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

ABQ - 2300Z Update

2240Z: Heading into 23Z, ProbSevere indicated a likely severe storm SE of ABQ with ProbWind 88%, ProbHail 76%, & even ProbTor of 21%. MESH values are slightly higher than 1", & the prescence of a mid-level mesocyclone along with -20C reflectivity greater than 50 dBZ all indicating the potential for severe hail.
Interestingly enough, there continues to be little correlation between increasing trends in the GLM fields & increasing storm severity (gif below). This has been noted in past HWTs with western storms which may be a limitation with using GLM products in this region.

Zooming out, GOES-16 IR/VIS data shows some cu development & cooling cloud tops across southern NM.

Looking at the CI fields, not too much is expected with this development with values generally 50% or lower & severe CI probs only around 10%

And finally, little to no increasing trend in GLM Flash Density makes me even more confident in anticipating little to no development of this convection over southern NM

Peter Sunday

Supercell Merger VIA VIS/IR Toggle

Saw this VIS/IR Toggle with the supercells merging across Garden, Sheridan, and Cherry Counties in Nebraska. The coldest cores at the end of the animation are in the eastern portion of Sheridian where the main two supercells merged. Had Prob East on the image and did see where it was showing probabilities of cells along the forward flank could develop.

Supercell

Late December storms

A negatively-tilted shortwave brought some low-level moisture return to the gulf states this week, and with the moisture, some scattered severe storms.

A couple tornadic storms affected portions of east Texas. The NOAA/CIMSS ProbSevere model now incorporates the GOES-16 satellite growth rates, and a storm affecting Cherokee Co., TX, had a strong normalized growth well before it produced severe weather.

Figure 1: AWIPS2 screen captures of MRMS MergedReflectivity, ProbSevere contours, and NWS warnings for a storm near Rusk, Texas.

The ProbWind values vacillated largely between 50% and 75% for this storm, before producing a tornado at 00:56 UTC and multiple wind damage reports in the town or Rusk, TX. The strong GOES-16 vertical growth rate, large ENI flash rate (~30-70 fl/min), and stout kinematic fields (eff. bulk shear ~ 45-50 kts; meanwind 700-900mb ~ 35 kts) combined to produce these moderate-strong ProbWind values. The MRMS MESH remained rather low (~ 0.2 - 0.6 in), signaling that this was not a severe hail situation. ProbTor had a maximum value of 12% before the first tornado report.

This storm featured jumps in ProbWind value (one produced by a large increase in flash rate, indicative of a lightning jump), and being an outlier storm amongst its neighbors, in terms of probability value. Both features in ProbSevere objects have been identified by forecasters as indicating possible severe weather.

A second storm formed further south and later in the night, which also produced a damaging tornado, touching down northeast of Beaumont, TX, and later northwest of Lake Charles, LA, blowing off the roof to a restaurant.

Figure 2: AWIPS2 screen captures of MRMS MergedReflectivity, ProbSevere contours, and NWS warnings for storm heading into southwest Louisiana.

The kinematics for this storm were very favorable, with effective bulk shear of 50 kts, meanwind 700-900mb of 45 kts, and 0-1 km storm-relative helicity near 300 J/kg. The first tornado touched down at 07:41 UTC, when ProbTor was about 30%. ProbTor then jumped from 30% to 50% at 08:00 UTC, the time of the second tornado report. This jump in ProbTor value was coincident with an increase in total lightning (a lightning jump) as well as an increase in low-level rotation.

Figure 3: Time series of ProbTor and predictor values for this storm affecting southeast TX and southwest LA.

A tornado warning was issued at 08:10 UTC, when ProbTor had just increased to 90%. The third tornado reported, at 08:20 UTC, was rated EF1 and destroyed the roof of a restaurant in DeQuincy, Louisiana.