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Updated weather summary for Southern Ontario and the
National Capital Region issued by Environment Canada
At 5:56 P.M. EST Tuesday 3 December 2013.

..2013 tornado count updated..

On Saturday November 23, as a sharp cold front crossed Eastern
Ontario, a very rare late season tornado took some residents just
north of Prescott by surprise. The tornado was spun from a vigorous
storm leaving significant structural damage to a farm silo and other
minor damage in the area. It was rated an enhanced Fujita scale one
tornado (ef1) with winds estimated at 150 kilometres per hour.
The enhanced Fujita scale ranges from 0 to 5, 5 being the

Two more investigations were also completed in November.
An ef0 tornado was confirmed in teviotdale, just south of Mount
Forest, on July 19 2013 and another ef0 tornado occurred in magiskan
lake, northeast of Cochrane, on August 2nd 2013. The total count of
tornadoes in Ontario in 2013 now stands at 22. The Ontario tornado
season normally runs from late April to early October and, on
average, 12 tornadoes are verified. Other occurrences of late season
tornadoes in Ontario are the Leamington tornado on November 29 1919,
the Exeter tornado on December 12 1946, and the Hamilton tornado on
November 9 2005.

Please note that this summary may contain preliminary or unofficial
information and does not constitute a complete or final report.


The following is the EC summary of weather events over the stormy past weekend of Friday, July 19, 2013 and Saturday, July 20, 2013. EWR adds some of our graphics and info from our own monitoring activities below the summary.

Environment Canada Summary:

Updated weather summary for all of Southern Ontario and the
National Capital Region issued by Environment Canada
At 10:46 AM EDT Monday 22 July 2013.

==weather event discussion==

A hot and humid air mass ahead of a cold front provided the perfect
combination to set off severe thunderstorm activity across Central
and Southern Ontario Friday. The severe weather became extensive
during the afternoon and evening hours resulting in the biggest
severe weather outbreak of the season. An exceptionally large area
was affected, from Windsor to Ottawa and from Lake Erie to North Bay.

Friday morning, thunderstorms gave severe wind damage to callander
(near North Bay) resulting in the declaration of a state of emergency
for the town.

Severe thunderstorms continued to develop eastward and southward. In
the early afternoon, storms produced a swath of damage from Pembroke
to Petawawa where cars were flipped over, roofs blown down, trees
uprooted, street lights snapped, and trailers overturned. By late
afternoon, wind damage was reported in dozens of communities in a
broad swath from Lake Huron and Georgian Bay through to Eastern

The severe storms developed southward during the evening hours,
causing wind damage in the Golden Horseshoe and in Southwestern
Ontario. Flooding and downed trees were reported in Niagara Falls
with rainfall estimated at 75 to 100 mm. 150 mm was reported to have
fallen at Rondeau bay.

2 minor injuries were reported in Chatham late Friday evening when a tree fell on a car with the people in it.

Hundreds of thousands of residents were left without power following the storms. As of this morning, approximately 17,000 homes remained
without power.

Environment Canada storm damage teams have investigated damage in
Barrie, Orillia, Gravenhurst, Hamilton, Petawawa, callander and
Dufferin County. The most severe damage was found near honeywood, in
duffern county, where estimated winds of 150 km/hr destroyed a cattle
barn and threw the roof 300 metres. This damage rates ef1 on the
enhanced Fujita scale. Evidence thus far indicates that the storm
damage in Ontario was caused by straight-line, downburst winds.

Below is a list of the most significant damage reports that
Environment Canada has received as of 7:00 PM Sunday.

Time(lcl) location event description

11:20 AM Gravenhurst 2.5 cm hail

12:40 PM Petawawa and roof damage, trailers flipped,
Pembrooke power outages

12:55 PM Petawawa plaza front facet off, windows blown out,
Roof caved in

1:55 PM Gravenhurst large trees down, power lines down

2:30 PM Coldwater trees down and snapped, power outages

2:45 PM Gravenhurst cars overturned

2:50 PM Orillia trees down, power lines down, street
Lights snapped

2:55 PM lake dalrymple power lines and trees down

3:00 PM W of Ottawa roof damage, crop damage, trees down

3:00 PM’s of Gull Lake 150 trees down on South Morris island

3:15 PM Barrie funnel cloud, trees down – caused
Damage to homes

3:20 PM se of tree damage

3:20 PM Bobcaygeon trees uprooted

3:30 PM Kanata large hail

4:00 PM N of Arthur trees down

4:35 PM Barrie building damage, trees snapped,
Power outages

4:50 PM Listowel wind gust of 92 km/h

5:10 PM Ottawa trees down (primarily in west end)

5:10 PM Borden wind gust of 96 km/h

5:10 PM mulmar barn roof thrown 300 metres, barn
Destoyed near honeywood, ef1 damage,
Winds estimated at 150 km/hr.

