Thread by @NOAANCEI

1/7
The State Climate Extremes Committee has verified a new Tennessee 24-hour precipitation record of 20.73”, measured in McEwen, TN on August 21, 2021. Follow this thread for more on the new record. bit.ly/McEwenTNRecord @NWSNashville @NWSSouthern

2/7
On August 21, 2021, several rounds of heavy thunderstorms impacted western Middle Tennessee. Deadly flash flooding devastated Waverly, TN, and the wastewater treatment plant in McEwen, TN recorded a stunning 20.73” of rainfall in under 24 hours. bit.ly/McEwenTNRecord

3/7
The McEwen site is “non-network,” so it isn’t part of a formal weather observation network. Confirmation of a state record at a non-network site is unusual with extra scrutiny required, but other sites in the area reported 20-40% of their yearly rainfall in just 8-12 hrs.

4/7
Other compelling evidence: @nwsnwc confirmed a 1/1000 chance of these observed 24-hour rainfall totals occurring in any given year near the McEwen site: bit.ly/McEwenTNRecord

5/7
Numerous area rivers and streams were overwhelmed by the torrential rainfall, resulting in major flooding: bit.ly/McEwenTNRecord

6/7
Estimates of rainfall from radar also suggested the rainfall in western Middle TN could be historic, further lending credibility to the McEwen observation: bit.ly/McEwenTNRecord

7/7
Finding the rain gauge well-sited/calibrated and the meteorological evidence extremely compelling, the State Climate Extremes Committee voted unanimously to confirm the new TN state 24-hour precipitation record of 20.73” in McEwen, TN on Aug 21, 2021. bit.ly/McEwenTNRecord

FINAL NOTE: According to currently recognized state records, the newly-confirmed McEwen, TN record is now the largest 24-hour precipitation record in any non-coastal state. Learn more about state records and the SCEC: bit.ly/AboutSCEC

CORRECTED: The link to the full report on the new TN 24-hour precipitation record can be found at bit.ly/McEwenTN. Sorry for any inconvenience!