• Upslope & Downslope
• Winter weather preparation
• What is a blizzard?
• Severe weather outbreak on 11/10/02
• Preliminary aftermath
• Tiffin, OH Chase Report
• Touch Down or Spin Up?
• Convergence versus Confluence
• What happens when lightning strikes water?
• What makes convection tick?... CAPE, CIN, and LI Explained
• Gustnadoes
• Summer Solstice

Greetings,

Thought I'd send out a little message to introduce to you or offer a
refresher on what the terms "upslope" and "downslope" mean.  They are
relevant in areas with significant topography nearby, such as the Colorado 
Front Range where I live (there are, of course, other examples).  Fort 
Collins, CO is located about half way between Cheyenne and Denver, and is 
still on the High Plains, so it's very flat here, but the foothills and 
Rocky Mountains are just a few miles to the west.  Also interesting is 
that the High Plains slope upward from eastern Kansas all the way here.  
So even here on the Plains, the altitude is 5,000'; meaning that the 
normal surface pressure here is around 850mb!

Upslope and downslope aren't very tricky concepts; the names are fairly
descriptive.  Upslope conditions exist when surface air flow forces a
given parcel of air uphill.  When that air parcel travels uphill, the
ambient pressure decreases, because pressure always decreases with
altitude in any fluid.  Whip out your high school chemistry or physics
textbook, and find the Ideal Gas Law.  In a hurry, you'd see that if the
ambient pressure is lower than that of the parcel's, the volume of the
parcel must increase, and then the temperature must decrease so the parcel 
can assume the same pressure as its environment.  Get it?  The parcel is 
introduced into a new lower pressure.  It wants to be at that pressure 
too, but in order to that, it must cool down.  In nerd-ese, this is called 
adiabatic expansion.

Conversely, downslope is when a parcel at a higher altitude is brought
downhill by the mean air flow.  The ambient pressure continuously
increases, so the parcel's pressure also wants to increase, but in order
to do that, the volume must decrease and the temperature will 
correspondingly increase.  This is called adiabatic compression.

How do these affect our weather?  Well, during upslope conditions, we get 
low clouds or even fog, drizzle, rain, snow, etc.  The strength of the 
surface wind impacts the intensity of the precipitation.  Why does upslope 
induce precipitation?  The air is cooled to the dewpoint temperature and 
this makes clouds form.  It's like an updraft in a thunderstorm, just not 
as violent or vertical, but rather gentle, and the air rises gradually 
with the terrain.  However, it can be responsible for very heavy rain or 
snow, and can last for several days at a time.  Basically, upslope days 
are cool, overcast, damp.

During downslope conditions, we expect warm, dry, windy weather.  To get
downslope HERE, we need westerly winds, meaning that the wind is coming
from the west, and so the air is coming over the Rockies (at 14,000'...
or 9,000' higher than the elevation here on the western High Plains). 
As the more dense air heads eastward over the mountains (it was
upsloping on the west side of the mountains), it gets an assist from
gravity, causing it to race down the terrain.  All the time it's sinking, 
it's also warming and drying.  By the time it reaches us down here, it can 
change a 20-degree serene wintry day into a sunny, parched, 60-degree day 
with up to 100mph winds.   That's an extreme example, but certainly not 
impossible.  Downslope windstorms are a common occurence here, mostly 
during the winter months, when we get 1-2 High Wind Warnings every week.  
Most are for 40-50mph winds, but on rare occassions, the winds can be much 
stronger and cause significant damage.

Feel free to ask questions or discuss this topic among the group!  Or if 
you have a new topic to introduce or ask about, please do.

Regards,
Brian

~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Brian McNoldy
President, MESO
URL:   http://www.mcwar.org/
EMAIL: mcnoldy@mcwar.org
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
"Did you ever dance in the rain or thank the sun just for shining?"

For those of you who haven't read the Nor'easter article at www.mcwar.org, 
(in the ARTICLES section) I would like to highlight some winter 
preparation tips included in that article.  Some of us are going to have 
some pretty warm temps this weekend: a perfect time to get some of this 
stuff done!

