The May 26-27, 2010 Eastern New York and Western New England Backdoor Cold Front Severe Weather Event

On the evening of 26 May 2010, an anomalously warm and humid air mass was over much of the Northeast. Several record maximum temperatures were achieved across New York (NY) and New England that afternoon with widespread readings of 32-37°C. Surface dewpoints were between 15-21°C. A backdoor cold front approached late in the afternoon from eastern New England and southeastern Quebec. Convection rapidly developed ahead of the cold front and its associated mid-level short-wave trough. The strong to severe thunderstorms first developed in the vicinity of the Champlain River Valley around 0000 UTC 27 May 2010 and moved southward across extreme eastern NY and western New England to Long Island by 0600 UTC. There were a total of 70 severe weather reports of damaging winds in excess of 50 knots and severe large hail (greater than 2.5 cm) that occurred across eastern NY and New England.

Eastern NY and western New England were located near the right rear quadrant of a 300 hPa, 105 knot jet streak over eastern Maine and New Brunswick. This jet streak enhanced a plume of upper-level divergence over the region impacted by the severe weather. There was a plethora of instability in place ahead of the back door cold front. The 0000 UTC Local Area Prediction System (LAPS) analysis had surface-based convective available energy (SBCAPE) values of 1000-4000 J kg-1 over eastern NY and western New England. The 0000 UTC sounding at Albany yielded an SBCAPE value of 3948 J kg-1 and mid-level lapse rates approaching 8°C km-1. The Downdraft CAPE value was extremely high at 1697 J kg-1. The sounding exhibited a deep elevated mixed layer from the surface to around 600 hPa, indicative of the potential for strong winds to mix to the surface with the convection. The 0-6 km deep layer bulk shear was only around 25 knots. However, the better deep layer 0-6 km bulk shear was found over central and eastern New England. The KGYX (Gray, ME) sounding had a 0-6 km shear value of 62 knots. The shear increased westward associated with the deep cutoff cyclone over the Canadian Maritimes (Atlantic Canada). The 0-6 km deep layer shear intersected the abundance of instability for a mesoscale convective system (MCS) to develop over western New England. The MCS produced several bowing convective elements, which resulted in widespread straight-line wind damage. There were also some embedded supercells within the organized linear severe convection.

This talk will take a multi-scale approach in analyzing the event from the synoptic-scale to the storm-scale, in order to understand the convective environment associated with the back door cold front that produced the severe weather outbreak on 26-27 May 2010. Observational data used in the analyses will include surface and upper air observations, satellite imagery, and Albany (KENX) WSR-88D 8-bit radar data. The storm-scale analysis will examine some impressive outflow boundaries with the cold pool to the MCS that focused some of the severe convection.