Storm Spotting – Solidifying the Basics PROFESSOR PAUL SIRVATKA COLLEGE OF DUPAGE HTTP://WEATHER.COD.EDU Focus on Anticipating and Spotting

• What do you look for? • What will you actually see? • Can you identify what is going on with the ? Is Gilbert married? Hmmmmm….rumor has it….. Its all about the updraft!

Not that easy! • Various types of and storm structures. • A is a “big sucky • Obscuration of important thing” and underneath the features make spotting updraft is where it forms. difficult. • So find the updraft! • The closer you are to a storm the more difficult it becomes to make these identifications. Conceptual models Reality is much harder. Basic Conceptual Model Sometimes its easy! North Central , 2-28-17

(Courtesy of Matt Piechota) Other , not so much. Reality usually is far more complicated than our perfect pictures

Rain Free Base

Dusty More like reality Scattered Cumulus Under Deck Sigh...wall ! • Wall clouds help spotters identify where the updraft of a storm is • Wall clouds may or may not be present with tornadic storms • Wall clouds may be seen with any storm with an updraft • Wall clouds may or may not be rotating • Wall clouds may or may not result in tornadoes • Wall clouds should not be reported unless there is strong and easily observable noted • When a clear slot is observed, a well written or transmitted report should say as much Characteristics of a Tornadic Wall

• Surface-based • Rapid vertical motion (scud-sucking) • Persistent • Persistent rotation Clear Slot • The key, however, is the development of a clear slot

Prof. Paul Sirvatka ESAS 1115 Severe and Unusual Storm Type : Tornado Types • tornado • Non-supercell tornado • QLCS tornado • Land (water) spout • A is not a tornado but can and should be reported for what it is More traditional supercell - Classic You are not going to have problems identifying this tornado. But neither will Doppler . More traditional supercell - HP More traditional supercell tornado

Tail Cloud

Clear Slot

A Reasonable Look for a Clear Slot

Photo by Jeff Duda No (readily) apparent clear slot Possible -type beginning?

Photos by Matt Piechota Occlusion (wrapping of cold air around the low-level ) taking place - clear slot

Rear Flank Gust Front

Rear Flank Downdraft

Clear slot beginning Washburn IL tornado 2-28-17 (Courtesy Matt Piechota) Washburn IL tornado 2-28-17 (Courtesy Matt Piechota) Multicells and Multicell storms will pose a different problem Tornado embedded within line A Whole Spectrum of Rotation

QLCS – Quasi Linear Convective System

LEWP –

QLCS Tornado LEWP-T Misovortex 2. Warm sector (AR/MO/IL): 28/00z sounding from OUN exhibited a steep-lapse-rate environment with substantial low-level moisture. Strong capping and neutral-weak will allow this air mass to Convective Outlook from 2-28-17 6Z

“Forecast soundings suggest very large could accompany this activity and a few strong tornadoes are possible, especially if discrete structures evolve…

“Damaging should be noted with this [cold] frontal convection and tornadoes may also be embedded along the line.” QLCS Tornado? “[R]ecently, Atkins and Laurent developed more than one theory for mesovortex formation because they saw different evolutions within the QLCS. This one requires a locally intense updraft along the gust front to tilt and stretch streamwise running down the boundary. The resulting would be of a single sign and not a couplet.” Summary • Find the updraft • Think about what kind of storm it is • What are the associated with your spotting • Get a good radar image (e.g. GRLevel3 or Radarscope) and know where the greatest rotation is • Report what you actually see, not what you hope to see NEXLAB Weather http://weather.cod.edu

Storm Chasing http://weather.cod.edu/chasing

Paul Sirvatka [email protected]