How Can the Past Winter Pattern Influence Hurricane Season?

Earlier in the year, I explained the drivers of this winter's record setting warmth and lack of snow. At the top of the list are the strongly "positive" behavior of the North Atlantic and Arctic Oscillations. (Read my earlier post which explains the specifics of each oscillation) The effects that each oscillation produces can linger for months even after the numbers positive or negative have stabilized. In most seasons when one or more teleconnection is abnormally strong (as was the case the last 3 winters), the change in air pressure, temperature and ocean temperature, the dynamical imprint on the atmosphere can be much greater.  These imprints seem to trickle down into the large scale wave changes and stochastic processes that drive our weather patterns.

A great example of these changes are seen in the Atlantic Ocean sea surface temperatures. Remember the last few winters consistently cold and snowy pattern?  This was largely driven by record low Arctic and North Atlantic Oscillation levels.  Remember that the North Atlantic Oscillation are caused by changes in pressure of the Icelandic Low and the Azores High. If the Azores High becomes weaker, the Icelandic Low stays north/stronger, the NAO is negative, more frequent cold air outbreaks/more clipper snows.  When the Azores high becomes stronger, the NAO goes positive, not as much cold air.  

What does this have to do with hurricane season?  Look at the pressure patterns over the Atlantic in the spring following a strongly NEGATIVE NAO winter. The Azores High (shown in light green) is smaller and weaker.

Dec, Jan and Feb 2009-2010

Dec, Jan and Feb 2010-2011

The steering currents around the high stay weak.  These weak trade winds from the east don't cause upwelling of deeper colder water. Here are the steering winds over the last 2 winters into early spring.

  

Now this early spring

The turnover of water is much smaller which allows the sea surface temperature to increase.  Here are the Atlantic sea surface temperatures in early spring in 2010 and 2011 after a STRONGLY NEGATIVE NAO winter.  Very warm water is located in the tropical storm development areas.

Now look at this winter's NAO signature.  Remember our mild pattern?  Look at the Icelandic Low and the Azores High.  The High is very strong which kept cold air locked up in Canada.   

The Icelandic Low stays further north which kept the flow across the US and the Great Lakes out of the west NOT THE NORTHWEST.  The Azores High allowed the steering currents to stay strong which is now causing the upwelling of water off of Africa and into the central Atlantic development region.

Currently, the Atlantic Sea Surfaces are much cooler than in springs past covering a larger area.  

So the positive NAO this past winter was a result of a stronger High in the central Atlantic. This strengthened the trade winds which caused upwelling of cooler water which has led to a cooler Atlantic development area.

Will this result in fewer tropical storms developing earlier in the season?  Will this result in less tropical storm or hurricanes affecting the east coast or Gulf coast?  We shall see...

Late Season April Snow On The Way!

Late April snowfalls are indeed rare birds.  The last time Northeastern Ohio had measurable snowfall after April 20th was in 2005 when more than a foot of wet snow fell between the 23rd and the 25th. Normally, it takes me 35-40 minutes to drive home. That evening after the 10PM news, I didn't get home until 1:45AM!  25 mph along the interstate straddling tracks in the snow made by the semis ahead of me. By far the worst drive through snow I've ever had.

CLICK ON IMAGE FOR CURRENT OHIO RADAR

The biggest concern will be for downed powerlines across central PA. Leaves on the trees in early spring have the ability to hold more than leaves in late fall. Copious amounts of heavy wet snow will no doubt bring power lines down.  Luckily in northern Ohio, the amounts of snow will be far less.  We have several factors working against widespread snowfall:  1) The track of the storm steers the moisture north, away from northern Ohio.  2)  The ground temperatures are in the lower 40s.  3) The Lake Erie water temp is 50.  Still, evaporative cooling (cooling process within the cloud as precipitation falls--the chill you feel when you step out of the shower) will cause temps to drop sufficiently enough during the night low enough to allow snow to accumulate in spots.  Here are projections through midday Tuesday.

Here are the times in Cleveland when we had snowfall after April 20th since 1948:

2005     April 23-25th  12.4"

1971     April 24            0.1"

1968     April 25            0.2"

1967     Apri 24             0.1"

1963     April 30            0.3"

1953     April 20-21st    1.7"

Do We Need More Spring Rain?

The quick answer is a surprising YES!

The frequent rains of February proved to be a little misleading. Thoughts of another record setting spring like last April through June have proved to be premature.  The hottest March on record with several days of 80+ rapidly dried the ground out across northern Ohio. Soil conditions were still too wet for farmers to turn over the fields. April has proved that weather patterns can change drastically.  Only 0.33" of rain at Hopkins Airport with average temperatures running a degree above normal. (Expect the cool weekend to lower the monthly average). As of April 18th, as I drive into rural Lorain and Medina counties, many farmers' fields seem ready to go.

