Lightning Safety Week


This week is National Lightning Safety Week.  Each year on average around 62 Americans will
be killed by lightning with several hundred more being struck.  Already this year eight people have been
killed by lightning with many more being hit but surviving. 


Those surviving a lightning strike tend to
have a variety of long-term, debilitating symptoms that plague them for the
rest of their lives.  Of those struck and
killed by lightning nearly 90 percent will be male with nearly one-third being
young men between the ages of 20 to 25.   The safest locations during a thunderstorm are
inside an enclosed building or in your vehicle. 
If you see or hear a thunderstorm approaching seeking shelter
immediately is prudent as storms can move quickly.  


Some reminders; stay away from trees, open
areas, like lakes and golf courses and although cordless and cell phones are
safe, try not to use a wired phone until after the storm has passed.

Wet and Dry


There are many variables that a meteorologist will take into
account when making a forecast.  One of
these variables lately has been soil moisture. 
Although the first half of June was wet across the entire area, the
northern valley had been quite dry during the spring season, plus, did not see
quite as much rain as the southern valley did earlier in the month. 


So most of last week, Grand Forks with drier
topsoil conditions saw slightly warmer daytime temperatures than we did as the
Suns energy was not being used to evaporate as much soil moisture.  At night, the opposite is true, higher soil
moisture content will usually keep temperatures higher, so with drier
conditions the northern valley was significantly cooler than the southern
valley during the mornings.  


Now that we have seen very little rainfall
over the course of the past week, soil moisture differences will not play as an
important of a role in our forecasts.

Shelf Cloud

Clouds come in all shapes and sizes.  One of the more interesting cloud formations
passed through Fargo Moorhead on Saturday evening.  Although mistakenly called a wall cloud by some,
it was actually a shelf cloud that moved across the area. 

Shelf Clouds are sometimes seen along a gust
front, which is the name given to the leading edge of the gusty surface wind
created by rain-cooled thunderstorm downdrafts. 
This heavy dense air spreads outward, which will cause the humid air
ahead of the storm to be lifted and condense into the cloud giving it the
appearance of a shelf, therefore the name.

A Shelf cloud is then the result of
thunderstorm downdrafts whereas wall clouds and tornadoes are associated with
updrafts, so a completely different cloud formation mechanism is involved in their
formation.  

However, that rush of air
from the storm often produces damaging wind, especially when the shelf cloud is
associated with a squall line which was the case Saturday evening.

Shelf Cloud

Crazy Snow Season

The official snow season at all sites in the United States
runs from July 1 to June 30 of the following year. By the time June rolls around, usually the
snow season has long since been forgotten as summer is in full swing.

Unfortunately that was not the case this week
in the northwestern part of the United
States
. On Tuesday, Pullman, Washington,
which is south of Spokane,
saw a light accumulating snow. Then the
following day, Wednesday, residents of Great
Falls
, Montana
woke
up to 6.8 inches, the second highest snowfall ever recorded in the month of
June.
The snow was so heavy that that
many trees, full of leaves, fell over due to the weight of the snow, causing
power outages throughout the city.

The
good news for residents of Great Falls
is temperatures will be in the 70s and 80s next week and summer weather will
return once again.

Up, Up and Away

With the recent downpours in the area a question came into
the weather center about how all that rain can stay in the clouds.  It is a good question, as even a small cumulus
cloud weighs hundreds of tons.  The
answer is rising air keeps clouds and its moisture in the sky. 

Most cloud droplets are extremely small, only
one micron in size (one millionth of a meter) and only weak updrafts are needed
to keep the cloud airborne.  Gradually
given the right conditions these droplets do increase in size, but as long as
the updrafts are strong enough the droplets will stay in the cloud.  At a certain point the droplets become heavy
enough to overcome the force of the rising air, and all that water falls to the
ground. 

This rising motion within
clouds, especially in severe thunderstorms, can exceed 100 mph at times.

Weather Doing its Thing

From a meteorologists perspective, the weather
has been interesting lately. As the old saying goes, "We are in
marketing, not production", but after six months of consistently cold and
generally unpleasant weather conditions, most conversations I have start with
"Can’t you do something about this"?

Our area is not unique as many parts
of the world have had colder than average temperatures recently. As a matter of fact, planetary temperatures
are about one-half degree cooler than they were last year, which is quite
substantial when averaged over the entire globe.

I could give you the
standard reasons for all of this including the recent climate shift in the
Pacific Ocean, or the fact there has been very few Sun spots in the last 18
months (which can correlate to global cooling), but perhaps the best answer is
the unscientific one; the weather is just being the weather.

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Cold Snowy Spring

June 1 marked the beginning of the summer season
and gives us an opportunity to look back at the spring months of March, April
and May.   Spring 2008 will probably be
remembered most for how snowy it was. 
Fargo Moorhead finished with 28.1 inches of snow which made this spring
the third snowiest on record. 

Many parts
of the Minnesota
lakes country had their snowiest spring ever with snowfall amounts between
thirty and fifty inches in parts of that area. 
Although no where near the top ten coldest, the spring season did finish
3.5 degrees below the long term average with an average temperature of 39.2 for
the season.  

The abundant snow in
combination with a few rain events in May added up to 5.20 inches of rain for
the season which is almost exactly matches the average spring rainfall of 5.15
inches.
 

Cold May

May 2008 turned out to be our sixth straight
month with below average temperatures in Fargo Moorhead.  The average temperature last month was 53.9
degrees which is 3.5 degrees below the 30 year average.  To our north, Grand Forks finished the month 5.8 degrees
below average, so it was a very chilly month in this region. 

About 75% of the lower 48 states finished the
month of May below average (see image below), so we were not alone in having a cool month.  May 2007 was a month that finished well above
average for most of the country, this year, well below, the weather does have a
tendency to balance out in the long run. 

Precipitation wise, the airport received 1.89 inches of rain, which is
about three-quarters of an inch below the norm. 
This week has the potential to erase the rainfall deficits that parts of
this area recorded during the spring season.


Temperature Measurement

A question came into this weather center this
past week asking how precisely temperatures are measured.  All official air temperatures are recorded by
the tenth of a degree.  So if we report a
current temperature of 70 degrees for example, the actual temperature being
recorded would be between 69.5 and 70.4 degrees.

That in turn answers the second part of the
question sent in to us, are temperatures rounded up and down, and from the
example, yes they are.  All official
temperatures and records are given in the whole degree and if two days share a
record high of say, 100 degrees, if one was 99.6 and the other as 100.2, both
would be treated as the same temperature and share the record. 

Plus, it should be noted that many different
types of thermometers with differing accuracy has been used through the years
making subtle differences in records somewhat irrelevant.
 

Currently Dry

Even with some recent rain, the Climate
Prediction Center still has almost all of North Dakota and extreme western
Minnesota in either their abnormally dry, or drought category.  They divide drought into four categories;
moderate, severe, extreme and exceptional. 

Southeastern North Dakota and valley areas in west central Minnesota are in the
abnormally dry category and the recent rains have been very beneficial.  Extreme northwestern Minnesota
and much of northeastern North Dakota
are currently in the moderate drought category. 
That area missed most of the snow and rain events that hit the Fargo
Moorhead area during the spring and this last bout of rain was not enough to
change their status. 

The eastern part of
North Dakota and western Minnesota could easily turn wet with just a good storm
or two, but western North Dakota is going to have a harder time getting out of
the their extreme drought status