...DERECHO HIT SOUTHERN NEW ENGLAND ON WEDNESDAY AUGUST 2 2006...

THE NATIONAL WEATHER SERVICE IN TAUNTON MASSACHUSETTS...IN 
CONSULTATION WITH THE STORM PREDICTION CENTER IN NORMAN 
OKLAHOMA...HAS DETERMINED THAT THE EXTENSIVE DAMAGE THAT OCCURRED ON 
WEDNESDAY AUGUST 2 WAS CAUSED BY WHAT IS TERMED A "DERECHO." 

A DERECHO IS A LONG-LIVED...WIDESPREAD...AND RAPIDLY MOVING 
CONVECTIVE WINDSTORM THAT ESSENTIALLY IS COMPRISED OF A FAMILY OF 
DOWNBURST CLUSTERS. DOWNBURSTS CAN BE EITHER MICROBURSTS OR 
MACROBURSTS...DEPENDING ON WHETHER THE DAMAGE SWATH IS LESS THAN OR 
GREATER THAN 2.5 MILES. THE RESULT OF THIS FAMILY OF DOWNBURST 
CLUSTERS IS WIDESPREAD STRAIGHT-LINE WIND DAMAGE OVER A LARGE AREA. 
THE WINDS ASSOCIATED WITH DERECHOS ARE NOT CONSTANT AND MAY VARY 
CONSIDERABLY ALONG ITS PATH...SOMETIMES BEING BELOW SEVERE LIMITS 
(57 MPH OR LESS) AND SOMETIMES BEING VERY STRONG (GREATER THAN 100 
MPH IN EXTREME DERECHOS). 

THE WORD DERECHO WAS COINED BY DR. GUSTAVUS HINRICHS...A PHYSICS 
PROFESSOR AT THE UNIVERSITY OF IOWA...IN A PAPER PUBLISHED IN THE 
AMERICAN METEOROLOGICAL JOURNAL IN 1888. DR. HINRICHS CHOSE THIS 
TERMINOLOGY FOR THUNDERSTORM-INDUCED STRAIGHT-LINE WINDS AS OPPOSED 
TO THE WORD TORNADO. DERECHO IS A SPANISH WORD WHICH CAN BE DEFINED 
AS "DIRECT" OR "STRAIGHT AHEAD" WHILE TORNADO IS THOUGHT BY 
SOME...INCLUDING DR. HINRICHS...TO HAVE BEEN DERIVED FROM THE 
SPANISH WORD "TORNAR" WHICH MEANS "TO TURN."

THE MODERN-DAY STRICT DEFINITION OF A DERECHO REQUIRES THAT ITS 
LENGTH BE GREATER THAN 240 MILES...HOWEVER THE STORM PREDICTION 
CENTER ACKNOWLEDGES THAT TRUE DERECHOS CAN BE SOMEWHAT SHORTER IN 
LENGTH. THE WEDNESDAY STORM ORIGINATED IN NORTHWEST MASSACHUSETTS 
IN THE SLOPES OF THE BERKSHIRES AND TRAVELED SOUTHEASTWARD...
IMPACTING MUCH OF MASSACHUSETTS SOUTH OF THE MASS PIKE...NORTHEAST 
CONNECTICUT...RHODE ISLAND...AND IT FINALLY EXITED THE CAPE AND 
ISLANDS. THIS WAS APPROXIMATELY 175 MILES. 

TREES AND WIRES WERE REPORTED DOWN IN CONWAY...ASHFIELD...AND 
CHARLEMONT IN FRANKLIN COUNTY MASSACHUSETTS SHORTLY AFTER 4 PM.
SIMILAR DAMAGE OCCURRED IN HAMPSHIRE AND HAMPDEN COUNTIES AFTER 
THAT. THERE WERE REPORTS OF TREES DOWN ON HOUSES AND SOME CARS.
SHORTLY AFTER 5 PM...A VERY OLD ROOF WAS BLOWN OFF OF AN APARTMENT 
COMPLEX IN SPRINGFIELD...WHICH MADE THE 11 UNITS ON THE FIFTH FLOOR 
UNINHABITABLE. IT IS ESTIMATED THAT STRAIGHT LINE WIND GUSTS OF 
70-80 MPH HAD OCCURRED THERE. 

