Archive for February, 2012

Calming down the wind
February 25, 2012

By Meteorologist Mike Skurko

Very gusty conditions across New England today should start calming down as we finish out the weekend.  But why does this occur?  What in nature causes some days to be windy and others to be calm?

In nature, everything moves from regions of surplus to regions of deficit.  Nature looks for balance.  The air from a region of high pressure will move towards a region of low pressure, trying to balance out these two systems…i.e. carrying the “surplus of air” with the high pressure system to replenish the “deficit of air” with the low pressure system.  Therefore, a difference in air pressure over an area will get the air moving…creating the wind.  The larger the difference, the faster the wind.

Looking at the Northeast U.S. today, the surface pressure in Philadelphia, Pennsylvania at 1 p.m. today was 1007 millibars.  The surface pressure in Portland, Maine at 1 p.m. was 989 millibars.  That means the difference in pressure between these two cities was 18 millibars.  Massachusetts is located in between these two locations, and therefore is caught in nature’s attempt to transfer the air [which is generating the wind] to balance out these surface pressures.

Looking ahead at our computer models for tomorrow, the surface pressure at 1 p.m. is predicted to be 1030 millibars for Philadelphia and 1022 millibars for Portland…a difference of only 8 millibars.  Because this difference is not as great, the atmosphere does not need to transfer the air as vigorously.  This will mean the winds will not be quite as strong tomorrow.  The difference between these two cities is expected to drop to only 1 millibar in the overnight hours from Sunday night to Monday morning…a time which the winds are expected to go calm across much of the region as much of the Northeast will be under the same ridge of high pressure.

Know your watches & warnings
February 24, 2012

By Meteorologist Mike Skurko

Gusty winds coming in this weekend have prompted numerous advisories across much of the Northeast U.S., including us in western Massachusetts.  Looking back through recent weather blog entries, we haven’t covered wind-related advisories from the National Weather Service.  Therefore, it’s time for another round of Know Your Watches & Warnings.

HIGH WIND WARNING:  Sustained winds of 40-73 mph for at least one hour, or any gusts above 58 mph

WIND ADVISORY:  Sustained winds of 31-39 mph for at least one hour, or any gusts of 46-57 mph

You may notice that the criteria for a high wind warning also matches a component of severe thunderstorms…for a severe thunderstorm warning to be issued, one criteria is wind gusts above 58 mph.  Theoretically then, every severe thunderstorm warning also qualifies as a high wind warning.  This is very true, but pointless.  There is no need to issue both warnings, and the severe thunderstorm warning would take priority as it is deemed by the National Weather Service as a more dangerous hazard.  Think about it…would it make sense to issue a wind advisory for a tornado warning?  No, the tornado warning (i.e. the higher-priority warning) is enough by itself.

Whose winter is this anyway?
February 19, 2012

By Meteorologist Mike Skurko

Congratulations! You’ve now made it two-thirds of the way through the winter season (today marked day 60 of 89).  A very obvious statement…this year’s snowfall totals in the Pioneer Valley have been well below average so far.  But exactly how far below average have they been for the first two-thirds of winter, and how would it compare to other cities around the country?  Are we experiencing snowfall totals closer to Philadelphia’s? Charlotte’s? Atlanta’s?  Whose winter is this anyway?

Well depending on how you slice it, our snowfall totals so far this winter compare closer to a typical winter in the I-80 corridor from Chicago to Omaha.  If you throw out our October nor’easter, however, our snowfall totals compare closer to a winter in New Mexico!

Our official snowfall total from Bradley International Airport comes in at 19.1 inches so far this 2011-2012 winter season, which is about 66% of our normal snowfall for this point in the winter season (29.0 inches is the normal).  If we purely stay at that 66% pace, we will end up with about 32 inches of snow by the end of the season.  The map below shows that 32 inches of snow for a season would be more typical for parts of the Midwest…based on the snowfall averages from a few cities shown below:

However, one thing is fairly obvious…our October nor’easter, which produced 12.3 inches of snow at Bradley, is greatly skewing our snowfall totals.  If we ignore that storm and look at November, December, January, and February, we have only fulfilled 23% of our normal snowfall total this season (6.8 inches of snow, compared to our normal of 29 inches).  If we stay at that 23% pace, we would only end up with 11.5 inches of snow for the season…which compares more closely to parts of New Mexico out west (or Knoxville, Tennessee in the east…which also averages exactly 11.5 inches of snow per season).

Advantages of Bradley Radar
February 16, 2012

By Meteorologist Mike Skurko

Two standard principles of radar: One…the radar beam travels higher in altitude as it moves further from the radar (because they’re initially pointed up towards the clouds).  Two…a radar will hit the top of far away clouds because of the curvature of the earth, which appears to bend distant clouds downward and cause the radar to overshoot them (pictured below).

Unfortunately for the Pioneer Valley, our closest radars from the National Weather Service straddle us …Albany to the west, Boston to the east…but may be reaching their limits by time the radar beams get to the Connecticut River and the more populated areas of western Massachusetts.  It can be common for these two radars to depict the same storm cell differently.  They are looking at two different levels of the storm, receiving two different intensities and two different locations.   Carrying back over a great distance, those slight, subtle errors can be extrapolated greatly into misrepresenting the storm cell on the map…either in the wrong location or the wrong reflectivity.

