GOOD RIDDANCE CHRISTOBAL...

June 11, 2020

Christobal was only the 3rd remnant tropical system to track through Iowa since the advent of records back in 1886. Things are set to improve the next 24 hours but the storm took its toll on eastern Iowa with excessive rains of more than 5 inches and widespread flash flooding. The area just west of the circulation from Missouri, Iowa, SE Minnesota, and western Wisconsin took the brunt  of the 2-5" totals..Ir's very easy to see where the storm tracked by observing the rain swath.

This graphic from the NWS in the Quad Cities shows some specific rainfall numbers.

In the wake of the system, river levels rose to much above normal levels throughout my area with most of eastern Iowa in the 80-90 percent threshold for June 9th.

The massive amount of water delivered over such a widespread region over such a small period of time caused many rivers and streams to overflow their banks. Here's a good example of how rapidly the smaller watersheds responded. This is the English River in Kalona Iowa (just south of Iowa CIty). The river went from 4.9 to 16.36 feet in 24 hours time

Flash flooding was common with scenes like this within the heavy rain axis. The image was taken by Britt Zander in Fayette, Iowa.

What we could really use now is a healthy dose a dry pleasant summer weather. For the most part, that appears to be where the pattern is headed. We start the ball rolling with decreased moisture levels. This was the amount of water vapor available Tuesday evening when Christobal was coming through. In NE Iowa, some spots were maxing out on PWAT values near 2.50 inches. I never officially heard if we broke the June PWAT record but I know we well within striking range. 

At any rate, where the PWAT values were highest (2.50") they are progged to be down around 0.30" Sunday evening. You can see my area on the western flank of that very dry northwest flow.

If the EURO is right precipitation really turns spotty over the next 10 days depicting precipitation departures that look like this.

However, I am leery about this trend as the EURO keeps the MJO nearly stationary in phase 2.

That is still a relatively wet phase for the central Midwest during the month of June. 

If we get into a position in the northwest flow where my area is located within the air mass battle zone (the ring of fire), convective clusters can peal southeast along that boundary. One or two MCS complexes, which are common this time of year and suddenly you find yourself in some hefty totals. I haven't seen much evidence of this yet but I wonder if the MJO is sending out a message regarding that potential. Something to watch.

 

Meantime, the next chance for such a set-up comes late Friday night or Saturday.in the northeast half of my area. You can see long the baroclinic boundary it paints this for rainfall from a southeast moving disturbance. This mainly impacts NW Illinois.

Whatever happens, the next couple of days look quiet and comfortable. Friday will be the warmest day of the weekend with highs 78-82  After that readings will head for the 70s with much lower humidity, Saturday could be cloudy and at times wet in my northeast counties while dry but seasonal weather prevails elsewhere. Overall, confidence is lower than I would like to see with the Saturday system but we have a little time to get it figured out. Roll weather,,,TS

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© 2019 Terry Swails