July 8 Severe Weather
The combination a strong midlevel trough digging into the Great Lakes, a strong jet maximum and a surface cold front triggered yet another severe weather outbreak on July 8th. On midday Tuesday, a few non-severe cells popped over our region as the air mass was unstable with very little if any capping. However, ridging aloft appeared to inhibit convection as the afternoon coninued. Meanwhile, upstream, a mesoscale convective vortex (MCV) over the Great Lakes produced a surface boundary supporting another line of showers and storms across southwestern New York and western Pennsylvania. This line of storms intensified as it worked through NWS Buffalo's region. Instability was up to about 2500 J/KG. A midlevel trough was digging southward into the Great Lakes, increasing the southwesterly wind field at all levels from the Ohio valley eastward to the northeast. The 0-6KM Bulk shear up to 60 Kts had developed across central New York. However, midlevel lapse rates were not all that steep (around 6.0 km/C).
Around noon, the Storm Prediction Center upgraded the severe weather risk in central New York State from a slight to moderate risk. The environment was conducive for deep convection to have bowing segments with high wind, which was the convective mode that was eventually observed. There was enough low level wind shear to support rotation in the thunderstorms. The convection was "organized" with discrete bowing segments, as opposed to pulse type random thunderstorms.
There were quite a few media logged into the private chatroom with our partners and users but some notable media were missing. There was little to no interaction from any of them except for a few brief exchanges. We had one good exchange with one of the local broadcast media meteorologists on the potential for tornadoes. One EM asked about some specifics for severe weather potential for their county. There was also a question from one media person about whether a tornado had been verified yet. The interaction we had was good and everyone seemed appreciative.
Messages were periodically sent about what we were seeing on radar and what we were thinking about the evolution of the convective mode and elements and occasionally reminded everyone that other insights were welcome. Based on so much observed severe weather, there was extremely little interaction with anyone in the chatroom, which is quite discouraging.
We consulted the latest mesocyclone and VR Shear research when issuing the tornado warnings. Also looked at GR2Analyst NROT consulting the thresholds for support of tornado warnings. There were tornado warnings upstream with wind damage reported and the storm exhibited strong rotation based on the recent research so tornado warnings were issued. Earlier in the day, there were discussions about the LCL being a bit high (around 850 hPa) which may have been a factor in the lack of a tornadic circulation reaching the ground where we warned. There was straight line wind damage, sporadic in some areas, so we will have to investigate other parameters such as LCL levels in the future.
Above: Storm Prediction Center mesoscale discussions highlighting the severe weather threat.
Above: Loops of KENX radar reflectivity and storm relative motion. Notice the discrete severe thunderstorm with the significant rotation ahead of the line of thunderstorms. It had a history of weak tornadoes and it tracked into and through the southern Adirondacks and Lake George region, producing only a weak EF0 tornado near Warrensburg. The trailing line of thunderstorms produced some straight line winds across the region.
Above: Local storm reports listing severe weather reports.
Above: Storm Prediction Center graphic showing severe weather reports.
Above: Pictures of tornado damage near Warrensburg.