Severe Weather Events - When Weather Becomes More Than Just a Talking Point
Here's how you can use your home weather station to understand and predict extreme and severe weather.
I guess we all know what severe weather is. Fortunately there is no formal definition, so we can take it to mean, and include, just about anything that stops us in our tracks and makes us think "Now should I be going out in this?"
But I suppose I should be a little more specific.
Firstly, this is a big topic - too big for one page. So I'mrestricting this page to severe weather events that mostly occur in the warmer months of the year. Check out
for the storms, freezes and floods
that are more typical of the cooler months. There is of
course considerable overlap, but that's weather.
So let's include in severe weather anything out of the
ordinary, expected range of daily events from Spring
through to Fall that could, if we didn't prepare adequately,
be hazardous to our lives and property. Our definition is still
wider than National Weather Service's definition of severe
thunderstorms - storms which produce any one of
Damaging winds, or winds measuring 58mph (93kph)
Hail 3/4 inch (1.9cm) in diameter or larger
If you have a good home weather station, among the most
interesting projects are observing the often rapid changes in
wind speed and direction, air pressure, humidity and
temperature in advance and during an extreme or severe
weather event. The rate and total of precipitation can also
come up with some surprises.
Even more worthwhile is being able to predict severe weather
in advance of the weather office. That's not all that easy
these days, with the improvements in equipment, facilities
and modelling available to meteorologists, but it's fun trying.
And it's not cheating to step beyond your own home weather
resources and consult the fascinating information derived from
weather radar and satellite images.
Remember also that the average person today has access to more
information than was available to professional meteorologists
only a decade ago. You, of course, being above average and
possessing your own weather station, are even better off.
But you can do far more than just record the changing weather.
Numbers on a screen tell their own story, but that story becomes
far more interesting and dramatic if accompanied by descriptions
of what is happening outside.
And I'm not talking about just words. Just imagine how much
more interesting the record of a passing severe weather event,
such as a storm would be if it included descriptions of cloud
types, the effect of wind, rain and hail, and a summary of
any damage to your area.
Take it a step further and include photos, video, on the spot
audio recordings, and screen prints of critical radar or
satellite images and you have a fully documented multi media
Now this may get you a reputation as a weather geek, but I
guarantee that you'll get a much greater adrenalin rush
than you are ever likely to experience on a golf course.
Perhaps just a little word of caution here. It's very easy
to get carried away with weather watching, particularly
when major weather events are developing with great rapidity.
Unfortunately severe weather comes with its own risks to
life and property, and a contingency plan for protection
of your family, your property and yourself is a great idea.
Before you get too involved in watching a particular severe
weather event develop, spend a few moments taking care
of everything valuable to you. And keep in mind that the
time may come for you to head for cover, so put your weather
station receiver onto battery power, and wait out the
storm safely, knowing that there will always be another
OK, enough of this preambling.
Severe weather can be divided into several categories, related
to the driving force behind the events. So in order of
decreasing destructive potential, here we go. Most of the links
in the following section will take you to more detailed
articles on the weather types.
Now anyone who's searched the net looking for severe weather related
topics will know that the amount of material is huge,
particularly when hugely destructive phenomena like tornadoes
and hurricanes are included. I can't hope to cover all the
information available, but I can suggest the better sites
where you can find out what you want to know.
In general, the first places to look are the official weather
sites, which do an excellent job in providing educational
and background information. In the USA visit
and its weather sites such as the
National Weather Service
Storm Prediction Center.
My aim in these pages is suggest ways in which
you can make the most of the capabilities your weather station
gives you when severe weather events come your way. Although
I am sure you already have a good weather knowledge, by
focussing on understanding the progress of extreme weather
through an area I hope to be able to add a little more to your
experience than just facts, figures and news reports.
Major Weather Systems
Included here are large weather systems that can last for days
as they develop, approach and pass over an particular place.
They are typified by a central zone of intense low pressure,
usually form over oceans or large seas, and make themselves felt
in strong destructive winds, often flooding rain, and abnormally
high tides in coastal areas.
When they form in tropical areas they are known as
Hurricanes, Typhoons or Cyclones,
depending on which part of the world
you are in. Most of them remain at sea until they degenerate,
acting as a hazard to shipping, aircraft, and the odd island.
