a second round of rain during the day on Wednesday. 24 Hr rainfall in inches (above, bottom image) ending at 7am on Wednesday, June 10 showing rainfall totals from Cristobal. 

South-central and southeast Wisconsin missed out on most of the heavy rain from Cristobal, but its low pressure broke June records and brought gusty winds to the area. Of note, The Fond du Lac airport managed to record a 51 mph wind gust as the system passed by on Tuesday. Additionally, Madison recorded a low pressure of 988.0 mb (29.2 in) which broke the previous record lowest June pressure of 990.2 mb (29.24in).

Peak wind gusts in mph (above image) recorded during the day on Tuesday and overnight into early Wednesday morning. On the right is a brief social media post announcing the broken low pressure record in Madison.

As mentioned earlier, even though Cristobal had moved off to the north during the early hours of Wednesday, a good amount of tropical moisture remained in its wake. A second low pressure system and attendant frontal boundary approached from the west on the heels of Cristobal and brought a secondary swath of rain during the daytime hours on Wednesday. Interestingly enough, parts of south-central and southeast Wisconsin saw more rain out of this secondary round than what fell in association with the passing of Cristobal.

A lot of the heavy rain that fell during the day on Wednesday fell during a period of an hour to and hour and a half. This caused localized flooding, including the partial closure of Interstate 41 on the south side of Fond du Lac. A few embedded cells also became strong enough to produce up to 1 inch hail. Below is a summary of storm reports that occurred during the day on Wednesday.

..TIME...          ...EVENT...              ...CITY LOCATION...                      ...LAT.LON...
..DATE...          ....MAG....         ..COUNTY LOCATION..ST..               ...SOURCE....
                       ..REMARKS..

0616 PM          Heavy Rain                    3 E Lomira                             43.59N 88.38W
06/10/2020      M2.09 inch                   Fond du Lac        WI                Mesonet          

            Mesonet station CW6301 Campbellsport. 

0616 PM           Heavy Rain           2 SSE FOND DU LAC                   43.76N 88.43W
06/10/2020       M2.70 inch                   Fond du Lac        WI               Broadcast Media  

            REPORTED FROM WFRV. 

0616 PM           Heavy Rain                   3 E LOMIRA                           43.59N 88.38W
06/10/2020       M2.09 inch                    Fond du Lac        WI               Mesonet          

            MESONET STATION CW6301 CAMPBELLSPORT. 

0615 PM            Heavy Rain                Howards Grove                        43.83N 87.83W
06/10/2020        M2.14 inch                   Sheboygan          WI               Mesonet          

            Mesonet station FW1977 Howards Grove. 

0615 PM            Heavy Rain              2 NW MIDDLETON                     43.12N 89.53W
06/10/2020        M1.84 inch                        Dane               WI               AWOS             

            AWOS STATION KC29 MIDDLETON. 

0615 PM             Heavy Rain             HOWARDS GROVE                   43.83N 87.83W
06/10/2020         M2.14 inch                   Sheboygan          WI              Mesonet          

            MESONET STATION FW1977 HOWARDS GROVE. 

0605 PM             Heavy Rain            2 SW FOND DU LAC                   43.77N 88.48W
06/10/2020         M2.77 inch                    Fond du Lac        WI              ASOS             

            ASOS STATION KFLD FOND DU LAC AIRPORT. 

0602 PM              Heavy Rain                 3 NNE Riley                            43.06N 89.60W
06/10/2020          M1.87 inch                        Dane               WI              Mesonet          

            Mesonet station AS276 4 SE Cross Plains. 

0602 PM               Heavy Rain                3 NNE RILEY                          43.06N 89.60W
06/10/2020           M1.87 inch                       Dane               WI              Mesonet          

            MESONET STATION AS276 4 SE CROSS PLAINS. 

0546 PM                Flash Flood           2 SSW Fond Du Lac                   43.75N 88.46W
06/10/2020                                                Fond du Lac        WI             Public           

            I-41 in Fond Du Lac County closed (both 
            lanes) from Military Rd to US 151 due to 
            water over roadway. 

0530 PM                 Heavy Rain                 Beaver Dam                         43.46N 88.84W
06/10/2020             E3.00 inch                     Dodge              WI             Public           

            Estimated 3.0 inches of rain in about an 
            hour. 

0406 PM                 Heavy Rain              2 WSW Windsor                      43.21N 89.38W
06/10/2020             M2.00 inch                      Dane               WI             Mesonet          

            Mesonet station CW2086 Waunakee. 

0406 PM                 Heavy Rain                    3 E Lomira                          43.59N 88.38W
06/10/2020             M1.87 inch                  Fond du Lac        WI             Mesonet          

            Mesonet station CW6301 Campbellsport. 

0402 PM                  Heavy Rain                  3 NNE Riley                         43.06N 89.60W
06/10/2020              M2.19 inch                      Dane               WI             Mesonet          

            Mesonet station AS276 4 SE Cross Plains. 

0355 PM                  Heavy Rain              2 NW Middleton                       43.12N 89.53W
06/10/2020              M2.03 inch                       Dane               WI             AWOS             

            AWOS station KC29 Middleton. 

0145 PM                  Hail                   2 SSW Oconomowoc Lake             43.08N 88.47W
06/10/2020              M1.00 inch                    Waukesha          WI             Public           

            Time estimated from Radar. 

0140 PM                  Hail                         1 S Oconomowoc                      43.09N 88.50W
06/10/2020              M0.75 inch                   Waukesha           WI             Public           

0124 PM                  Hail                               1 NE Merton                         43.15N 88.30W
06/10/2020               E1.00 inch                   Waukesha           WI             NWS Employee     

0121 PM                  Tstm Wnd Dmg                Merton                              43.14N 88.31W
06/10/2020                                                   Waukesha           WI             Public           

            Large Trees snapped. 

0116 PM                   Hail                            1 N Hartland                           43.11N 88.35W
06/10/2020               M0.70 inch                   Waukesha           WI            Broadcast Media