5:15 PM Napanee trees down, gas leaks, power outages

5:30 PM Innisfil funnel cloud, limbs down

5:30 PM Waterloo arpt wind gust of 119 km/h, trees down

5:35 PM sw of Bradford funnel cloud

5:40 PM Guelph dozens of trees snapped or uprooted,
Hundreds of branches down, damage to
Homes from fallen trees or limbs

5:45 PM Casselman 53 mm rain

5:50 PM Kitchener trees down – caused damage to homes,
-Waterloo power outages, damage to bus shelter

5:50 PM Stratford trees down

5:55 PM Port Carling mature trees down, trees snapped
Port Severn

5:55 PM Gravenhurst large trees down, power lines down

6:00 PM Toronto Pearson wind gust of 104 km/h

6:00 PM paris tree damage, wooden balcony torn off
House, cinderblock warehouse collapse

6:10 PM Toronto trees down, including a
Historic century old tree, power
Lines down

6:30 PM Hamilton trees down

6:45 PM Stoney Creek trees down, trees snapped

7:05 PM Hamilton arpt wind gust of 104 km/h

7:10 PM St Catharines trees down, 75-85 mm of rain,

7:3o PM Chatham trees down, power lines down,

7:45 PM Grimsby trees down, power outages, 65 mm of

7:45 PM Waterdown trees down

8:20 PM Chatham-Kent trees down, power outages

8:30 PM Ancaster trees and power lines down, small

8:45 PM norwich wind gust of 90 km/h, trees down

9:00 PM mulmur barn damage, crop damage, roof
Damage, power outages

9:10 PM Hamilton arpt wind gust of 106 km/h

9:20 PM Mount Hope trees down, trampoline blown onto
Roof, crop damage

10:00 PM Port Colborne wind gust of 98 km/h

11:00 PM Port Colborne wind gust of 93 km/h, power outages

02:00 AM (sat) Waterloo arpt wind gust of 91 km/h

Reports with exact time unknown:

St George trees and hydro lines down
Essex County trees down
Simcoe County trees down
Rondeau bay 150 mm rain
Chatham minor injuries to two passengers of
A car
Wiarton large tree uprooted
Blenheim trees down, flooded basements, power
Niagara Falls 75-100 mm rain, flash flooding
Beamsville/ 75-85 mm rain, flash flooding

This weather summary contains preliminary information and may not
constitute an official or final report.

Observations from EWR:

EWR’s rain gauge measured 35mm of rain by the completion of the frontal passage Saturday morning. In the radar animation below, covering the time from 7:28 pm Friday to 9:01 am Saturday morning, two storm systems collided over the Niagara Escarpment at Grimsby at approximately 9:10PM Friday evening (early part of the animation). The westernmost system advanced eastward along the north shore of Lake Erie from the St. Thomas area, and colliding with the system moving southerly across the GH-GTA from the Kitchener-Waterloo area. The Lake Erie system was strongly electified, and the light show was impressive. The gust front from that system was strong with torrential rain in wind as it passed over Dundas, Ancaster and Hamilton. The bulk of the rain we measured at EWR came from that gust front.

20130720 Click image to start animation if it doesn’t start on its own.

[click on any of the following images to see them full size]


This Storm Relative Velocity* image, taken at 6:20pm on Friday, shows two areas of rotational development along the gust front of the storm line that had just arrived from the Kit-Wat area. The inverted pink triangle is a “TVS signature” sent out by the KBUF radar system, indicating conditions for tornadic rotation exist. Immediately to the right of the TVS signature is a very tight “couplet” – bright red and green, indicating that rotational winds exist. The beam centre at this distance from the Buffalo station is about 4300 feet, so it is unknown if this rotation yielded a waterspout or not (its over Lake Ontario at this point).

South of Cobourg, another area of suspected rotational development – quite a large area, suggesting the storm cell is developing a rotating core. The bright green is suggestive of a strong in-flow jet.

When this storm passed over Dundas, there was a strong “fresh earth” smell to the storm leading edge, and a bit of “greenness” to the advancing shelf. Both are suggestive that there had been tornadic activity in the cell in its travels, or at least very strong updraft over open land.

* Storm Relative Velocity – a radar measure of the direction and intensity of winds in a storm, relative to the wind velocity over ground of the storm. Visualizes the wind within a storm, as opposed to the wind we feel over ground. Green – winds flowing toward the radar station, red, flowing away. To be tornadic the couplet must straddle a radial – a line drawn from the radar site to a couplet.


This image is a zoom-in of the previous one, to get a better look at the couplet. Key elements are the tight and intense colour change. This is indicative of very tight rotation, consistent with a small but well defined funnel, tornado or waterspout.


A combined Storm Relative Velocity (right) and Base Reflectivity view of the previous area, approximately 20 minutes later. The storm line has moved further across the lake. The previous couplet has dissipated, and a new TVS has come up, although there isn’t any overt indication in the SRV pattern to indicate a cell. These views only represent one angle sweep – the lowest tilt – there may have been more evidence in higher tilts.

The Coboug pattern is better defined and is most likely a strong inflow jet. This is borne out by the shape of the cell in the Base Reflectivity scan. This is a tornadic supercell in the making, but it didn’t mature much beyond this phase.

