Archive for May, 2012

2012 Hurricane Forecasts
May 31, 2012

By Meteorologist Mike Skurko

Tomorrow is the official start of hurricane season, despite already having two named storms this year (Alberto and Beryl, both weak tropical storms, spun near the Carolina coast not too long ago).  Here is a look at the outlooks for this season forecasted by three agencies…Accuweather, Colorado State University, and NOAA.  They are the most often-referenced for long-range hurricane prediction.

Overall, you can see the general trend seems to be for a slightly less-than-active hurricane season.  Most of those numbers are falling at or below average, and certainly quieter than 2011.  Experts have noted two key factors to a less active season than last year.  One, surface pressures in the Atlantic are generally higher than last year.  Two, a developing El Nino later this summer tends to limit hurricane development (El Nino often brings stronger wind shear to the Atlantic…which effectively “rips apart” a tropical disturbance at high levels before it can mature.)

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Don’t Fry Day
May 25, 2012

By Meteorologist Mike Skurko

The Environmental Protection Agency designates each Friday before Memorial Day as “Don’t Fry Day” to raise awareness of sun safety.  This joint effort with the American Cancer Society, the American Academy of Dermatology, and others wants to remind people to take precaution when out in the sun now that summer is almost upon us.

Most of it is common sense you may already know…use sunscreen with a high SPF, wear a shirt and hat on high UV days, and sunglasses can also prevent harmful damage to eyes from UV rays.  Also try to stay out of the sun when sunlight is most direct between 10am and 4pm if you can.  As a simple example, a two-hour chore of yard work is much better in the early morning or before sunset instead of right in the middle of the day.

But here are some facts perhaps you didn’t know:

– Approximately 76,000 new cases of melanoma will be diagnosed this year, the deadliest for of skin cancer.

– One American dies every hour from melanoma

– Skin cancer is the most common form of cancer among 20 to 30-year-olds

Another thing the EPA reminds people…tanning to get more Vitamin D is a poor excuse.  Studies have shown that even people in living in the sunshine of Hawaii have Vitamin D deficiencies just like people in the continental U.S.

 

A warm Mother’s Day
May 13, 2012

By Meteorologist Mike Skurko

A summer-like day for all of the mothers across the Pioneer Valley today with the high temperature topping out at 84 degrees.  This was our warmest Mother’s Day since 1993 at Bradley International Airport.  Our normal high for the second Sunday of May is around 70 degrees.  Today’s 84 is closer to the normal high for early July!

 

Prince Charles does the weather
May 12, 2012

By Meteorologist Mike Skurko

The BBC network celebrated their 60th anniversary this past week…and Prince Charles surprised the studio with a live lunchtime weather report.  Not the best forecast, but we’ve all seen celebrities do a lot worse.

Adiós to La Niña
May 6, 2012

By Meteorologist Mike Skurko

Forecasters at the National Weather Service announced earlier this week that La Niña is over for now.  La Niña is a cooling of waters in the central Pacific Ocean, which has been linked to global climate phenomenon…such as the severe drought in the southern U.S., as well as historically active hurricane seasons.  Here in New England, La Niña’s effects are not as drastic or well-predicted as other parts of the world.

This image from NASA shows a depiction of our last significant La Niña event in 2007.  The cooler than normal ocean waters are represented in blue:

This chart shows the oscillation between El Niño events (red) and La Niña events (blue).  You can see at the very end of the graph how temperatures have returned to average after the recent spike in cooler conditions since 2010:

The topic of La Niña being gone, and the Pacific warming back to normal, has been a great part of hurricane forecasts for the 2012 season.  Researchers at both Colorado State University and Accuweather are predicting “near-normal” hurricane and tropical storm numbers…both teams predicting twelve named storms, which is the average number of storms over the last few decades.  The National Hurricane Center’s 2012 outlook is not released until the end of May.

La Niña events have been linked to lower wind shear in the Atlantic.  Strong wind shear…a drastic change of direction and speed of winds with height…is a killer for hurricanes.  Low wind shear, like that during La Niña, allows tropical systems to develop more maturely.  The last two La Niña seasons, 2010 and 2011, both saw an impressive total of 19 named storms.

This could bode well in New England’s for avoiding another Hurricane Irene repeat.  Since the 1950s, six storms have made landfall in New England at hurricane strength (technically, Irene doesn’t fall in this category).  Those years are 1954 (Carol and Edna), 1960 (Donna), 1976 (Belle), 1985 (Gloria), and 1991 (Bob).  A close inspection of the graph above indicates that most of those years were in a La Niña state, with 1954 trending towards a full-scale La Niña by 1955.  Hurricane Bob is the exception in 1991, where a long-lasting El Niño was underway.  Still, with 5 of those 6 hurricanes during a La Nina…history may indicate that a hurricane striking New England would not be in our favor if we trend away from La Niña this summer.

As far as the drought in Texas and other southern States, long-range forecasters say that the drought may already be so severe that La Niña’s farewell alone will not be enough bring complete relief to those dry regions in the immediate future.

Super moon explained
May 5, 2012

By Meteorologist Mike Skurko

Tonight’s full moon is dubbed a “super moon” because it will appear 14% larger and 30% brighter than other full moons.  The reason for this is due to the moon’s elliptical orbit around the earth.  It does not maintain the exact same distance around the earth.  Tonight the moon will reach its closest point to earth, known as “perigee”, which is about 50,000 kilometers closer than it’s furthest point (“apogee”).

The coincidence of a full moon occurring while it is at perigee is dubbed the “super moon”.  A lunar orbit around the earth takes about 27 days, whereas a lunar cycle (new moon, first quarter, full moon, last quarter) takes roughly 29 days…so even though the moon reaches perigee about once a month, it doesn’t always exactly line up with the full moon.

Two things to consider about the “super moon”…it has little effect on tides, only a matter of a few centimeters.  Secondly, it may not appear any different to the naked eye.  For a moon that is 14% larger in the night sky, it is very difficult to notice that slight difference at first glance.  In this image from NASA, the moon on the left is 14% bigger than the moon on the right.  Tough to tell, isn’t it?

Some of the spectacular photos of the moon appearing enormous in the background is the result of an optical illusion.  The exact cause of this illusion is still debated, but it is basically due to theories regarding relative size and apparent distance.  Moons that appear just above the horizon appear much larger than a moon high in the sky.  A common theory is illustrated below by the Ebbinghaus illusion.  A moon close to the horizon appears larger because it is being compared to smaller objects in the background, such as trees and buildings.  A moon higher in the sky, however, loses this relative comparison.  It appears smaller when being sized up against the large vastness of the black, night sky.

Here in the Ebbinghaus illusion, both blue middle circles represent the moon, and both are exactly the same size.  However, the moon on the right appears larger because it is being compared to smaller objects surrounding it (which represents smaller trees/buildings).  The moon on the left appears smaller because it is being compared to much larger circles around it, which represents larger clouds and the large emptiness of the entire sky.