More than one friend sent me a link to a Yahoo! story today about how rainy forecasts are misunderstood. The article contends that only half of the population fully understands what the visual forecast icons and percentages mean.

What do I mean by visual forecasts?

Tuesday has a 50% chance of showers. What does that even mean? Let’s look at another example.

Monday and Tuesday of next week have a 40 and 50 percent chance of rain, respectively.

What confused people is what the percentage actually stands for. Many surveyed thought by saying “there is a 50% chance of rain” means that it will rain for half the day or only half the area will get rain. Although I can see what they are thinking, they are unfortunately wrong. The saying “50% chance” means given the atmospheric conditions at this time, half the time it rains and half the time it doesn’t.

As seen in the survey, this is a very common misconception. Meteorologists may not do a good enough job explaining this feature of the forecast. Some people don’t even use “chances of” on their extended forecasts.

My former boss at WTNH and good friend Geoff Fox never puts percentages on his 8-day forecasts. It is misleading to people, he would say. It took me a couple of days to understand what he meant.   A good communicator is just as powerful as an icon. Geoff does a great job of explaining each tricky forecast so not to mislead any viewers.

Next time you hear “there is a chance of rain” you’ll know what the meteorologist is talking about…even if we are only right 50% of the time.

A common question one may ask is, “If the sun reaches its highest elevation in our sky on June 21st, why then is that not the hottest time of the year?” The answer is the oceans. The oceans store heat (high specific heat capacity), therefore actual changes in mean Earth temperature are delayed by several weeks, i.e. the hottest days of summer are usually in late July or early August, over a month from the summer solstice.

Below, a graphic which represents the sun’s zenith angle/elevation angle for a latitude of 50 degrees North at the winter and summer solitices and equinox. Hartford’s latitude is roughly 41 degrees North. This means you would have to subract 9 degrees from the zenith angle or add 9 degrees to the elevation angle to calculate how far above the horizon the sun would be in the sky at these times.

UV Index

The Ultraviolet (UV) Index is an international standard measurement of how strong the UV radiation from the sun is at a particular time on a particular day. To read the American Meteorological Society’s definition of ultraviolet radiation, click here. The UV index is a scale primarily used in daily forecasts aimed at the general public.
 

UV index is dependent on many variables, including stratospheric ozone, sun’s elevation angle, latitude, time of day, altitude, weather conditions, air pollution, and surface reflection. UV rays can be further broken down into UVA, UVB, and UVC.

UVA (long wave) – The aging rays are equally intense year round at any time of the day. UVA damage is linked to premature aging, weakened immunity and a predisposition to skin cancer.

UVB (medium wave) – The burning rays are strongest at midday. UVB rays are associated with premature again, weakened immunity and the development of skin cancer. About 10% reach the Earth’s surface.

UVC (short wave) – The strongest and most dangerous, are filtered out by the ozone layer.

When conditions are right, UV indices can make it into the very high (dangerous) range in Connecticut. To help reduce the sun’s harmful effects, try reducing sun exposure between 10 am - 4 pm, applying sunscreen with SPF 15 or higher every 2 hours when outside, wearing sunglasses with UV–A and UV–B protection, wearing a wide-brimmed hat, and using lip balm with SPF 15 or higher.

SPF

What is SPF? SPF refers to Sun Protection Factor and applies only to UVB radiation. It is a multiple of how much time you can stay in the sun without burning your skin. For example, if you normally burn without any sunscreen in 10 minutes, a sunscreen with an SPF 20 would allow you to stay in the sun for 200 minutes without burning.

Tanning

The skin’s first defense against UV rays is melanin, a chemical present in a variety of colors and concentrations in most people’s skin that helps with defense from the sun. UV rays act upon melanin, causing the melanin to spread out or grow, increasing its presence in response to the sun’s exposure. The result is a “sun tan”. The darker the skin color, the more melanin the skin has for protection. Hence, fair skinned people are most susceptible to burning.

