Thursday, July 21, 2016

2016 Drought Conditions vs 2012

The dry conditions in northern Ohio are getting worse as the daytime temperatures reach the lower 90s coupled with higher humidity levels--heat index between 100 and 105--this weekend.  Many people are comparing summer to 2012 both in temperature and in degree of dryness. Is it a valid comparison? How do our dry conditions compare to other years in mid July?  When was the last time we had conditions this dry in mid July in northern Ohio?

The index that's used in determining the degree of dryness or wetness historically is the Palmer Drought Severity Index. It gives us a good barometer in comparing drought events of the past.

According to the National Drought Mitigation Center:  "The PDSI is calculated based on precipitation and temperature data, as well as the local available water content (AWC) of the soil. (Link here) From the inputs, all the basic terms of the water balance equation can be determined, including evapotranspiration, soil recharge, runoff, and moisture loss from the surface layer." 

The more negative the number, the more severe the drought.  Whereas higher numbers indicate wetter conditions. Each week the Climate Prediction Center updates the drought conditions nationwide for each climate division. I circled Ohio for reference.

Based on the PDSI, this summer shows little similarities to the summer of 2012 nationally. The PDSI is falling to 2012 levels in some spots in northern Ohio but the overall degree of dryness in 2012 was far more severe. You could argue that the summer of 2007 is a closer match to 2016. I threw in the Super El Nino summer of 1998 at the end since we are at the end of the Super El Nino of 2015-16.

2016


2015

2012
2007
1998


Friday, July 15, 2016

Preliminary WINTER 2016-17 Outlook

My HIGHLY Preliminary WINTER 2016-17 outlook showing the average temperatures for DECEMBER THROUGH FEBRUARY.  Yes it's early and no, its not too late to gather the pieces. This is will be revised later this summer and again in the fall.



It is looking more likely that a weak La Nina (this post back in early June describes La Nina) will be the driver from the tropics this upcoming winter. Last winter, we had a very strong El Nino.

Take a close look at the snowfall numbers vs the 30 year average for these LA NINA years. I put this graphic together in early June.  HINT...HINT!

Again, all of this is HIGHLY PRELIMINARY and will need to be updated in the fall. This is why no specifics are indicated just general thoughts.

Snowfall departures below are snowfall amounts vs the 30 year average in past La Nina winters


Wednesday, June 22, 2016

Severe Event Likely Tonight. How Do I Convey The Message?

A significant severe weather event is likely across the Ohio Valley tonight. The Storm Prediction Center has western Ohio under a moderate risk, a slight risk for the center of northern Ohio overnight. We are only under a moderate risk a few times a year.  So far, no tornado warnings have been issued for any county in northern Ohio, a rarity this late into June. This is a situation that we need to take seriously.


Radar shows the first of two storm clusters passing just south of northern Ohio. Notice the movement: Northwest to Southeast on the eastern edge of the central US ridge.


At a speaking engagement recently, I surveyed the group of around a hundred people what word they think of when I say the words severe when referring to the weather. The majority of them said tornado. Yet statistically, roughly 10% of severe storms produce a tornado. This is why you will rarely hear me use the word severe unless the situation absolutely warrants it. The word severe is very powerful and conjures up powerful imagery and perceptions. Weather situations like the one tonight (June 23, 2016) reminds me of the psychology behind our weather forecasts.

I'd like to say that I make a forecast with a cold, rational eye but I don't. I take into account how people with react to EACH WORD knowing that most people will react with their preconceived weather notions they've developed over time. Viewers hear the word severe and they think tornado. They panic and fear the worse even if the cold hard facts say otherwise. Its hard to reverse that mindset. I learned that real quick after my first major lake effect event twenty years ago.

If I could make a poster with bullet points for meteorologists, it would list these five at the top

*  Public perception is very powerful

*  We need to be better communicators of information. Quality of the information is better than clicks or social media engagement

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

*  For the public, risk is personal and evokes powerful imagery.  Mass media is for the masses.  Yet the masses in this era of smartphone weather apps want personal forecasts. Huge conundrum.

*  Too much emphasis on uncertainty breeds confusion and inaction. (I am hugely guilty of this as a technical weather geek) We need to find a delicate balance between voicing uncertainty and sticking to a forecast without blowing the event out of proportion.

Friday, June 10, 2016

Developing La Nina Is Old News!

Many meteorologists including myself have written about the state of the winter El Nino and the strong probability that ENSO would transition to an infant La Nina in spring/summer of 2017 for a while now.  Main news sources give the impression at this transition out of El Nino as something new.  I tweeted a preliminary La Nina outlook based on CPC analogs BACK IN NOVEMBER!


Recently, NOAA stated in their newest bulletin, very accurately, that El Nino was finished as of June 9th. These transitions don't occur instantly. The transition away from El Nino toward La Nina has been ongoing for months.

The region used in determining the state of the equatorial Pacific is the ENSO 3.4 region.


All Nino regions (especially the key Nino 3.4 region) temperatures have been falling since the start of the year.


This animation showing the ocean temperatures vs normal values show this perfectly. See the cooler water on the right side (east).

A larger spherical look at the ocean temperatures show the transition even better starting in January. The last image is what the mature La Nina looked like in January of 1999.




