Archive for October, 2013

Partly cloudy vs. Mostly sunny
October 27, 2013

By Meteorologist Mike Skurko

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These two terms, partly cloudy and mostly sunny, are among the most commonly used in weather reports … whether it’s on tv, online, on your weather app, in the newspaper, etc.  But is there really a difference between the two terms? The answer is yes.

They seem similar, and both suggest a “nice” forecast with a decent amount of sunshine.  There are guidelines provided by the National Weather Service that define a more specific amount of cloud cover that denotes which phrase should be used.  Here is the hierarchy based on the fraction of sky that is filled with clouds:

0 to 1/8: Sunny

1/8 to 2/8: Mostly sunny

3/8 to 5/8: Partly cloudy or partly sunny

6/8 to 7/8: Mostly cloudy

8/8: Cloudy

This shows that, by definition, mostly sunny suggests a little less cloud cover than partly cloudy.  If you see the forecast has two back-to-back days with the first day being mostly sunny and the second day being partly cloudy, this means the first day will feature a little more sunshine.

Note that at night, the term sunny or mostly sunny would obviously be changed to clear or mostly clear.  There is also some leeway for interpretation for the forecast.  For instance, I prefer to use partly cloudy if it’s closer to 3/8 and partly sunny if the sky cover is closer to 5/8.  Some forecasters also incorporate the term “mix of clouds and sun” if it’s close to the 50-50 mix covered by the “partly cloudy or partly sunny” range.


Frost advisories done for the season
October 24, 2013

By Meteorologist Mike Skurko

Temperatures dropped to 33 degrees in Springfield on Thursday morning, with some upper-20s reported across Franklin County as well.  Temperatures are expected to be similarly cold for Friday morning.  However, no frost advisories are being issued for either of the two nights (or any subsequent nights).

Frost advisories are only issued during the growing season, which according to the National Weather Service has ended for western Massachusetts, as shown on the map below (the Berkshires will not see frost advisories either, but they are handled by the NWS office in Albany and not shaded on this particular map from the Boston office).

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Our next frost advisories will not be issued until the spring.  At that point, it would happen on a cold night after the growing season has begun.  In other words, no need to protect plants if they’ve already stopped growing at this point, or haven’t started growing yet in the spring.  Think about it … it would be stupid to issue a frost advisory every single night of the winter when temperatures are always below freezing.

Northeast Massachusetts, the Hartford area, and much of Rhode Island are seeing their frost advisories tonight.  Meanwhile, frost advisories can still be issued for the Boston area and out along the Cape in the days/weeks to come until their growing season is deemed officially over.

2013 World Series and weather
October 23, 2013

By Meteorologist Mike Skurko

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Since you’ve probably read every way the experts have been analyzing the World Series between the Red Sox and Cardinals, here’s one you probably haven’t read about … the weather.

First of all, this form of analysis is completely ridiculous.   Although it did successfully predict the Cardinals to win in 7 games against Texas in 2011 (I didn’t do it for last year’s series).

In the 109 World Series played in the modern era, the city with the colder annual temperature has won 48 times and the warmer city has won 45 times (16 World Series have been contested against teams from the same city).  This includes wins by the cooler city in four of the last five series…Philadelphia in ’08, New York in ’09, San Francisco in ’10, and St. Louis in ’11.  Looking at this year’s matchup between Boston and St. Louis would give this “cooler” edge to Boston, which has an average high temperature about 7 degrees cooler than St. Louis.

Looking at annual precipitation it’s even closer.  The wetter city has won 47 times and the drier city has won 46 times (again, 16 World Series being played by teams from the same city).  This would also give a slight edge to Boston, which averages about three more inches of precipitation per year than St. Louis.

Therefore, if these weather odds gave any indication of the winner, the slight edge would go to the Boston Red Sox.  However, being in this position as the “cooler, wetter” city doesn’t favor Boston.  They have a 2-3 record in the World Series as this city.  Meanwhile, St. Louis boasts a 6-4 record as the “warmer, drier” city in the series.

Throwing out the three World Series they’ve played against one another (1946, 1967, 2004), this would give a 1-1 record for Boston and a 4-3 record for St. Louis, thus closing this gap.  Furthermore, throwing out these three series would also widen the gap for the cooler and wetter cities.  This (I believe) should continue to give Boston the slight edge.

I guess the World Series really could be dubbed the “Fall Classic” since the cooler, wetter city has won a handful more championships.

Cooler weather digs in
October 19, 2013

By Meteorologist Mike Skurko

Temperatures in the lower-60s hold for the next couple of days, but a trough will be digging through the northern part of the country this week.  This will eventually allow our first real autumn chill to settle into western Mass for the second half of the week.

Below are three computer models depicting Sunday, Wednesday, and Friday.  The dotted red and blue lines are atmospheric thicknesses…which are directly related to temperature profiles, as explained on this weather blog entry from two years ago: The 540-Line.  Notice the blue line I have highlighted in each model below.

Tracking the movement of this line easily depicts the trough settling into western Massachusetts later in the week.  On Sunday (and Monday and Tuesday), the trough is still hanging back a bit to our north and west.  Each of these days have high temperatures expected to be in the lower-60s for Springfield.  By Wednesday, the trough starts digging in and drops our high temperature to the mid-50s.  By Friday, you can easily see why our high for Springfield will barely get to 50 degrees.

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Days are getting longer … by thousandths of a second
October 12, 2013

By Meteorologist Mike Skurko

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As the daylight hours continue to dwindle in the fall, we all know that means a slightly longer night.  After all, every day has to be exactly 24 hours long, right? Wrong.  A recent article published by the Washington Post explains how the earth’s rotation rate is slowing down, effectively adding 0.002 seconds to each day.

You probably didn’t realize it, but this means the day becomes one full second longer every 500 days.  At that rate, each day becomes a full minute longer about every 82 years!

According to the article, a day in the life of the dinosaurs was about 23 hours long, with 385 days in a year.  The speculation is that 200 million years from now, our day on earth would last about 25 hours, with only 335 days per year (which will likely cause more stores to start displaying Christmas decorations in August.  Kidding.)

While 0.002 seconds per day may seem insignificant to our daily lives now, this subtle slow-down is extremely important in today’s technology-driven world.  The article cites that smartphones, GPS systems, and power grids cannot get more than one-millionth of a second out of sync.  As an example, a GPS system that is a millionth of a second out of sync would result in a location error of two-fifths of a mile.

The reasons behind earth’s slow-down and the fluctuations in time can be found on the full article: With earth spinning more slowly, time isn’t flying as fast as before