Thursday, January 25, 2018

40th Anniversary of the Blizzard of 1978

When you ask people about historical winter weather across northern Ohio, The Blizzard of 1978 is at the top of the list. Here is a news clip from WJW FOX 8 from that evening, January 26, 1978. 

The Ohio Turnpike was completely shut down.  The only time in its history!

What most people don't remember is that we had more than 20" of snow on the ground BEFORE the 25/26th BLIZZARD. 

*  We had TWO big storms earlier in the month. 

*  The first blizzard hit on the 8th and 9th.  9" of snow fell between the 8th and the 9th. Wind gusts were near 50 mph

*  We had a 10 day break then 12" of additional snow fell between the 19th and the 21st (storm number two) just five days BEFORE the Great Blizzard.

*  Only 8" of snow fell in Cleveland, 5" in Akron, 14" in Mansfield. 

The National Weather Service defines a blizzard NOT WITH SNOWFALL but with sustained winds of at least 35+ mph for at least 3 straight hours with 1/4 mi visibility or lower. Again, heavy snow storms are not necessarily blizzards

What caused the problems wasn't the new snow but the near hurricane force winds which gusted above 60 mph for almost a day (80+ mph gusts reported in many areas. 100+ mph near Lake Erie). These winds blew the snow already on the ground from the previous snows creating the 20+ snow drifts across the state.

In fact, the snow from the Great Blizzard was nowhere near the top 50 snowiest 2 day storms on record. 

For historical perspective, 18 of the top 50 snowiest 2 day periods since 1940 occurred between 2000 and 2009.  

Thursday, January 11, 2018

Snowfall Forecast Communication: We Need to do Better

I've written variations of this post many times over the last 5 or so years and it bears repeating. I rarely post snowfall maps/computer model projections further out than 2-3 days on social media platforms. Why?  Look at these long range computer model projections starting Monday--4 days prior--for the snow event Friday and Saturday, January 12 and 13th.

Sunday Evening 1/7 (Model #1. I forgot to save Model #2 for comparison)

Monday Morning 1/8 (Model #1 vs #2)

Monday Evening 1/8 7PM (Model #1 vs #2)

Tuesday Evening 1/9 7PM (Model #1 vs #2)

Wednesday Evening 1/10 7PM (Model #1 vs #2)

Look at the HUGE difference between each model.

Many people posted these images online and even showed them on the air. In most instances these were shown to convey the fact that we had a long way to go before an official forecast could be made with a high degree of certainty. Uncertainty was being conveyed. It has the best of intentions. I get it. I've done it. Makes sense, right?

Except in the real world, most humans rarely interpret this type of information--data--through a rational filter. Data makes us feel conflicted. We, whether we like it or not, overly simplify complex ideas. Computer model projections are a prime example. That's how we're wired. It's well documented with behavioral scientists.

We look at the numbers, pick one out--say 20" of snowfall--react impulsively to it without historical perspective (by the way that's never happened in 24 hours from a general snow event since record keeping began) or context and before you know it, hysteria ensues. We see it on social media every time. Unfortunately social media reactions spread at an exponential rate devolving as the comment thread lengthens. Before you know it, the benign, educational intent of the snowfall uncertainty post is lost. It involuntarily morphs into a totally different story that spreads like wildfire changing with every re tweet and re post. The old game where you sit in a circle an say a sentence to the person to your right and that person to their right applies here. When the message comes back around to the beginning, it's changed entirely. Do you see the problem?

All of us meteorologists here at WJW FOX 8 always choose to wait until we have a high degree of certainty before we post any snowfall numbers usually in some sort of range. The aim is to eliminate what I just described in the paragraph above. This was my post Thursday morning, roughly 36 hours before the event begins. (Note: Andre Bernier, our evening meteorologist had a more basic snowfall map the night before not shown here)

How do we combat our hard wired human nature? The answer is simple:  We don't. WE QUALITY CONTROL OUR INFORMATION!

