Severe Weather Awareness Week - Thursday Statement

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE GRAY ME
800 AM EDT THU May 2 2019

The National Weather Service has declared the week of April
29th through May 3rd...SEVERE WEATHER AWARENESS WEEK in New
England. This is the fourth in a series of five Public
Information Statements on topics related to severe weather
awareness.

...SEVERE WEATHER AWARENESS - TORNADOES...

Tornadoes are nature's most violent storm. By definition, a
tornado is a violently rotating column of air that extends
from the base of a thunderstorm cloud to the ground.

In addition to the three basic ingredients needed for the
formation of thunderstorms and severe thunderstorms (low-level
moisture, an unstable atmosphere, and a source of lift), winds
at various levels in the atmosphere factor into the
development of tornadoes.

Usually, prior to the development of a tornado, a pre-tornadic
thunderstorm develops an internal circulation (in other words, a
mesocyclone forms). The stronger the rotation, the greater the
chance that a tornado may develop. Although the National Weather
Service's Doppler radar generally cannot detect the actual
tornado, the radar does detect the rotation of the mesocyclone and
thereby gives some indication of the possibility that a tornado
may be forming (or has already formed).

The scale used to measure tornado damage is the Enhanced
Fujita scale (named after Theodore Fujita, a famous tornado
damage expert). This scale is commonly referred to as the E-F
scale. Based on scientific studies of tornado damage, the
original Fujita scale was modified and the new "Enhanced
Fujita Scale" was officially implemented in 2007.

  EF-0 - Light damage (winds 65 to 85 mph)
  EF-1 - Moderate damage (winds 86 to 110 mph)
  EF-2 - Considerable damage (winds 111 to 135 mph)
  EF-3 - Severe damage (winds 136 to 165 mph)
  EF-4 - Devastating damage (winds 166 to 200 mph)
  EF-5 - Incredible damage (winds over 200 mph)

Peak tornado activity in northern New England occurs between
June and August, but tornadoes have occurred as early as May
and as late as November. Most tornadoes occur between 3 and 9
pm and have an average forward speed of about 30 mph. For the
40 year period between 1950 and 1990, 74 tornadoes occurred in
Maine while 68 tornadoes occurred in New Hampshire. Based on
these data, each state had averaged about two tornadoes per
year. During this period, the average path length of the
tornadoes was 1.08 miles for Maine and 1.64 miles for New
Hampshire. The strongest tornado observed in Maine was an F2,
while the strongest tornado observed in New Hampshire was an
F3.

In 2018, there were 3 confirmed tornadoes in New Hampshire and
none in Maine. For comparison’s sake, in 2017, there were 7
confirmed tornadoes in Maine (including 5 in one day) and none
in New Hampshire.  

Here is a list of the 76 documented tornadoes in Maine and New
Hampshire since 1995.

EF2/F2
     Jul 08 1996  Cobbosseecontee Lake, Maine
     Jul 03 1997  Greenfield, New Hampshire
     May 31 1998  Antrim, New Hampshire
     Jul 06 1999  Pittsfield/Barnstead/Strafford,
                  New Hampshire
     Aug 09 2000  Cornville, Maine
     May 21 2006  Hampton Falls, New Hampshire
     Jul 24 2008  Deerfield to Freedom, New Hampshire
                  (50 mile path length)

EF1/F1
     Jul 23 1995  New Hampton, New Hampshire
     Jun 21 1997  Rome, Maine
     Jul 03 1997  Swanzey, New Hampshire
     Oct 01 1998  South Paris, Maine
     Aug 13 1999  Sweden, Maine
     Aug 13 1999  Plainfield/Enfield, New Hampshire
     Jul 18 2000  Newry/Hanover, Maine
     Jun 17 2001  Newry/Hanover, Maine
     Jul 24 2001  Penobscot County (16 miles northwest of
                  Patten)
     Jul 24 2001  Oakfield, Maine
     May 31 2002  West Paris, Maine
     Jul 04 2002  Aroostook County (8 miles west of
                  Littleton)
     Nov 24 2005  Phippsburg, Maine
     Sep 29 2006  North Berwick, Maine
     May 24 2009  Eagle Lake, Maine
     May 31 2009  Westfield, Maine
     May 31 2009  Easton, Maine
     Aug 21 2009  Norway to Hartford, Maine
                  (up to 700 yards wide)
     Jun  5 2010  South Paris, Oxford, Hebron, Maine
     Jul 21 2010  Newfield to Limerick, Maine
     Jul 21 2010  Buxton to Gorham, Maine
     Jul 21 2010  Shapleigh to Alfred, Maine
     Jun  1 2011  Bryant Pond, Maine
     Jun  1 2011  New Portland to Embden, Maine
     Aug 21 2011  Canaan, New Hampshire
     Jul 15 2014  Saint Albans, Maine
     Jul 28 2014  Limington, Maine
     Jul 01 2017  Bridgton, Maine     
     Jul 01 2017  Denmark, Maine
     Jul 01 2017  Bridgton, Maine
     Aug 05 2017  Millinocket, Maine
     Aug 05 2017  Sherman, Maine
     May 04 2018  North Walpole to Acworth, New Hampshire

