Wilkes-Barre tornado

A pronounced shortwave traversed the eastern Great Lakes with a trailing cold front spawning severe storms in New York and Pennsylvania. The Storm Prediction Center forecasted a 2% outlook for tornadoes within 25 miles of a given point (Figure 1).

Figure 1: SPC tornado outlook from 06/13/2018 2000Z. 

Wednesday evening, an embedded supercell emerged from a linear storm segment over north-central PA. Strong low-level rotation, adequate effective bulk shear and meanwind in the 1-3km layer (both 35-40 kts), as well as very high 0-1km storm-relative helicity (> 200 J/kg) produced ProbTor model output over 40% when the storm was first tornado-warned by the NWS. As 0-2km MRMS AzShear decreased, so did the probability of tornado. Then, from 0152Z to 0202Z, the ProbTor value jumped from 20% to over 80% as both low-level and mid-level rotation increased in this storm. A wind report (but likely tornado damage) was received from Wilkes-Barre at 0215Z, with multiple injuries and cars flipped over. See Figure 2 and Figure 3 for a depiction of the evolution of this storm.

Figure 2: ProbTor contours, NWS warnings, and MRMS MergedReflectivity from 0100Z to 0230Z.

Figure 3: Time series of ProbTor and constituent predictors. NWS warnings and preliminary LSRs are plotted as well.

An accumulation of the 0-2km MRMS AzShear nicely shows the cycling nature of the strong low-level rotation in the storm, with white pixels exceeding 0.015 s^-1 over Nordmont and Pennsylvania state lands, and then over the city of Wilkes-Barre (Figure 4).

Figure 4: MRMS low-level rotation track over the Wilkes-Barre, PA region for the evening of June 13, 2018.

The GLM and ABI instruments from GOES-16 also captured the evolution of the storm (Figures 5 and 6).

Figure 5 shows a 4-panel of new GLM products (produced via Eric Bruning's GOES-R Geostationary Lightning Mapper Tools), along with MRMS MergedReflectivity. Here, the FlashExtentDensity is the count of flashes in 10-km boxes over 3 min, updated every min; the TotalEnergy is the accumulated energy of all GLM flashes in each box over 3 min; and the FlashAvgArea is the average area per flash over 3 min in each 10-km box. We see increases in the FlashExtentDensity and the TotalEnergy fields from 01:15Z to 01:20Z, 01:40Z to 02:00Z, and then a smaller increase from about 02:10Z to 02:20Z. The second jump in total lightning activity corresponds well with increased rotation in the storm and increased probability of tornado.

In Figure 6, note the cooling cloud tops as the storm enters Luzerne county. The cooling starting at about 01:40Z corroborates the increased lightning activity from GLM. Evolution of products from infrared and optical imagers (i.e., ABI and GLM) with high temporal resolution data is an active area of research for severe storm nowcasting at CIMSS.

Figure 6: 10.35µm channel from GOES-16 mesoscale sector for 0130Z to 0230Z. Note the cooling cloud-tops prior to and during tornado occurrence.

EDIT:

The National Weather Service in Binghamton, NY has confirmed an EF2 tornado, beginning approximately at 10:00pm EDT.

Location...Wilkes-Barre Township in Luzerne County Pennsylvania
Date...June 13 2018
Estimated Time...1000 pm EDT
Maximum EF-Scale Rating...EF2
Estimated Maximum Wind Speed...130 mph
Maximum Path Width...200 yards
Path Length...0.75 mile
Beginning Lat/Lon...41.2436/-75.8467
Ending Lat/Lon...41.2390/-75.8392
* Fatalities...0
* Injuries...6