An incredible microburst this morning in Easthampton and Holyoke, Massachusetts leveled a sizable part of a forest on the west side of Mount Tom. A drone that flew over the damage caught this incredible site with thousands upon thousands of trees snapped in half by the powerful winds.
The environment was conducive to severe thunderstorms and while damage was isolated in Connecticut this microburst across the border was very very impressive.
Here’s how the storm looked on radar prior to the downburst. It was only marginally impressive with some exceptionally weak/broad rotation at 8:37 UTC.
By 8:46 UTC the cell appears to be “bowing out” a bit on reflectivity taking on the shape of a backwards “C” while outbound velocities at ~6kft AGL strengthen a bit more. Also, Barnes ANG Base records a wind gust to 48 knots.
KBAF 080846Z AUTO 18032G48KT 130V220 3SM +RA BR SQ SCT013 BKN023 OVC034 17/16 A2971 RMK AO2 PK WND 18048/0846 RAE0759B15 P0007 T01720156
2 minutes later radar shows a more well defined inflow notch as the reflectivity echoes over the microburst race northeast.
This was the result.
Initially I thought the volume scan at 8:48 UTC was depicting a divergent wind signature which is typical of microbursts. Upon further thought I don’t think that was the case. The radar was sampling the atmosphere at over 6,000 ft AGL which is far too high to capture a divergent wind signature from a microburst hitting the ground. More likely, the radar showed a rapid evolution from a fairly ordinary cell to a quick hitting bow echo with a rear inflow jet aided by a low level jet in excess of 60 knots. The “inbound” velocities that you see in the radar image above were likely from a poorly sampled comma head or bookend vortex that quickly formed as the rear inflow jet developed.
Winds were up to 100 mph from this microburst that was approximately 1/4 mile wide and about 1 mile long from the Easthampton/Holyoke town line and points north along the west slope of Mount Tom.
Based on the aerial pictures from earlier today here’s an approximate representation of the damage path.