Of interest, is the well defined “gust front” shelf or roll cloud formed ahead of the storm over Niagara. Notice the thin cloud line in the base reflectivity scan, and the thin green and red line in the SRV scan, stretching from Youngstown in a gentle arc eastward out of the frame, just ahead of the main cloud mass.


This image is the same as the previous scan, just one radar cycle later. The TVS icon has dropped, but the Cobourg cell is maintaining its integrity.

While watching storms is exciting, wonderous and exhilarating, living with the reality of their awesome power, is not. Pray for the folks of Moore, Oklahoma, they will need a long time to heal and recover.

2013-05-20: NEXRAD radar trace from KTLX east of Moore, Oklahoma, and just prior to the tornado moving into town The classic tornadic curl of this EF4-5 tornado is clealy evident. The purple core of the tornado is known as a “debris ball” – the amount of debris sucked up into the tornado produces a high reflectivity signal, and is sadly characteristic of a violent on-the-ground tornado. Moore is in the open space to the right(east) of the debris ball. Image courtesy “rrick8”, posted at 3:20PM 2013-05-20 at

The mechanism of formation of tornados is still matter for discovery by science. There are presently several hypotheses, and probably, there isn’t one single mechanism. One of the more popular is the formation by the rolling of air under the strength of the gust front out of a supercell, and its twisting up into the updraft of the storm cell. Yet, when you view a tornado like the one below, recently shot May 25 in Kansas, its truly hard to conceive how these actually get built. How this one stayed together is a natural wonder to behold…

(view this full screen to really see it)

by Anthony Watts (originally posted April 29, 2011 on WUWT).

In times of tragedy, there always seems to be hucksters about trying to use that tragedy to sell a position, a product, or a belief. In ancient times, tragedy was the impetus used to appease the gods and to embrace religion to save yourselves. In light of this article on the Daily Caller Center for American Progress blames Republicans for devastating tornadoes it seems some opportunists just can’t break the pattern of huckster behavior in the face of disaster.

I can’t think of a more disgusting example of political opportunism that has occurred such as we witnessed today from The Center for American Progress via their Think Progress blog, as well as the New York Times op-ed piece that suggests predicting severe weather is little more than a guessing game. Certified Consulting Meteorologist Mike Smith of Wichita, KS based WeatherData Inc. said of the NYT piece:

The cruelty of this particular April, in the number of tornadoes recorded, is without equal in the United States.

This may or may not be true. The statement is at least premature. The NWS Storm Prediction Center March 8th changed its methodology which allows more reports of tornadoes and other severe storms to be logged (see first note here). We don’t know yet whether this is a record April.

Tornadoes in particular, researchers say, straddle the line between the known and the profoundly unknowable.

“There’s a large crapshoot aspect,” said Kevin Trenberth, a senior scientist at the National Center for Atmospheric Research in Boulder, Colo.

To add to the mix, Peter Gleick says at the Huffington Post  “More extreme and violent climate is a direct consequence of human-caused climate change (whether or not we can determine if these particular tornado outbreaks were caused or worsened by climate change).”

In the Think Progress piece, again, Dr. Trenberth is quoted:

“Given that global warming is unequivocal,” climate scientist Kevin Trenberth cautioned the American Meteorological Society in January of this year, “the null hypothesis should be that all weather events are affected by global warming rather than the inane statements along the lines of ‘of course we cannot attribute any particular weather event to global warming.’”

It should also be noted that during that AMS conference in January, Dr. Trenberth called people who disagreed with that view “deniers” in front of hundreds of scientists, even after being called out on the issue he left the hateful term intact in his speech. Clearly, he is a man with a bias. From my perspective, these articles citing Trenberth are opportunistic political hucksterism at its finest. Unfortunately, many from these bastions of left leaning opininators don’t bother to cite some inconvenient facts, leaving their claims to be on par with superstitions that were the part of our dark past.

First, let’s look at the claim of tornadoes being on the increase, in parallel with the climate change that is claimed. In my previous essay Severe weather more common? Data shows otherwise I cited this graph from the National Climatic Data Center:

Obviously, when NCDC tallies the number of F3-F5 tornadoes from this recent outbreak, and gets around to updating that graph, there will be an uptick at the end in 2011 that is on par or even higher than the famous 1974 tornado outbreak. The point though is that despite the 1974 uptick, the trend was down.

The NYT article says:

The population of the South grew by 14.3 percent over the last decade, according to the Census Bureau, compared with 9.7 percent for the nation as a whole. Of those states hardest hit by tornadoes this year, some were among the fastest growing, notably Texas and North Carolina.