Fortunately our Pinpoint Doppler Radar, situated atop Terminal B at Bradley International Airport since January of 2000, can help correct these errors.  It’s pretty simple…for a storm over Springfield, our Doppler radar at Bradley is only 15 miles away.  The radars at Albany and Boston are both more than 80 miles away.  Bradley has a much closer view of the storm, and can help settle any discrepancies from surrounding radars…filling in part of the “gap” on the outskirts of the National Weather Service network of radars over the Pioneer Valley.

18 miles closer to summer
February 12, 2012

By Meteorologist Mike Skurko

With a night of bone-chilling cold returning to western Massachusetts, here is something warm to think about:  each passing day puts us 18 miles closer to the start of summer!

We all know the earth is in constant rotation and is constantly revolving around the sun.  It is also constantly tilting back-and-forth toward and away from the sun, which causes our seasons.  Ever since the first day of winter (the Winter Solstice) the northern hemisphere has been gradually tilting back towards from the sun.

The earth tilts to a maximum of 23.4 degrees towards the sun at the Summer Solstice, and 23.4 degrees away from the sun at the Winter Solstice.  That means over half a year, the earth will change its tilt a total of 46.8 degrees.  Since one degree of latitude is about 69 miles, then 46.8 degrees equates to a total of 3,229 miles.  Divide that distance over half a year, and you’ve got yourself about 18 miles per day!

Here’s another way to think about it… a rate of about 18 miles per day means we would be about 282 miles closer to summer from here to the end of February.  That’s the same distance of a car ride from Springfield to Wilmington, DE.  Theoretically then, we would enjoy the slightly warmer weather Delaware is having by the end of the month (their average high is about 5 degrees warmer than ours).

That may not seem like a lot, but continue that journey southward by a rate of 18 miles a day and you’ll be enjoying sunny Florida weather before you know it.  I actually checked both the math and Google maps…you’d hit West Palm Beach, Florida (pictured below) on the last day of April!  Or if you’re that impatient, you’d be in North Myrtle Beach, South Carolina (my yearly vacation spot) by March 30.

“Nobody lives at the airport!”
February 11, 2012

By Meteorologist Mike Skurko

Earlier this week, we had the opportunity to go inside our Pinpoint Doppler Radar at Bradley International Airport (pictured below).  For years, Bradley Airport has also served as the official climate station of the Pioneer Valley.  No matter what city you may originally be from, you may be used to the idea of “current conditions” coming from airports, both big and small.  But why is this the case?  As comedian George Carlin once said (also pictured below), “That’s real stupid because nobody lives at the airport!”

The reason why most official weather instruments are stationed at airports is simple: the vast open and flat terrain makes the information it collects as accurate as possible.  In the middle of an airfield, there is nothing to create shadows and influence the temperature.  There is nothing to block the wind, nor channel the wind into higher gusts.  It can also accurately collect wind-driven precipitation.  The bottom line is…for weather instruments, the middle of a flat airfield is the most natural, undisturbed place to gather data.

It is also very unlikely for airports to change their location, which will promote year-to-year consistency with the data…something very important to gaining meaning from yearly records.  Sure, terminals maybe rebuilt and highways may be rerouted, but the actual airfield itself usually goes undisturbed.  National Weather Service offices, television stations, and private weather companies are more likely to change their location (even if only every few decades) more often than an airport.

For example, Bradley Airport has been around since the 1940s…well before the National Weather Service moved to its current location in Taunton, MA, and even before WWLP, WGGB, or WSHM television stations here in Springfield began broadcasting!

There is also a secondary reason why major weather instrumentation is located at airports.  It can be argued at aviation requires the most accurate information possible, and the clearest depictions of radar that can be developed.  For most people, if the temperature differs by a degree or two, or the location of some precipitation is a few miles off, it’s not that big of a deal…or certainly not compared to the problems those slight errors can create for pilots.

National Weatherperson’s Day
February 5, 2012

By Meteorologist Mike Skurko

February 5th is National Weatherperson’s Day, commemorating the birthday of a Boston native who was one of America’s earliest weather observers.  You can read the full history, and special message from the National Weather Service in Boston at the link below

http://www.erh.noaa.gov/box/announcement/NationalWeatherPersonsday.html

Super Bowl Prediction (revisited)
February 4, 2012

By Meteorologist Mike Skurko

In a blog entry from September 8th, the beginning of the NFL season, we took a look at some interesting weather/climate stats for the Super Bowl…and if those odds hold true, the New York Giants would be the favorite in Super Bowl XLVI.

Here is the excerpt from that entry:

This year’s Super Bowl is being played in Indianapolis for the first time, making it the 14th different city to host the Super Bowl… For the 13 cities to host the Super Bowl so far, the first Super Bowl that city hosted has usually been won by the team from the warmer climate.

In 10 of those 13 games, the warmer city won the Super Bowl.  That would mean, if those significant odds hold true, the New York Giants would hold the edge over the New England Patriots in the first Super Bowl ever held in Indianapolis.

For Patriots fans, it should come as comfort that of the three “colder cities” that won, one of them was New England (they defeated Philadelphia in Super Bowl XXXIX, the first time it was ever hosted in the city of Jacksonville)

While most of you may think this whole method is nonsense…I will point out that a similar city/climate analysis on this weather blog in October successfully predicted the Cardinals over the Rangers in seven games in the World Series!