A bold of lightning I captured on camera near Tazewell, VA

According to the National Weather Service, lightning kills on average 49 people in the United States each year, and hundreds more are injured. As we enter the summer months, we are starting to see more thunderstorm activity. Many days these storms pop up in the humid airmass that often resides across our area without much warning. Here are a few things you can do to stay safe this summer when lightning becomes a threat.

Lightning Strike Video

Lightning tips via the National Weather Service

Lightning: What You Need to Know

• NO PLACE outside is safe when thunderstorms are in the area!!
• If you hear thunder, lightning is close enough to strike you.
• When you hear thunder, immediately move to safe shelter: a substantial building with electricity or plumbing or an enclosed, metal-topped vehicle with windows up.
• Stay in safe shelter at least 30 minutes after you hear the last sound of thunder.

Indoor Lightning Safety

• Stay off corded phones, computers and other electrical equipment that put you in direct contact with electricity.
• Avoid plumbing, including sinks, baths and faucets.
• Stay away from windows and doors, and stay off porches.
• Do not lie on concrete floors, and do not lean against concrete walls.

Last Resort Outdoor Risk Reduction Tips

If you are caught outside with no safe shelter anywhere nearby the following actions may reduce your risk:

• Immediately get off elevated areas such as hills, mountain ridges or peaks
• Never lie flat on the ground
• Never shelter under an isolated tree
• Never use a cliff or rocky overhang for shelter
• Immediately get out and away from ponds, lakes and other bodies of water
• Stay away from objects that conduct electricity (barbed wire fences, power lines, windmills, etc.)

Here in the two Virginias, we feel the effects of tropical systems that make landfall somewhere in the United States almost every year. When I say effects, I am referring to residual moisture that moves across our area after a landfalling tropical system gets swept along in the westerlies or sometimes the effect is more direct. Some systems stay organized enough to impact our weather in a major way.

The center the remains of Bill passed to our north, dry air also moved in from the southwest, limiting rainfall.

This past weekend, the remenants of Tropical Storm Bill passed to our north after maintaining strength and structure thanks to very supportive upper level wind conditions and very moist soil across the centeral United States (some studies show that Bill may have actually continued to pick up energy from the warm and moist soil, much like a tropical system pulls energy from a warm ocean surface).

Hurricane Hugo

Because we are located several hundred miles from the ocean, even major hurricanes weaken signifigantly before reaching us. However we are not completely out of the danger zone. In 1989, hurricane Hugo struck Charleston, SC and moved directly northwest toward Bluefield. I clearly remember this storm and it’s intensity; trees were destroyed, buildings were damaged and flooding took place. In fact, Hugo was still classified as a tropical storm as the tropical system moved across our area.

Flooding from Camile

While wind damage is a threat, flash flooding as a result of torrential tropical rains that get squeezed out of the atmosphere as air is lifted over our beautiful mountains is much more of a natural hazard. In 1969, hurricane Camile made landfall along the gulf coast of Texas and caused major flooding in the Blue Ridge Mountains of Virginia. 153 people lost their lives in Virginia due to some areas receiving 30 inches of rain. That over 2.5 feet!!!

This is from the National Weather Service flood safety website:

“While Hurricane Camille will long be remembered for the catastrophic damage it produced along the Gulf coast, the inland flooding will long be remembered in Virginia. Two days after making landfall, Camille had been downgraded to a tropical depression and turned east from the Ohio Valley into the Central Appalachians. During the evening of the 19th, Tropical Depression Camille began to interact with a very humid late summer air mass over central and western Virginia along with a stalled east to west oriented frontal boundary. This combination of factors, along with the higher terrain in the Blue Ridge Mountains, produced continuous thunderstorms from late in evening on the 19th through the morning hours on the 20th. The heaviest rain fell across Rockbridge, Amherst and Nelson counties, where rainfall totals of 10 to 30 inches were reported.”

• http://www.floodsafety.noaa.gov/states/va-flood.shtml

The dog days of summer are here, but what exactly are they? I once thought that dog days were given the descriptive name because it was too hot, even for dogs to leave cool areas.

Hubble Space Telescope image of Sirius, the “Dog Star.” photo: NASA

The dog days of summer were actually recognized by ancient Greek civilizations. In late July, the star Sirius and the constellation Canis Major begins to rise in the morning sky. The Greeks actually thought that it was the “dog star” Sirius that caused the hot weather that also impacts the Mediterranean Sea area.