Let’s look at trends of tornado related deaths with population. From Harold Brooks. a research meteorologist with the NOAA National Severe Storms Laboratory in Norman, Oklahoma. we have this graph:

Source: NOAA’s US Severe Weather Blog, SPC, Norman Oklahoma

Let’s look at other figures. Today, Dr. Roger Pielke Junior got an updated graph from Harold Brooks at NOAA to bring it to 2010:

That graph is a testament to the improved lead times, accuracy, and and dissemination of severe weather warnings by the National Weather Service, whose members did an outstanding job during this severe weather event. CCM Mike Smith, in his book Warnings The True Story of How Science Tamed the Weather talks about the vast improvements we’ve witnessed since the early days of severe weather forecasting. He writes today of the recent outbreak:

There is no question that the current storm warning program, a collaborative effort of the National Weather Service, private sector weather companies like AccuWeather, broadcast meteorologists, and local emergency managers have saved hundreds of lives during these recent storms through excellent forecasts and warnings.  This image shows the tornado warning (red hatched area) for Birmingham that was issued more than 20 minutes before the tornado arrived.

Can the warning program be improved? Certainly. The National Weather Service’s new dual-polarization radar will improve flash flood warnings and will incrementally improve warnings of tornadoes that occur after dark.

But in the immediate aftermath of these tragic storms we seem to have learned two things:  People need to respond to today’s highly accurate warnings. For some reason, the media (see examples here and here seems determined to downplay the quality of the warnings which may have the effect of driving down response rates.

Second, they must have a place to take shelter. Most mobile home parks and many homes in the South do not have underground shelters or safe rooms. Mobile home parks and housing developments should look to constructing these in the future.

With 30 minutes of advance warning in this case, and many other advance warnings during this outbreak, plus the supersaturation of live television coverage, plus the fact that weeks in advance, my colleague Joe D’Aleo, co-founder of the Weather Channel and now at Weatherbell LLC,  discussed the likelihood of a super-outbreak of severe weather occurring due to the juxtaposition of cold air from snowpack in the northern plains with warm moist air in the south, it would seem Dr. Trenberth’s claim of “a large crapshoot aspect” doesn’t hold up. The death toll issue seems to be shelter, not lack of forecasts, warnings, or awareness. People knew the storms were coming, they just had few options for shelters that would survive at F3-F5 category tornado intensity.

The attempts at linking the tornado outbreak this week to “global warming” have been roundly criticized in the meteorological community. Just yesterday there was a denouncement of the tornadoes to global warming link in this story from

“If you look at the past 60 years of data, the number of tornadoes is increasing significantly, but it’s agreed upon by the tornado community that it’s not a real increase,” said Grady Dixon, assistant professor of meteorology and climatology at Mississippi State University.

“It’s having to do with better (weather tracking) technology, more population, the fact that the population is better educated and more aware. So we’re seeing them more often,” Dixon said.

But he said it would be “a terrible mistake” to relate the up-tick to climate change.

Anticipating this sort of nonsense in the current political climate that seeks to blame humans for the weather, last month, the National Weather Association, representing thousands of operational meteorologists, forecasters, and television-radio meteorologists in the United States adopted their first ever position statement on climate change and severe weather events. They state:

Any given weather event, or series of events, should not be construed as evidence of climate change.

The NWA emphasizes that no single weather event or series of events should be construed as evidence of a climate trend. Daily weather is subject to extreme events due to its natural variability. It is only the occurrence of these events over decades that determines a climate trend.

No clearer statement could be rendered. It mirrors what a NOAA scientist at the Storm Prediction Center said yesterday to Fox News:

Greg Carbin, the warning coordination meteorologist at NOAA’s Storm Prediction Center in Norman, Oklahoma, said warming trends do create more of the fuel that tornadoes require, such as moisture, but that they also deprive tornadoes of another essential ingredient: wind shear.

“We know we have a warming going on,” Carbin told Fox News in an interview Thursday, but added: “There really is no scientific consensus or connection [between global warming and tornadic activity]….Jumping from a large-scale event like global warming to relatively small-scale events like tornadoes is a huge leap across a variety of scales.”

Asked if climate change should be “acquitted” in a jury trial where it stood charged with responsibility for tornadoes, Carbin replied: “I would say that is the right verdict, yes.” Because there is no direct connection as yet established between the two? “That’s correct,” Carbin replied.

Historically, there have been many tornado outbreaks that occurred well before climate change was on anyone’s radar.  Here’s a few:

1908 Southeast tornado outbreak 324 fatalities, ≥1,720 injuries

1920 Palm Sunday tornado outbreak ≥380 fatalities, ≥1215 injuries

1925 Tri-State tornado ≥747 fatalities, ≥2298 injuries

1932 Deep South tornado outbreak  ≥330 fatalities, 2145 injuries

1952 Arkansas-Tennessee tornado outbreak 208 fatalities

1965 Palm Sunday tornado outbreak 256 fatalities

April 3-4 1974 Super Outbreak 315 fatalities

All of these occurred before “climate change” was even on the political radar. What caused those if “global warming” is to blame? The real cause is La Niña, and as indicates on their page with the helpful meter, we are in a La Niña cycle of ocean temperature in the Pacific.

Here’s what it looks like on satellite measurements. Notice the cool blue:

The US. Climate Prediction Center talks about the reason for such outbreaks in relation to ocean temperature cycles:

What impacts do El Niño and La Niña have on tornado activity across the country?

