Tuesday, July 31, 2012

2012 Northeast Ohio Drought Compared to Past Droughts

The National Weather Service in Cleveland has an excellent write up on the current OHIO drought and how it compares to past droughts. The NWS hydrologist Sarah Jamison goes into great detail on what constitutes a drought and the parameters that are used in determining drought severity.


I wanted to take the drought analysis one step closer to home. The NWS analysis was for Ohio as a whole. Why not use the same data (Palmer Drought Severity Index) but for Northeastern Ohio instead?  After all, a hyper local analysis should give a more accurate description of the conditions in locations like Cleveland, Akron, Ashtabula, Lorain and Mansfield.

Online Graphing
Drought Conditions: Lower means drier/higher means wetter

I kept all graphical elements the same as the NWS graph except I used the PDSI numbers for the northeastern Ohio climate region instead of the Ohio numbers. The data is available for free at the NOAA/NCEP/CPC site for drought monitoring. The lower the number the drier the conditions.



Compare the graph above with the NWS Ohio drought graph below.

Several things stand out:   First the drought of 1988 wasn't as severe in NE Ohio as it was in other parts of the state. The 1930-31 and 1934-35 drought didn't recover as fast in NE Ohio as in the rest of the state (red line). Third, the current drought started off far wetter in December/January (presumably due to lake effect snow melt--even with the mild winter conditions) than the rest of Ohio. Finally, the drop in the PDSI from January to July is the largest drop over a 6 months span since the huge drop from December of 1990 to July of 1991.

What does all of this mean short-term?

  • Drought conditions will continue through August and September which will increase the probability of above normal temperatures. Dry air feeds the dry air which makes the ground drier still.  The drier the air, the easier it is to heat up. August of 1988 had 11 days at 90 or better.  We can count on a handful of 90 degree days before Labor Day.

  • This drought came on fast even after an incredibly wet 2011 and early 2012. This summer hasn't been as dry as the summer of 1988.  We need frequent storms that are short in duration producing an inch or less of rain. This will do wonders in alleviating the dry ground conditions heading into the fall.  The pattern would need to significantly change for this to happen. It is showing some signs of this change as of early August.

  • Given the lack of soil moisture in the middle of the continent (which feeds the ridge of heat which has broken apart fronts this summer) the pattern will be very difficult to overcome between now and mid September.

By the way, everyone is trying to draw correlations to winter snowfall and the summer drought.  I'll have more on this in the weeks ahead. Until then, keep watering the garden!

Friday, July 13, 2012

Media and the Recent Heatwave: Try Telling the ENTIRE Story

The heat wave last week was one of the most extreme in recent memory here in Ohio. Temps climbed to 98 on July 7th in Cleveland for the first time since 1995. Akron reached 101 which was the first 100+ since the drought summer of 1988.  Almost 2800 high temperature records were either tied of broken in early July after almost 3300 records tied or broken in June.

Once again the media continues to use this event as a Global Warming rallying cry saying that this US centered heat wave is a direct result of Global Warming.

Months ago, I wrote about the need for the media to report the complete story on these hot button science issues. Informing the public on "the whys" in simple, easy-to-digest terms can be done. Yet reporters continue to latch onto one element that sells without telling the entire scientific story. This recent heat wave coverage is another example.

I am not diminishing the significance of this heat wave by any stretch. Our dry winter has given way to a drier spring and summer. Drought conditions now envelop more than 50% of the 48 contiguous states.

The resultant effect on corn prices are already bring felt as corn futures were lowered by 12% July 11th.  Yet two weeks of record breaking heat and increasingly worse drought conditions from the west to the Ohio Valley is an invitation for the media to release the proverbial global warming dogs warning that this drought, is driven by Global warming.

As I have repeatedly stated, I am not debating Global Warming. I am not here to debate the temperature data sets used in determining global temperatures. I am highly critical of using Anthropogenic Global Warming (regardless of what data set you use) as the root cause of every weather disaster from US landfall hurricanes to east coast snowstorms to heat waves. I said this when the east coast was hit with Hurricane Irene last August. I said this during the extreme cold felt in Alaska last winter. I said this especially during the recent tornado outbreaks this past spring.  Sighting Global Warming as the cause the recent US heat wave is putting the cart before the horse. What the National media fails to address are the antecedent conditions that are needed to produce heatwaves. What are these antecedent conditions?  Let's work backward from each effect to its cause or causes. Its not a simple linear cause-and-effect relationship as one might expect. Addressing each one individually helps put into context each ingredient from what we see and feel--the heat and drought--to the more nebulous concepts in the atmosphere--the jet stream for example--that drive them.

First, the warming needs to not only be present at the surface where we measure it but throughout the mid levels of the atmosphere.  This warming is driven by the large scale high pressure ridge which develop each summer across the continent varying in strength from year to year.  This high pressure ridge promotes sinking air and little cloud cover.  The drought conditions in the midwest enhance this ridge making it stronger which warms the atmosphere further and higher which suppresses cloud development further which makes the drought conditions worse.  This feedback mechanism becomes self-sustaining which is necessary in making the heat more record-setting and long lasting and tougher to break. This high pressure heat ridge is called a "block".

Let's step away even further. What causes these high pressure ridges?

Ridges like the one in late June/early July are created by the overall wave pattern across the hemisphere. Now its getting a bit nebulous so stay the course here!  The atmosphere flows like a river of water. In fact, the fluid equations that describe blood flow through the heart are similar to what describes atmospheric motion. Liquid water, blood, oil or air. They are all fluids. Now imagine a rock in a stream which deflects the flow water. Ever notice the little "spins" of water on the other side of the rock?

