25th Conference on Severe Local Storms

P4.15

A storm-scale analysis of the 16 June 2008 significant severe weather event across New York and Western New England

Thomas A. Wasula, NOAA/NWS, Albany, NY

On 16 June 2008, a widespread severe weather event occurred across much of upstate New York and portions of New England. The Storm Prediction Center posted a moderate risk that afternoon from the Mohawk River Valley, Greater Capital Region and southwestern New England southward into the Mid Atlantic region. The Northeast United States had over 100 severe reports of damaging winds in excess of 50 knots (58 mph), and large hail (greater than 1.9 cm in diameter). There was also one confirmed tornado in the lower Hudson Valley. The vast majority of the severe reports were large hail, with a few hail stones exceeding 5.0 cm in diameter. The severe convection was focused ahead of a surface cold front and a potent short wave trough rotating around a strong 500 hPa cutoff low, meandering southeast from Southern Ontario and Lake Superior.

Observational data, as well as short range deterministic and probabilistic model guidance suggested a major severe weather outbreak was about to occur. A cyclonically curved upper-level jet was located southwest of New York with a plume of divergence over the Northeast in the afternoon. Much of the southern portion of the Albany forecast area was in the favorable left front quad of a mid-and upper-level jet streak. The 1800 UTC KALB sounding indicated convective temps would be in the mid to upper 70sF, if appreciable surface destabilization happened ahead of the surface cold front. Surface based convective available potential energy values of 1000-2000 J kg-1 were expected with steepening mid-level lapse rates to around 7C km-1, coupled with wet bulb zero heights falling to 9-10 kft. The bulk shear values in the 0-6 km layer were in the 45-50 kt range, suggesting the possibility of isolated to scattered supercells. The forecaster thinking for predominant convective mode this day, however, was for mainly multi-cellular convection with large hail and damaging winds due to the steep lapse rates and strong jet dynamics.

This poster presentation will focus on a detailed radar analysis of the event, utilizing some of the new tools available for operational forecasters during the past few warm seasons. Those tools include 3-D investigations of traditional base and derived products. The storm-scale analysis will focus on helpful techniques to determine the features that produced the copious hail reports. It is hoped these tools will continue to aid forecasters enhance warning language with the new one inch hail criteria in place this year.

extended abstract  Extended Abstract (2.1M)

Poster Session 4, Forecasting Techniques and Warning Decision Making Posters I
Tuesday, 12 October 2010, 3:00 PM-4:30 PM, Grand Mesa Ballroom ABC

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