Psychology plays a huge role in weather forecasts. As a meteorologist who reaches hundreds of thousands of people each morning on the top rated morning show in Cleveland, Ohio, I owe it to each viewer to quality control what I say and what I create visually to accompany it. The psychological element--how the viewer perceives what we say--is a critical weather cast element that is often overlooked by on air meteorologists. The words/numbers that we say/post on the air and online can be more powerful than the weather itself.  In this age of posts solely created for clicks with the hopes of a long, viral lifespan, quality is too often sacrificed. That's fine for a cute picture or a clever, humorous meme but when a major weather event is eminent over a large population area, high quality information created for the masses is of the utmost importance.

Recently the National Weather Service has implemented a program in the works for several years that streamlines their winter season watches, advisories and warnings in an effort to simplify the forecast message for the general public. The great folks at the NWS Office in Cleveland recently hosted a seminar for media personnel highlighting these changes. The information was invaluable.

As meteorologist we always need to remember the psychology behind what we do. As communicators of science (data) need to put ourselves in the minds of the public and ask: "How is the viewer going to interpret what I say?" So when I create a snowfall forecast range map, I take into account how people react to EACH WORD knowing that many will perceive these range to fit their location.

We must remember:

*  Public perception is very powerful

*  We need to be better communicators of information

*  Choice of words is of the utmost importance in conveying severity of the weather

*  Mass media is for the masses. Risk is personal to the public. Yet people want personal forecasts. Huge conundrum.

* Human beings dislike uncertainty.

*  Too much emphasis on uncertainty breeds confusion, inaction and ultimately apathy when the next snow or weather event of importance happens.  Basic psychology here.  We need to find a delicate balance between voicing uncertainty and sticking to a forecast geared to the general public without causing social media unrest

Sunday, August 20, 2017

What Will The Solar Eclipse Look Like in Northern Ohio?

Total Solar Eclipses occur over any fixed position on the earth every 370 years or so. The last total solar eclipse viewed from contiguous United States was on Feb. 26, 1979  The last time a TOTAL solar eclipse crosses the United States coast to coast was in 1918.  Interestingly the moon's shadow will move across the U.S. at over 1000 mph!

Here are the details on when and how much of the solar eclipse will be visible over northern Ohio. All graphics courtesy AJ Colby

Monday, July 31, 2017

Are Days With Oppressively High Dew Points More Common Now?

In June, days with dew points higher than 70 were more common in the 1950s and the 1990s/early 2000s than in the last 15 years.


In July (two graphics above) 12 years since the late 1940s had at least 15 days with 70 degree dew points. The peak in the data period was over a 25 year period from the late 1970s through the early 2000s. We have trended below normal since the early 2000s in August.

In August, spikes of 70 degree dew points in August in the 1980s through the early 2000s. Small peaks in the late 1950s, 1980s and late 1990s in September with a small peak in the last 7 years.

How about 80 degree dew points?

Its only happened three times since the late 1940s. Twice in 1995 and once in 1998

Monday, July 10, 2017

Are Summer Temperatures in Northern Ohio Getting Warmer?

Many people have asked if summer temperatures are getting warmer in northern Ohio over the years. Answering this question isn't easy because there are so many automated observation stations that yield different answers depending where you are across our 20+ county area. Cleveland Hopkins isn't an accurate representation of Geauga County.  Akron or Canton isn't good in representing Sandusky. See the problem?

Luckily, Ohio is broken down into ten climate divisions to make our quest easier.

Using the NCEI (National Center for Environmental Information) "Climate at a Glance site, it was easy to plot the average temperature for the divisions that encompass northern Ohio.

(I also used the Southern Regional Climate Center site to show 5 year averages (blue and red bottom graphic) for each division. I used divisions two, three, six and seven to best reflect all northeastern Ohio counties).  These graphs above give us a pretty good idea on long term trends dating back to the 1890s. 





