Archive for August, 2013

August 2013 recap
August 31, 2013

By Meteorologist Mike Skurko

After last month was the warmest July on record for the Pioneer Valley, we came back to normal for August.  Our average high temperature was 81.2 degrees at Bradley International Airport, which was 1.5 degrees below normal.  Low temperatures were also about 4 degrees below normal.  Keeping with that theme, we did not record any 90-degree days this past month, making a strong argument that we managed to avoid the dog days of summer this August.  You can see on the graph below that high temperatures never strayed to far from 80 or 81 degrees.

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Not only is this a good turnaround from last month, it’s also a good turnaround from last year.  August 2012 had an average high temperature of 85.7 degrees, and recorded six 90-degree days.

While this August will go down in the record books as very rainy, it was actually closer to normal than you would think.  We recorded 6.69 inches of rain this month.  However, recall back to August 9th where we had 3.79 inches in just one day.  If you subtract that day out of the mix, we had 2.90 inches of rain for the rest of the month, which is a full inch below normal.

10 years of weather in three minutes
August 25, 2013

By Meteorologist Mike Skurko

After more than ten years in service, NOAA retired the GOES-12 satellite this past week.  Much of the satellite imagery seen on television for the eastern United States from 2003 to 2010 came from GOES-12.  After its age no longer met the high standards of the National Weather Service, it was was replaced by GOES-13 and repositioned to assist with coverage in South America in 2010.

As part of the “retirement” process, known as decommissioning, GOES-12 was sent further away from earth in its orbit, the remaining fuel is expended, and its transmitters are turned off.  This is done to prevent any collisions with other operational spacecraft, as well as not to interfere with currently transmitting signals.

GOES stands for Geostationary Operational Environmental Satellite, and the first GOES-1 was launched in 1975.  Geostationary means it has a fixed position 22,300 miles above the earth.  This allows it to stay in the same location above earth as both the satellite orbits and the earth revolves at the same rate, thus providing a continuous loop of imagery for the same fixed location (in the case of GOES-12, the eastern U.S.).

NOAA has released a movie clip showcasing GOES-12’s ten years of recording condensed down to three minutes.  Look closely and you can pot a few memorable weather events such as Hurricane Katrina in 2005 and our Christmas Blizzard of 2009.

90-degree heat returns, but not for very long
August 18, 2013

By Meteorologist Mike Skurko

The weather for western Massachusetts over the past week couldn’t be any more comfortable for mid-August.  High temperatures in Springfield since Monday averaged 77.6 degrees, about 2 degrees below normal (with overnight lows about 6 degrees below normal this past week).

Hotter weather will return to the region, with high temperatures hitting the 90-degree mark in Springfield by Wednesday.  Fortunately, we are lucky that excessive humidity is not expected to accompany this heat.  Below is a computer model for the expected dewpoints on Wednesday afternoon.  While these numbers in the mid-60s will be noticeable, it will not be oppressively in the 70s like some of the heat waves this past summer.

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Those dewpoints may get closer to 70 degrees on Thursday, with high temperatures once again in the lower-90s for Springfield.  That should be it, and it does not look like we will get a third 90-degree day on Friday to make the heat wave official.  A cold front will be coming through the region Thursday night, and temperatures comfortably drop back to the upper-70s/lower-80s for Friday and into next weekend.

2012 warmest on record for U.S., top-10 globally
August 15, 2013

By Meteorologist Mike Skurko

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2012 was among the ten warmest years on record for the entire world.  NOAA recently finished their annual “State of the Climate” report for 2012.  While we are more than halfway through 2013, this comprehensive study gathers data from 52 countries, analyzed by nearly 400 scientists around the world, thus the length of time it takes to provide a final assessment.

It was already known that 2012 was the warmest year on record for the United States.  This report reveals some startling statistics for the rest of the globe.  A few of the highlights include:

– Sea ice shrank to its smallest “summer minimum” in 34 years.

– Greenland had 4 times its average ice melt.

– For the first time in several years, neither El Nino or La Nina existed for a majority of the year.

– Sea surface temperatures ranked the 11th warmest on record

– Sea levels reached a record high, and continue rising at an average rate of 2.8 to 3.6 millimeters per year

– Antarctic sea ice extent reached a record high of 7.51 million square miles

A PDF of the full 258-page report can be found on NOAA’s website: http://www.ncdc.noaa.gov/bams-state-of-the-climate/2012.php

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“Hurricane Tips From Cuba”
August 10, 2013

By Meteorologist Mike Skurko

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A recent article in The New York Times talks about the joint collaboration between the United States’ National Hurricane Center and Cuba’s Meteorological Institute during hurricane season.  Despite having embargoes in place and no formal political relations since the Cold War, those ill feelings are put aside when it comes to hurricane forecasting.

According to the article, both weather agencies openly communicate about data analysis and storm track prediction.

“A hurricane that hits Cuba doesn’t ask for a visa before entering the United States, said Jose Rubiera, the director of Cuba’s National Prognostic Center (part of their Meteorological Institute).

Here is a link to the full article from The New York Times: Hurricane Tips From Cuba

Friday’s record rainfall totals
August 9, 2013

By Meteorologist Mike Skurko

These maps come from the National Weather Service’s network of SKYWARN reports, as well as automated rain gauges from local airports (such as Barnes Regional Airport in Westfield).  The 3.79 inches of rain recorded at Bradley Int’l is a new record for the Pioneer Valley, the previous record for this date being 3.75 inches in 1982.