Questions people frequently ask are, “When is the best time of day to tan?” “How do I get the best tan?” The sun’s rays are most intense from 10 am – 2pm when it is highest in the sky. Obviously, the absence of clouds during this time frame would be the ideal time to tan. As mentioned earlier, surface reflection plays an important role in what happens to the UV rays once they reach Earth’s surface. Wading waist deep in water would be far more conducive to receiving a tan over playing wiffle ball on a grass field. The green grass would absorb but not reflect the sunlight the way in which water does. Essentially, the rays from the incoming UV rays and the reflected rays from the ground are “tanning” you at the same time. Please keep in mind that too much sun exposure could lead to sunburns, eye damage such as cataracts, skin aging, and skin cancer.

Research also suggests that being physically active, which increases blood circulation, increases the amount of melanin that will be pulled to the surface of your skin. One of the papers may be viewed here.

Common Myths

“Tanning beds and sun lamps are a safe way to get a tan.” False. UVA is emitted from tanning beds and sun lamps at rates of up to 5 times as much as the sun!

“After years of being out in the sun and not taking sun safety precautions, would starting now make any difference?” Definitely. Research has shown that being “sun safe” regardless of what age, you can reverse some of the damage that has been done while also slowing the appearance of further sun–related skin damage.

“There is no need for protection on a cloudy day.” False. Up to 80% of the sun’s damaging rays go through light clouds, haze and fog.

“People with medium to dark skin never burn.” False. Although people with medium to darker skin tend to tan more easily than others, they can still get sunburns. They can also suffer from overexposure to UV-light. It is still important for these skin types to use sunscreens and avoid being in the sun longer than they need to be.

“I heard that in order to get a suntan you have to burn first.” False. Sunburn does not fade into a tan. Sunburn indicates over exposure to UV-light and actually damages the skin, leaving it inflamed (as indicated by the skin’s red coloring and sensitivity), dry, chapped and visibly unappealing. In fact, sunburn can lead to premature aging and potentially skin cancer. Always practice moderation when tanning and use the proper sunscreen protection when tanning outdoors.

Capitol building in full bloom

Allergies affect different people at different times throughout the year. The three most common types of pollens are from trees, grasses, and ragweed. Allergic diseases are a major cause of illness and disability in the US, affecting more than 35 million people with upper respiratory symptoms. Pollen allergy (hay fever) is one of the most common chronic diseases.

The first allergy culprit of the year comes from tree pollen, which in Connecticut normally blooms in the months from March to June. Contrary to what many people believe, trees with brightly colored flowers usually do not bother allergy sufferers. Instead, the non-flowering plain looking trees cause the greatest allergy symptoms. Some of the top allergy producing trees in Connecticut are Oak, Birch, Cottonwood, Maple (begins in February), Hickory, Sycamore, Walnut, Beech, and Elm.

Weather plays an important daily role on the actual levels of the allergenic concentrations in the air. When the forecast calls for a warm, dry, breezy day, make sure you take antihistamines or use nasal sprays before venturing outside. These atmospheric conditions favor the greatest concentrations of airborne pollen as the wind transports small, light pollen grains away from the source (trees in this case) and into your nose.

On colder, wet, and more humid days, water vapor in the air condensates onto the pollen grains. This in turn makes the particles heavier, and less likely to be transported away from their source by the wind. This is also seen around daybreak (the coolest part of the day) before the sun comes out and heats up the surface of the earth. The moisture eventually evaporates from the surface of the trees, freeing the pollen and making it airborne again.

The graphic below displays the four day forecast for pollen levels around the Hartford area.

4day Pollen 4cast for Hartford Area

Allergy sufferers, stay updated on future weather forecasts and daily pollen reports.

I am an avid writer and I often find fun things to write about on other websites. One of those websites I frequent is Twitter. Twitter is a pseudo social networking sight with mini blogging capabilities. If you think writing a text message was hard with 160 characters, Twitter restricts you to only 140 characters. Try summarize what you’re doing or thinking in one sentence… it’s not easy!

