Public Information Statement
Issued by NWS Portland, ME

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000 NOUS41 KGYX 271123 PNSGYX PUBLIC INFORMATION STATEMENT NATIONAL WEATHER SERVICE GRAY ME 730 AM EDT WED APR 27 2016 THE NATIONAL WEATHER SERVICE HAS DECLARED THE WEEK OF APRIL 25TH THROUGH 29TH, 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. ...SEVERE WEATHER AWARENESS - 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 AND NEW HAMPSHIRE. 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 HAILSTONES DAMAGE HOMES, BUILDINGS, AND VEHICLES. IN ADDITION TO THE LIGHTNING, FALLING TREES AND LARGE HAIL ALSO POSE A SIGNIFICANT THREAT TO PEOPLE, AS WELL. 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 AND NEW HAMPSHIRE, 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 MESO-CYCLONES 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. 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 AND NEW HAMPSHIRE, 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. DURING 2015 IN MAINE, THE MOST SIGNIFICANT HAIL REPORTS WERE 2.75 INCHES IN NORTH BERWICK AND 2.5 INCHES IN WATERBORO. IN NEW HAMPSHIRE, THE MOST SIGNIFICANT REPORT WAS 2.50 INCHES IN ROCHESTER. HERE ARE SOME OF THE LARGER HAILSTONES REPORTED IN MAINE AND NEW HAMPSHIRE 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 1 2011 KINGFIELD, MAINE 2.50 INCHES AUG 4 2007 FT. KENT, MAINE MAY 27 2011 BINGHAM, MAINE JUL 19 2015 ROCHESTER, NEW HAMPSHIRE 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 MAY 29 2012 WESTMORELAND, NEW HAMPSHIRE JUN 29 2013 ANDOVER, MAINE SEP 11 2013 WINDHAM, MAINE SEP 12 2013 UPTON, MAINE JUL 3 2014 STATHAM, NEW HAMPSHIRE 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 THE OTHER TOPICS THAT WILL BE COVERED IN PUBLIC INFORMATION STATEMENTS ISSUED BY THE NATIONAL WEATHER SERVICE THIS WEEK. THURSDAY....TORNADOES FRIDAY......FLASH FLOODS $$ JENSENIUS NATIONAL WEATHER SERVICE GRAY, MAINE NNNN

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