SUMMER SO FAR, WHAT I EXPECTED AND WHAT'S HAPPENED....

July 21, 2020

About 6 weeks ago I wrote this statement, "With sea surface temperatures setting up the way they are I've had a change of heart and suspect much of the summer we may reside on the northern fringe of NW flow aloft. With that in mind (along with the change in the EURO weeklies) I'm amending my summer outlook downward to include near to slightly below normal temperatures". I also called for summer rainfall to end up near to above normal. Summer in the weather world is defined as June-August.

 

Now that we're halfway through the summer we have pretty much stayed on the fringe of the storm track (the rim of fire) but the warmth is still winning out so I'm off on my temperature assessment. As you can see most of my area is running 1-2 degrees above normal with a few spots as much as 3.

The average high hasn't been all that bad, running about 83-86. However, the killer has been the humidity and we all know first hand the steam the creates.

Cooling degree days (average temperatures above 65 degrees) are actually not that out of line outside of an obvious spike the first 10 days of July.

Rainfall has been biased above normal in much of eastern Iowa by 2-6 inches. Conversely, its been below normal in Illinois by 1-3 inch amounts.

With another 40 days to go before the end of summer we will see how it all ends up. Chances are pretty good temperatures will end up above normal and I will get beat in my slightly below to near normal prediction. The EURO shows this for temperature departures through September 4th

As for precipitation I don't put a heavy emphasis on model rainfall forecasts in late summer. What falls at this time of year tends to be hit and miss and can be quite varied over relatively small areas. If the EURO has its way the central Midwest does show a decided trend to be dry. That does make sense if the warmth is a significant as the EURO thinks. That puts the ring of fire over the upper Midwest and that's where the heaviest and most consistent rains would fall. Here's the rainfall anomalies the rest of summer.

Speaking of rain, this weeks chances look best Tuesday (and perhaps again Friday). Neither threat looks to be very dynamic or focused so those spots that do see rain should generally pick-up light amounts. That said, when convection is involved one always needs to caution that there could be narrow bands or isolated pockets where heavy downpours can easily dump more than an inch. That should be the exception as opposed to the rule.

 

I will close with the promise of more heat this weekend when the combination of highs near 90 and high dew points could send heat indices over 100. Sunday appears to be the worst day with HX values of 105 or greater, similar to what we experienced last Saturday. Yipee! That's what I have for now. Roll weather...TS.

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© 2019 Terry Swails