Heavy snow over interior Southern
New England December 23, 1997
|Low pressure moved from the Ohio
Valley into Upstate New York. A secondary low pressure center formed along the New Jersey
coast. This second storm rapidly intensified as it moved northeast to a position just
southeast of Nantucket.
At first glance, this may look like rain with embedded
thunderstorms. But actually, it is an area of rain only along the Massachusetts and Rhode
Island coasts. Over the remainder of the area it is snow. On this color scale, snow
usually falls in intensities that show up as blue, or green. Once in a while, an area of
yellow will show suggesting very heavy snow. In this picture...not only are there large
areas of yellow, but even a line of red north of Worcester MA. This suggests areas of very
In fact, Ayer MA in northwest Middlesex County reported a
total of 21 inches accumulation from this storm, including 8 inches of snow in one hour.
Nashua NH reported 20.5 inches. Chelmsford MA reported 20.1 inches, including 6 inches in
one hour. Worcester MA reported 18 inches.
Bow Echo enters Brockton MA on May
|A strong cold front moved across
the region during the mid to late afternoon of May 21st, producing strong thunderstorms
and numerous reports of damaging winds. A downburst occurred in the Brockton MA area,
producing winds estimated at 70 to 100 mph and causing extensive damage. A Severe
Thunderstorm Watch was issued for all of southern New England; subsequently, Severe
Thunderstorm Warnings were issued for Hartford, Tolland, and Windham Counties in northern
Connecticut, and for Hampden, southern Worcester, Plymouth, and Barnstable Counties in
In the image, note the
"horseshoe" pattern of the line of thunderstorms south of Boston. Dry air is
being drawn into the rear of this storm. The evaporation and cooling caused as this dry
air entered the storm resulted in the downburst that moved through the Brockton area. Also
note the thin line from Middleboro MA to East Greenwich RI; this is the leading edge of
the cool air outflow from these thunderstorms.
Tropical Storm (formerly Hurricane)
Floyd comes ashore Sept. 16, 1999
|Hurricane Floyd generated a lot
of headlines as it approached the United States in September 1999. The storm turned north
and moved ashore in North Carolina; it then moved back over the coastal waters as it moved
up the coast on September 16. Around 8 o'clock in the evening, Floyd moved ashore at Long
Island, NY, just east of Kennedy Airport. The storm then moved northeast across eastern
Connecticut and northeast Massachusetts.
One of the
Realities of New England hurricanes is that most of the heavy rain occurs along and to the
left of the storm track. Note where most of the rain is located in this image. It is along
and west of the path the storm eventually followed. Note also that there is very little
rainfall to the east and south of the storm.
Doppler Velocity Image,
Thunderstorm Circulation, Great Barrington MA May 29, 1995
|A line of thunderstorms moved
from New York into western New England. One thunderstorm moving out of Columbia County NY
into southern Berkshire County MA produced a tornado as it approached the town of Great
Barrington MA. This tornado destroyed the fairgrounds and killed 3 people trapped in an
automobile. The tornado remained on the ground for 18 minutes, lifting off the ground near
Sandisfield, MA, near the Hampden County line.
image is an example of how Doppler Radar displays not just where the storms are, but also
the motion within the storms. In the picture the WFO Taunton radar is off the picture to
the right. Red is motion away from the radar, while green and blue are motion toward the
radar. The is one spot, which the radar computer has flagged, where there are red and blue
readings directly next to one another. If the red is "to the right of the
radial" from the radar, then this shows a counterclockwise circulation. What you are
seeing in this image is not the tornado, but rather the parent circulation that would,
within 8 minutes, give birth to the Great Barrington tornado.
Thunderstorms in Franklin County MA June 13, 1996
|Showers and thunderstorms
developed during the afternoon along a weak cold front that moved slowly east across the
area. Wind damage was reported in several locations across central and western
Massachusetts. One-inch hail was reported in the town of Leverett MA (Franklin County). In
addition, thunderstorms traveling along an identical path over a short period of time (or
"training") produced very heavy rainfall and flash flooding in parts of western
Massachusetts. The Sawmill River in Leverett saw the worst flooding in 100 years. Rainfall
was measured at 3.19 inches in Greenfield MA, 2.85 inches at Amherst MA, and 1.29 at
In the image, note the large area of
red southeast of Greenfield MA. This thunderstorm is producing hail and heavy rain over
Leverett. Meanwhile, the two small red cells northwest and south-southeast of Northampton
would, within 30 minutes, travel over Leverett as well.
Smoke Plume from Malden Mills
fire December 12, 1995
|This image shows how sensitive
the Doppler Radar can be. The radar is in "clear air mode", taking twice as long
to do a complete scan of the atmosphere as it does in "precipitation mode". It
is clearly detecting the plume of smoke particles, with the strongest concentration near
Lawrence MA and lesser concentration of particles downwind to the southeast.
Ocean effect snow over
Nantucket January 18, 1997
|Very cold west winds moving over
the warmer ocean water created a band of snow showers that grazed Marthas Vineyard and
moved directly across Nantucket MA. This is similar to the "lake effect snows"
that occur to the lee of the Great Lakes each winter. Amounts from such snow bands can
vary greatly over the space of a few miles. Nantucket reported a total accumulation of 8
inches. Tisbury (on Marthas Vineyard) received 3 inches, Vineyard haven 1.5 inches, and
Edgartown 0.8 inches.
As a bonus, note the thin line
extending from Taunton toward the southeast. This is how sunrise appears on the radar. The
steady stream of energy from the sun is interpreted by the radar as precipitation all
along that particular radial. Sunset looks similar, but to the west. The location and time
of occurrence changes with time of year as does the location of sunrise and sunset.
Heavy prolonged rainfall in Northeast Massachusetts - October 19-21, 1996
| An extremely prolonged
Noreaster pounded southern New England with very heavy rainfall and strong winds. Winds
gusted as high as 81 mph over coastal Rhode Island with gusts of 50 to 60 mph common in
all coastal areas. Rainfall totals of 6 to 12 inches fell in eastern Massachusetts and
southern New Hampshire with 2 to 5 inches elsewhere. Some totals include Newburyport MA
13.03 inches, Bedford MA 11.21 inches, East Woburn 10.75 inches, Groveland MA 10.10
inches, Rockport MA 9.68 inches, Boston (Logan Airport) 7.92 inches.
This image is an estimate made by the radar as to how much rain
fell. It is based on the total amount of energy reflected back to the radar; it uses
equations based on comparisons of past rainfall with observed radar reflectivity. Note the
two maxima of rainfall...one near Boston and the second in western Connecticut. The storm
drew on moisture from a tropical system well offshore; this enhanced the amount of
moisture available for rain. For a while, this moisture was fed up across Long Island into
western Connecticut. When the storm shifted, the winds drawing on the moisture also
shifted and refocused the area of maximum rainfall in northeast Massachusetts.
Squall Line of Thunderstorms
moves through Central New England May 31, 1998
|A powerful cold front combined
with a warm and humid air mass to produce widespread severe weather across southern New
England. Wind damage and large hail were common and there was a tornado in northern
Hillsborough County NH near Antrim.
The image shows
the radar reflectivity image as a squall line becomes severe. The line has evolved from a
straight line into a bow-shaped line. This comes about as outflow from one storm races
ahead of the outflow from the adjoining storms.
The image worcvel.jpg
shows the radar's velocity measurements from the same time. The fastest motion is located
near the head of the bow, which is near Worcester. A wind gust to 104 mph was measured
from this squall line at Worcester.