Anyway, so as I was on Twitter this afternoon/evening, I started noticing a common factor. Many of the people I was following were tweeting (posting a twitter message) about the weather. It’s not like they didn’t have a huge spectrum to comment about. The picture above is a snap shot of what was happening. Everything from tornado warnings in red, blizzard warnings in orange, and flood warnings in green.

That got me thinking. Are we at a time that we no longer are content with hearing about weather warnings from the chief meteorologist at your favorite TV station? We no longer pay attention to the alerts as they scroll across our screen? Do people still tune into their NOAA radios?

As many people know, I currently work at WeatherBug. We do have the desktop application that was very revolutionary at its inception. Now folks at work or in front of the computer could receive near real-time alerts as soon as they’re issued.

The chirping WeatherBug app is still as strong as ever, but I do see a competitor from Twitter. Check out a screen capture from my twitter feed.

Not only did many of these warnings come out in real-time, but they lack the generic tone of a NWS alert. If I lived in North Carolina (and weren’t a meteorologist) today, I would have sat in my basement with my wireless internet and continually pressed refresh on twitter for updates.

I think it will be very interesting to see how Twitter will effect the news-delivering in the upcoming few years. Before you forget, click on the button to the right and add us to your Twitter!

It’s only March, but preliminary hurricane forecasts for the 2009 season are already being made. The Atlantic hurricane season officially begins on June 1st. Ok, so what if the National Hurricane Center (NHC) predicts storm activity will be above normal this season. Does that mean Connecticut has a legitimate shot at seeing one? Are we out of the woods if they say it will be a slow season? Here’s what I found.

This map shows all category 1 to 5 hurricanes whose centers have passed within 10 nautical miles of CT during the period 1851 to 2005

Hurricane Carol in 1954 and Hurricane Gloria in 1985 were reminders that CT was still vulnerable to the awesome power of Mother Nature and the destructiveness of hurricanes. Although unlikely, history reminds us that we are not invincible to these storms and they will strike again. Unfortunately, today’s youth in CT are most likely under the assumption that hurricanes only strike the Gulf States and Florida. If the every 30 or so year rule continues, the next one is not that far away.
There are other atmospheric/oceanic players that contribute into whether or not CT will have an increased/decreased chance in seeing any hurricanes this year. One of them is the ENSO (El Nino-Southern Oscillation) phase. The tables below indicate the frequency of landfalling hurricanes for the Southwest and Southeast Connecticut shorelines during the different phases of ENSO over a 154 year period.

SW CT Hurricane landfalls with ENSO condition

SE CT Landfalls with ENSO condition

What does all of this mean? Connecticut is soon going to be due for a category 1 or 2 hurricane (3 is not out of the question but has never been observed) to make landfall. If a storm similar to the 1938 hurricane were to happen this day in age, the devastation would be catastrophic. However, if the La Nina phase holds on through the hurricane season, I think the Connecticut Coastline will be spared this year. Even if the ENSO phase becomes positive (El Nino), Connecticut has between a 3-6% of being struck by a hurricane, so I wouldn’t put my money on it. Stay tuned to my ENSO updates for further analysis.

What a week it has been for weather across the country.

Central Plains: Just when residents of the Central Plains thought spring was starting, they were in for a rude awakening. Last week temperatures were above average for the entire region, some places reaching 60º (15º above average). That warm feeling and the belief spring was coming left faster than you can say sublimation. Beginning Monday morning, a strong system delivered late season blizzard conditions, dumping between 6 inches and a staggering 37 inches across Wyoming. To make matters even worse, now the residents are dealing with some of the worst flooding in recent memory. The National Weather Service issued a Civil Emergency Message saying

As of Wednesday afternoon, the Elm River at Westport has reached all time record levels. As a result, the Elm River has begun to flow into the northern portion of Moccasin Creek.

This is not a good situation for those folks and it will continue to get worse. There are reports of bridges collapsing and entire interstate highways completely closed.