Look at last year's April rainfall compared to average.  Most areas from upstate New York through Ohio to northern Mississippi were more than 10" above normal. The trend continued through June.

Now this April. Quite the opposite but not to extreme. Rainfall is slightly below normal going back 60 days.

Soil moisture over the last 3 weeks has dropped significantly in the east.

Our pattern that shows a somewhat persistent zonal to WNW flow aloft still concerns me. The last two weeks of April should feature near normal temperatures with a few shots of cooler air. If the cooler air is accompanied with clear skies, expect a few more frost advisories to be issued so keep an eye on the nighttime forecasts. The WNW/NW flow could bring weak fronts with less frequent hard rains.

Should you plant your garden in early May? I wouldn't.  No way.  I was burned one year as a late May freeze wiped everything out.


How will the rest of the spring shape up?  Here are the questions to ask:


* No more La Nina. Does the neutral ENSO conditions prevail?
* Where will the warm/cool pools develop in the Atlantic
* Will the PDO continue to weaken?
* Will the northern Pacific warm pool back to the west and cool?
* How much variability will the MJO introduce into the pattern?
* Will any widespread precipitation extremes in the middle of the continent (wet or dry) enhance/weaken storm systems before they can impact Ohio?

Weekend Tornado Outbreak Videos

The weekend tornado outbreak was not record setting but it did feature some long track tornadoes. One report had a tornado with a track at 60 miles! Typically, the tornado number is adjusted lower once the National Weather Service examines the reports weeding out multiple reports. The video from storm chasers is breathtaking. Special thanks to all storm chasers who make these videos possible.

High Risk Severe Storms/Tornadoes Saturday

A HIGH RISK for severe storms and tornadoes Saturday and Saturday night for the middle of the country was issued by the Storm Prediction Center.  High risks are very rare, normally reserved for drastic severe weather situations. No doubt many long path tornadoes will develop tomorrow.

Historically, high risk areas are relegated to the traditional "tornado alley" areas. Below is the HIGH RISK climatology put together by University of Oklahoma graduate student Patrick Marsh who runs a blog about meteorology data, severe storms and a slew of other meteorology related topics.

Upon first inspection, the map seems straight forward.  Yet the work involved in creating this easy-to-read map is not so simple. Normally I steer clear of detailing complex descriptions due to their esoteric nature. However this time, I made an exception. Here is Patrick Marsh's explanation on how he took almost 20 years of HIGH RISK data and morphed it into the above graph.

 I took the polygon outlining the first Moderate [High] risk during a given year, regardless of time of issuance. This means I treated a 12 UTC issuance the same as a 1630 UTC issuance and 2000 UTC issuance. I took the risk polygon, placed it on a 4km grid (specifically grid number 240), and activate all grid points that fell inside the risk polygon. This left me with a grid of 1′s (inside outlook) and 0′s (outside outlook). I created a grid for each year and then summed all the grids together. This gave me a grid containing the number of times each grid point was within the first Moderate [High] risk of the year. I then divided each grid point by the number of years I was examining. This left me with the probability that a grid point would be contained in the first Moderate [High] risk of the year.

Got all that?

What about the areas where the FIRST HIGH RISK is issued each year? The same technique was applied.

The same system will move through OHIO and CLEVELAND on Monday.  Even if the parent cold front is a shadow of its Saturday self, we can anticipate some severe storms. More updates this weekend

Tornado Statistics

Severe weather season is here.

As this winter's La Nina weakens, the strength of the southern jet stream won't be as strong this spring.  So the frequency of tornado outbreaks over the next 3 months shouldn't be as high.  Yet the middle levels of the atmosphere remain strongly cool.  While we don't anticipate tornado outbreaks like what we had last year, a few outbreaks will occur.

Here are some historic tornado statistics. We start with the time of day tornadoes occur.

Tornadoes By Month...

Strong tornado trends since 1950 (EF3-5)

EF0 Tornado Reports to Total Reports

Remember these statistics when the next outbreak occurs.

Dallas Tornadoes & Global Warming

The footage showing the Dallas tornado tossing tractor trailers like toys is fascinating and scary.  Thankfully no one was killed yesterday

Evidently a CNN meteorologist said that the Dallas tornadoes were brought on by Global Warming.  The meteorologist stated further:

“That’s kind of the climate change we are seeing. You know, extremes are kind of ruling the roost and really what we are seeing, more become the norm.”

Normally, I stay calm and cool when erroneous statements like this make headlines.  Yesterday evening, something inside me went off. So I went on a twitter rant. Social media venting in general rarely results in anything positive.  The pot become stirred.  Words are taken out of context. Objective analysis becomes obscured in a cloud of emotion.  Passion and enthusiasm fade into a mire of negativity.  Once you are there, it becomes very difficult to extricate ones self.  Last night on twitter, I danced on the precipice of the mire. I noticed the err in my way so I stopped dancing and cooled down.  All of this happened in roughly 10 minutes.  Did you follow all of that?

