The National Hurricane Center has stopped issuing advisories for former tropical storm Gordon, which is morphing into a post-tropical weather system. But the system, still loaded with moisture, is predicted to unleash a broad swath of heavy rainfall and flooding over the next few days.
The flood risk is predicted to shift from the Gulf Coast states Wednesday toward Arkansas, eastern Oklahoma and southern Missouri on Thursday and Friday. Then, when it interacts with a cold front over the weekend, rainfall may intensify from Missouri and Illinois into the Ohio Valley. Before Gordon is totally gone, its remnants may sweep through the eastern Great Lakes and interior Northeast early next week.
“[A]lthough Gordon has weakened, the threat of heavy rainfall and flooding will continue for the next few days,” the National Hurricane Center said in its final advisory on Gordon.
While Gordon’s remnants weaken in the days ahead, it is also slowing down as it rounds the edge of a ridge of high pressure centered over the East Coast. Before it gets picked up by a frontal system moving in from the north and west, its meandering, slow pace may even increase the flood threat compared with what we have seen so far.
Although the center of Gordon was in the vicinity of Jackson, Miss., Wednesday afternoon, its heaviest rainfall was generally occurring in a feeder band to the east, over southern Alabama and the western Florida panhandle.
The Mobile region has been particularly hard hit by flooding and some wind damage, which spurred approximately 30,000 power outages at Gordon’s peak. More than eight inches of rain has fallen in parts of the region. The National Weather Service office in Mobile tweeted that were “[n]umerous reports of flooding and roads washed out” midday Wednesday.
Heavy rain and flash flooding in that area is predicted to taper Wednesday night as the remnants of Gordon move toward the southern Arkansas/northern Louisiana border region.
On Thursday, the Weather Service calls for torrential rainfall in Arkansas. “Banded heavy rainfall and wrap around north and east of the surface low may drop three to six inches of rain in some locations with locally higher amounts possible,” the service wrote in its Wednesday midday discussion. Given the potential for storms to move over the same regions repeatedly, isolated higher totals are likely.
From there, the heavy rain will attempt to make it into eastern Oklahoma as a frontal zone becomes enmeshed with the system provoking another region of heavy rain to breaks out across northern Missouri into Illinois. “[D]eep moisture will be augmented by moisture siphoned from the remnants of Gordon,” the Weather Service wrote.
It may be that this frontal zone in the Midwest is able most effectively wring out Gordon’s moisture, leading to some of the heaviest totals. Totals upward of 10 inches or so are not impossible, which would lead to areas of flooding.
Moisture from the frontal zone and Gordon are expected to continue to drop heavy rain into the weekend across parts of the Midwest and into the Ohio Valley. The eastern Great Lakes, northern Mid-Atlantic (mainly to the northwest of Washington and Baltimore) and interior Northeast may see some of this moisture as well and end up with several inches of rainfall.