Home Preparation

Here are a few ideas of things you can do around the house to prepare for 
winter storms:
* Purchase a battery-powered NOAA weather radio.  Use it.
* If you have a woodstove or a fireplace, stack one week's supply of 
  firewood near a door, and cover with a plastic tarp.
* Have your fireplace flue cleaned and checked. 
* Have your woodstove pipe connectors checked for leaks.
* Have your furnace cleaned and checked.
* Fill a garbage can with a sand/salt mixture and keep it in a spot close 
  to where you are most likely going to need it.
* Check windows and doors for drafts and leaks.  Update weather stripping.
* Make sure all gutters are clean and clear.  Clogged gutters mean icicles. 
* Have a good supply of nourishing food that doesn't need to be thawed, 
  heated, or cooked.  
* Mark any obstructions near your driveway.  Snowplows and emergency 
  services vehicles have been known to get stuck on stone walls, rock 
  gardens, boulders, etc.
* Check, test, and refresh batteries in all smoke and fire detectors.
* Have a flashlight and extra batteries for each person in the household, 
  stored in an easily accessed site.  
* After reading this article, go directly to your nearest hardware store 
  and purchase carbon monoxide detectors.  Install them immediately.  Yes, 
  they are THAT important.

Car Preparation

* Have your car completely winterized.  Top off all fluids, and keep a 
  reserve bottle of wiper fluid in the truck.
* Do any repairs you've been putting off.
* Check your tires, and make sure they're all well treaded and have proper 
  pressure... including the spare
* Put blankets, a change of clothes, a shovel, a scraper, a bag of sand or 
  salt, matches, a flashlight, and non-perishible munchies in your car.  
  Don't forget a first aid kit.
* That chip in your windshield will spread in the cold weather.  Fix it 
  before it does.
* Take a defensive driving course.  In addition to possibly saving your 
  life, your insurance rates will be lowered.
* Keep the gas tank full.

Nancy K. Bose, 
Vice President, M.E.S.O, Inc.
www.mcwar.org
"Chasing down the demons"

MESO-ites,

With the winter months looming ever closer, it seemed appropriate to
clear up some terminology.  Lots of people are very liberal with the
term "blizzard", applying it to any time there's heavy snow.  Well, to
have a blizzard, it doesn't even have to be SNOWING!

There is a big difference between a Winter Storm Warning and a Blizzard
Warning.  For a winter storm, expect severe winter weather conditions,
including heavy snow or ice accumulations.  Winter Storms can be
life-threatening (70% of deaths in vehicles, 25% at home, and 5%
stranded outdoors), and hold five of the top ten costliest natural
disaster records in the U.S.

For a blizzard, there are only two requirements: 35mph+ winds for at
least 3 consecutive hours, and a 1/4 mile visibility or less due to
blowing snow.  Notice there's no mention of snowfall rate or total
accumulation in there!  The reduced visibility is caused by snow, but
could be either snow blowing around as it's falling, snow blowing around
that has already fallen, or a combination of the two.  Often associated
with a blizzard are dangerously cold wind chills, white-out conditions
(visibility is basically zero), and deep snow drifts.

So this winter, you'll be able to use the terms "winter storm" and
"blizzard" the way they were meant to be used!  Also, you can find a
load of winter weather safety tips (for cars, home, or outdoors) in our
new article "Nor'easters: Comprehension. Preparation. Survival."
available from the Articles section at www.mcwar.org.

Regards,
Brian

~~~~~~~~~~~~~~~~~~~~~~~~~~~
Brian McNoldy
President, MESO
URL:   http://www.mcwar.org/
EMAIL: mcnoldy@mcwar.org
~~~~~~~~~~~~~~~~~~~~~~~~~~~
"Did you ever dance in the rain or thank the sun just for shining?"