Let's be clear. The statements by the CNN meteorologist needs to be separated into two subjects which need to be addressed individually. 

1.  Tornadoes and Global Warming.
2.  Extreme weather events and Global Warming.

The portion that I am concerned about here is correlating Global Warming to tornadoes.  The Storm Prediction Center has an excellent FAQ section on their website. One of the questions is simply stated:  

Does "global warming" cause tornadoes?  Here is the answer word for word from the SPC site:

Does "global warming" cause tornadoes? No. Thunderstorms do. The harder question may be, "Will climate change influence tornado occurrence?" The best answer is: We don't know. According to the National Science and Technology Council's Scientific Assessment on Climate Change, "Trends in other extreme weather events that occur at small spatial scales--such as tornadoes, hail, lightning, and dust storms--cannot be determined at the present time due to insufficient evidence." This is because tornadoes are short-fused weather, on the time scale of seconds and minutes, and a space scale of fractions of a mile across. In contrast, climate trends take many years, decades, or millennia, spanning vast areas of the globe. The numerous unknowns dwell in the vast gap between those time and space scales. Climate models cannot resolve tornadoes or individual thunderstorms. They can indicate broad-scale shifts in three of the four favorable ingredients for severe thunderstorms (moisture, instability and wind shear), but as any severe weather forecaster can attest, having some favorable factors in place doesn't guarantee tornadoes. Our physical understanding indicates mixed signals--some ingredients may increase (instability), while others may decrease (shear), in a warmer world. The other key ingredient (storm-scale lift), and to varying extents moisture, instability and shear, depend mostly on day-to-day patterns, and often, even minute-to-minute local weather. Finally, tornado record keeping itself also has been prone to many errors and uncertainties, doesn't exist for most of the world, and even in the U. S., only covers several decades in detailed form.

As my tweets said last night, I am not against Global Climate Change. As a meteorologist with a focus in physics and mathematics, my stance has been luke warm on blaming any and all "extreme" weather event on global climate change.  Why not mention the connections to the change in southerly jet stream position and strength to severe weather and how La Nina can drive this? How about mention that the changes in temperature with height as primary driver of thunderstorm complexes not just warming at the surface? 

If the CNN meteorologist made an argument that global climate change is a driver for upper level wind/temperature changes over time which make conditions much more favorable severe weather/tornado outbreaks,  I'd listen.  Yet the met jumped right into blaming global warming for the tornadoes in Dallas.  How can anyone make the jump from "A" to "Z" without addressing components "B" through "Y"
first? 

This all might sound like a game of semantics.  After all, if the conclusion is correct, who cares how we get there. Why bother with what lies in between "A and Z" if we know the endgame as fact?  In this case, the conclusion, or endgame, drawn on CNN--later refuted earlier in this post from the Storm Prediction Center website--is way off course.


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How about Metropolitan tornadoes?  These tornadoes occurred in a downtown location.  That rarely happens!

According to the National Weather Service Dallas/Fort Worth office:

http://www.spc.noaa.gov/wcm/2012/20120403-summary.pdf


"Over the last 60 years (since 1952), a total of 172 tornadoes have been reported in either Tarrant or Dallas Counties, Texas. Of these, 42 have been rated at least EF2 (wind speeds over 110 mph). The strongest, rated EF4, hit Dallas on April 25, 1994, killing 3 people and injuring 48. Neither county has ever reported an EF5-rated tornado."

An incomplete list of downtown/metro tornadoes from the Storm Prediction Center in the link below:

http://www.spc.noaa.gov/faq/tornado/downtown.html

Xenia Tornado - April 3, 1974 - A Look Back

On April 3rd back in 1974, the 2nd deadliest tornado outbreak in US history (2nd only to the outbreak last year).  The Xenia tornado touched down around 4:30PM and was on the ground for more than 30 miles killing 32 people.  All told, 12 tornadoes touched down in Ohio in less than 24 hours with 148 tornadoes across 13 states!  Half of the buildings in Xenia were destroyed

Imagine television weather reports like this in 2012. The archaic radar loop hardly has any detail!

Original 8mm footage of the tornado as it approached

The photos of the damage below tell it all.

HIGH SCHOOL BEFORE (ABOVE) AND AFTER (BELOW)

The "Ohio History" website has even more great photos and some video.

http://www.ohiohistory.org/etcetera/exhibits/swio/pages/content/1974_tornado.htm

Mega-Million Jackpot: The Odds Compared to Other Events

The Mega-Millions lottery jackpot is now very close to the highest lottery jackpot in history. So many stories of people snatching up lotto tickets praying that their ticket answers their financial prayers along with their kids, grandkids and future generations of grandkids....assuming they don't blow their ca$h like the lotto winner from West Virginia in 2002.  He blew $100+ million in a little under 4 years!  How does that happen?