According Bob Hensen at Weather Underground, a recent study found that about a 1/3 of first year La Nina events returned of persisted for a second year. This behavior seems to be more frequent over the last 150 years.  It is possible that La Nina could linger into 2018.

It takes months for the effects of any ENSO state (El Nino, neutral or La Nina) to be reflected in the atmosphere. So its very difficult to predict at this time what the winter will be like for specific locations. But we can perform some basic albeit general statistical comparisons between snowfall and La Nina.

Using the ERSSTv4 ocean temperature dataset, a list of La Nina strengths can be determined. Hat tip to Eric Webb.


Based on these years and rankings, I matched up our Cleveland snowfall for these La Nina years. Here is what I found.  The majority of these years had ABOVE NORMAL SNOWFALL in Cleveland!

This is no guarantee of above normal snowfall during the winter of 2016-17 as there are other factors yet to be determined. 

Last year, I posted my thoughts on the upcoming winter (2015-16) around Labor Day. Expect some more detailed thoughts on the effects of La Nina on the upcoming winter of 2016-17 around the same time this year.  Until then, let's enjoy summer!

Thursday, June 02, 2016

Is It Accurate to Say "It's Cleveland" When Talking About Our Weather?


Good morning everyone. This is a pet peeve of mine so bare with me:  

It's highly inaccurate to say "It's Cleveland" when making a GENERIC reference to our overall NE Ohio weather. I know I've upset many by saying this. We've been indoctrinated with this for decades and generations myself included. This phrase really only applies to winter conditions such as lake effect snow events or a strong lake breeze (especially in spring) which don't happen often. Most times (see image below showing the 6 week changes since early May) the changes are felt over a multi-state area! These regional changes don't originate here in northern Ohio nor are they religated to just northern Ohio. Again, the only exceptions that are strictly local in nature are Lake Effect snow events and lake breezes.


Tuesday, May 24, 2016

Memorial Day Temperatures Doing A Complete 180!

Back on May 10th, I posted this long range outlook showing that our confidence of warm finish to the month of May was very high. This was my thinking at the time.



The first 23 days of May were cool not only in Cleveland and northern Ohio but across 85% of the US.

The final 8 days will feel summer like across a 15 to 20 state area.

Who says realistic long range outlooks aren't possible?

Friday, May 20, 2016

The Weather Cast

Some days weather casts flow with metronomic ease. Each segment evolves with seemless precision incorporating sprinkles of down-to-earth science, flawless grammar resulting into an easy to understand message. It permeates the air with the richness of a chocolate cake. Other days it's like driving a dump truck through a nitroglycerin factory with no chance of rescue.  I've blown up a bunch of factories.





Monday, May 16, 2016

How Rare is May Snow in Cleveland?

Sunday marked only the 12th time since the late 1800s we have had measurable snow in May.  The latest report of snow at a National Weather Service reporting station in Cleveland was May 27, 1907 when we had a trace. Keep in mind that weather reports were recorded at different location around downtown Cleveland from 1870 through the 1930s.  Readings started at Hopkins Airport southwest of the city in the mid 1920s.  

Snow cover in Middlefield, Ohio
It wasn't until the late 1930s when records became consistent and searchable. Officially, we only had a trace at Hopkins Sunday.  850 mB temps were between -5 and -7 early Sunday morning with surface tempertures in the mid to upper 30s.   The rare instances of May snowfall is list below. 





All May snowfall instances recorded at Hopkins Airport (post 1938) and downtown Cleveland 1870 to the late 1930s



Monday, May 09, 2016

Are These Big Spring Temperature Changes Something New?



Many times throughout this spring people have commented to me how they never remember wild swings in temperature in northern Ohio quite like what we've experienced this year.  Rather than assume a specific conclusion, I went back and found the high temperatures for every day since 1975 from March 1st through April 15th and again for April 16th through May 31st. I highlighted each instanced where the day-to-day high temperature change was greater than 20 degrees either. In other words, if the high temperature one day was say 38 and the high temperature the following day was 60, that counted. If the high temperature fell from 75 to 52, that would also count.  Here is what I found.


The number of occurrences haven't varied a lot over the last 40 years between March 1st and mid April. I thought the numbers would have been higher since the late 1990s.

Historically, large temperature fluctuations after April 15th don't occur as often due to the lack of residual cold air left over from winter. So far this year (2016) we haven't had an occurrence since April 15th.

What I found interesting is that the occurrences of day-to-day high temperature drops of 30 degrees is significantly higher than temperature jumps of 30 degrees especially before April 15th.


As much as perceive these fluctuations to be a new thing here in northern Ohio, it is quiet common in early spring and has been for at least 40 years. This is another classic example of the Recency Effect as work.  That is we overly weight in our minds more recent events with greater significance and quickly dismiss events further back in time. Note that these conclusions are derived ONLY from Cleveland temperature data.


Friday, May 06, 2016

How big is the largest Alberta Fire?

The Fort McMurray fire as of Thursday May 5th is around 85,000 hectares or 210,000 acres! These comparison to big cities around North America are staggering. Images courtesy Macleans.






The Omega Block in the middle of North America kept central Canada dry accelerating an already dry region from this past winter. Well above normal temperatures surged north.

Omega Block (looks like a double)

More heat this weekend. Some relief is on the way late this weekend as the temperatures will fall back into the 50s.

Saturday high temperatures

Rainfall Sunday into early Tuesday

Cooler air Sunday