	This morning (11/10/02), when I saw the SPC convective outlook for 
Kentucky and Ohio, I sent a heads up out to all members who might be 
affected.  Little did I know how the day would unfold.  
	The first call was from John Griswold, just as the storms were 
popping in Indiana.  Grizz and Jason had ECHO out for what would be her 
maiden voyage.  I offered to stand by and offer remote data assistance 
for them, and that began a long evening.  
	Just as the storms were starting to enter NW Ohio, I was joined 
online by Chris Howell, MESO Science Officer, and Brian McNoldy, MESO 
President.  As we discussed the developing storms, all the time relaying 
info to the ECHO staff, Allan Detrich, our media director appeared 
online.  The line of storms was at that time within striking distance of 
Al, and after some discussion, we got him on the right track to intercept 
a storm in Tiffin, OH.  
	With three remote data assistants; one in Colorado, one in 
Michigan, and one in New York, we watched every move those storms made for 
hours.  Data was shared with our members in the field in a timely and 
controlled manner.  We were all at our best, those in the field traveling 
into the storms to be able to document and record, and those at their 
monitors, helping in whatever way possible.  Teamwork.  
	ECHO with Grizz and Jason ended up right underneath the storms in 
Northern Kentucky, and tracking and data updates were sent from her to the 
rest of us.  ECHO proved herself admirably, doing just what she was 
designed to do...even providing a haven for other chasers and spotters out 
on the road.  Great job, guys.  A landmark for all of us, and we were all 
there with you...in spirit. 
	Meanwhile, Allan drove towards his appointment with destiny in 
the small town of Tiffin, Ohio.  Al has developed as quite a storm 
tracker, and his ability to track and chase has grown at an incredible 
rate.  Allan hit the storm in Tiffin ON THE MONEY.  He got a "Hail Mary" 
shot from his car window, that I have attached.  It's a truly incredible 
shot, and one only the great Detrich could have managed.  Split second 
timing, aided by razor sharp professional instincts:  Allan caught a 
tube, in OHIO, in NOVEMBER, at NIGHT... and on his birthday.  
	While Allan, Grizz and Jason were out in the soup, Chris, Nancy 
and Brian continued to monitor developing situations, and expanded their 
updates and collected data to others across the country.  Chasers and 
spotters sent IMs and E mails throughout the evening to MESO's online 
staff.  
	Allan's spotting and documentation of the Tiffin Tornado is the 
only hard fast evidence that there WAS a Tiffin Tornado.  A report of the 
event has been sent to SPC.  Though we are cautious of tossing around 
terms like "outbreak", if only half of the tornadoes reported are 
accurate, we would really be justified in using that term.
	I'm so proud of the work we all did tonight, and as always, so 
very proud of MESO and the wonderful people involved in it.


Nancy K. Bose, 
Vice President, M.E.S.O, Inc.
www.mcwar.org
"Chasing down the demons"

Related to yesterday's Weather Tidbit is an astounding figure, which has
sadly been growing.  As of 7am MST on 11/11, the storms of 11/10 are
responsible for 34 deaths and 100+ injuries, some critical.  Those
numbers have been growing steadily as missing persons are found dead or
injured under debris.  I invite you to see the path of destruction for
yourself at http://www.spc.noaa.gov/climo/reports/021110_rpts.html to
get a sense of the extent of this November Outbreak.  The tornado Allan
spotted is now in the list, and the same tornado might have been
responsible for a death near Republic in Seneca County (he saw it near
Tiffin in that county).

Anyway, there are scores of people to add to your prayers on this
Veteran's Day.

Brian

~~~~~~~~~~~~~~~~~~~~~~~~~~~
Brian McNoldy
President, MESO
URL:   http://www.mcwar.org/
EMAIL: mcnoldy@mcwar.org
~~~~~~~~~~~~~~~~~~~~~~~~~~~
"Did you ever dance in the rain or thank the sun just for shining?"

November 10th started out slow, I had the day off and had seen the high 
risk warnings the day before, so I was fully prepared to hit the road if 
needed. Most of the preliminary reports said it would be worse to the 
south, but one never knows. I got plenty of things done early in the day, 
to make sure I was free for later.