Not to burst anyone's bubble but for lotto winners who win more than $150,000 are twice as likely to go bankrupt in under 5 years than the general population!

...I'd still take my chances.

Anyway, the numbers are staggering. The odds of getting all of the numbers correct on your ticket are...wait for it...

176,000,000 to 1

So, hypothetically, at $1 a ticket, if you spent $176,000,000 in tickets, does this guarantee that you would win the jackpot?  Absolutely not!  Remember that the odds are statistical not actual.  Who is to say that the same two winning tickets with the same numbers haven't been printed?  

How about the odds of some other events:

odds of dying in a fire:  1,116 to 1
odds of fatally slipping in the bath or shower:  2,232 to 1
odds of dying in an airline accident:  20,000 to 1
odds of dying from a lightning strike:   84,000 to 1
odds of dealing a ROYAL FLUSH:   649,350 to 1
odds of being injured by hail:   5,114,000 to 1
odds of being killed by hail in a years time:  734,400,000 to 1

Early Spring Patterns & March Heat

One prominent meteorologist recently said that the combination of elements (teleconnections) which when pieced together dictate specific weather patterns are like the elements of a movie. You can vary any one of the elements of a movie just a little (sound, background sound, brightness, character development, storyline, the way its shot, etc) and the effect can be dramatic for some movie watchers.  Yet that same change for another group of film goers could have very little effect.

The winter of 2011-12 is an example of this metaphor. The northern Pacific was cold (PDO) like last winter. La Nina was present just like last winter but it was shorter and not as strong. Yet the biggest change to a more stable arctic/north Atlantic this winter had far different results than the winter of 2010-2011.

SNOWFALL LAST WINTER:  65"
SNOWFALL THIS WINTER SO FAR:  38"

An easier way to put it is this way: You change grandma's soup recipe by adding too little salt and pepper and skimp on the paprika and it might bear no tasteful resemblance to grandma's soup.  Got it?

This March is yet another example of how the combination of elements driving our weather patterns can and do yield different results when compared to other time frames like last year.



Here is the weather pattern scorecard so far for March
                                   
                                                        LAST MARCH        THIS MARCH

LA NINA                                        STRONG                   WEAKENING
MJO PHASE (equator)                    PHASE 3-4 (COOL)  STRONG PHASE 6 (WARM)
ARCTIC                                          POSITIVE                  POSITIVE
NORTH ATLANTIC                       POSITIVE                  POSITIVE
PDO (NORTH PACIFIC)                  COOL                        COOL
SNOW COVER                                    19%                            20%
PNA (PRESSURE OUT WEST)     POSITIVE                  WEAKLY POSITIVE


Forget the specifics on each element  for a moment and look at the similarities.  

All but the LA NINA stage and the MJO are similar to last year. 

Last March when we were finally able to take a breath as the perpetual snow cover was melting away, the temperatures finally started to rebound but there was still some winter chill left. You probably remember if you tried to golf at Big Met around St. Patrick's Day in 2011.

This year, the trees are starting to bloom.  I hear the sound of lawn mowers.  I smell fertilizer.  I see daffodils attempting to flower.  Scary yet awesome sight and sounds in mid March.  A sensory overload to say the least. 

This week (March 14-20th) we have broke almost a thousand record high temps. We reach a high of 83 on Tuesday. That was a first in March since 1945 and only the 3rd time in a century! Its not only Cleveland but the eastern 2/3rds of the US.

Now do you see how difficult it is to compare this March and early spring to last spring? 

The weather pattern ISN'T ALWAYS THE SAME AS THE SUM OF ITS PARTS!

Has this HOT MARCH pattern happened before? You bet.  If we look at ALL 17 INSTANCES where we hit 80+ in March in the last century, the pattern (sum of the parts) looks almost identical:

Here are the patterns for the last 80 degree days in March:  1998, 1990 and 1983

How about 1945 and 1910--the last 83 degree days in March? 

THEY ALL HAVE RIDGES IN THE EAST AND TROUGHS/COLD IN THE WEST!

I talked with the Ohio Dept. of Natural Resources Agricultural R&D Office in Wooster about the growing season so far. According to Dan Herms, we are almost 4 weeks ahead of last year. He says that this early warmth--as long as the temperatures don't drop--won't harm the trees of plant. He also says that you shouldn't plant flowers just yet.

Why should we wait to plant our garden? 
Why should we stay away from Lake Erie?
And Why could Christmas trees be the most susceptible to this early spring warmth?

My next post will explain!!!