Warm-Season Lake-/Sea-Breeze Severe Weather in the Northeast Patrick H. Wilson, Lance F. Bosart, and Daniel Keyser Department of Earth and Atmospheric Sciences, University at Albany, Albany, NY Thomas A. Wasula NOAA / National Weather Service, Albany, NY CSTAR II Grant NA04NWS Northeast Regional Operational Workshop VIII Presentation 2 November 2006

Research Goals  Investigate thermodynamical and dynamical processes along with physiographic effects  Increase understanding of this phenomenon

Methodology – Part I  Warm-Season: April – October  Domain: OH, PA, MD, DE, NJ, NY, VT, NH, MA, CT, RI, ME  Selected cases from Storm Prediction Center archived storm data 2000-present  Verified from National Climatic Diagnostic Center archived radar data

Methodology – Part II  Obtained NCEP/NARR gridded datasets for each case and plot important weather variables  Collected soundings, radar data, and surface observations  Classified cases into separate categories and conducted case study analyses

Case Classifications  Pure Case: mesoscale forcing primary; synoptic-scale forcing secondary  Mixed Case: mesoscale forcing and synoptic- scale forcing working together  Null Case: convection suppressed by lake-/sea-breeze processes

Case List  Pure Cases 9 August 2001 (Ontario) 6 July 2003 (Erie) 7 August 2005 (Chesapeake) 2 August 2006 (Ontario)  Mixed Cases 9 April 2001 (Erie) 19 June 2002 (Atlantic) 24 July 2003 (Erie and Ontario) 1 August 2005 (Huron and Ontario) 24 April 2006 (Chesapeake)  Null Case 11 July 2006 (Atlantic)

1200 UTC 9 August 2001 (Pure Case)

1200 UTC 9 August

1200 UTC 9 August 2001

1200 UTC 9 August Note: Parcel taken from lowest 500 m to determine CAPE

1500 UTC 9 August

1800 UTC 9 August

1800 UTC 9 August

1700 UTC 9 August 2001

1700 UTC 9 August 2001 Radar Composite

1800 UTC 9 August 2001 Radar Composite

1900 UTC 9 August 2001 Radar Composite

2000 UTC 9 August 2001 Radar Composite

2100 UTC 9 August 2001 Radar Composite

2200 UTC 9 August 2001 Radar Composite

2300 UTC 9 August 2001 Radar Composite

0000 UTC 10 August 2001 Radar Composite

0100 UTC 10 August 2001 Radar Composite

0200 UTC 10 August 2001 Radar Composite

9 August 2001 Storm Reports

Pure Cases: Preliminary Conclusions  Ridge axis in place at the surface or aloft  Low unidirectional wind shear in low-levels (< 10 m s -1 for hPa layer)  T > 30 ° C, T d > 20 ° C, CAPE > 1500 J kg -1  Placement and timing signal by θ e -ridge axis (θ e > 335 K)  Intersections of boundaries enhance convection  Tendency to become squall lines and prefer valleys  Occur most often during hottest months of summer

1200 UTC 19 June 2002 (Mixed Case)

1200 UTC 19 June

1200 UTC 19 June 2002

1200 UTC 19 June Note: Parcel taken from lowest 500 m to determine CAPE

1500 UTC 19 June

1800 UTC 19 June

1800 UTC 19 June 2002

1800 UTC 19 June 2002 Radar Composite

1900 UTC 19 June 2002 Radar Composite

2000 UTC 19 June 2002 Radar Composite

19 June 2002 Storm Reports

Mixed Cases: Preliminary Conclusions  Troughs generally in place at the surface or aloft  Typically more wind shear (speed shear and veering winds) in low levels  20 ° C 320 K  Cyclonic vorticity and cyclonic vorticity advection important  Intersection of boundaries enhance convection  Occur most often during late spring and early autumn

1800 UTC 11 July 2006 (Null Case)

1800 UTC 11 July 2006

1800 UTC 11 July 2006 Radar Composite

11 July 2006 Storm Reports Lake and sea breezes can suppress convection.

1800 UTC 6 July 2003 MODIS Satellite Questions?