I got a call from Lisa Dutton about 3:00 p.m. and she told me that Van 
Wert, Ohio had been hit by a large tornado and I had just checked radar 
and saw some interesting cells out in front of the main squall line. One 
particular cell was growing by leaps and bounds and was heading just south 
of Findlay, in a NE direction towards Seneca county and Tiffin, just 15 
miles from where I live.

I talked with the editors at The Blade and they decided to put me on 
overtime and get my "Storm chasing Butt" into the field to see what I 
could come up with. I quickly consulted with Nancy, Bose, Chris Howell and 
Brian McNoldy before heading out, got all necessary cell phone numbers, 
printed out one last radar image, grabbed a rain jacket, cameras and hit 
the road.

I headed South on SR 53, a direct route towards Tiffin, and was met by 
some amazing cloud to cloud lightning and wind gusts to about 50mph, as I 
approached Tiffin, I skirted the North part of town along Second St. and 
stopped quickly to photograph a group of bar patrons looking up at the 
ominous sky. As I as shooting that, I got knocked on the head, by what I 
thought was a walnut, but I discovered was inch to inch and a half hail. 
The air was still and hail was falling. 

I looked to the sought and saw several funnel clouds swirling around each 
other. In the distance, two funnels pulled down from the cloud base and 
formed one. I slammed on the brakes and leaned out of my truck window and 
got about 10 frames off of the tornado before the whole town went BLACK. 
The tornado turned black instantly the second it touched the ground.  I 
tried to get in behind the tornado and was blown from one lane of the road 
to the other in a second. I gave up my pursuit at that time, because I did
not know if there were other tornadoes in the area, and it was too dark.

I headed in the direction of the first hit of the tornado and as I topped 
a hill, a tree blew down over the road, I slammed on the brakes and 
skidded into the outer branches, no harm done, just a good scare. I back 
tracked and found the initial touchdown, it hit a subdivision and 
completely demolished several homes, one of the houses second story and 
roof were over 100 feet from the foundation. I was there before the rescue 
personnel and photographed people digging through the foundation for
survivors. Fortunately, the only fatality was a dog.

Later that night I was sent to Fostoria and Port Clinton and ended the 
night around 10:00 p.m. and the rest is history. 

My tornado photo ran in the next days' paper and then ran in newspapers 
and magazines all over the world. Reportedly in Egypt, Hong Kong, London, 
Australia, the front page of the New York Times, The Boston Globe, six 
columns in USA Today, a full page in Time Magazine, and will be published 
later in December in Life Magazine's Pictures of the year edition. 

This proves that even if the photo is not the best ever shot - if it is 
the only shot from the news event, it is certainly the best!

Allan Detrich

                                  ______________________________
                               Staff Photojournalist - The Toledo Blade
                                     www.allandetrich.com
                                     Storm Chasing Gallery
                                      RoadKill Kronicles®
                                        the machine®
                                      DetrichPix@aol.com
                                      419.332.8830 - Home
                                      419.345.0049 - Cell

In a paper I was studying by Dr. Charles Doswell, I discovered that I had 
retained some very critical misconceptions about tornadogenesis and basic 
identification.

A common phrase in spotter/chaser terminology is that a tornado is "on the 
ground" when the funnel cloud touches land.   Dr. Doswell explains that 
this is definitely not the case.

Dr. Doswell explains that the observed descent of the funnel cloud is not 
really a descent at all.   "As the vortex intensifies, its central 
pressure falls. When the pressure is reduced to that which permits 
condensation of water vapor into cloud material, the funnel-shaped cloud 
appears. It often appears to descend for perhaps two distinct reasons: 1) 
Near cloud base, the pressure doesn't have to fall as far for the air in 
the vortex to reach condensation as it does further down, or 2) The 
circulation intensity is actually increasing downward. We do not know the 
actual distribution of pressure in tornadoes, of course, and the tornadic 
pressure field may have many complexities. However, it is unlikely that 
clouds from above are descending to create the funnel-shaped cloud...
generally, descent dissipates clouds."

