19 June 2006 Severe Weather

 

There was extensive wind damage across central and eastern New York on this day, with large hail in Vermont, Connecticut and Massachusetts. The 1200 UTC sounding from KALB showed 2355 j/kg of CAPE and fairly unidirectional west-southwesterly winds (Fig. 1). A cold front was forecasted to track through during the afternoon. The 850 Mb plot showed a low-level jet segment of 30+ Kt tracking through the region enhancing the convergence and low-level forcing (Fig. 2). The 500 Mb plot showed winds around 50 Kt pushing into the region, a threshold SPC uses to indicate enhanced severe weather threats (Fig. 3). At 250 Mb, there was an upper jet segment of around 80 Kt tracking through the eastern Great Lakes, heading into Canada, potentially putting our region in the right-entrance region of the upper jet (Fig.4).

 

 

Figure 1. Upper air sounding from KALB at 1200 UTC 19 June 2006. Note the instability and unidirectional shear.

 

 

Figure 2. 850 Mb upper plot with wind isotachs overlayed. Note the low-level jet maxima over PA and western NY. Also note the temperature difference between Albany, Buffalo and Manawaki, showing a strong cold front at 850 Mb moving into the region.

 

 

Figure 3. 500 Mb upper plot with wind isotachs overlayed. Note the mid-level jet segment over western NY and PA. Also note the cooling aloft taking place over the Great Lakes and OH Valley, gradually advecting into our region.

 

 

Figure 4. 250 Mb upper plot with isotachs overlayed. Note the upper-level jet segment in the eastern Great Lakes tracking gradually east and northeast.

 

Infrared satellite pictures showed the developing line of convection ahead of the cold front (Fig. 5) in the region of greatest instability (Fig. 6). The LAPS CAPE analyses showed the axis of instability over our region during the afternoon (Fig. 7).

 

 

Figure 5. Infrared satellite picture with MSLP, 500 Mb heights and temperatures overlayed. Click on figure for a movie of the developing convection over the region between 1830 UTC and 2000 UTC 19 June.

 

 

Figure 6. Surface plot with MSLP and Lifted Index overlayed. Lifted Indices < -2 are colored salmon. Click on the figure for a movie showing the evolution of the axis of greatest instability between 1800 UTC and 2100 UTC 19 June.

 

 

Figure 7. LAPS analysis of CAPE with MSLP overlayed. Note the greatest instability ahead of the surface trough. Click on the figure for a movie showing the evolution of the CAPE and MSLP between 1800 UTC and 2100 UTC.

 

An overview of the radar reflectivity and base velocity from KENX shows a line of convection tracking through eastern NY, eventually affecting southern and western New England. Note some rear inflow notches and bows in the line in the reflectivity (Fig. 8) and the depiction of strong winds in the velocity displays (Fig. 9). Once the storms reached the axis of highest instability with CAPE values near 4000 J/Kg, explosive development occurred with storms rapidly becoming severe. A reflectivity cross-section of one of the biggest storms shows extreme reflectivity values easily penetrated the freezing level, reaching great heights (Fig. 10). The high reflectivities aloft supported the presence of large hail in the storm that affected eastern NY and northwest CT. The severe weather reports reflected the linear nature to the storms initially, and the hail producing storm in eastern NY and northwest CT (Fig. 11).

 

 

Figure 8. Four-panel of Base Reflectivity from KENX at the 0.5 (upper left), 0.9 (upper right), 1.3 (lower right), and 1.8 (lower left) elevation angles. Click on figures for movies showing evolution of the Base Reflectivity centered at different points from 1903 UTC to 2243 UTC 19 June.

 


 

Figure 9. Four-panel of Base Velocity from KENX at 2025 UTC 19 June at the 0.5 (upper left), 0.9 (upper right), 1.3 (lower right), and 1.8 (lower left) elevation angles.

 

 

Figure 10. Reflectivity Cross-Section from storm that affect eastern NY and northwest CT. Click on the figure for a movie of the evolution of the storm from 2138 UTC through 2247 UTC 19 June.

 

Map of 060619_rpts's severe weather reports

 

 

 

Figure 11. List of severe weather reports in NY, the Berkshires of MA and northwest CT from 19 June.