Heavy rain will hit already soggy regions of the U.S. this week
More rain is on the way in the coming days to portions of the central and eastern United States, bringing more moisture to areas already saturated from a summer of heavy rain.
Parts of the Mid-South and Appalachian region are at risk of heavy rains and potential flooding, as are portions of the South and Midwest.
The National Weather Service has issued a slight risk (Level 2 out of 4) of flash flooding and excessive rainfall in Kentucky, where flood watches had also been issued through Monday night. The alerts reflect the potential for slow-moving thunderstorms to drop a quick several inches of rain on the hill terrain.
Although the pattern this week is less favorable for widespread flooding and storminess than last week, concerns remain.
From the Midwest to the lower Mid-Atlantic coast, other pockets of flooding rain are possible Monday through Wednesday, especially from Kentucky and Tennessee to portions of the central Appalachians of western North Carolina that have recently been hit with intense rains.
Over the past two months, dozens of major flood events have wreaked havoc across the Lower 48, affecting cities – including New York and D.C. – and rural areas alike. Some areas may not be able to handle more water.
For much of the central and eastern U.S., this has been one of the most humid summers on record which is directly feeding into heavy rainfall events. Scientists have long cautioned that a warming atmosphere may be conducive to heavier rainfall and more flooding.
Partly to blame is something called a “ring of fire” pattern. An intense and stagnant heat dome – or ridge of high pressure with hot, sinking air – will be parked over the Mid-South and Mississippi Valley, stretching from the Ozarks to the Appalachians. Moisture will swirl around that dome, leading to a ring of showers and thunderstorms to the north.
Flood watches stretch from northern Missouri to southwestern Virginia, where up to several inches of rain is expected Monday.
Monday morning started with flash-flood warnings in and around St. Louis, where 2 to 4 inches of rain fell over a short period and more was anticipated. Flooded roads were also reported in north-central Missouri.
But portions of North Carolina and Virginia appear to be exiting their waterlogged pattern after a flooding frenzy that began in early July with Tropical Storm Chantal and crescendoed with multiple rounds of intense downpours and summertime thunderstorms.
Other zones to watch
Outside the flood watch region on Monday, two zones appear particularly at risk for heavy rainfall through the workweek. One is in the northern Plains to the Upper Midwest and Great Lakes regions on Tuesday and Wednesday. Another is near the Gulf Coast from Florida to Louisiana mid- to late week.
Low pressure passing through the northern U.S. will have ample moisture to work with, drawing on water stored in crops, particularly corn. A phenomenon called “corn sweat” will exacerbate humidity in agricultural regions in the coming days. Between Monday evening and Wednesday, two or three thunderstorm complexes could roll through the region, each dropping a sporadic inch or two of rain.
Otherwise, there are signs that tropical moisture could juice up the atmosphere along the Gulf Coast this week, amplifying the intensity of potential showers and thunderstorms. Some of the moisture will be left behind by a tropical disturbance that dissipated Friday after moving into Louisiana without strengthening into a named storm. That leftover tropical moisture is still present.