26 June 2009 Severe Weather Outbreak

(Click on any image to see loop or larger image)

A cold front associated with a strengthening upper-level disturbance supported the development of severe thunderstorms with in some cases exceptionally large hail. The front was split, with one axis of convection in western and northern NY to parts of Vermont. The other axis of convection extended from southern NY into southern New England. Vertical cross sections of some of the thunderstorms revealed reflectivities aloft > 70 dBZ, which is very rare.

Satellite loops

Water Vapor – Note the upper low tracking across the region

Visible loop – Note the cyclonic vorticity and multiple bands of convection

Data and Forecasts

Compare GFS and NAM theta-e forecasts at the surface and 925 hPa with MSAS observed surface theta-e, surface dew points and the wind barbs identify the actual cold front in the Great Lakes area. There was a definite prefrontal boundary in southern NY and New England, with the surface front further north and west. Both the GFS and NAM showed the larger CAPE values in southern areas.

Loop of the High Resolution WRF predicted composite reflectivity, which made quite a good prediction.

Radar Loops

KENX Loop from 1800-1900 UTC of reflectivity and Severe Thunderstorm Warning Polygons – Previous polygons were not available due to data archive issues. NWS Binghamton and NWS Buffalo had warnings in effect for the storms in central and western NY, even though they are not displayed in this loop.

KENX Loop from 1900-2000 UTC of reflectivity and Severe Thunderstorm Warning Polygons - Previous polygons were not available due to data archive issues. NWS Binghamton and NWS Buffalo had warnings in effect for the storms in central and western NY, even though they are not displayed in this loop.

KENX Loop from 2000-2100 UTC of reflectivity and Severe Thunderstorm Warning Polygons

KENX Loop from 2100-2200 UTC of reflectivity and Severe Thunderstorm Warning Polygons - Previous polygons were not available due to data archive issues. NWS Upton and NWS Taunton had warnings in effect for the storms in NY, NJ and New England, even though some are not displayed in this loop.

KENX Loop from 0030-0130 UTC 6/27 of reflectivity and Severe Thunderstorm Warning Polygons - Previous polygons were not available due to data archive issues. NWS Upton and NWS Taunton had warnings in effect for the storms in NY, NJ and New England, even though some are not displayed in this loop.

Four Dimensional Storm Investigator Images of specific severe thunderstorms as viewed from the KENX radar

Plan view and vertical cross section of a severe thunderstorm in Sullivan County, NY, in NWS Binghamton, NY forecast area. Note the extremely rare 75+ dBZ core.

Plan view and vertical cross section of a severe thunderstorm NEAR Hartford, CT, in NWS Taunton, MA forecast area. Note the extremely rare persistent 75+ dBZ core.

Hail Swaths in New York, New Jersey, Pennsylvania and New England

Mesocyclone tracks New York, New Jersey, Pennsylvania and New England – Orange and Red represent the stronger mesocyclones

12Z 26 June Soundings

ALY BUF WMW

ALY BUF WMW

Storm Prediction Center Outlook

Storm Prediction Center Mesoscale Discussions

Albany Area Forecast Discussions

Surrounding Area Forecast Discussions – NWS Burlington, VT, NWS Binghamton, NY, NWS Taunton, MA and NWS Upton, NY

Warnings and Severe Weather Reports

Another perspective of severe weather reports for individual NWS offices, courtesy of The Iowa Environmental Mesonet division of Iowa State University Department of Agronomy

NWS Buffalo, NY

NWS Binghamton, NY

NWS Albany, NY

NWS Burlington, VT

NWS Upton, NY

NWS Taunton, MA

Any questions or suggestions, please e-mail Neil.Stuart@noaa.gov