Since a strong jet stream is an important ingredient for severe weather, the position of the jet stream helps to determine the regions more likely to experience tornadoes. Contrasting El Niño and La Niña winters, the jet stream over the United States is considerably different. During El Niño the jet stream is oriented from west to east across the southern portion of the United States. Thus, this region becomes more susceptible to severe weather outbreaks. During La Niña the jet stream and severe weather is likely to be farther north.

Note the collision zone in the US southeast during La Niña patterns.

Finally, Let’s examine the claims of global warming being linked to the tornado outbreak. If this were true, we’d expect the globe to be warmer, right?

Thunderstorms (and all weather for that matter) form in the troposphere, that layer of the atmosphere that is closest to the surface, and extends up to the stratosphere.

Image: – click for details

Dr. Roy Spencer, climate scientist from the University of Alabama, Huntsville, tracks the temperature of the troposphere. The university system that he tracks the temperature daily with is inoperable, due to the storms. People who have been watching it prior to this event know the current global tropospheric temperature is lower in April than the norm, but we can’t show it today. The last global value he plotted showed this:
The global temperature anomaly of the troposphere today is about the same as it was in 1979. If there’s any global warming in the troposphere, it must be a figment of an overactive imagination on the part of people who seek to link it to the recent tornado tragedy.

Dr. Roy Spencer sums it up pretty well on his blog today:

MORE Tornadoes from Global Warming? That’s a Joke, Right?

It is well known that strong to violent tornado activity in the U.S. has decreased markedly since statistics began in the 1950s, which has also been a period of average warming. So, if anything, global warming causes FEWER tornado outbreaks…not more. In other words, more violent tornadoes would, if anything, be a sign of “global cooling”, not “global warming”.

Anyone who claims more tornadoes are caused by global warming is either misinformed, pandering, or delusional.

The people that seek to link this tragedy to the political movement of climate change should be ashamed of themselves. The only “deniers” here are the ones who deny all the long established counter evidence of their bogus claims for political gain.


For those who wish to help with this tragedy there are options:

There’s a service called which can help you get status on relatives and friends who may be affected.

There are several ways to register or look for messages from those affected by a disaster:

  • From a computer, visit and click on the “List Yourself or Search Registrants” link under “How to Get Help.”
  • From a smart phone, visit
  • Call 1-800-RED CROSS (1-800-733-2767) to register.

There is of course financial help needed for the relief efforts of the American Red Cross. Text REDCROSS to 90999 to donate $10 to relief efforts from your cell phone bill. Or visit the main website.

Crossposted from WattsUpWithThat. If you are a science buff, and a weather/climate buff especially, you should be visiting WUWT regularly, The world’s most widely-read climate site.

Stunning map of NOAA data showing 56 years of tornado tracks sheds light on the folly of linking “global warming” to severe weather
by Anthony Watts, WUWT

…has been turned into a stunning image of the United states. Each line represents an individual tornado, while the brightness of the line represents its intensity on the Fujita Scale. The result, rendered by John Nelson of the IDV User Experience, shows some interesting things, especially the timeline bargraph that goes with the map, which show that the majority of US tornado related deaths and injury (prior to the 2011 outbreak which isn’t in this dataset) happened in the 1950′s to the 1970′s. This is a testament to NEXRAD doppler radar, improved forecasting, and better warning systems combined with improved media coverage.

Here’s the data description, the big map of the CONUS follows below.

The National Weather Service (NWS) Storm Prediction Center (SPC) routinely collects reports of severe weather and compiles them with public access from the database called SeverePlot (Hart and Janish 1999) with a Graphic Information System (GIS). The composite SVRGIS information is made available to the public primarily in .zip files of approximately 50MB size. The files located at the access point contain track information regarding known tornados during the period 1950 to 2006. Although available to all, the data provided may be of particular value to weather professionals and students of meteorological sciences. An instructional manual is provided on how to build and develop a basic severe weather report GIS database in ArcGis and is located at the technical documentation site contained in this metadata catalog.

It is also worth noting that the distribution of strong tornadoes -vs- weaker tornadoes (rated by the Fujita scale) is greatly lopsided, with the weakest tornadoes far outnumbering the strong killer F5 tornadoes (such as we saw in 1974 and 2011, both cooler La Niña years) by at least an order of magnitude:

And here’s the entire map, click for a very hi-resolution version:

Mike Smith covers a lot of the history contained in this data set in his book Warnings The True Story of How Science Tamed the Weather.

He talks about the vast improvements we’ve witnessed since the early days of severe weather forecasting and is well worth a  read if you want to understand severe weather in the USA and how the detection and warning methods have evolved. He has another book just out (Reviewed by Pielke Sr. that explains the failure of this system in Joplin in 2011.

In Mike Smith’s first book, “Warnings: The True Story of How Science Tamed the Weather,” we learned the only thing separating American society from triple-digit fatalities from tornadoes, weather-related plane crashes, and hurricanes is the storm warning system that was carefully crafted over the last 50 years. That acclaimed book, as one reviewer put it, “made meteorologists the most unlikely heroes of recent literature.” But, what if the warning system failed to provide a clear, timely notice of a major storm? Tragically, that scenario played out in Joplin, Missouri, on May 22, 2011. As a wedding, a high school graduation, and shopping trips were in progress, an invisible monster storm was developing west of the city. When it arrived, many were caught unaware. One hundred sixty-one perished and one thousand were injured. “When the Sirens Were Silent” is the gripping story of the Joplin tornado. It recounts that horrible day with a goal of insuring this does not happen again.

