Where Does This Summer's Rainfall & Humidity Rank?

No big surprise here.  Even after an almost 2 week rainfall break in late July/early August, this summer still ranks 2nd all-time through August 19!

The individual rainfall events have been significant. Here is the number of 1/2" inch rainfall days.

28 of the 80 total days have had at least 0.1" rainfall. That is far and away the most of any summer.

The volume of rain water that's fallen across northern Ohio this summer is DOUBLE last summer!

For comparison, 6.6 trillion gallons of roughly 5% the volume of Lake Erie!

Our original summer outlook highlighted ABOVE NORMAL rainfall with an active July which has worked out very well.  We were hoping for near storm days and more dry breaks which would have allowed for more 90 degree days.  My initial call was for 10-15 days above 90. We went with slightly above to account for drier periods. As of this August 20th we stand at only 6. 

Number of severe thunderstorm warnings still running BELOW AVERAGE.

Continental upper level pattern has matchup pretty well with our initial outlook. 500mB heights vs normal in the images below show every 15 days starting June1st. Notice the frequent LOW in the central US and high pressure ridges flanking it.

How about the humidity.  Where does this summer rank?  2021 ranks 5th since 1948. Interesting summer of 2018 was more humid overall as was the summer 2010. The most humid summer was 1995

The extreme humidity has come in spurts.  We measure extreme humidity period in hours above a certain level. So far this summer's extreme humidity is lagging behind last year. In fact EVERY summer in the last 5 years has featured MORE EXTREME humidity than summer 2021.  See image below.

How Does This Summer's Rainfall Compare To Recent Years?

It goes without saying that most of Ohio is well above normal rainfall since June 1st this summer (2021) A large portion of northern Ohio has received 10-15" of rain since June 1 with some areas close to 20 inches! Actual rainfall numbers are highest in eastern Huron, southern Lorain and most of Medina Counties. 

Images below show rainfall vs normal. (Note the legend numbers are different for each image. Zero contour is the same for each)

How about last summer 2020?  Most of northern Ohio was well below normal--with the exception of portions of Portage, Geauga, Trumbull and Ashtabula counties. 

Summer of 2019 rainfall departures are comparable to this summer overall. 

Now the summer of 2018:

...and finally the summer of 2017:

BELOW NORMAL Summer Rainfall in Northern Ohio...Where?

It's hard to believe but there are spots in northern Ohio that are near/slightly below normal with rainfall since June 1st.  When you look at the rainfall vs normal OVERALL across northern Ohio this summer the dark blue areas (2-6" above normal) stand out.

But when you zoom in closer, the "drier" areas become more visible. The counties below which have significant areas of below normal rainfall since June 1 (tan colors--see legend to the right) are CUYAHOGA, LAKE, ASHTABULA, ERIE, HOLMES & TUSCARAWAS.  I want to reiterate that this doesn't mean these areas are dry and without rainfall. It means that the amount of rain is below normal not zero.

CUYAHOGA

LAKE

ASHTABULA

ERIE

HOLMES

TUSCARAWAS

Has This Summer Rainfall Been Unprecedented Across Ohio?

On July 5th we took at look at the summer pattern thus far. Check it out if you haven't already.

Here are the updated rainfall totals VS normal broken down in three periods: 

First period is June 1 to June 15

Shades of blue indicated rainfall 3/4" or more above normal. Tan colors indicated below normal rainfall.

Second period is from June 16 to June 30.  Heaviest rainfall was from Medina county west to just south of Findlay. 

Now the final period is from July 1 to July 11.  Heaviest rain across the southern half of northern Ohio.

Finally the summer totals overall from June 1 to July 11.

Purple colors show 8" or more since June 1. Green colors show between 4-8". 

Soil moisture has increased significantly over the last week

Our summer outlook issued in late April highlighted frequent rain/storms this summer with above normal rainfall.

Pattern looks to continue through the end of July!

What Summer Was The Most Humid?

First a brief tutorial on why we use dew point versus relative humidity:

It's more of an absolute measure which isn't relative to temperature. For example a relative humidity of 50% when the temperature is 95 degrees would feel incredibly tropical.  An RH of 50% when the temperature is 55 degrees wouldn't feel nearly as humid.  A dew point of 70 is super-tropical all the time.  A dew point of 45 is comfortable regarding of temperature or time of year.   This graphic illustrates this idea very well. 

So far through July 7 we've had about half of the total number of 70 degree dewpoint hours compared to last summer. 

What's the most humid summer since 1950 in northern Ohio (Cleveland)?  1995

2018, 2010, 1987 and 1973 round out the top 5

I did some research on the years with the highest heat indices measured in hours in northern Ohio. You can read about it HERE (written in 2019)

There is an upward trend for more humid summers over the last few decades in northern Ohio.

Summer Weather Pattern Thus Far. Will It Continue Into July?

The pattern across the US has featured THREE dominant features. Ridge of high pressure western areas, persistent trough/low pressure in the central US and the Bermuda High starting to inch west along the east coast. It took us more than 300 days in northern Ohio to reach 90 degrees. The longest stretch without a 90 in over 10 years!

Temperatures since mid May have fluctuated across the central/eastern US. Storm systems have been frequent.  Below shows upper level pressure pattern on the left.  Temperatures on the right.  You can see how the domes of COOL and WARM air developed over time.  Each image is a 6 day period from mid May through mid June.

May 15-20: upper level heights & temperatures vs normal

May 21-26: upper level heights & temperatures vs normal

May 27-June 1:  upper level heights & temperatures vs normal

June 2-7: upper level heights & temperatures vs normal

June 8-13:  upper level heights & temperatures vs normal

June 14-19:  upper level heights & temperatures vs normal

Evolution of storm systems was mainly in the central US since early June. Below are the pressure anomalies since mid June across the corn belt. BLUE areas are consistent low pressure areas.

Widespread rainfall across the Ohio Valley over the last month. Below normal indicated with tan colors.

Rainfall over the last two weeks (June 20-July 4)

Hard to believe but a large portion of Ohio NEEDS RAIN when looking at the rainfall numbers since June 15th.

How about rainfall vs normal since June 1st?

Green areas are above normal

Warmer colors are below normal

Yet the daily rainfall occurrence is more frequent.

Temperatures are running above normal since June 1st.

Interesting to note that the EPO (East Pacific Oscillation) has turned negative since mid June. This has partial supported the Pacific Northwest ridge of heat (along with other factors) which in turn has kept the central US trough locked in.

Long range outlook shows the same general pattern through mid July: Central US trough with semi-frequent frontal passages through the first three weeks of July.  The Bermuda high is stronger which should support more heat in new England, mid Atlantic and portions of the Ohio Valley. More heat out west.

OVERALL rainfall will be above normal across Ohio and a large portion of the Midwest.