What is A Drought? How Does Summer 2024 Compare to Others?

Rainfall over the last 24 hours as of this writing (August 3) has been the most widespread in quite some time across Ohio and surrounding states. We needed it!

Yet each summer, it seems as if we go through the same process:  Rain at the beginning in May and early June with a gradual drying out with limited rain across northern Ohio by late June/July and into August. The grass gets brown. We mow every two weeks or longer versus every other day in early May. Most of us will mix in the word "drought" in  everyday conversation describing the conditions as we exclaim "this happens every summer."  At least that's how we perceive it. But is this really the case?  What does the data show?

First what is the definition of a "drought"?

Drought is generally defined as "a deficiency of precipitation over an extended period of time" resulting in a water shortage. This is per the National Integrated Drought Information System on drought.gov (a great resource). However drought can mean different things to different regions. If you are a farmer, a drought means below normal rainfall resulting in damage to crops. So not enough water means low crop yield for the season. 

Scientifically, drought can be measured through comparing precipitation departures over a period of time along with soil moisture, evaporation, temperatures among others.  A great way to compare year to year is to use the US Drought Monitor.  This is a blend of around a dozen different variables including the ones listed above. This is combined along with potential drought impacts and other expert insight. 

The US Drought Monitor index is on a scale of zero to four. One being low on the drought scale up to four meaning highly extreme drought conditions as defined above.

Just looking at precipitation changes since April you can see how the conditions in parts of Ohio/southern Ohio, the Ohio Valley and into the Carolinas/SE US have dried out significantly.

Interestingly, the corn belt and most of the Great Lakes, conditions have not been dry at all. In fact, soil moisture has been well above normal.

Back to the original question. What about the comment that we are always in a drought every summer here in northern Ohio.  Is this true?

Look at the Drought Monitor history for Ohio as a whole. Here are the years since 2000 (data only goes back that far) with portions of the state in at least a D2 drought with areal percentages.  The last time ANY part of Ohio was under a D2 drought was 2016.

Can we go back further?  Absolutely, but we need to use a different set of data.  It's called the Palmer Drought Severity Index. This data goes back more than 100 years. The PDSI is good at determining long term drought using temperature and precipitation data to estimate dryness.  So a +4 shows extremely wet conditions. A -4 is extremely dry. 

Here are the PDSI conditions across the US as of late July:

Notice that the conditions across Ohio are not as severe when looking at the LONG TERM drought conditions.

Let's go back in time just looking at the summer months of June, July and August combined. To do this, we can examine specific climate divisions versus state wide conditions. Here in northern Ohio, we have four climate divisions that encompasses our viewing area. Two, three, six and seven.

I highlighted some of the memorable drought summers for Division two. The dust bowl years of the 1930s, the early 1950s and 1960s were long periods with summer drought. Of course 1988, 1991 and the early 2000s also featured very dry summers.

Here is climate division 3:

Climate division 6:

Climate division 7:

As you can see, there are much drier periods over the last 100 years across northern Ohio.  There are also (green bars on these charts) with above normal summer wet conditions.  In fact in the last 30 years, the summers with above normal wet conditions have outnumbered the abnormally dry ones. 

Number of Abnormally Dry summers (JJA) Since 1995

Climate Division 2:  9 of 30 summers

Climate Division 3:  12 of 30 summers

Climate Division 6:  9 of 30 summers

Climate Division 7:  9 of 30 summers

While our lawns dry out each summer to some degree, is it true that every summer or even most summers in northern Ohio we end up with drought conditions?  Not even close

Ohio: How Often Are We Directly Affected By Tropical Systems?

FOX 8 Roof cam showing our live trucks at E. 55th Marina - October 2012

Some impressive names come to mind right off the top. Hurricane Sandy. Hurricane Ike.  Hurricane Katrina.  Yet all of these didn't have official tropical designations when they passed over Ohio.  Yet we were impacted significantly by many of them. Here is the break down:

A total of 27 have tracked across Ohio. Most recently the remains of Nate in 2017. 

Image:  James Parish

Only 11 tropical systems (mainly depressions and extra-tropical storms) have passed within 100 miles of Cleveland. 

If we expand our search a total of 36 tropical systems have passed within 200 miles of Cleveland.

The only system (8 total) that were classified as a Tropical depression or Tropical Storm per the National Hurricane Center over Ohio were: Unnamed storm in 1888 (TS), Audrey 1957 (TS), Frederic 1979 (TS), Hugo 1989 (TS), Isadore 2002 (TD), Nate 2017 (TD), Dennis 2005 (TD) and  Bill 2015 (TD). 

Storms that were designated Tropical Storms over Ohio (4 total)

The last tropical storm to pass over Ohio was Hugo in 1989.

The last tropical depression was Bill in 2015

How about July?  Only 4 systems.

Unnamed storm in 1896, Bob in 1979, Claudette in 1979, Most recently the remains of Dennis in 2005. 

