Archive for August, 2014

NOAA updates Atlantic hurricane season forecast
August 9, 2014

By Meteorologist Mike Skurko

With the peak of Atlantic hurricane season nearly here, NOAA forecasters have increased the likelihood of a below-normal season.

“We are more confident that a below-normal season will occur because atmospheric and oceanic conditions that suppress cyclone formation have developed and will persist through the season.” said Gerry Bell, Ph.D., lead seasonal hurricane forecaster at NOAA’s Climate Prediction Center, a division of the National Weather Service.

In their initial outlook in May, NOAA predicted a 50 percent chance of a below-normal season, a 40 percent chance of a normal season, and a 10 percent chance of an above normal season.  Those numbers are now 70 percent, 25 percent and 5 percent, respectively.

The chart below shows their new numbers predicted for the Atlantic hurricane season.  The new range of numbers shows one less named storm, and the possibility of no major hurricanes at all:

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The initial factors relating to a below-normal hurricane season can be found in our CBS3 Pinpoint Weather Blog entry from May.

The entire press release from NOAA can be found here: http://www.noaanews.noaa.gov/stories2014/20140807_hurricaneoutlook_atlantic_update.html

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Hawaii bracing for back-to-back hurricanes
August 7, 2014

By Meteorologist Mike Skurko

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Hurricane Iselle is expected to make landfall late Thursday night on the Big Island of Hawaii.  The category 1 storm is packing winds of 75 mph, and will bring excessive rain and high surf to the islands.  Below is a forecast graphic from the National Weather Service in Honolulu depicting the landfall of the hurricane around 10 p.m. Hawaii Standard Time (4 a.m. Friday for us).  You can see how the eye of the storm will pass right over the big island, with waves above 20 feet expected in advance of the storm.  A wind speed of 54 knots shown below equals 62 mph.

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Believe it or not, Hawaii does not frequently see a direct hit form a hurricane.  It does get brushed by storms in the Central Pacific, similar to how New England gets brushed by hurricanes but infrequently sees a direct landfall.  Iselle will be the first hurricane to make a landfall on the Hawaiian Islands since 1992, with only two others directly hitting Hawaii since 1950.

That makes the next point even more unbelievable … another hurricane, Julio, is on the heels of Iselle and has Hawaii in its path.  While it did strengthen to a Category 2 hurricane earlier today, it is expected to weaken this weekend.

Meteorology 101: cold pool aloft
August 6, 2014

By Meteorologist Mike Skurko

You here this expression a lot in weather forecasts – “cold pool aloft.”  What exactly does that mean? Why is it commonly attributed to afternoon cloud development and a chance of rain showers?

A cold pool aloft is exactly as it sounds … it’s a cooler-than-normal pocket of air in the higher levels of the atmosphere.  Frequently, these cold pools are assessed at about 10,000 to 20,000 feet.  It doesn’t create a chilling effect at the surface for us, many times not having a significant impact on the day’s temperatures.  But it does aid in cloud and thunderstorm development higher up in the atmosphere.

As a parcel of air at the surface warms up during the day, it wants to rise.  This is because warmer air is less dense/more buoyant than the cooler air around it.  As it rises, the parcel of air cools off as well according to laws of thermodynamics.  Eventually, it finds an equilibrium in the atmosphere.

However, when a “cold pool aloft” exists, the parcel that began rising from the surface wants to continue rising through the cold pool.  Even though the parcel was cooling as it rises, it still remains relatively warmer than the cold pool and wants to continue its upward journey.

With these air parcels being allowed to continue rising, it induces more cloud development and rain/thunderstorm potential.  This is why cold pools aloft are often described as an unstable atmosphere.

Tropical Storm Bertha innocently passes by
August 5, 2014

By Meteorologist Mike Skurko

A disorganized and quickly weakening Tropical Storm Bertha will make its closest pass by New England on Wednesday, but it will have no effect on the weather around the region.  It was briefly upgraded to category 1 hurricane status (74-82 mph), but was downgraded early Tuesday morning as it passed by the Carolinas.  The orange shaded area inside the yellow line represents the storm’s tropical storm force wind field of at least 39 mph, with maximum winds estimated near 50 mph.

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While the storm has no impacts on the weather, it will impact the surf.  The National Weather Service has issued a Rip Current Statement for ocean-facing beaches along the southern New England Coast.

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Massachusetts tornado facts
August 3, 2014

By Meteorologist Mike Skurko

After an EF-2 tornado touched down just north of Boston on Monday morning, the National Weather Service compiled a bunch of information regarding tornadoes in Massachusetts.  Monday’s tornado was rare for two reasons – it was the first tornado on record in Suffolk County, and occurred at about 9:30 in the morning.

Here is a bunch of graphics regarding tornado frequency across the state by month, strength, and county:

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July 2014 recap
August 2, 2014

By Meteorologist Mike Skurko

Temperatures were about a degree above average in June, and we continued that pace for this past July.  We also got a little more rain returning to the region over the last month after about a two-inch deficit in June.  Our total precipitation for the year is 1.87 inches above normal.

We had our first official heat wave of the year July 1 – 3, with highs reaching 93, 95, and 91 degrees.  Our total number of 90-degree days this summer is now at ten (Bradley International’s yearly average is 18).

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