Landmasses like North America act like a rock in a stream deflecting, shifting, slowing or speeding up the behavior of the atmosphere that flows above it.  Remember that the earth spin like a top. The speed of the earth's rotation increases closer to the north and south pole than at the equator. This change in velocity at different latitudes and its interaction with landmasses causes turbulent spins like a rock in a stream which causes persistent low and high pressure areas. Each low and high resides in these troughs and ridges around the hemisphere. 

Often times, the wave pattern can get struck. Instead of the waves flowing in a typical "trough-ridge-trough" pattern, the waves stop progressing. The jet stream "breaks the wave".  Either you get stuck under a trough (unsettled, cooler pattern) or a ridge (dry and warmer pattern).

Click on this link for an animation of the current jet stream pattern.

This past winter, the US was stuck under a ridge (milder winter) yet Europe was stuck under a persistent trough (cold and snowy). Are the waves slowing down causing more blocks and persistent weather?  According to one paper, it depends on what season you look at.  Little change in speed has been observed during the summer months since 1980. Notice how flat the red line is in the following graphic.

Image courtesy of "http://earlywarn.blogspot.com/2012/04/slowing-rossby-waves-leading-to-extreme.html"
As we take a few more steps back, we see that the tropics (thousands of miles away from the US) can act as enhancers of these ridges and troughs. El Nino and other changes in the oceans close to the equator and further north are reflected "down the atmospheric stream".  These can cause a chain of effects throughout the atmosphere ultimately impacting the troughs and ridges across the US like the one that was present during the last heat wave.

Experts at the National Center for Atmospheric Research have found these connections to El Nino and La Nina. “Teleconnections are important,” says NCAR's Kevin Trenberth, who has studied ENSO's global impacts extensively. “A lot of blocking is traceable back to the nature of convection in the tropics.”

Ultimately, are these "blocks" that cause heat waves more frequent and what does the future hold?  According to NCAR, computer projections are not very good at predicting the beginnings of these blocks and how long they will last.  "Looking toward the end of this century, the preliminary analysis indicates a slight increase in blocking overall. However, two recent studies suggest that blocking might actually decrease in the northern Atlantic and Pacific, as the average location of the polar jet stream shifts northward." According to the following study.

So what does all of this mean?  As we pull back from the US heat and examine the causes from afar first, we find that:

1) Heatwaves caused are local events caused by heat ridges governed by the wave pattern across the hemisphere
2) Hemispheric waves slow or speed up depending on the season. Jet stream behavior causes wave breaking which creates a "block"3) The behavior in the tropics both in the oceans and the tropical atmosphere can enhance the development of a ridge over the US
4) The changing oceans outside of the tropics (North Pacific, North Atlantic, Arctic Ocean et all) can effect the overall wave pattern
5) The drought conditions present in the central US feed the ridge which reinforces the blocking ridge even further
6) Computer projections of blocking patterns for the future decades are not very reliable
6) Some scientists believe that changing arctic ice due to Anthropogenic Global Warming could have an effect on the overall wave pattern
7) Randomness inherent in the atmosphere makes blocking ridges very difficult to forecast

Here they are. Seven bullet points. Some easy to understand; some not so basic. Remember that these often don't exhibit a linear relationship. The simple "butterfly effect" looks good but its an over simplification. I mentioned in a previous post months ago that predicting the influence of teleconnections like El Nino on regional weather patterns is like trying to recreate Grandma's soup. You can measure each ingredient exactly, cook the soup yet it might not taste quiet the same each time. 

Once again, the science gets overly simplified by the media.  Simplification becomes the mantra for these type of stories. Maybe that's what the general public wants.  Maybe that's what sells and gets ratings.
 I realize that in this flash-and-dash media world we live, simplification is more important than getting it right. But just once, couldn't a reporter take just one or two of these points, expand on one or two of them as they relate to the recent heatwave/drought?

Is this too much to ask?

Monday, July 09, 2012

Thermometer Photos from Saturday's Heat

Officially, Hopkins reached 98 for the first time since July 14, 1995. Akron hit 101 late Saturday afternoon--the first triple digit reading sin 1988. Heat index peaked at 112!

Rather than writing about the causes of the heat this past week/weekend, I figured I'd show some thermometer photos sent to me at the peak of the heat Saturday.

Jack Kuwik, Hudson
Brian Gawlak, Canton
Matt Higgins, Kamm's Corners
Debbie Ballachino, Garfield Heights at 3:20PM

Monday, July 02, 2012

Derechos & The Ring of Fire: Storm Threat Continues

Most people have never heard of the term "Derecho" until this past week. A Derecho is a violent, long lasting straight line storm system that can reach severe limits. Its a term that Meteorologists rarely use because its somewhat technical and more so, because they don't occur very often. Unlike ordinary severe storms that pop up typically in summer, these are large complexes that can travel hundreds of miles. Derechos behave like a larger scale weather system which makes they especially powerful and potential destructive. Instead of slowing down, Derechos can GAIN forward speed which makes the forecasting that much more difficult.

This is what happened on Friday; a smaller scale event happened yesterday. The potential still exists for a repeat over the next few days.


Great swirl photo taken in Sandusky as the storm moved through

Notice how fast the line of storms moved from 2PM to 8PM.

75% of West Virginia was without power over the weekend.

The line continued through D.C. and off of the east coast

The "Ring of Fire" ahead of the heat ridge continues to act as the roller coaster sliding these storm clusters right into Indiana and Ohio. While the energy isn't quiet what it was Friday, the conditions for more storm clusters are still present.