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Helene slowly winding down as we take stock of calamitous flooding in the Southeast and look ahead – The Eyewall

Helene slowly winding down as we take stock of calamitous flooding in the Southeast and look ahead – The Eyewall

Published Date and Time: 2024-09-27 15:49:55


As of 3 PM ET, there are 16 “catastrophic” Flash Flood Emergencies in effect across the Appalachians. They range from Virginia to North Carolina to Tennessee and South Carolina and Georgia. The criteria for issuing flash flood emergencies is much more stringent than that of the typical flash flood warning. There needs to be an imminent risk of severe damage and/or loss of life. At least 16 counties or communities are reconciling that at present, not to mention the ones that have already been through things today. Rain is finally, mercifully winding down. But as noted this morning, the damage has been done.

Helene’s center is on the Kentucky/Tennessee border and being absorbed by an upper low in that region, leading to a widespread heavy rain event from Tennessee and Arkansas into the Ohio Valley. (College of DuPage)

The next phase for Helene will be as a localized flood producer in the Ohio Valley, but hopefully not as prolific as we’ve seen in Appalachia.

Another 1 to 3 inches of rain is possible from western Tennessee across the Ohio Valley to Cincinnati. (NOAA WPC)

It’s been tough to keep tabs on reports and damage and incidents. I think the death toll has come in around 25 so far based on various reports. Power outages sit around 4 and a half million or so at this hour. Rain totals have been enormous across Georgia, South Carolina, and North Carolina, with over 20 inches in some spots.

Preliminary estimate of rain totals across Upstate South Carolina and western North Carolina as of this morning. (NWS Greenville-Spartanburg)

Just one example of a river gauge gone crazy is in Asheville, NC for the Swannanoa River at Biltmore.

The Swannanoa River at Biltmore will crest about 6 feet or more above the previous record set in 1916. By some accounts, this may be the highest since at least the 1790s. (NOAA NWS)

Forecast to exceed the flood of 1916, the gauge likely topped the presumed 26 foot level set back in spring 1791 according to Tennessee Valley Authority records. Whatever the case, this will be a devastating flooding event in Asheville and western North Carolina as a whole. According to the Georgia Climate Office, the 48 hour rain total of over 11 inches in Atlanta is the new record for a 2 day period, breaking a record by about 1.5 inches that has stood since 1886.

Anyway, the toll of Helene looks pretty horrible. The forecasts were incredibly precise and well done, but at a certain point, there is only so much you can do. We hope for the best for those impacted by Helene, particularly as a blog based in Houston which has seen plenty of flooding calamities.

Two other notes today before closing. First, Tropical Storm Joyce did indeed form from Invest 98L in the Atlantic. It is of no threat to land.

Second, the odds of development on the Caribbean area of interest next week remain at 30 percent. I continue to see two consistencies in the modeling with this one. First, most are capping this one’s intensity. You will occasionally get a rogue GFS model run that churns out a strong hurricane, but for the most part, models have a substantially lower ceiling with this than they did with Helene at this point in its life cycle. That signals that perhaps this one has a chance to not be a huge ordeal. Secondly, they cannot agree on track at all. There’s no theme of note here, with solutions running the gamut across the Gulf. I would contend that this is not one to lose sleep over right now. We’ll assess things through the weekend and come back refreshed Sunday or Monday with the latest.





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