1 June 2011 Significant severe weather outbreak with record hail in the Berkshires and EF3 tornado in central Massachusetts. (click on images to enlarge)

 

Severe Thunderstorms affected portions of East Central New York and Western New England during the afternoon and early evening hours. Large (and historic) hail was the main threat with only a few wind reports. Hail sizes of greater than one inch in diameter were common, and there were three reports of baseball size hail or larger! The 2.75" (baseball) hail was reported in both Saratoga Springs and Eagle Bridge (Rensselaer county). The Saratoga Springs hail dented buses! One of the largest hail stones in more than 40 years in the Albany CWA fell at Shaftsbury, VT where a 3.25" hail stone was measured (and photographed)! According to storm data, this is the 2nd largest hail stone to fall in our CWA, with a 3.50" hail stone in Warren County back in 1968 being the largest. However, the next day hail stones about 4.00" inches in diamater were reported from Windsor, MA in the Berkshires with photographs. While there were several severe hail events, there was very little wind damage. The storms had strong and persistent (sometimes rotating) updrafts due to the substantial instability.

 

Severe weather parameters from the morning showed the potential for explosive development of storms with violent updrafts due to the potential for 4000+ J/Kg of surface-based CAPE from the 12Z ALB sounding. These values are very rare around here, and I can think of only one or two other instances in the last 6 years where the CAPE was near 4000 J/Kg. Also, the 850-500mb lapse rates were very steep at 7.6 C/Km, which yielded the potential for very large hail combined with the large CAPE. These steep lapse rates can be attributed to an Elevated Mixed Layer with origins across Northern Mexico! The drill topic from the Science Team of EML's was put to use very quickly! The 5-day backward HYSPLIT trajectory is shown below showing origin of the EML across northern Mexico.

 

The deep layer 0-6 km shear magnitude was initially 33 kt from the 12Z ALB sounding and showed a mainly unidirectional westerly wind profile. The surface winds were southerly up the Hudson Valley, but above the surface, winds turned westerly pretty quickly. The shear magnitude did not substantially increase until mid to late afternoon east of Albany where more rotating supercell structures were noted.

 

Severe Thunderstorm Watch #410 was coordinated with SPC and it was agreed upon that our entire area would be included in the watch after the initial proposal did not include Dutchess and Litchfield. The watch was coordinated in the morning before severe thunderstorms developed.

 

A special 16Z sounding was done, as it was determined that storms would be too close to Albany to wail until 17Z or 18Z to launch. This data was very useful and provided the basis for knowing the environment the storms were developing in with 3452 J/Kg of actual surface-based CAPE and 41 kt of 0-6 km shear, indicative of supercells being the convective mode. As a surface dewpoint boundary shifted east of the Capital Region by mid afternoon, the threat of supercells moved towards Western New England and eventually the Mid Hudson Valley and Litchfield CT.

 

From a radar perspective, the storms mainly north and east of the Capital Region that produced the giant hail had extremely tall reflectivity cores. Methodology for warning for one inch hail utilized results from a local NWS Albany, NY hail study worked very well on this day. A few of the supercells that produced the giant baseball+ size hail had 50+ dBZ cores of greater than 40 kft and 60-70 dBZ cores from around 20 kft all the way to the ground! Also, the traditional grid-based VIL in the stronger cells exceeded 70-75 at times! These were truly impressive hail signatures, and rarely seen in the Northeast. The radar signatures gave us confidence to place enhanced wording in SVR and SVS statements to mention destructive hail. This was a very rare time when NWS Albany, NY issued a warning with baseball size hail mentioned!

 

Some of the supercells in Saratoga, Washington, Bennington and Windham counties exhibited rotation, but was mainly confined the mid levels. Reflectivity patterns indicated an occasional classic hook echo, but the SRM data was not supportive of issuing any TORs based on weak and inconsistent low level rotation.

 

Overall this was a very significant severe event for our area, with truly giant and historic hail stones. Amazingly, the immediate Capital Region was spared from the convection.

 

 

Above: Soundings from Albany, NY from 12Z 1 June (left), 16Z 1 June (center) and 00Z 2 June (right).

 

 

Above: Parcel trajectory from HYSPLIT model (left) and El Paso, TX sounding from 00Z 27 May, showing the parcels that advected into the northeastern U.S. resulting in the Elevated Mixed Layer seen in the Albany, NY soundings above.

 

 

Above: Loops of surface maps from 1 June.

 

 

Above: Loop of visible satellite imagery. Note the overshooting tops in much if the convection.

 

 

Above: Radar loops from 1 June. Note the hook echoes that formed in some of the thunderstorms, and the extremely high reflectivities where large hail was observed.

 

 

Above: Radar Vertically Integrated Liquid (VIL) and radar Echo Tops, showing the extreme values of VIL suggesting damaging hail, and Echo Tops between 50, 000 and 60, 000 feet.

 

 

Above: Debris ball seen on radar reflectivity within the hook echo while the tornado was on the ground. Note the very high reflectivity represented as purple within the hook echo feature. The image to the left is from the Taunton, MA radar and the right image is from the Upton, NY radar, showing debris at over 8000 feet above the ground.

 

 

Above: Vertical cross section of storm relative velocity from the Albany, NY radar showing a slice through the tornadic circulation near Springfield, MA. Note the bottom of the radar beam was at around 8000 feet, and the top of the impressive circulation was around 16000 feet. The values of gate-to-gate velocity are over 60 kt inbound and outbound.

 

 

Above: Satellite image of a supercell exiting the Catskills (left), and a picture of the supercell taken out the window of NWS Albany, NY.

 

 

Above: Pictures of hail from Massachusetts and Vermont, including the hailstone being considered for a state record in Massachusetts (left) at nearly 4 in diameter.