Christobal has come and gone. For some, especially east of the circulation center it wasn't much to write home about. Just some rain and breezy conditions. To the left of the track, what a difference. As expected the rain was torrential and significant. A number of counties from Iowa City, Iowa northward into Minnesota and WC Wisconsin underwent flash flood warnings with a number of roads washed out or under water. In the counties in red where warnings were issued, rainfall rates of 2 inches an hour were common.
Doppler rain estimates reveal how sharp the eastern edge of the heavy rain band was. This coincides nicely with the storms track which ran right up the spine of the Mississippi.
In this satellite taken at 6:30 pm Tuesday evening the center of circulation is situated near Dubuque. A strong secondary piece of energy is quickly following.
Here's how the pressure fields were initialized it at the surface at 7:00 pm Tuesday depicting a 989 surface low directly over Dubuque.
Again notice how all the heavy rainfall is situated west and north of the center. The dry slot as you would see with a strong winter snowstorm is streaming up the Mississippi into the low. At this point the storm is losing its tropical identity fast. Rainfall is rapidly shutting down anywhere south of the low.
Most times once a tropical system departs the weather improves rapidly behind it. That will not be the case around my area Wednesday as the trough that pulled Christobal northward deepens and closes off over Kansas City. You can see the two energy sources mingling within the mean trough. That's pretty cool.
The practical aspect of this development is that scattered showers and a few storms will continue around the region into Wednesday. The best forcing will be over the northern half of my area and here some additional heavy rain is possible. The EURO shows this for additional rain from 7:00 am Wednesday to 7:00 am Thursday. That swath through NE Iowa is significant. Fortunately it's narrow but where it develops it is likely to cause issues where it falls on saturated ground. We'll need to monitor how this situation evolves and sets up early Wednesday.
This secondary rain is the result of the upper air low coming in the back door behind Christobal. It gives new meaning to the phrase, don't let the door hit you in the rump!
Additionally gusty winds will come in behind a cold front Wednesday afternoon. The EURO shows 10 meter gusts over 40 mph. A wind advisory may be needed in spots.
Finally, after a dry day with lower humidity Friday, another fast moving cold front slips by during the overnight. It may bring a quick shower or storm. Amounts would be light. More important, the front brings in some fresh air for the Saturday Sunday period. Weekend highs will likely be well below normal by a good 10 degrees. Dew points are shown in the 30s by Sunday morning and that means a big push of cool dry air is coming. Actually, it's just what the doctor ordered for our rain soaked fields. Crazy stuff! Roll weather...TS