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NOAA says above-normal hurricane season still on track
August 8, 2013

By Meteorologist Mike Skurko

With the peak of hurricane season just a couple of weeks away, NOAA has updated their hurricane outlook from their initial forecast in May.  NOAA still predicts a 70-percent chance of an above-normal hurricane season, with 13 to 19 named storms, 6 to 9 hurricanes, and 3 to 5 major hurricanes.

According to expert hurricane forecasters with NOAA’s Climate Predicition Center, the atmospheric conditions expected to produce an active season are still in place.  Those factors include above-average Atlantic sea surface temperatures and a strong rainy season in west Africa (which helps produce the weather patterns that lead to tropical formation off the African coast).

Fortunately, NOAA predicts a smaller chance of an “extreme” hurricane season, as they have shaved off the high-end numbers of their hurricane forecasts.  The initial forecast in May called for as many as 11 hurricanes and 6 major hurricanes.  Among the reasons for these minor tweaks include the lack of hurricanes through July and a decreased likelihood for a La Nina to develop (which often strengthens hurricane season).

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Meteorology 101: hail formation
August 4, 2013

By Meteorologist Mike Skurko

This afternoon’s thunderstorms featured small amounts of hail across the Springfield area.  While this thunderstorm did go severe just before exiting western Mass, much of the hail-produced was smaller than the warning criteria of 1-inch in diameter (quarter-sized), despite the excessive amount of it captured by viewers.

So what can cause such a seemingly-freakish “hailstorm” like today?  I suspect the cooler airmass over the region played a part.

Hail is formed by water droplets that get carried by thunderstorm updrafts to very high, very cold levels of a storm cloud.  Starting out as just a simple, small ice crystal, it can continue growing by colliding with more and more super-cooled water droplets and other crystals in the high levels of those thunderstorm clouds.  When the ice crystal becomes too large for it to remain suspended in the cloud, gravity allows it to fall back to earth.  As these ice crystals fall, they melt into raindrops (whereas in the wintertime, they stay frozen in the form of snowflakes).

Occasionally, a strong updraft may be able to “catch” the falling ice crystal, blow it back up into the storm cloud, and allow it to continue growing.  This will allow the ice crystal to develop into a larger, denser hailstone.  The stronger the updraft, the larger the hailstone (such as the massive ones found during tornado outbreaks in the Great Plains).  Eventually though, the hailstone will be too large for the updraft to keep it suspended, and will ultimately fall to the surface.  Because it has grown so large form the initial tiny ice crystal, it cannot entirely melt into a raindrop before it reaches the ground.  Thus, it pings off the surface as a hailstone!

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Various meteorological variables will determine the likelihood of thunderstorms that produce large hail, small hail, or any hail at all.  One of those factors is the freezing level.  Sorting through an array of upper-level meteorological models, the freezing level over Springfield at 6 pm this afternoon was estimated at about 2700 meters, or 8900 feet.

This is a lower-than-normal height for early August, thanks to the expected upper-level trough dropping down across the Northeast today.  This map below illustrates how most of the country is seeing freezing levels of at least 14,000 feet or higher this morning (in fact, our freezing heights seemed to lower a little bit as that trough dug in through the afternoon).  While this may not seem like a huge difference, that extra few thousand feet can be the difference between a hailstone having enough time (i.e. distance) to melt away or actually reaching the surface as a solid (but small) hailstone.  The first map is the expected freezing level from earlier this morning:

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This second map shows the expected freezing levels for Thursday morning … when our heights will be “back to normal” up closer to 15,000 feet despite the rain we’re expecting.

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Origins of “the dog days of summer”
August 2, 2013

By Meteorologist Mike Skurko

Despite our seasonal weekend ahead, and our record-warm July in the books, those sweaty “dog days of summer” may still await before August is through.

Most people use that phrase, “the dog days of summer,” to refer to the excessive heat and humidity through August.  This term gets associated with the lazy behavior that dogs exhibit to avoid the hot weather (with their human companions exhibiting this behavior too).  But that is not how or why the “dog days of summer” originated.  That can be traced back a couple thousand years.

The “dog days of summer” was coined by the ancient Greeks in reference to the “dog star” – Sirius, the brightest star in the sky.  Stars move around our night sky, sometimes appearing to rise and set over the horizon as its position changes relative to earth.  The ancient Egyptians (not the Greeks) first noted that Sirius appeared to rise just before the hottest part of the year, and set a few weeks later.  Thus they thought that this star was responsible for the heat.

The Greeks were then the first to refer to Sirius as the “dog star.”  Sirius is located on a constellation known as Canis Major, which is also paired with the constellation Orion (remember in the movie Men In Black they were looking for a galaxy on “Orion’s belt” and thought it was in reference to the stars).  In Greek astrology, Canis Major was one of Orion’s dogs hunting with him in the night sky.  Thus with Sirius being the brightest star of Canis Major, it became dubbed the “dog star.”

On a side note…here’s a nice little reminder:  with many vacations already over and back-to-school preparations starting, we are just arriving at the middle of summer.  Considering that astronomical summer began on June 21 and ends on September 22, that means Monday, August 5 will be the midpoint of our summer season.