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NOUS41 KCAR 011228
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PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE CARIBOU ME
828 AM EDT WED MAY 1 2013

THE NATIONAL WEATHER SERVICE HAS DECLARED THE WEEK OF APRIL 29
THROUGH MAY 3, SEVERE WEATHER AWARENESS WEEK IN NEW ENGLAND. THIS IS
THE THIRD IN A SERIES OF FIVE PUBLIC INFORMATION STATEMENTS ON
VARIOUS TOPICS RELATED TO SEVERE WEATHER AWARENESS.

TRAGICALLY EACH YEAR, SEVERE THUNDERSTORMS AND TORNADOES HIGHLIGHT
THE DEADLY THREAT CAUSED BY NATURES MOST VIOLENT STORMS. THE
NATIONAL WEATHER SERVICE ENCOURAGES THE PUBLIC TO BECOME MORE AWARE
OF THOSE THREATS SO THEY CAN ACT APPROPRIATELY WHEN SEVERE STORMS
THREATEN.


SEVERE THUNDERSTORMS, DOWNBURSTS, MICROBURSTS, MESO-CYCLONES, AND
HAIL

BY DEFINITION, A SEVERE THUNDERSTORM IS ONE WHICH PRODUCES WIND
GUSTS OF 58 MPH OR MORE, OR HAIL 1 INCH IN DIAMETER OR GREATER.
SEVERE THUNDERSTORMS CAN ALSO PRODUCE TORNADOES.

IN NEW ENGLAND, SEVERE THUNDERSTORMS ARE NOT UNCOMMON DURING THE
SUMMER. EVERY YEAR, THE NATIONAL WEATHER SERVICE GETS NUMEROUS
REPORTS OF WIND AND HAIL DAMAGE THROUGHOUT MAINE. SEVERE
THUNDERSTORM WINDS DOWN TREES AND BRANCHES ONTO HOMES, BUILDINGS,
VEHICLES, AND POWER LINES. SCATTERED POWER OUTAGES ARE OFTEN THE
RESULT OF LIGHTNING OR WIND-FALLEN TREES AND BRANCHES. ALSO,
WIND-DRIVEN HAIL FROM THUNDERSTORMS FLATTENS AND/OR DAMAGES CROPS IN
THE STATES. ON RARE OCCASIONS, LARGE HAIL STONES DAMAGE HOMES,
BUILDINGS, AND VEHICLES. IN ADDITION TO THE LIGHTNING, FALLING TREES
AND LARGE HAIL ALSO POSE A SIGNIFICANT THREAT TO PEOPLE.


THUNDERSTORM WINDS, DOWNDRAFTS, DOWNBURSTS, AND MICROBURSTS

DURING THE DEVELOPMENT OF A THUNDERSTORM, WARM AIR RISES UPWARD IN
THE ATMOSPHERE (AN UPDRAFT) CAUSING THE FORMATION OF CLOUDS AND
PRECIPITATION. AS A THUNDERSTORM MATURES, COOL, PRECIPITATION-LADEN
AIR SINKS DOWNWARD THROUGH THE ATMOSPHERE (A DOWNDRAFT). WHEN A
DOWNDRAFT REACHES THE GROUND IT SPREADS OUT CAUSING THE COOL, GUSTY
WIND THAT OFTEN ACCOMPANIES A THUNDERSTORM.

IN SOME THUNDERSTORMS, INTENSE DOWNDRAFTS DEVELOP. WHEN THESE
DOWNDRAFTS REACH THE GROUND, THEY SPREAD OUT VERY QUICKLY CAUSING
STRONG AND OFTEN DAMAGING WINDS AT THE GROUND. THESE INTENSE
DOWNDRAFTS ARE CALLED DOWNBURSTS AND CAN CAUSE SIGNIFICANT WIND
DAMAGE OVER LARGE AREAS. IN THE CASE OF DOWNBURSTS, THE DAMAGE IS
GENERALLY REFERRED TO AS STRAIGHT-LINE WIND DAMAGE SINCE FALLEN
TREES GENERALLY LINE UP IN THE SAME DIRECTION. IN MAINE, MOST
THUNDERSTORM WIND DAMAGE IS CAUSED BY DOWNBURSTS.

A SPECIAL TYPE OF DOWNBURST IS THE MICROBURST. MICROBURSTS GET THEIR
NAME BECAUSE THEY GENERALLY AFFECT A MUCH SMALLER GEOGRAPHICAL AREA,
BUT THE WINDS IN A MICROBURST CAN BE VERY INTENSE. LIKE THE GENERAL
DOWNBURST, MOST OF THE DAMAGE WITH MICROBURSTS LINES UP IN ONE
DIRECTION, ALTHOUGH, THERE MAY BE A TENDENCY FOR THE DAMAGE TO
RADIATE OUTWARD. MICROBURSTS ARE USUALLY ACCOMPANIED BY HEAVY RAIN
AND/OR HAIL AND CAN HAVE WINDS AS STRONG AS THOSE IN A SMALL TORNADO.

UNDER CERTAIN ATMOSPHERIC CONDITIONS, THUNDERSTORMS CAN BEGIN TO
DEVELOP A CIRCULATION WITHIN THE THUNDERSTORM CLOUD. THESE STORMS
ARE OFTEN CALLED MESOCYCLONES BECAUSE OF THE COUNTER-CLOCKWISE
CIRCULATION THAT DEVELOPS WITHIN THE STORM. THE UPDRAFTS AND
DOWNDRAFTS IN THESE STORMS CAN PERSIST FOR HOURS AS THE STORM MOVES
ALONG ITS PATH. SEVERE WINDS AND HAIL ARE ALSO MORE LIKELY WITH
MESO-CYCLONES, AND IF THE ROTATION WITHIN THE STORM BECOMES MORE
INTENSE, THERE IS AN INCREASING POSSIBILITY THAT THE STORM MIGHT
PRODUCE A TORNADO. NATIONAL WEATHER SERVICE DOPPLER RADAR ALLOWS
METEOROLOGISTS TO MONITOR AIR MOVEMENT WITHIN THESE STORMS AND TO
SEE THE DEVELOPMENT AND STRENGTH OF ANY CIRCULATION WITHIN THE STORM.

