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 M.S. Thesis Seminar Presentation Department of Earth and Atmospheric Sciences, University at Albany, Albany, NY 1 July 2008

Background and Motivation  Sea breezes studied well before 20th century and accurately described thermodynamically: Wales (1914) and Clowes (1917) Images from (top)  Complexity of sea-breeze front due to its lobe-and-cleft structure not realized until recently: Galvin (2006) and Fig. 1 from Galvin (2006) (bottom)

Background and Motivation (continued)  Significant impact of prevailing synoptic-scale flow pattern on sea breeze evolution and intensity: Estoque (1962) Fig. 5 (left) and Fig. 9 (right) from Estoque (1962) 5 m s −1 offshore prevailing geostrophic wind5 m s −1 onshore prevailing geostrophic wind

Background and Motivation (continued)  Many examples of sea-breeze convection cases found in literature: Kingsmill (1995) in FL, Medlin and Croft (1998) in AL, Bennett et al. (2006) in Great Britain, etc.  Fewer cases in literature for Northeast exist: Moroz and Hewson (1966) from MI, Clodman and Chisholm (1994) and King et al. (2003) from Ontario, and Wolf (2004) in IL  Lots of research for Great Lakes during winter (lake-effect snow), but much less research during summer (lake-/sea- breeze severe convection)

Research Goals  Investigate influence of thermodynamic and dynamical processes, along with physiographic effects from complex Northeast topography, on lake-/sea-breeze severe weather  Increase awareness and understanding of lake- /sea-breeze severe convection

Methodology  Warm season: April–October  Domain area shown by map  Selected cases from search of SPC archived storm data, along with input from NWS meteorologists, for 2000–2006  Verified from NCDC archived radar data OH PA NY VTME MD DE NJ CT RI MA NH

Methodology (continued)  Obtained 32 km-resolution NCEP/NARR gridded datasets for all cases to perform synoptic-scale analyses  Acquired 20 km-resolution RUC gridded datasets for three cases to perform mesoscale analyses  Collected soundings, radar data, satellite images, water temperature 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 of similar importance  Null Case: convection suppressed by lake-/sea-breeze processes

Case List Cases chosen for RUC analysis highlighted  Pure Cases 9 August 2001 (Ontario) 6 July 2003 (Erie) 7 August 2005 (Chesapeake) 2 August 2006 (Ontario)  Mixed Cases 19 April 2002 (Erie) 19 June 2002 (Atlantic) 24 July 2003 (Erie and Ontario) 1 August 2005 (Huron and Ontario) 30 June 2006 (Erie and Ontario) 23 July 2006 (Erie and Ontario)  Null Case 11 July 2006 (Atlantic)

Storm Formation Areas and Tracks: All Cases Legend Red: Storm Formation Areas Pink: Tornado Risk Area Green: Null Case Area Arrows: Storm Tracks

SPC Verification of Cases using Convective Outlook Reports for 2003–2006  Pure Cases (3) Slight Risk: 2, General Thunderstorms: 1  Mixed Cases (4) Slight Risk: 1, General Thunderstorms: 3  Null Case (1) Missed Null Area (Slight Risk)

Case Example  2 August 2006 (Ontario) Pure 1200 UTC 2 August 2006: 200 hPa NARR Analysis

1200 UTC 2 August 2006: 500 hPa NARR Analysis Pure

1200 UTC 2 August 2006: Surface NARR Analysis Pure BUF

1200 UTC 2 August 2006: Sounding Parcel taken from lowest 500 m to determine CAPE Pure

1600 UTC 2 August 2006: 925 hPa RUC Analysis Pure

1600 UTC 2 August 2006: CAPE and 1000–700 hPa Wind Shear RUC Analysis Pure

1700 UTC 2 August 2006: Surface Observations Pure

1800 UTC 2 August 2006: NARR Cross-Section Analysis Pure −3.5 −3.0 −2.5 −2.0 −1.5 −1.0 −

1700 UTC 2 August 2006: Radar Pure

1800 UTC 2 August 2006: Radar Pure

1900 UTC 2 August 2006: Radar Pure

2000 UTC 2 August 2006: Radar Pure

2100 UTC 2 August 2006: Radar Pure

2200 UTC 2 August 2006: Radar Pure

2300 UTC 2 August 2006: Radar Pure

1702 UTC 2 August 2006: Visible Satellite Pure

1825 UTC 2 August 2006: Visible Satellite Pure

1902 UTC 2 August 2006: Visible Satellite Pure

2002 UTC 2 August 2006: Visible Satellite Pure

2125 UTC 2 August 2006: Visible Satellite Pure

2202 UTC 2 August 2006: Visible Satellite Pure

2302 UTC 2 August 2006: Visible Satellite Pure

2 August 2006: SPC Storm Reports Pure 40 wind and 5 hail reports

Case Example  19 June 2002 (Atlantic) Mixed 1200 UTC 19 June 2002: 200 hPa NARR Analysis