Dr. Doswell further states that tornadoes do not drop down, but they spin 
up!  "The intense part of the vortex can build downward, but this is not 
the same as a tornado descending. What is actually happening is that the 
vortex at the surface increases its intensity (and decreasing its scale at 
the same time) to tornadic proportions, eventually producing winds 
capable of tornadic damage... but the vortex itself is almost certainly 
already in contact with the ground. 

Strictly speaking, "the vortex" should not be equated to "the tornado," 
since the vortex can be present but with non-damaging wind speeds. Prior 
to the commencement of damaging winds at the ground, the surface vortex is 
weak and spread out... as it intensifies, the winds increase and the 
size of the circulation contracts.  The vortex also can intensify upward 
(as we think happens in the tornadoes that are called "landspouts" - see 
below). Rather than "touchdown" I would prefer to consider the observed 
process of the  commencement of tornadic winds at the surface to be one of
"spin-up"... I hasten to add that "up" in this context does not imply 
ascent, but rather an increase of spin intensity."

So technically, there are no touch downs, and tornadic activity is 
determined by the vortex intensity at the surface, and not the funnel 
cloud "spinning up" above.  


Nancy K. Bose, 
Vice President, M.E.S.O, Inc.
www.mcwar.org
"Chasing down the demons"

As you read forecasts or weather discussions, you'll commonly come
across the terms convergence and confluence (or divergence and
difluence).  As a forecaster or an interested weather weenie, you should
know the difference between these terms, as they are not synonymous!

First of all, these terms apply to all fluids, but we'll use air (our
atmosphere) as an example.  At all times, our atmosphere is
characterized by complex wind fields... air moving in different
directions, at different speeds, and at different levels.  These wind
fields are also noticeable on all scales, from tiny eddies just a
fraction of an inch in diameter to planetary waves that are 10,000 miles
long.  The easiest scales to visualize the terms in questions will be on
the order of thunderstorms on up through troughs and ridges (i.e.,
mesoscale).

So, on to the definitions.  Convergence occurs when differences in wind
speed force the air to "pile up" at a point or line.  Of course, air
doesn't really pile up, instead, it moves up or down.  If convergence
occurs at the surface, the air will not compact itself, nor can it
penetrate into the ground, so it moves upward (upward vertical motion
forced by surface convergence).  Similarly, if convergence occurs in the
upper levels of the troposphere, the air can't successfully enter the
highly-stable stratosphere above, nor will it compact itself, so it
moves downward (downward vertical motion forced by convergence aloft).

Divergence is the opposite of convergence... air exits a point or line. 
Surface divergence leads to convergence aloft, and vice versa (see
figure: http://opwx.db.erau.edu/~mullerb/Vert_motion.gif).  Whether
there is surface convergence or divergence aloft, upward vertical motion
is induced, which leads to generally fouler weather (clouds, rain, snow,
thunderstorms, etc).  And you guessed it... surface divergence or
convergence aloft leads to generally fairer weather.

Now on to confluence and difluence.  In this case, differences in wind
direction force air to accelerate or decelerate.  In a purely confluent
zone, air comes together, but its speed increases, thus avoiding
convergence.  And in a purely difluent zone, air spreads out, but its
speed decreases, thus avoiding divergence.  These are just as important
in forecasting weather.  It's possible to have directional convergence
and not speed convergence, or to lack directional convergence and have
speed divergence.  The sum of the two terms (speed and direction)
dictates the final outcome.

A great figure demonstrating the difference between all four terms can
be found at http://opwx.db.erau.edu/~mullerb/div_con.gif.  

Happy observing,
Brian

~~~~~~~~~~~~~~~~~~~~~~~~~~~
Brian McNoldy
President, MESO
URL:   http://www.mcwar.org/
EMAIL: mcnoldy@mcwar.org
~~~~~~~~~~~~~~~~~~~~~~~~~~~
"Did you ever dance in the rain or thank the sun just for shining?"