Of course, alarmists like Peter Gleick (who knows little about operational meteorology and is prone to law-breaking) like to tell us severe weather (and days like Joplin) are a consequence of global warming saying at the Huffington Post:

“More extreme and violent climate is a direct consequence of human-caused climate change (whether or not we can determine if these particular tornado outbreaks were caused or worsened by climate change).”

But in this story from

“If you look at the past 60 years of data, the number of tornadoes is increasing significantly, but it’s agreed upon by the tornado community that it’s not a real increase,” said Grady Dixon, assistant professor of meteorology and climatology at Mississippi State University.

“It’s having to do with better (weather tracking) technology, more population, the fact that the population is better educated and more aware. So we’re seeing them more often,” Dixon said.

But he said it would be “a terrible mistake” to relate the up-tick to climate change.

Again, for a full understanding I urge readers to click, read, and to distribute these two WUWT essays:

The folly of linking tornado outbreaks to “climate change”

Why it seems that severe weather is “getting worse” when the data shows otherwise – a historical perspective

The visual graphical representation of weather that you see on computer and TV weather displays starts out as a series of numbers generated from the radar echos obtained when the radar dish sweeps the sky. The most common visual presentation from these numbers is something known as “reflectivity data”. There are several different types of reflectivity data based on what part of the radar scan information is used.

As the radar dish sweeps around the sky, it makes a stepwise tilt up, sampling the atmosphere in layers, resetting eventually and starting the tilt cycle all over again. This happens because the dish focuses the beam, and it can only cover a narrow layer in each sweep. The reflectivity radar display you see on TV and on EWR represents a “stacked” composite of one or more of those tilt layers (indeed, one such full layer presentation is known as “composite reflectivity”).

Other reflectivity presentations may use only the bottom few layers. This is done for two main reasons: one, to speed up the time it takes to obtain the necessary scan data, and secondly, to focus on and illuminate storm structure nearest the ground – the area where tornadoes form. These are the various “base reflectivity” scans. EWR uploads two reflectivity scan sets in the Scan B scans on our main page. The principal display that you first see, is a full composite reflectivity scan, composed of all layers currently being swept by the radar dish. This scan is the slowest to update, because it has to collect all layer levels before data can be sent out.

If you click on any of the Scan B scans, you’ll see the first level Base Reflectivity scan (BR1) (you can distinguish it from the composite scan (CR) on our display by its black background). This scan shows only the first tilt level, and is important because it allows you to see the storm cell structure down where tornadic activity might be. The composite scan obscures this bottom detail by adding information from layers further above. Composite reflectivity scans give you a better sense of the size and overall content of the storm; base reflectivity scans give a better sense of the energy in the bottom layers close to where you live.

In impending severe weather, get into the habit of switching back and forth between the scans. If tornado activity is possible, watch the base reflectivity scan (BR1) particularly – it will present more timely data, and show you the characteristic hook structure a rotating supercell (where the tornadoes usually are) takes on when it’s gearing up to drop tornadoes. The composite scan obscures this detail with rain reflections.

Presenting these images is a bit of a visual art form. The US National Weather Service uses a colour scheme designed not only to show certain features, but to also be visible to those who have colour blindness issues. This compromises, to a degree, the extent to which the display can be used to highlight certain storm features. Our software, as is the case with others, allows us to design colour displays (“palettes”) for specific purposes.

EWR has designed some high quality palettes for winter displays that are capable of giving a good indication of the nature of the precipitation, once some experience is gained in their use, and we’ve correlated the displays with actual weather observations to further fine-tune their accuracy. Winter is tricky. Snow can be difficult to interpret from radar displays because its less reflective, and its buoyancy in the air floats it around, confounding the radar’s ability to discern the cloud structure. However, we’re comfortable with what our winter and mixed precipitation displays can tell us.

The next project will concentrate on summer storm weather. EWR will show a variety of different display palettes over the coming months as I explore how best to squeeze the most useful information out of the data. This data is a constant, and key display elements will not change – red into light purple in the display will still mean severe, potentially dangerous storm conditions (the light purple is an indication of a significant hail core). EWR alerts trigger at 60dBZ (strong echo return to the radar), well in the red zone. Red in the displays triggers at 50dBZ, and in any radar display, indicates that conditions have moved beyond merely strong to possibly severe, so caution is advised.

Most of the palettes changes we will be playing with will be below the 50dBZ level. Active rain begins around the 20 dBZ level, but this is variable and dependent to a degree on local topography and conditions. I’m looking to fine-tune this region in order to provide a clearer picture of whether there is active precipitation or just heavy cloud. This is especially important when its desirable to separate out dangerous storm characteristics from just plain soggy weather.