1200 UTC 19 June 2002: 500 hPa NARR Analysis Mixed

1200 UTC 19 June 2002: Surface NARR Analysis Mixed WAL

1200 UTC 19 June 2002: Sounding Parcel taken from lowest 500 m to determine CAPE Mixed

1800 UTC 19 June 2002: 500 hPa Vorticity NARR Analysis Mixed −10 −8 −6 −4 −

1800 UTC 19 June 2002: 925 hPa RUC Analysis Mixed

1800 UTC 19 June 2002: CAPE and 1000–700 hPa Wind Shear RUC Analysis Mixed

1800 UTC 19 June 2002: Surface Observations Mixed

1800 UTC 19 June 2002: Radar Mixed

1900 UTC 19 June 2002: Radar Mixed

2000 UTC 19 June 2002: Radar Mixed

2100 UTC 19 June 2002: Radar Mixed

1732 UTC 19 June 2002: Visible Satellite Mixed

1902 UTC 19 June 2002: Visible Satellite Mixed

2002 UTC 19 June 2002: Visible Satellite Mixed

2132 UTC 19 June 2002: Visible Satellite Mixed

19 June 2002: SPC Storm Reports Mixed 3 wind and 27 hail reports

Case Example  11 July 2006 (Atlantic) Null 1200 UTC 11 July 2006: 200 hPa NARR Analysis

1200 UTC 11 July 2006: 500 hPa NARR Analysis Null

1200 UTC 11 July 2006: Surface NARR Analysis Null OKX CHH

1200 UTC 11 July 2006: Sounding Parcel taken from lowest 500 m to determine CAPE Null

1200 UTC 11 July 2006: Sounding Parcel taken from lowest 500 m to determine CAPE Null

1800 UTC 11 July 2006: 925 hPa RUC Analysis Null

1800 UTC 11 July 2006: CAPE and 1000–700 hPa Wind Shear RUC Analysis Null

1800 UTC 11 July 2006: Surface Observations Null

1800 UTC 11 July 2006: NARR Cross-Section Analysis Null −3.5 −3.0 −2.5 −2.0 −1.5 −1.0 −

1600 UTC 11 July 2006: Radar Null

1700 UTC 11 July 2006: Radar Null

1800 UTC 11 July 2006: Radar Null

1900 UTC 11 July 2006: Radar Null

2000 UTC 11 July 2006: Radar Null

2100 UTC 11 July 2006: Radar Null

11 July 2006: SPC Storm Reports Null 21 wind and 32 hail reports

24-hour Quantitative Precipitation Estimates ending at 1200 UTC 12 July Null

Pure Case Conclusions  No synoptic-scale disturbance present, 1000–500 hPa thickness ≥570 dam, land/water temperature difference ≥5°C in afternoon  T ≥30°C and T d ≥20°C in afternoon, CAPE ≥1500 J kg −1 and CIN ≥−125 J kg −1 from 1200 UTC soundings  Placement and timing signal given by 925 hPa θ e -ridge axis with θ e ≥335 K, and tendency to sometimes become squall lines  1000–700 hPa onshore wind shear ≥15 kt for organized storms, and boundary intersections can further enhance convection  Occur most often during hottest months of summer with a moist atmosphere (PW ≥40mm)

Mixed Case Conclusions  Synoptic-scale disturbance present, 1000–500 hPa thickness ≥555 dam, land/water temperature difference ≥5°C in afternoon  T ≥20°C and T d ≥10°C in afternoon, CIN ≥−100 J kg −1 from 1200 UTC soundings  Placement and timing signal given by 925 hPa θ e -ridge axis (320 K ≤ θ e ≤ 350 K) and presence of cyclonic vorticity advection  1000–700 hPa onshore wind shear ≥20 kt for organized storms, and boundary intersections can further enhance convection  Occur most often during late spring, early autumn, and cooler portions of summer (PW ≥25mm)

Null Case Conclusions  Preexisting convection interacts with a lake or sea breeze and crosses over into the marine air  Convection suppressed with the boundary layer too stable to maintain updrafts (less CAPE, more CIN)  Significant θ e -difference (≥10°C) between the contrasting air masses  Conditions for severe convection can be highly favorable aloft in the null region due to synoptic-scale patterns  Key to these cases is boundary layer characteristics

Summary Flowchart Is PW ≥25mm at 1200 UTC, and will CAPE be ≥500 J kg −1 by 1500 UTC? Severe weather highly unlikely NoYes Will the water be ≥5°C cooler than the air over land after 1500 UTC? Will there be onshore surface flow ≥5 kt by 1500 UTC to persist the rest of the day? Is there a synoptic-scale disturbance present? Lake-/sea-breeze-induced severe weather unlikely Yes No Yes No Pure case likelyMixed case likely

Null Case Questions  Is there a persistent lake or sea breeze present (synoptically and/or mesoscale driven)?  Is large CIN (≤−125 J kg −1 ) present to promote a deep and possibly impenetrable cap?  Is there a significant departure in temperature and θ e between air masses (lake-/sea-breeze air vs. non- lake-/sea-breeze air)?

Eating Establishment in Park City, UT on 26 June 2007 during 22nd WAF conference Thank you to all of my family and friends and the faculty, staff, and graduate students of the department for all your help, education, and moral support!

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