DURING THE SUMMER OF 2011, MAINE HAD NUMEROUS THUNDERSTORMS THAT
PRODUCED DAMAGING STRAIGHT-LINE WINDS. TRAGICALLY, ONE PERSON WAS
KILLED WHEN A TREE FELL ON THEIR CAR. FALLING TREES CAUSED BY
THUNDERSTORM WINDS WERE ALSO RESPONSIBLE FOR TWO DEATHS IN THE AREA
IN 2006. THE FIRST DEATH OCCURRED IN FRYEBURG, MAINE ON JUNE 19 WHEN
A TREE FELL ON A TENT IN WHICH PEOPLE WERE CAMPING. THE SECOND
OCCURRED IN WATERBORO, MAINE ON SEPTEMBER 9 WHEN THE TOP OF A TREE
FELL ON A VEHICLE KILLING THE DRIVER.


HAIL

THE CIRCULATION THAT ACCOMPANIES A MESO-CYCLONE IS ALSO A FACTOR IN
HAIL FORMATION. HAIL INITIALLY FORMS WHEN LIQUID WATER DROPLETS ARE
CARRIED UPWARD BY THE UPDRAFT TO A LEVEL WHERE THE DROPLETS FREEZE.
EVENTUALLY, THE SMALL HAIL STONE MAY BEGIN TO FALL DOWNWARD, ONLY TO
BE CAUGHT ONCE AGAIN BY THE PERSISTENT UPDRAFT OF A MESO-CYCLONE.
EACH TIME THE HAILSTONE GOES THROUGH THIS PROCESS, IT GETS LARGER
AND HEAVIER. EVENTUALLY, THE HAILSTONE WILL BE BLOWN AWAY FROM THE
UPDRAFT OR WILL BECOME TOO HEAVY FOR THE UPDRAFT TO SUPPORT AND THE
HAILSTONE WILL FALL TO THE GROUND.

IN MAINE, HAIL IS FAIRLY COMMON DURING WELL-DEVELOPED SUMMERTIME
THUNDERSTORMS. ALTHOUGH MOST HAIL THAT REACHES THE GROUND IN
NORTHERN NEW ENGLAND IS AN INCH OR LESS IN DIAMETER, OCCASIONALLY
HAILSTONES OVER 2 INCHES IN DIAMETER WILL FALL. LARGE HAILSTONES CAN
FALL AT SPEEDS FASTER THAN 100 MPH AND CAN DO CONSIDERABLE DAMAGE TO
CARS, HOMES, AND BUILDINGS, AND CAN BE A SIGNIFICANT THREAT TO
PEOPLE, AS WELL.

HERE ARE SOME OF THE LARGER HAILSTONES REPORTED IN NORTHERN NEW
ENGLAND SINCE 1995.

3.00 INCHES
     JUN 19 1995  SPRINGFIELD, MAINE
     JUN 22 2008  MT. CARDIGAN, NEW HAMPSHIRE

2.75 INCHES
     AUG 24 1998  TAMWORTH/FREEDOM, NEW HAMPSHIRE
     JUN 01 2011  KINGFIELD, MAINE

2.50 INCHES
     AUG  4 2007  FT. KENT, MAINE
     MAY 27 2011  BINGHAM, MAINE

2.00 INCHES
     AUG 18 1996  LINCOLNVILLE, MAINE
     JUL 11 2006  EXETER, NEW HAMPSHIRE
     JUL 11 2006  HAMPTON FALLS, NEW HAMPSHIRE
     JUL  9 2007  CONCORD, NEW HAMPSHIRE
     AUG  4 2007  GRAND ISLE, MAINE
     AUG  4 2007  CARIBOU, MAINE
     AUG 30 2007  ROME, MAINE
     JUL 18 2008  STRAFFORD, NEW HAMPSHIRE
     JUN  5 2010  SOUTH PARIS, MAINE

FOR BOTH SEVERE WINDS (58 MPH OR GREATER) AND LARGE HAIL (1 INCH OR
GREATER IN DIAMETER), THE NATIONAL WEATHER SERVICE ISSUES SEVERE
THUNDERSTORM WATCHES AND WARNINGS. A WATCH INDICATES THAT THE
ATMOSPHERIC CONDITIONS ARE FAVORABLE FOR SEVERE WEATHER TO DEVELOP.
A WARNING INDICATES THAT SEVERE WEATHER IS IMMINENT OR IS ALREADY
OCCURRING. IF YOU HEAR A WARNING FOR YOUR AREA, BE PREPARED TO SEEK
A SAFE SHELTER IF YOU ARE IN THE PATH OF THE STORM.

HERE IS A LIST OF TOPICS COVERED IN PUBLIC INFORMATION STATEMENTS
ISSUED BY THE NATIONAL WEATHER SERVICE THIS WEEK.

MONDAY......SEVERE WEATHER AWARENESS - BASIC DEFINITIONS
TUESDAY.....THUNDERSTORMS AND LIGHTNING
WEDNESDAY...SEVERE THUNDERSTORMS - DOWNBURSTS, MICROBURSTS, AND HAIL
THURSDAY....TORNADOES
FRIDAY......FLASH FLOODS

$$

RUNYAN