Has Ohio been impacted by tropical remnants in June?  5 times

Unnamed storms in 1902 and 1939, Audrey 1957 (still a tropical storm), Candy 1968, Bill in 2015

Below are maps showing rainfall totals from 10 of the tropical system to impact Ohio and surrounding areas.  Many people asking if Sandy was a tropical storm/depression when it drifted into western Pennsylvania and close to Ohio.  At that point, it was a weakening low pressure system with no official TD or TS designation.

Hitting 0.400 is hard. How about 0.390?

Photo Courtesy: SABR

The last player to hit 0.400 was Ted Williams in 1941. It hasn't happened since.

Check out his running batting average throughout the season. With the exception of a 9 game stretch in the middle of the season and the first 28 games, his average was above 0.400 consistently.

Let's lower the bar slightly to 0.390+ and check the list at different periods throughout each season since 1950. 

50 GAMES INTO SEASON

200+ Plate Appearances

*  28 players

*  Rod Carew is on the list 3 times

*  Wade Boggs twice

75 GAMES INTO SEASON

300+ Plate Appearances

*  Tony Gwynn twice

100 GAMES INTO SEASON

400+ Plate Appearances

125 GAMES INTO SEASON

500+ Plate Appearances

AVERAGE AT/ABOVE 0.390 AND UNDER 0.400 AT END OF SEASON SINCE 1950

Tony Gwynn          1994                0.394

George Brett          1980                0.390 

Look at the running averages for Brett and Gwynn. Gwynn had a handful of games in the first month of the season above 0.400 then consistently stayed in the 0.385 range before ending at 0.394.  Brett started off very slow then quickly climbed to 0.401 by game 82 and stayed around 0.400 for roughly 20 games before ending at 0.390

Where Does This Recent Tropically Humid Stretch Rank?

Our recent stretch of 90+ degree heat was accompanied by high humidity.  It doesn't always work out that way but in most instances here in northern Ohio and surrounding states, 90 degree heat and high humidity go hand and hand.

Where does last week's summer humidity rank?

Before we answer this, let's set some ground rules.  Since last week's hot and humid stretch was 7 days total (90+ degrees with a dew point of at least 70), I initially used this as the benchmark then dropped it to 6 days in length. 

After downloading the average dew point for EACH DAY since 1950, sorting them only highlighting dew points at/above 70 degrees (considered tropical), here is the list of the most humid 6+ day stretches since 1950:

So where was this past week's high humidity ranked?  TIED FOR 16TH HIGHEST among all 6+ consecutive day stretches with dew points at/above 70.

The last time we had a stretch like last week was in the summer of 2022!

Late June Heat...For How Long?

Our first heat wave in northern Ohio since 2021 continues. The long range outlook picked up on this pattern change a few weeks prior to the start.

June started out dry but with "cooler" daytime highs in northern Ohio. June 10 was 61 degrees with low 40s for overnight lows. Then a two day "teaser period" of warmth then the first of a weeks worth of 90+ degrees starting on June 16.

You can see how the high pressure ridge (Bermuda High) expanded across the eastern seaboard to near record high levels starting Monday June 17. By the weekend, the heat ridge (dome) gradually dissipated as the ridge flattened in the deep south.

The position of the ridge east of Ohio allowed a few "weak fronts" (disturbances) to clip the southern Great Lakes with small but potent storms with heavy rainfall. Future radar from Thursday June 20 to Saturday June 22.

Rainfall totals from June 16 to June 19:

Heat Advisory was issued from Monday through Saturday across northern Ohio.

Heat Advisories and Excessive Heat Warnings extended into Michigan and New England.

Tuesday high temperatures were running well above normal eastern US with well below normal temperatures across the west.

Northern Ohio heat index forecast was showing 100+ in spots where storms didn't develop.

The last time we had a heat index 100+ was in 2022. We measure the heat index in total hours.  Here are the totals since 2012 with the warm summers of 1995 and 1988 for reference.

Dew points at/above 75 degrees only occur in small periods this far north. We reach this level June 19. We average around 2 days with humidity levels this high each summer. 2019 was the last summer with above normal of days with dew points at/above 75°.

Anytime we experience extreme weather, people will compare the current conditions to past events they remember. Stretches of heat like this elicit memories of the summer of 1988.  However, there are big differences between 2024 heat and 1988 heat.

The 2 week period where we reached 100° degrees (this was the last time) featured some cool overnight lows. In fact, we broke four low temperature records starting three days AFTER we broke the all-time high temperature record of 104°

Look at June 20, 1988 high temperatures across the US.  

Now high temperatures on June 19, 2024

Another note about the summer of 1988 in northern Ohio.  We reached 90° 35 times. Only 14 of the 35 days at/above 90° had a dew point at/above 70° (tropical) and only 5 of the 13 days at/above 95°.  So plenty of 90s with relatively lower humidity that summer.

Will this heat continue?   Expect a break as the heat shifts to the central US.

May Snowfall History in NE Ohio

Some have mentioned they remember "snow" in June from year's past.  After checking the observations and cross referencing with air temperatures and other conditions, the reports were probably hail and not snow. Here is the POST I wrote back in 2020 which goes into more detail.