The Greeks and other cultures recognized the dog days of summer as being from around July 23^rd until August 23^rd. This is typically the hottest time of the year for many locations in the northern hemisphere.

The suns most intense rays actually strike the northern hemisphere during the summer solstice in late June. By August, the suns rays have lowered in intensity. Late July and early August is still the hottest time of year because there is generally a lag of 1-2 month lag in the seasons. That’s because it takes time for the atmosphere to warm in the summer and cool off in the winter.

You may have also noticed that the daylight hours are getting shorter, and that the sun is lower in the sky at high noon. We’ve already started the move toward fall celestially. Our temperatures are soon to start cooling off as less solar radiation is absorbed here in the northern hemisphere.

Get out and enjoy what is left of the Dog Days of Summer!

Higher elevations change colors first. Notice the green trees in the valley below.

Fall is about to officially begin, and it won’t be long until the leaves start changing colors. The weather plays a big part in how vivid fall colors are and how long they last. For example, a summer drought may cause a tree to lose it’s leaves early. Likewise an early frost or freeze can damage leaves and cause them to fall off. Strong winds can also blow leaves off of trees faster, reducing the duration of fall color.

But what causes the leaves to change color? According to NOAA, there are actually four primary pigments that produce color within a leaf. During the growing season, leaves produce chlorophyll which is green. As the days get shorter, trees begin to shut down for the winter. They also stop producing chlorophyll. As the green fades away, a leaves true colors begin to show.

Fall colors

We have had a fairly dry late summer, and that may have some impact on fall foliage. However we are also experiencing prime conditions that help cultivate vibrant colors. According to the United States Arboretum, a dry fall along with sunny days and clear and cool frostless nights result in the brightest colors.

Fall colors will be here before you know it. I hope you are able to get out and enjoy the leaves this year!

Normally when I post on our weather blog, I break down a topic or talk about a weather subject.  In this post, I want to talk about why I believe fall is the best time of the year in our area.  Much of the subject matter in this post is a matter of opinion, but that’s what blogging is all about, right!?

Dry Weather - Typically Fall is when we receive the lowest amount of precipitation.  As we start to see more influence from the westerlies, the tropical airmass that typically resides over the southeastern US begins to erode and is suppressed to our south.  Dry continental air from Canada helps to suppress popup afternoon showers and thunderstorms and often we see several days in a row of nice weather.  Warm sunny days and clear/cool nights are common in September and October.

Fall Colors - I think many of us take for granted the beautiful colors that we are able to enjoy each year.  I spoke with several people from North Carolina visiting the area last week.  They were in awe of the views.  While trees do change color in the Piedmont area of North Carolina, you generally only see trees that are close to you.  I have compared driving through a forest in an area that has flat topography equivalent to driving through a “tunnel of trees.”  You only see what is a few hundred feet away.

Winter is on the Way - When I was younger, winter was my favorite season.  Looking back, I think that was mostly due to the possibility that snow may have kept me out of the classroom! I still love winter and have been an avid skier for 23 years.  For skiers, the changing leaves are a sure sign that the slopes will soon be covered with snow once again.

Although fall officially lasts through December 21st, meteorological fall ends on November 30th.   We still have several warm days left before snow starts flying, so get out and enjoy the beautiful fall conditions.

As we approach summer, you’ll hear us begin to talk more about how moisture content in the atmosphere make it feel warmer than it really is. If the temperature outside is 85 degrees, it will feel hotter if it is more humid. This is because evaporation is slower when the air is closer to being fully saturated.

Evaporation is a cooling process. When you get out of a pool, you feel cold. That’s because as water on your skin changes phase from a liquid to a gas, energy is absorbed by the water vapor during the phase change.

Dry and unsaturated air allows for rapid evaporation and faster cooling. Humid and more saturated air causes evaporation to take place at a slower rate, causing less cooling. Adding a breeze can enhance the evaporation process as well.

If you visit a pool after a cold front has moved through and a cool and dry Canadian airmass is in place, you’ll feel the rapid evaporation effect on your skin once you get out of the water. You’ll either want to get back in the water to stop the evaporational cooling or grab a towel to get the water off and end the chilling effect.

So the bottom line is that it feels hotter on humid days because moisture that is always on the surface of your skin cannot evaporate efficiently. When the air is dry, that moisture evaporates faster and you feel cooler. We can speed up the evaporation effect by pushing more air molecules past our skin.  That’s why a gentle breeze or a fan helps to battle hot conditions.