EF0/F0
     Jul 28 1997  Ft. Kent, Maine
     Aug 27 1997  Charleston, Maine
     Jul 23 2002  Aroostook County (7 miles northwest of
                  Knowles Corner)
     Aug 08 2004  Sebago Lake, Maine
     Aug 13 2004  Sanbornton/Meredith, New Hampshire
     Aug 01 2005  North Twin Lake, Maine
     Nov 24 2005  Brunswick, Maine
     Sep 29 2006  Effingham, New Hampshire
     Jul 15 2007  Long Lake in Aroostook County, Maine
     May 31 2009  Oxbow, Maine
     Jun 26 2009  Stockholm, Maine
     Jul 18 2009  East Bethel, Maine
     Jun  2 2010  Shin Pond, Maine
     Jun  5 2010  Gorham, New Hampshire
     Jun  8 2011  Little Madawaska Lake, Maine
     Jun  8 2011  Aroostook County, Maine
     Jun  9 2011  Aroostook County, Maine
     Jul 26 2011  Colebrook, New Hampshire
     Jun 25 2012  West Alton, New Hampshire
     Jul 17 2012  Bridgewater, New Hampshire
     Jul 24 2012  Woolwich, Maine
     Jun  2 2013  Pleasant Ridge Plantation, Maine
     Jul 17 2013  Danforth, Maine
     Jul 19 2013  14 miles north of Chamberlain Lake, Maine
     Sep 11 2013  15 miles east of Churchill Dam, Maine
     May 26 2014  Ludlow, Maine
     Jul  4 2014  Lake Winnipesaukee, NH (Waterspout)
     Jul 24 2014  Lake Winnipesaukee, NH (Waterspout)
     Jul 27 2014  Sebago Lake, ME (Waterspout)
     Jul 30 2015  Warner, New Hampshire
     Jul 18 2016  Pittsburg, New Hampshire
     Jul 18 2016  Hanford, Maine
     Jul 01 2017  East Sebago, Maine  
     Jul 01 2017  Otisfield, Maine
     Jun 18 2018  Bath to Easton, New Hampshire
     Jun 18 2018  Near Mt. Pemigewassett, New Hampshire   

To alert the public to the threat of tornadoes, the National
Weather Service issues TORNADO WATCHES and WARNINGS. A TORNADO
WATCH indicates that atmospheric conditions are favorable for
the development of tornadoes. A TORNADO WARNING indicates that
a tornado is imminent or is already occurring. If you hear
that a TORNADO WARNING has been issued for your area, seek
safe shelter immediately if you are in the path of the storm.

Due to the usually short life-span of tornadoes in northern
New England, there is often little, if any, advance warning.  
Tornadoes in New England generally touch down and then lift
off the ground very quickly. Many of the tornadoes that have
occurred in the past have occurred while severe thunderstorm
warnings have been in effect. If you hear that a SEVERE
THUNDERSTORM WARNING is in effect for your area, also be alert
for the possibility of a tornado. A low rotating cloud, large
hail, and/or a load roar are all signs that may precede the
touchdown or arrival of a tornado.

Here are some tornado facts and safety tips:

   *  Flying debris causes most deaths and injuries in
      tornadoes.

   *  The safest place in your home during a tornado is your
      basement.

   *  Stay away from windows.

   *  Get out of vehicles or mobile homes as they offer little
      protection. Seek shelter in a substantial building.

   *  Do NOT seek shelter under a bridge overpass. Bridge
      overpasses offer little, if any, protection from wind-
      driven debris.

Here is a list of the remaining topics that will be covered in
Public Information Statements issued by the National Weather
Service this week.

Friday......Flash Floods
$$

Watson
National Weather Service
Gray, Maine

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