JUST SAY NO TO STORMS...

Jun 3, 2021
Yesterday I wrote a post on the lack of severe weather this year throughout the Midwest. I just wanted to follow up on a couple of points. First, a nice article from the NWS in Chicago that has some impressive facts. Here it is.

Lack of Severe Weather
Meteorological Spring 2021 featured an abnormal lack of severe weather, let alone thunderstorms. Here are some fast facts:
The only day on which severe weather was reported in northern Illinois was April 29. Typically, our area sees 9 days of severe weather or flash flooding by June 1.
No severe weather or flash flooding was reported during the entire month of May, which was the first time this has happened since 2002 and only the 14th time since 1950 (the year that National Weather Service storm report records date back to).
Chicago O'Hare has only reported thunder two times so far this year. Normally, thunder is reported on about 45 days per year.
NWS Chicago has issued 2 Severe Thunderstorm and 0 Tornado warnings so far this year, which is amongst the lowest totals across all 122 NWS forecast offices in the U.S..
The majority of severe weather in 2021 has remained in the Southern and Central United States.
Combined number of Severe Thunderstorm and Tornado Warnings issued by NWS Offices from January 1 to June 2, 2021. Plot courtesy of the Iowa Environmental Mesonet.
Annual number of Severe Thunderstorm Warnings issued by NWS Chicago. Data for 2021 are through June 2, 2021. Plot courtesy of the Iowa Environmental Mesonet.
All severe thunderstorm reports (tornado (red), damaging wind (blue), and hail (green)) across the continuous United States from January 1, 2021 to June 1, 2021.

What does this mean going forward? 
Typically, May, June, July, and August are the most active months for severe weather and flash flooding across the NWS Chicago forecast area.
Average number of days per month (bar plot) and cumulative number of days (line) during which severe weather or flash flooding is reported within the NWS Chicago forecast area.

A quiet spring does not always mean the rest of the year will be quiet. Similar years with a slow start to the severe weather season:
       2002: Two tornadoes after June 1
       1990: Five tornadoes after June 1, including the Plainfield F5 Tornado
       1978: Seven tornadoes after June 1, including three F2s
       1969: Four tornadoes after June 1, including an F2
       1968: One tornado after June 1
       1959: Eleven tornadoes after June 1, including three F2s
       1958: Ten tornadoes after June 1, including four F2s
       1950: One tornado after June 1

Bottom Line: Don't let your guard down. Thunderstorms will occur this summer, and some will likely be severe. A quiet spring does not mean we're out of the woods! 
Thanks to the NWS Chicago for the information.

The big takeaway for me was the fact there have been only 2 days this year with thunder. A normal year produces about 45 days! Also, the fact that not a single severe thunderstorm or tornado warning was issued in May is pretty astounding. You have to go back 19 years to find an occurrence like that.

Here's something that's been going around the viral world that needs to be addressed. Over the past few days I have seen a thread indicating that last years derecho is the reason this year is void of severe weather. The concept being floated is that the derecho was so powerful that it zapped all the energy out of the atmosphere necessary to produce storms this year. Without a doubt that is completely false and without any merit. Nothing more to say about that!

On the topic of the derecho I did think this is a tidbit worth sharing. Research indicates that 8 percent of all the lightning that occurred in Iowa last year was generated in the derecho. When you consider some years see more than 60 days a year with thunderstorms that's an electrifying statistic.
Well, there was no doubt about the quality of our weather Wednesday. Highs were close to 80 under partly sunny skies. Throw in a gently breeze and dew points of 45-50 and it doesn't get much better than that. 

The 80 degree temperatures do represent a return to warmer weather with a summery feel come the weekend and beyond. Here are the 7 day temperature departures Saturday to Saturday, June 5-12th.
Towards the weekend moisture levels will increase allowing humidity levels to go up as well. However, compared to the GFS, the EURO is roughly 6 degrees lower on dew points Saturday and 4 on Sunday. Considering the recent dryness of the pattern and the limited evapotranspiration from the corn I like the lower levels of the EURO. That will make those highs in the 80s more tolerable.

Despite the warmth and humidity it still looks like rain chances are minimal until late Monday or Tuesday when some spotty showers or storms could work their way into the picture. That adds up to a summery weekend ahead with sunshine, highs in the mid to upper 80s, and no rain. Great if you don't need a soaker. 

By the way, models are still adhering to a dry pattern in the long term with 2 week rainfall departures that look like this on the EURO and GFS ensembles.

The EURO ensemble
The GFS ensemble
That's what I have for you tonight. Have a rock solid day and roll weather...TS