Crepuscular rays over Tazewell County (Photo: Travis Roberts)

Brilliant rays of light are sometimes visible in a clear blue sky in our area during the summer months after sunset. These are sometimes called sunbeams, but are officially known as crepuscular rays.

These unique optics are caused by clouds over the horizon casting a shadow. They are often seen in the warmer months of the year when towering cumulus clouds form.

They can often be seen at sunset and are created as the taller cumulus clouds block sunlight. Particles in the atmosphere reflect light that we see, but the shadow is causing part of the sky to not be illuminated.

If you see a neat weather event, snap a picture and send it to the WVVA Weather Team of Facebook or Twitter. We’d love to share your picture with our viewers!

Cold air settles into low spots on a calm morning

On clear and calm nights, we often talk about how deep and sheltered valleys will likely be colder than ridges.  These common fall and winter conditions makes for a tricky forecast, with a wide range of low temperatures in the early morning hours.

Valleys get colder than surrounding ridges on clear and cold nights because an inversion sets up. This is where the air near to the ground get colder than air above it. This happens because on clear nights with light winds, the ground loses heat through radiational cooling.  The heat radiates out as longwave radiation and escapes into outer space.   This causes the air closest to the ground to cool rapidly.

On a calm night with light winds, the colder air drains into lower areas like valleys.  This is because of density differences between the very cold air near the ground and relatively warmer air above it. Sometimes you can see colder air that has drained  into valleys via fog.  The colder air in the valley cools and reaches the dewpoint. This is when air becomes completely saturated and condensation takes place, creating the fog you see.  You can also sometimes see frost in lower valleys while hillsides remain above freezing.

Sometimes a southerly wind flow above the surface can also develop.  The warm air rides up and over the colder air in the valleys at night.  Ridgetops often warm much faster than valleys with this setup. When this takes place, I’ve seen temperatures below freezing in valleys while high elevations are in the 50s.

So get ready, it is the season for clear and calm nights with wide temperature ranges.

With the arrival of bitterly cold air, I wanted to share a few “cold weather lifehacks” that I have found helpful.

1. Dress for the weather

Typically when air temperatures are expected to be below 20, I dress in layers.  Even if I am working in the studio, I will wear two pair of pants (usually a pair of athletic pants for the bottom layer).  Even if you are working indoors, layering up makes those trips from the car to the front door much easier. Plus, if you have an emergency on the road, you will be better prepared for cold weather exposure.   Dressing in layers also better insulates your body from the cold.   Layers create air gaps between clothing articles, enhancing the ability to stay warm.

2. Ski Goggles

I love to snow ski and have been a skier all my life.  A few years ago, I started wearing an elastic face mask when I had to go outside in near zero temperatures.  During one extreme cold weather event, I decided to throw on the goggles.  Now whenever temperatures drop near zero and I need to go outside to plow the driveway or do any other outside work, the goggles go on.  You can get an inexpensive pair for around $20 or $30.  I know that I’ll be pulling mine out this weekend!

3. Park Facing the Sun

If you leave home in the morning after the sun rises, harness that solar energy to melt your windshield. This is not only good during extremely cold weather, but also great for regular frosty mornings.  Park your car (if you have the ability) facing southeast.  The sun doesn’t rise due east during the winter months.  Instead, because of the lower sun angle, it rises just south of east.  Pointing your car southeast will allow more direct sunlight exposure to your windshield as the sun rises. Keep in mind, if buildings, trees or other obstacles block direct light from the sun, this will not work.

Winter weather is full of surprises.

4. Pay Attention to Weather Forecasts

This sounds trivial, but cannot be overlooked.  A few years ago just after a snowstorm that dumped over 12 inches of snow, a friend told me he never saw it coming.  This storm was well advertised, was headline news, was on the front page of every newspaper and was injected into almost every conversation on the streets.  Simply knowing what is coming the next day makes preparing much easier.

5. Know How to Cut Off Main Water Supply

If your pipes freeze and burst, would you know how to turn off the main water supply to prevent major property damage? Recently a pipe in the ceiling over my living room began leaking out of the blue.  I awoke in the middle of the night to the sound of water dripping and running.  Thankfully I was able to catch this leak and prevent any major damage.    The best way to fight freezing pipes is to prevent them from freezing.  Insulate pipes, leave cabinet doors open and you may need to leave faucets dripping.