A few points to consider when interpreting these temperature graphs:

1)   Interestingly and surprisingly, these northern Ohio climate divisions show very little long term temperature variations during the summer months (June, July and August).  We see general above normal warmth from the 1930s through the 1950s, a cooler trend from the 1960s through the mid 1980s and a warmer trend since the 1990s. Will this warmer trend continue? That's the big question

2)   Its very important to note that these graphs don't necessarily reflect any temperature trend on a larger scale nationally or globally. What occurs on the local level like northern Ohio can be very different from global trends. So using this data or any local data to dispel Climate Change ideas would be inaccurate.

NWS Cleveland ASOS
So how were these divisional temperatures calculated?

Were main reporting stations that we use on the air like Cleveland, Akron, Mansfield, etc the only ones used?  In searching for the answer, I remembered my discussion with Derek Arndt, Chief, Climate Monitoring Branch at the National Climate Data Center (NCDC) back in 2012 and my recent follow up in which he outlined the procedure:

"For our month-to-month reports, the climate divisional averages are constructed from all available stations (NWS) within the division at the time. We only use stations that are in the GHCN-Daily network of stations with a service record long enough to establish some kind of "normal". These are your familier NWS ASOS/AFOS/AWOS stations, NWS-commissioned COOPerative observers. .This preliminary makeup won't change dramatically from month to month. The major airport stations you mentioned will almost always be there, unless there are problems at the station. The more obscure cooperative observer stations may be a little less reliable and may drop in / drop out from month to month..."
"...After a few months the "paper based" records roll in (the ones that are literally recorded on paper and old-school mailed to the weather service). At that time, we'll recalculate the divisional averages, and call these our "final" values.  The preliminary average isn't a straight average. There are some mild gymnastics involved to account for missing stations; this has little impact on the outcome especially for temperatures."
That's probably more than you needed to know.  As a scientist, it's essential to ask these questions so that you can have some working knowledge of the process. Asking WHY or HOW is often times more important than the result.

Thursday, May 04, 2017

Why The Abrupt Cooler Pattern in the Northeast?

After the warmest April on record in places like Cleveland, Ohio and across much of the Ohio Valley and much of the eastern US, the pattern has not only reverted back to spring, it took several steps back resembling elements of winter. Throughout April, this high pressure ridge stayed east which allowed the ridge across the eastern US to build allowing above normal temperatures. Many were fooled into thinking that summer was here and we were in the clear to plant gardens. Not so fast!

Look at April temperatures versus the 30 year average:

Now look at the first week or so of May per the American model (GFS).

Why the sudden flip?  In this case, we have to look over Greenland for the answer.

Remember that across the mid-latitudes, troughs and ridges (valleys and peaks in the upper levels of the atmosphere) travel like a fluid through the atmosphere. When one location is lucky enough to be blanketed by a ridge, fair weather typically is the result. Once the succession of trough and ridges is changed by an interruption in the wave pattern, the weather will change at the surface. These changes (too much to go into here. See Southern Oscillation Index) often originate over the Pacific Ocean and propagate east. Currently, these changes are reflected over the northern Atlantic and Greenland.

Notice the red (high pressure) at the top inching west blocking/stalling the blue (low pressure systems) over the NE
We can quantify the strength of this ridge using the NAO of the North Atlantic Oscillation.  The more negative the index goes, the stronger the Greenland ridge. The NAO has been forecasted to drop close to -300. Historically this has only happened once in the month of May since record keeping began.  That was back in 1993.

NAO drops to -300 soon

But be warned, historically, this pattern over Greenland in May doesn't always produce a cold and rainy May. Look at the high temperatures in Cleveland during these years of record low May NAO:

Look at the resultant upper level pattern across the US in each of these years. All but 1948 and 2008 show dominant warmth.







The NAO this low (or any other index) isn't always a great predictor of temperature and the overall pattern. 

Unfortunately, unlike any of the previous instances of strongly negative NAO in May, this cold is locked in for at least another week.  So get ready for rain, scattered frost and perhaps some light snow!