Probably. Environment Canada will make the official determination, but the radar evidence from last night suggests a small strong F0 and perhaps a weak F1 one was quite likely. A compact but intense cell crossed into Southwestern Ontario east of Sarnia about 7PM in the evening July 23, 2011.

We watched the cell develop strong verticality over the next couple of hours with high hail densities evident high in the updraft. We noted an MDA event (“mesocyclone detection algorithm” – an automated detection of updraft rotation in a thunderstorm, converting it from an ordinary thunderstorm to a supercell) over this cell about an hour after it crossed the lake shore. The reflectivity radar trace indicated a large upper hail core.

The overall presentation of the cell didn’t suggest a classic tornadic mesocyclonic cell. However, when we looked at the storm relative velocity profile on the lowest tilt we found the couplet (yellow arrow) shown in fig. 1. The couplet didn’t show on further upward tilts, indicating some degree of rotation was occurring near or at the base of the cell. Since the distance between KDTX and the location of the couplet is about 80 miles, the SRV couplet indicated a velocity disturbance around 5000 feet. Since the beam is narrow, and above the ground, it cannot determine how low the disturbance went.

Figure 1. Storm Relative Velocity couplet, July 23, 2011, Lambton Co.

A velocity couplet in a storm relative velocity profile indicates a rapid change in the direction component of the velocity vector (velocity, by definition, is the combination of speed and its direction context). Storm relative velocity profiles measure changes within a wind profile, and therefore will show when there is a significant change in direction of wind, like occurs in a tight rotating air column).

Though the scale is not shown in fig. 1, the wind shift in the couplet can be measured. The light green portion of the couplet measures to -44 knots, to +15 knots for the immediately adjacent red bin. This translates to a wind shift (rotation) occuring at approximately 120 km/h. This measured amount puts the event at the high end of the F0 scale (64-116 km/h and the low end of the F1(117-180 km/h) range. The couplet doesn’t indicate whether or not any rotation actually reached the ground. Damage evaluation will confirm further if the duration was enough to consider a full fledged low power tornado. The SRV couplet survived on the radar scan for more than one cycle, indicating the event would possibly have been in play for several minutes.

AWCN11 CWTO 260626
Weather summary for all of Southern Ontario and the National Capital
Region issued by Environment Canada Toronto at 2:25 AM EDT Saturday
26 June 2010.

Microburst event confirmed in Amherstburg area
==weather event discussion==

The damage that occurred in a campground to the east of Amherstburg around 10:50 PM on Wednesday June 23 has been determined to have been caused by a microburst which is a very localized gust of damaging winds. The damage to the campground included a camper trailer flipped over and a large tent and small sheds being severely damaged. The damage occurred in a localized area approximately 60 metres wide by 600 metres long. Based on the type of damage that occurred the winds were estimated to be between 120 and 140 km/h which is the lower end of the Fujita one range. The Fujita scale uses damage to estimate the strength of winds in tornadoes and severe wind gusts and goes from zero (weakest) to five (strongest).

Environment Canada earlier confirmed that a Fujita scale 2 tornado (peak winds between 180 and 240 km/h) occurred in the Midland area around 6:30 PM Wednesday evening. The tornado began in the Rowntree beach area west of Midland and ended just west of Waubaushene for a total length of approximately 25 km. The maximum width of damage was around 300 metres. The most significant damage noted with this tornado was numerous mobile homes severely damaged or destroyed in a trailer park at the south end of the town of Midland. Damage outside of the Midland area was intermittent.

A second tornado spawned from the same thunderstorm that moved over the Midland area occurred at approximately 7:00 PM. This tornado began around the Maple Valley area approximately 10 km west of Washago and ended just east of Washago. This tornado was rated as a Fujita scale one tornado (peak winds between 120 and 170 km/h). The total length of the damage was approximately 12 km but was intermittent in nature. The maximum width was approximately 60 metres. The most significant damage from this tornado was to farm buildings (i.E. A barn and silo) and a garage.

With the confirmation of two tornadoes from Wednesday evening, the total count of tornadoes for this year so far in Ontario stands at four. Ontario normally gets around 11 tornadoes each season with the summer severe weather season beginning in late April and ending in early October.

Please note that this summary contains the observations at the time of broadcast and does not constitute an official and final report of the weather events or the high impact events attributed to the weather events.

EWR was unable to visualise the Midland storm as it was below the .5 degree tilt (lowest scan) of KBUF radar at that range, and KTYX radar was down.

[Please note – there are large files in the following discussion – allow time to load for the animations]

The evening of June 5 -6, 2010 was certainly an interesting evening from a weather perspective in the lower tip of Southwestern Ontario. A preliminary review of weather radar data suggests that at least two tornados passed through the area, although both may not have come to ground. What follows is an initial review of radar data that was observed via EWR and is based on a cursory analysis of radar imagery that was either observed first hand or is being reviewed as history. No analysis of atmospheric conditions has been conducted at this time.