South: As I go for the award for “Worst Transition Ever”, those same snow storms previously mentioned spawned tornadoes across Texas and Arkansas. This phenomenon isn’t as rare as you’d think. About once a year, a strong low pressure system moves in from the west, bringing a grab bag of weather to any state in its path. On the southern end of this storm, you will many times find severe thunderstorms. These thunderstorm soaked southern locations with up to 6 inches of rain.

Alaska: As you may or may not have heard, there is a volcano erupting to the southeast of Anchorage. In fact, I’d be willing to but that if Sarah Palin looked out her back door, she could see volcanic ash rising into the sky. On a serious note, the melting of glaciers caused by the eruption has in turn caused seriously flooding concerns for Alaskan officials. Rivers are up as much as 25 feet above normal heights with the dirty as mixing with the water.

The week isn’t over yet, and the east coast will have some rain showers all day tomorrow. At least there isn’t 2 feet of snow or a volcano right?

The day has come that every meteorologist lives for. Accuweather has finally issued its yearly 2009 hurricane forecast. Now it gives us something to talk about until the end of hurricane season.

This years’ forecast looks strikingly similar to last years’. Joe Bastardi, Accuweather’s leading hurricane expert, predicted an increase of tropical storm presence from the Carolinas to New England. He was correct in that count - Hurricane Hanna and TS Cristobal.

I think it’s pretty funny that they say “probably more random activity” for the East Coast. Could you get any less specific?

He also predicted a normal year for the Gulf of Mexico. Texas seemed to be the punching bag for Mother Nature last year with three hurricane landfalls. Hurricanes Edouard, Dolly, and Ike (with Gustav in the neighborhood) did extreme damage to the Texas coast. I think he was a little off there.

Bastardi does know his stuff though. In 2007, he was found to have the most accurate hurricane forecast.

This year he is forecasting thirteen tropical storms to form, four hurricanes hitting the US, and one hitting the US as a major hurricane. This is a considerably less than previous years.

Stay tuned for the official 4cast4you Hurricane Forecast! Coming soon!

The Western States are currently experiencing a wide variety of weather due to a developing and deepening area of low pressure to the lee of the Rockies. This is in response to an intense 500mb shortwave trough digging through the inter-mountain west. Below are the current warnings/watches provided by the NWS.

As you can see, a plethora of watches and warnings are out for the aforementioned areas.

On the northern side of the system, strong winds and heavy snows will combine to make blizzard conditions for portions of the Dakota’s, Wyoming, and Eastern Montana. Many ski resorts, from Utah to Colorado are forecast to receive around a foot of snowfall from this storm.

The southern flank of this storm seems to be quiet as of right now in the precipitation department. Those pink warnings you see in the Southwest States and Western Texas are red flag warnings. A red flag warning means that critical fire conditions are either occurring, or will be shortly. Dry conditions already present combined with low relative humidity and gusty winds from the deepening low pressure system set the stage for dangerous fire conditions. A new facet of the storm will show itself tomorrow afternoon through Tuesday evening in the form of showers and thuderstorms. Conditions seem to be favorable for large scale thunderstorm activity across the Plain States. The map below shows which areas are most likely at risk for experiencing severe weather tomorrow (Created by SPC), gusty winds and hail are likely and isolated tornadoes cannot be ruled out.

Does your Bufkit do this? Mine does!       

(Note: you can drag the scroll bar to make the animation faster…)

The fourth Bufkit Tutorial shows you step by step how to download and install the comet module and integrate it into Bufkit. This makes your CONRAD tab in Bufkit FULLY functional. This program is sweet and it comes with its own tutorial that is very user friendly. Bufkit integrates its summary into the program so you don’t need to understand all the workings behind the program to start using it.

You know you want to use the Convective Storm Matrix this Sping/Summer so Click Me and go to the fourth tutorial! Click the Bufkit button on the right or use the “Models” tab above to get to the rest of the tutorials.

Happy 4casting,

Vincent Sapone