1. The 1925 Tri-State Tornado What If It Happened Today? Pat Spoden NOAA/NWS WFO Paducah, Kentucky John Hart NOAA/NWS Storm Prediction Center Norman, Oklahoma

2. Anticipating This Historic Event Forecasting the Tri-State Tornado… Anticipating This Historic Event This tornado was quite possibly the “greatest” tornado in recorded history. It is natural to assume that such an event would be obvious to forecasters today. FACT: The Tri-State Tornado would not have been an easy forecast. FACT: The Tri-State Tornado would not have been an easy forecast. This is purely hypothetical! What would our forecasts have looked like? This is purely hypothetical!

3. Anticipating This Historic Event Forecasting the Tri-State Tornado… Anticipating This Historic Event US Weather Bureau did not issue watches or warnings in 1925. NOAA/NWS Storm Prediction Center formed in early 1950s. This is purely hypothetical! What would our forecasts have looked like? This is purely hypothetical!

4. Anticipating This Historic Event Forecasting the Tri-State Tornado… Anticipating This Historic Event Researchers have attempted to re-create the environment leading up to this event. Records are sparse and incomplete. But…we have a reasonably good idea of what the pattern looked like.

5. Anticipating This Historic Event Forecasting the Tri-State Tornado… Anticipating This Historic Event Our best guess… 6am Wed Mar 18th Morning temperatures in the 50s. Dewpoints in the 50s. Widespread rain before sunrise. Warm front lifting northward A typical windy March morning.

6. Anticipating This Historic Event Forecasting the Tri-State Tornado… Anticipating This Historic Event Our best guess… 6am Wed Mar 18th Strong upper trough approaching from the west. 60+ knot 500mb wind max over Arkansas. Cold aloft. Steep lapse rates. Relatively weak instability due to limited low level moisture.

7. Anticipating This Historic Event Forecasting the Tri-State Tornado… Anticipating This Historic Event Our best guess… 6am Wed Mar 18th Day2 Outlook would have been concerned about lack of low level moisture and weak instability. ENHD risk, centered over parts of Kentucky. Tornadoes a concern over the ENHD risk area. DAY2 SPC Convective Outlook

8. Anticipating This Historic Event Forecasting the Tri-State Tornado… Anticipating This Historic Event Our best guess… 6am Wed Mar 18th Here is one possible convective outlook. MDT risk, centered over parts of Kentucky. Concern for tornadoes focused on late afternoon and evening across MDT risk area. Some risk ahead of the surface low. Overnight Severe Tstm watch until 9am DAY1 SPC Convective Outlook

9. Anticipating This Historic Event Forecasting the Tri-State Tornado… Anticipating This Historic Event Our best guess… 7am Wed Mar 18th Morning storms in southwest MO are weakening. Watch expiring soon. Relatively quiet morning at SPC. Monitoring surface analyses, radar, models for trends regarding when storms will intensify.

10. Anticipating This Historic Event Forecasting the Tri-State Tornado… Anticipating This Historic Event Our best guess… Noon Wed Mar 18th Warm front continues to lift north. Small area of unstable air now forming near surface low. First thunderstorms are probably beginning to develop in south- central MO. Tornado watch until 6pm

11. Anticipating This Historic Event Forecasting the Tri-State Tornado… Anticipating This Historic Event Our best guess… Issued around Noon TORNADO WATCH Uncertainty on how far south storms will develop. East edge is the Paducah CWA boundary. North edge based on where warm-front might make it before low passes. (Also CWA boundary). Initially would probably not include WFO IND Conference Call : WFO Paducah WFO St. Louis WFO Little Rock WFO Memphis WFO Central IL Valid until 6pm

12. Anticipating This Historic Event Forecasting the Tri-State Tornado… Anticipating This Historic Event Our best guess… Issued around Noon TORNADO WATCH Probably would not include any of WFO Indianapolis’s area. Would eventually regret that decision. Would need a new watch for parts of Indiana in 3-4 hours. Valid until 6pm

13. Anticipating This Historic Event Forecasting the Tri-State Tornado… Anticipating This Historic Event A total of 9 strong tornadoes F2: 2 f3: 4 F4: 2 F5: 1 747 total fatalities Significant Evening tornado outbreak.

14. Anticipating This Historic Event Forecasting the Tri-State Tornado… Anticipating This Historic Event In summary, SPC would have probably issued… * DAY2 Enhanced Risk Outlook * DAY1 Enhanced/Moderate Risk Outlook * Tornado watch for Tri-State area would have likely been issued around Noon. * Several more watches would have been issued through the evening over IN, OH, KY, TN. * Local NWS office, TV/radio stations, and local emergency managers would have kept everyone informed.

15. Early On http://ejssm.org/ojs/public/vol8-2/map/map.php

16. A Likely Warning for SEMO

17. Wording  Radar indicated a tornado  Would have pathcast, or timeline of arrival, for several cities

18. Once we know there is a large Tornado on the Ground http://ejssm.org/ojs/public/vol8-2/map/map.php

19. First Warning for Southern Illinois Tornado Emergency

20.  Large tornado observed on the ground  Reports of significant damage  Expect the tornado to continue  Call-to-Action would be strongly worded

21. Impact Based Warnings

22. How we Handle Warnings  A “group” of forecasters would focus on that storm only  Numerous updates  Would call ahead to upstream county EM’s  Work closely with EM’s/Media  Social Media would play a big role  1 or 2 forecasters focus on this only

23. If This Event Happens Again  Outlook probably a Slight or Moderate  Watch in place  Lots of tornado warnings  Try not to warn for the same location twice  Once we get a confirmation and expect the tornado to be on the ground for a long time – may move to Catastrophic (Emergency) wording  Reports would be critical  Social Media would be critical  How long do we go with “Catastrophic” wording?