WHEN IT RAINS, IT REALLY POURS...

June 23, 2020

We told you last week we were going to get back into a wet and active period. It turns out the forecast was correct but in an understated way. Showers and thunderstorms the past 48 hours have dumped widespread heavy rain around my area, especially in many of my Iowa counties. In some spots, Doppler estimates are indicating as much as 6 inches of rain.

Add this on top or what the remnants of tropical storm Christobal produced and some places have had 10-12" of rain in just 3 weeks time. Below are the 30 day rainfall totals but this graphic does not include some 1-3" amounts that fell during the day Monday. There's a lot of pink in northeast Iowa indicating 10 or more inches.

These are the 30 day precipitation totals from the Iowa Mesonet. Again, these amounts only go out through Sunday so there are locations with significantly more..

Here are the 30 day departures through Sunday. Notice outside of my area, many places actually have significant deficits of 2-3 inches. Feast or famine!

With this heavy rain falling over the headwaters of the Iowa, Cedar, and Wapsi rivers to name a few, flooding is occurring (or will be) in those watersheds over the next few days..

The good news in the short term is that we are going into a cooler and less active weather pattern Tuesday-Thursday. While better, that doesn't mean we are free of rain chances entirely. A couple minor upper air disturbances along with cool air aloft will produce steep lapse rates resulting in afternoon cumulus and spotty showers and storms. These appear to be widely scattered, generally light, and most likely in the north during the afternoon. Some areas will avoid the showers altogether. Highs through Wednesday will only be in the mid-upper 70s which is well below normal.

 

The next concern is the return to more active weather and potentially heavy rain Thursday night into Friday. Deep moisture makes a rapid return along with a warm front generating what should be another heavy rain threat. Available water vapor Friday morning is shown back up in the 2.00" range. That's a red flag for torrential rains where any convection can fire, especially if an MCS can get rolling on the nocturnal jet. That will need to be watched closely where grounds are now fully saturated. 

As for rain totals, the EURO shows amounts like this through Friday morning.

Going a step further, the GFS has this through Monday morning.

Well, at least for now a little breather is in order from the recent heavy rains but there's potentially more where that came from for the start of the weekend. We'll keep an eye on trends in coming days. Roll weather...TS

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© 2019 Terry Swails