Not all data is yet available. The NWS has not yet released its Level 3 doppler data for June 5 & 6 for stations KDTX and KCLE. I can’t therefore recreate the Level 3 data observations made in real time that evening. EWR’s Scan A data from Storm Predator is autosaved, and I have over 600 images to review from that scan interval. Some other imagery came from screencaps made in real time.

The “Leamington” weather pattern started as a flow of very unstable convective air that got into motion over southern Michigan earlier in the day, Saturday June 5th. As this active weather flowed across Michigan, the NWS issued multiple tornado warnings, thunderstorm warnings, flood warnings and special marine alerts (Scan Animation 1, below).

EWR Scan B was reporting mesocyclones (rotating core updrafts in a thunderstorm that define it as a supercell) and TVS signatures (tornado vortex signatures – indications that tornadogenesis may be occuring within the mesocyclone envelope) east of Detroit at about 11-11:15PM Saturday night (yes, I have no social life).

By 11:30PM Saturday, an ETVS signature (Elevated Tornado Vortex Signature) was recording over a strong cell just south of Lake St. Clair. and EWR issued a special weather statement concerning these developments at 11:40PM, and the zone alert system issued an alert for SW Ontario at 11:38 PM.

On radar, the cell had characteristics of a tornadogenic supercell (fig. 1, 2), which was confirmed by a 3D volume scan (figs. 3, 4) taken at 11:35 and 11:39PM June 5.

11:35Pm June 5, 2010

Figure 1: 11:35PM scan: Cell shows a strong rear inflow jet, and a tornadic rotation area at its lower left.

11:39PM June 5, 2010

Figure 2: 11:39PM scan: The vortex is visible in the lower left, and its top end high density core is beginning to form (dark red dot near bottom centre of the cell).

Figure 5: 3D scan 11:36PM approx

Figure 3: 3D volume scan of base reflectivity showing the well defined elevated tornado. Its not clear whether this tornado reached ground. The red is approximately the 50-60 dbz reflectivity data. This volume scan is selected for only a narrow range of scan returns.

Figure 4 iso scan

Figure 4: 3D isosurface scan of the same volume as in figure 3.

This cell was tracked to about 12:30AM, then EWR was left to its own devices for the balance of the night. Environment Canada issued a tornado watch for the two at-risk regions at 12:00 midnight. This cell then passed through the region, as can be seen in the animations.

At about 2AM June 6, a second mescyclonic storm crossed over from Michigan south of Detroit (fig. 5), leaving a tornado watch zone established by the NWS. Animation 2 (below) shows this later flow pattern, starting about 10PM Saturday night. Both this and the 12 midnight storm can be seen moving through the area. Animation 3 focuses on the 3AM storm blamed for the extensive damage in the Leamington area.

Figure 5 provides a snapshot of the 3AM storm cell from 2:43AM through to 3:21AM. Supercell development and mesocyclogenesis can readily be seen in the cell. Discussion of the individual frames follows the figure.


Figure 5: Composite selection of frame grabs of the 3AM storm, seen as composite reflectivity scans, from 2:43AM to 3:21AM, June 6, 2010

Notes for Figure 5:
Scan 1: The storm (central red area with its lower reflectivity envelope of orange, tan and yellow), as it crosses into SW Ontario from Michigan south of Detroit. The scan indicates that the storm is likely feeding off the moisture provided by Lake St. Clair, and the heat from the Detroit-Windsor UHI;

Scan 2: A strong inflow is developing at the east end of the cell;

Scan 3: A classic “hook and notch” supercell is beginning to develop, with its leading edge v-notch (east side), and formative hook at the west end, indicating counter-clockwise mesocyclonic rotation in the main updraft is occuring.

Scan 4: The tailhook is now well formed at the east end (lower) and a weak echo region is developing at the bottom of the hook – this is likely the intake of the tornado reported in this storm.

Scans 5 & 6: Scan 5 still may have some tornadic action , but the tornado is dissipating by scan 6. Meso updraft is still evident in the kidney bean shape of the cell and the darker returns on the northwest wall indicated updraft remains very strong, which also means the flanking downdrafts and outflow gust fronts will be strong also. The position relative to Lake St. Clair and the international boundary line limit of the marine warning (orange line), places the storm right over the Leamington area.

Elapsed time for all of this : 30 minutes. EWR didn’t issue an alert for this later storm due to it relatively low radar density for a severe storm, less than 60dbz.

Although its possible that the storm damage occured solely as a result of the 3AM storm, the severity of the 12:45PM storm may have contributed to some of the damage. Both storms occured well after darkness, and damage from the earlier storm might not have been evident until the second storm ramped up, and caught people’s attention.

[Please note – these are large files – allow time to load for the animations]

Full radar scan Saturday afternoon to Sunday monring

Animation 1: Composite Reflectivity scan - from approximately noon Saturday to daybreak Sunday morning

Animation 2

Animation 2: A slight slower composite reflectivity animation running from approx 10PM Saturday June 5, 2010 to daybreak Sunday morning June 6, 2010

Animation 3

Animation 3: A frame-by-frame animation of the 3AM June 6, 2010, storm cell from the time it crossed into SW Ontario untill it passed out of the region.


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