Flash Flood Risk from Cristobal Shifts East of Twin Cities Metro

Tropical storm...you read that right...moves into the Midwest with flood warnings

Paul Douglas
June 09, 2020 - 10:39 am
Tropical Swirls 6-9-20

(Image courtesy of AerisWeather)

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"At least we don't get hurricanes! At least we don't get hurricanes! "

But once in a blue moon Minnesota does experience a gently-used tropical depression, the soggy remains of a hurricane or tropical storm. Such will be the case from Tuesday night into Wednesday morning, with the heaviest swath of rainfall expected to stretch from eastern Iowa and far southeastern Minnesota into western Wisconsin, where some 3-5" amounts are expected. Very heavy rain, falling over a relatively short period of time, on ground that is already partially saturated from recent heavy rains, may result in basement, street and stream flooding. For this reason The National Weather Service has issued a Flash Flood Watch from Tuesday afternoon into much of Wednesday.

If you've had flooding issues in the past, you'll to pay attention, especially if you live in Wisconsin.

Tropical Swirl. Tuesday morning visible satellite image, showing what's left of "Cristobal" pushing north. 

Tropical Swirls 6-9-20
(Image courtesy of AerisWeather)

Excessive Rainfall Potential. NOAA WPC has much of eastern and southeastern Minnesota, as well as western Wisconsin in a "moderate risk" of excessive rainfall, which implies a fairly widespread runway of 2-4" rains from tonight into Wednesday morning. One glimmer of good news: the tropical remains of "Cristobal" are forecast to accelerate to the northeast - there is no indication the system will stall, which would prolong heavy rains and make the flooding much more severe. 

Excessive Rainfall Potential 6-9-20
(Image courtesy of NOAA)

 

Tropical Tracks Since 1850 

What's left of Tropical Storm Cristobal is pinwheeling right up the Mississippi River, on a track projected to be farther west than any tropical system since records were first kept in the mid-1800s. So yes, this is an historic storm - extremely unusual - certainly for early June. The "spaghetti plot" above shows the track of every tropical system since 1850, so if anyone asks, this is extraordinary.

Predicted Rainfall Amounts

Predicted Rainfall Amounts 6-9-20
(Image courtesy of NOAA and pivotalweather.com)

I still believe the heaviest rains will impact eastern Iowa, far southeastern Minnesota and much of western and central Wisconsin. The Twin Cities metro will probably wind up on the western edge of the axis of heavy rain. Many spots in the MSP metro will pick up 1-2" tonight and Wednesday morning, with locally heavier amounts east of St. Paul, and some 3-5" amounts possible over western Wisconsin.

European Solution. The 06z ECMWF keeps the axis of heaviest rain well east of the immediate Twin Cities metro tonight and early Wednesday.

European Solution 6-9-20
(Image courtesy of WeatherBell)

 

Flash Flood Watch Shifts East. A watch means "watch out", conditions are ripe for flooding of streets, streams and basements. The watch area has shifted east in the last few hours, the immediate MSP metro no longer in the watch area. 

Flash Flood Watch 6-9-20
(Map courtesy of Praedictix and AerisWeather)

The National Weather Service has issued a Flash Flood Watch, valid from 1:00p.m. this afternoon into Wednesday morning. The farther east you live or travel, the greater the potential for final rainfall amounts at the upper range of 2-4".

June is the wettest month of the year, on average, for all of Minnesota, but slugs of tropical moisture this far north are highly unusual. Some communities, especially St. Croix River Valley, far southeastern Minnesota and western Wisconsin, will pick up a month's worth of rain tonight.

No need to water the lawn or garden anytime soon, especially for our friends in Wisconsin!

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