We got word from the National Weather Service this morning that they’ll be sending a survey team to Wareham, MA today to investigate a possible “microburst” from the severe thunderstorms that rolled through there yesterday evening.  A squall line of intense thunderstorms marched through SE RI and southern Bristol County, bringing flash flooding and damaging winds.  There was a cluster of storm reports that came in from Wareham around 8pm– “Trees and wires down on Swift Ave… High and Sawyer Streets blocked by trees with wires down… tree down with wires down on Pinehurst Drive, 2 Utility Poles down– It’s those reports, combined with analyzing the Doppler radar from that time that will determine what actually caused the damage.  Our weather team yesterday noticed the bow echo on the radar within the squall line, which can sometimes lead to a microburst.

A “microburst” is a very localized column of swiftly sinking air that causes straight-line wind damage.  The damage can be similar to tornadoes–with fully grown trees knocked over. The difference is that the damage usually is going out (divergent) from the path of the thunderstorm, whereas tornadoes  have convergent damage along the path of the twister.

Microburst Illustration

I mentioned yesterday morning that we were concerned about the possibility of isolated severe storms bringing pockets of wind damage even a day after Hurricane Sandy made landfall.  In fact, we were even concerned about weak tornadoes forming.  They are usually short-lived and  occur in thunderstorms embedded in rain bands well away from the center of a hurricane.  Luckily, Sandy’s remnants are weakening and severe weather is not a concern today.  We’ll let you know what the NWS determines after their survey in Wareham today.