But when they come ashore their full power is apparent to all.
They are so significant that they each have their own name.
Almost as destructive, but with less of a publicity team behind
them, are the intense lows that form in more temperate areas
("The Perfect Storm"). Because they form in cooler seas, the
energy going into them is less, and they are overall less
destructive than hurricanes and their relatives. But it's only
a matter of degree, and their effects on coastal areas can be
just as dramatic.
Many of these occur during or on either side of winter, and
information on them is included in the
Tornadoes and Thunderstorms
Truly severe weather, thunderstorm related events are smaller than the large
intense lows discussed above, form much more quickly, are far
more common, and frequently more destructive.
The large and spectacular
usually form on the
boundaries of large airmasses when warm humid air rises over
an approaching mass of colder or drier air. When large storms rotate,
they are called supercells and it is these that are most
likely to produce the most severe weather conditions, including;
Tornadoes, although they
occur world wide, are just as typical of America as
apple pie. Their formation is controlled by an
unusual combination of climatic conditions which
often develop in mid continent North America,
particularly in Spring.
Downbursts and Microbursts.
thunderstorm phenomena, are outward,
often invisible bursts of cool air and can result
in tornado like destruction. Microbursts are less
than 2.5 miles (4km) in diameter, and have been
responsible for several aircraft landing disasters.
Another almost exclusively North
American thunderstorm feature, a
Derecho is a straight line wind with severe
gusts associated with rapidly moving lines of
thunderstorms and extending over a large area.
Although not as spectacular as tornadoes, derechos
give little warning and can be just as deadly.
Similar in appearance to tornadoes,
waterspouts are often less destructive. They
form over water, and their appearance may be due to
water vapour forming around the central very low
pressure zone rather than to water being lifted from
the surface. Best not to take too many chances though.
Hail is frequently associated with larger
thunderstorms, particularly supercells,
and becomes very dangerous and destructive when
hailstones reach golf ball size and larger.
deliver a lot of rain to a small area in a very
short time. Local flash flooding is often the
result. Slow moving supercells may result
in more regional flooding. Longer lasting river
are the subject of another article.
Unlike the examples of severe thunderstorm weather listed above, which may or may not occur in any particular thunderstorm, lightning is always present - no lightning, no thunder, no thunderstorm
Also associated with the summer storm and hurricane seasons are
long term heat related events, including droughts, heat waves
and fire weather. More information on these can be found in the
Hot Weather Pages.
Other occasional severe weather examples are strong winds, dust
storms and volcanic ash clouds. Neither of the latter two are strongly related to weather conditions, but the effect and area of
incidence of both can be monitored and predicted by forecasters.
Dust storms are usually associated with bare soil caused by
drought, and can be reduced in frequency and intensity by
careful land management.
Volcanic ash clouds are rare, but of more than passing
importance to those downwind of the volcano, as residents in
the vicinity of Mount St Helens will clearly remember. Ash
clouds are also critical to long distance aviation - high
concentrations of very fine suspended dust will stop jet engines,
at least until the plane loses enough altitude to regain
Not much of a problem to you and me, perhaps, but I'm sure
it would concentrate the mind of an unfortunate passenger.
In conclusion, severe weather events can be costly in lives,
property, and disruption to normal activity. And while
forecasting of both extreme and normal events has improved
markedly over the last 20 years, rapidly developing weather
can still keep forecasters on their toes.
And observation of severe weather provides periods of high
interest to those with their own weather stations, particularly
when the recorded data can be tied into visual observations as
the event builds, peaks, and passes.
Just a brief word about the photos you will see in
the articles connected to the links scattered throughout
this page. I have selected illustrations from NOAA's
to show both the type of weather and something of the
history of research and observation contained in these
collections. As much as possible they include historic
material, such as the first image of a hurricane acquired
from a satellite. I hope you like them, and there are
plenty more at the NOAA Photo Library site.
If you have records of a severe weather event from your area,
particularly if backed up by your own observations, I would
love to hear from you. Just use the
And as an aside, for some tips about preventing or minimizing severe weather damage to your home, visit this Home Protection page.
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But just before you move on...
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