AT APPROXIMATELY 515 PM...AN AM RADIO STATION TOWER WAS KNOCKED OVER 
IN DUDLEY MASSACHUSETTS IN SOUTHERN WORCESTER COUNTY. THE TOWER WAS 
240 FEET TALL. BASED ON CONVERSATIONS WITH THE STATION ENGINEER AND 
THE FACT THAT 70 TO 80 MPH WINDS HAD REACHED GROUND LEVEL 
ELSEWHERE...IT IS CONCEIVABLE THAT WIND SPEEDS AT THE TOP OF THE 
TOWER APPROACHED 100 MPH. 

DAMAGING WINDS CONTINUED TO CAUSE TREES AND WIRES TO BE BLOWN DOWN 
IN GRANBY...ENFIELD...THOMPSON...AND KILLINGLY CONNECTICUT. 
TREES FELL ONTO HOUSES AND CARS IN MEDWAY AND FOXBORO MASSACHUSETTS.
A VERY SIGNIFICANT DOWNBURST OCCURRED IN SHARON...STOUGHTON...AND 
BROCKTON MASSACHUSETTS. LARGE TREES WERE SNAPPED NEAR THEIR BASES OR 
UPROOTED ENTIRELY. UTILITY POLES CONSISTING OF SOUTHERN YELLOW PINE 
WERE SNAPPED 6 FEET ABOVE GROUND LEVEL NEAR ROUTES 24 AND 123 IN 
BROCKTON.

SHORTLY AFTER 7 PM...LARGE TREE LIMBS WERE DOWNED IN PORTSMOUTH AND 
TIVERTON RHODE ISLAND AND WIRES WERE DOWNED IN NEWPORT. IN WARREN 
RHODE ISLAND...12 STUDENTS HAD TO BE RESCUED WHEN THEIR BOATS 
CAPSIZED. THERE WERE NO INJURIES. THE DAMAGE CONTINUED ALL THE WAY 
TO THE SOUTHEAST MASSACHUSETTS COAST WHERE TREES AND WIRES WERE 
DOWNED IN DARTMOUTH...NEW BEDFORD...AND FAIRHAVEN.
CLOUD TO GROUND LIGHTNING WAS EXTREMELY FREQUENT AND STARTED SEVERAL 
BUILDING FIRES AS THE STORMS CROSSED THE REGION. IN ADDITION...
PENNY SIZED HAIL WAS REPORTED WITH A FEW OF THE STORMS...IN HOLDEN 
MASSACHUSETTS...SHARON MASSACHUSETTS...AND TIVERTON RHODE ISLAND.

THE AFOREMENTIONED LOCATIONS WERE CHOSEN TO ILLUSTRATE THE 
WIDESPREAD NATURE OF THIS EVENT. THERE WERE SEVERAL OTHER TOWNS 
NOT LISTED THAT REPORTED TREES...TREE LIMBS...OR WIRES DOWNED. 

THE LAST DERECHO TO AFFECT SOUTHERN NEW ENGLAND WAS ON JULY 15, 1995...
WHEN A BAND OF SEVERE THUNDERSTORMS RACED FROM THE UPPER 
PENINSULA OF MICHIGAN AT MIDNIGHT TO THE COAST OF MASSACHUSETTS BY 
8 AM. A WIND GUST TO 93 MPH WAS RECORDED AT OTIS MASSACHUSETTS IN 
BERKSHIRE COUNTY AND SEVERE WEATHER WAS REPORTED AS FAR EAST AS 
WORCESTER COUNTY BEFORE IT FINALLY BEGAN DISSIPATING BELOW SEVERE 
THRESHOLDS.