Someone recently asked me what happens when lightning hits water?  Sort of 
a CW lightning event, I guess.  My first response was "That's EASY...." 
but I halted quickly when I realized that thinking it through, I hadn't a clue.

I grew up near the water.  I knew that as a scuba diver, a lifeguard, a 
surfer and an avid fisherman, when lightning threatened, I got out of or 
away from the water.  I never really stopped to think of what really happened. 

A definitive answer came from Brian McNoldy, MESO president.  

Brian's answer:  

	"Since salt water is a good conductor of electricity, when 
lightning hits it, the current spreads out and dissipates along the 
surface, and it does so in a fairly short distance.  Even the strongest 
bolt would have a hard time penetrating to a respectable depth below the 
surface.
        Anything close to the strike and on the surface will feel the 
effects, including fish or jellyfish, etc.  If you're far enough away from 
the contact point, it's fine (not something to play "chicken" with though).
        HOWEVER, fresh water is a poor conductor, so fresh water lakes and 
swimming pools do not follow the same rules I just mentioned.  In that 
case, when lightning hits them, it meets an insulator, and is still "in 
search of" a conductor, like any pipes, drains, people, whatever, that 
might be in the water.  So during a thunderstorm, you're much safer to be 
in the ocean than in a swimming pool, assuming you HAVE to be in the 
water.  Best bet, get out at first warning."

Other sources included references to the magnitude of the lightning, the 
salinity of the water, as well as the volume of the water in their 
explanations (citing a comparison of dropping a radio into your bath tub 
in relation to dropping a radio into a lake)... but no one hit it on the 
head like our Bri!

Nancy K. Bose, 
Vice President, M.E.S.O, Inc.
www.mcwar.org
"Chasing down the demons"

What makes convection tick?... CAPE, CIN, and LI explained.


***
CAPE (Convective Available Potential Energy) is the amount of buoyant
energy available to an air parcel.  CAPE plays a direct role in how
rapidly an air parcel will rise... the higher the CAPE, the faster the
updraft.  It is also sensitive to surface moisture, or dewpoint.  Only
modest increases in dewpoint can significantly increase CAPE, and
therefore updraft speed.

 - Large values of CAPE (3000-7000+ J/kg) can result in very vigorous
widespread thunderstorms.
 - Moderate values of CAPE (1500-3000 J/kg) can result in smaller areas
of more concentrated convection.
 - Small values of CAPE (0-1500 J/kg) can result in shallow or no
convection.  


***
CIN (Convective INhibition) is the amount of energy required for the air
parcel to reach the "Level of Free Convection". This is a measure of the
"cap", or how much buoyancy is required to reach the LFC.  For an
appropriate amount of CAPE: 

 - Large values of CIN can inhibit any convection from occurring.  
 - Small to moderate values of CIN can inhibit weak convection but will
allow isolated strong pockets of convection to occur, sometimes
resulting in isolated thunderstorms.  
 - Very small values of CIN can allow convection to occur almost
anywhere, resulting in widespread thunderstorms.


***
LI (Lifted Index) is a measure of the stability of the lower
atmosphere.  Positive values indicate the atmosphere is stable, making
convection nearly impossible.  Negative values indicate the atmosphere
is unstable, and the more negative the LI, the more unstable the
atmosphere.  It measures a relationship between temperature and dewpoint
at the surface and at 500mb (18,000').

Typically, some kind of trigger is needed.  For near-zero LIs in the -1
to -3 range approximately, a strong trigger must exist to initiate
convection (jet streak aloft, extreme surface heating, etc).  For
moderately negative LIs (-4 to -7, approx), the trigger need not be as
strong.  And similarly, for very negative LIs (-8 to -15 or less) very
little external forcing is needed, the atmosphere is like a mousetrap...
a slight nudge and it will react violently.


