RAC + May 02, 2016 Severe Event

Posted: May 14, 2016 in Uncategorized

In early April of 2016, I had the opportunity to attend the National Weather Service hosted Radar and Applications Course (RAC) in Norman, OK. The course is a requirment for all NWS employees who are on the Meteorologist/Forecasting career track, and serves as a 1-week residence course which is a pre-requisite to being able to issue Severe/Tornado Warnings (a major draw for me to the operational Meteorology career choice). While attending this course, which is held at the National Weather Center in the unofficial Tornado Capital of the U.S., we undertook several challenging severe weather simulations in small groups to replicate a past event. While remembering how long and challenging those days really were, they served to prepare me for real-time severe events. I just didn’t realize how soon I was going to need to test those skills…

1

SPC Day 1 – 12z Outlook

The shift didn’t start out unusually; with me all-but sleepwalking into work for the morning shift at 5am. From what I can recall, there wasn’t too much in the way of activity ongoing that morning, but the office was gradually preparing for what was likely going to be an active afternoon. The Storm Prediction Center had a large chunk of our area outlooked with a Slight Risk of Severe Thunderstorms that afternoon, with a relatively early initiation time around the noon hour. Per the usual, cloudcover from overnight showers and storms were still hanging around for those in the east, however, they didn’t hang around for long which provided plenty of time for solar heating to take place.

RNK_12Z

RNK 12z (8am) Sounding

For those who are more Meteorologically savvy, both the 12z + 18z soundings from the event (both of which were launched by me) are provided to the right. Some main takeaways:

  • Plenty of instability
    • 2300+ MU CAPE
    • 816 DCAPE
  • SFC-1 km Shear – 10kt
  • SFC-6 km Shear – 44kt
  • SFC-3km Lapse Rate – 8*C/km

    RNK_18Z

    RNK 18z Special Launch May 02, 2016

  • ML CINH – (-17)
  • SFC LCL – 750m
  • 0*C – 9, 9965 feet
  • -20*C – 19,954 feet

Overall, just as the SPC mentioned in their own discussion, the main threats in an environment like this will be severe wind and hail. Supercells would be possible ahead of the main line of convection…and could be plentiful with not much in the way of a CAP in place.

Radar GIF

The setup sure didn’t dissapoint. Cells began to form rapidly ahead of the main boundary, with the first warning being issued around 2:40pm in the afternoon east of the Blue Ridge Mountains. Additional cells began to fire throughout much of the afternoon, and continued to produce very large hail, especially in the discrete cells ahead of the main line of convection. Throughout the event, my main duty was upper-air, social media, and verification of warnings as they were issued. These duties did allow me some time to practice my own form of storm interegation, and with some guidance from a fellow forecaster, actually issue the first warning of my career in the NWS.

The warning was actually a continuation warning of an already Severe Thunderstorm that was tracking across the higher elevations along the VA/WV state line. The storm was small and a bit unorganized at first, but ultimately became a well-organized supercell with an updraft capable of producing up to ping pong size hail. The one drawback of the storm was it’s location. That area of the CWA has very little in the way of population, with much of the storm track falling within the Jefferson National Forest, which plays host to a portion of the Appalachian Trail. Luckily (or unluckily), it did cross a few population centers along the way, dropping half-dollar sized hail in the process. About 20 minutes after the radar grab above, the storm would begin to combine with additional updrafts and fall below “Severe Criteria” as it began to push East into the Roanoke Valley. The now cluster of storms would go on to regain its severe tag and produce wind damage near the City of Buena Vista a bit later in the event.

BOverall, the office issued 23 Severe Thunderstrom warnings on May 2nd, which is the most warnings issued since the summer of 2013. All but 1 of the warnings verified with either the presence of 1″ + hail or wind damage. While my role was primarily behind the scenes, working an event like this was a tremendous experience for me, and will be remembered as my first “official” warning issued in my career. Plenty of personal lessons learned with this event. Shoutout to all of my co-workers who worked it in such a successful manner!

IEM Cow Verification Statistics

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