All three parameters (among many others) must act in concert to produce
a thunderstorm.  Very high CAPE, low CIN, but a positive LI can leave
you under blue skies because the atmosphere is too stable to initiate
convection.  High CAPE, high CIN, and a negative LI can leave you with
shallow cumuli that do little more than look pretty because the updrafts
cannot reach the LFC.  No CAPE, any amount of CIN, and a negative LI can
also leave you with blue skies because there's no buoyancy in the
low-level air.  Of course, the atmosphere is far more complex than the
picture I've painted here, but this will give you a general
understanding of some idealized situations.

It is absolutely critical in severe weather forecasting to understand
the relationship between these parameters.  A large amount of CAPE does
not make convection any more likely than zero CAPE.  However, if
convection IS initiated (negative LI, small enough CIN), the amount of
CAPE determines the character of the convection. 

A great reference is Howard Bluestein's "Synoptic-Dynamic Meteorology in
Midlatitudes: Volume II" which you can purchase through a search at
http://www.mcwar.org/store/store.html

Brian

~~~~~~~~~~~~~~~~~~~~~~~~~~~
Brian McNoldy
President, MESO
URL:   http://www.mcwar.org/
EMAIL: mcnoldy@mcwar.org
~~~~~~~~~~~~~~~~~~~~~~~~~~~
"Did you ever dance in the rain or thank the sun just for shining?"

The National Weather Service defines a gustnado as a "short-lived, 
ground-based, shallow, vortex that develops on a gust front associated 
with either thunderstorms or showers. They may only extend to 30 to 300 
feet above the ground with no apparent connection to the convective cloud 
above."

Basically, a gustnado is the result of downdraft winds along a gust 
front, getting it's "spin" from surface wind shear. It can take on the 
appearance of a tornado, but it is not contingent on the storm scale 
rotation associated with true tornadoes.  They are usually associated with 
a shelf cloud, found on the leading edge of a storm.  Many times they 
more closely resemble a debris cloud.  Winds associated with a gustnado 
can reach speeds of 70 - 80 mph, and thus can also create the same damage 
as an F0 or weak F1 tornado... but are much shorter lived.

As a spotter and a chaser, you can save yourself a lot of embarrassment 
by learning to differentiate between a gustnado and a tornado.  


Nancy K. Bose, 
Vice President, M.E.S.O, Inc.
www.mcwar.org
"Chasing down the demons"

It seemed timely to send out something on the Summer Solstice, being
that it's just a couple days away now (June 21).  First of all, what is
it??  For those of us in the Northern Hemisphere, it's the first day of
summer.  More specifically, it's the longest day of the year, defined by
the largest number of hours between sunrise and sunset.  The further
north you are, the more hours of daylight you have... in fact, the sun
won't set at all on the North Pole during the summer solstice.  By the
way, this also means that the sun won't rise at all on the South Pole on
June 21.

The reason we have seasons in the first place is the Earth is tilted on
its axis relative to its orbit around the sun.  (Imagine the plane that
Earth revolves around... Earth's axis is tilted 23.5 degrees relative to
that plane.)  So, on the summer solstice at local noon, the sun will be
directly overhead any place that's at 23.5N (the imaginary circle
enscribed around the Earth at this latitude is called the Tropic of
Cancer).  

I attached a PNG file that I made which shows the number of daylight
hours throughout the year, for a few selected latitudes.  At 40N on the
summer solstice (the 172nd day of the year), there are nearly 15 hours
of daylight.  Compare this to the winter solstice at 40N when you see
just over 9 hours of light in a day.  When you open the file I attached,
the left axis shows the number of daylight hours, the bottom axis is the
Julian Day, or day of the year, then the colored curves correspond to
the equator (red), 20N (orange), 40N (green), 60N (blue), and 80N
(purple).  I'd be happy to answer any questions you have about the plot.

Happy summer,
Brian

~~~~~~~~~~~~~~~~~~~~~~~~~~~
Brian McNoldy
President, MESO
URL:   http://www.mcwar.org/
EMAIL: mcnoldy@mcwar.org
~~~~~~~~~~~~~~~~~~~~~~~~~~~
"Did you ever dance in the rain or thank the sun just for shining?"