Caribbean Moisture Plume Continues Threat of Heavy Rain in the East

May 19, 2018

Deep tropical moisture will continue to surge into the eastern U.S. through this weekend, resulting in additional rounds of locally heavy rainfall over areas already saturated from this stagnant, wet pattern that has been in place this week.

This tropical moisture plume is being tapped from the western Caribbean Sea by southerly winds around the western periphery of the Bermuda high and a broad area of low pressure in the Deep South.

Add in a frontal system draped over the mid-Atlantic states that will lift northward and eastward this weekend intersecting the tropical moisture plume and you have a formula for numerous showers and thunderstorms in much of the East.

Happening Now

Right now, areas of rain and thunderstorms with locally heavy downpours currently stretch from Florida northward into the mid-Atlantic states and the Northeast.

Current Radar, Watches and Warnings

A mudslide was reported near Columbus, North Carolina Friday night, which is blocking roads and local residents cannot get out of their neighborhood. Polk County Emergency Management officials are reporting a woman is dead after being trapped by mud after a mudslide in Tyron, North Carolina.

Several houses were reportedly underwater near Globe, North Carolina, Friday evening, and a helicopter was dispatched to rescue two families that were stranded by floodwaters. This part of North Carolina has already seen 3 to 5 inches of rain and could get several more. Creeks in the area are expected to rise. 

Heavy rain near Martinsville, Virginia flooded numerous roads and may have caused the collapse of a department store's roof in town. 

(MORE: Flood Impacts in the mid-Atlantic)

More flood reports can be found at the bottom of this article. 


This tropical moisture pipeline will fuel downpours that result in a general 1 to 3 inches of additional rain from parts of New Jersey and eastern Pensylvania to Maryland, Virginia, parts of the Carolinas, Georgia and the Florida Peninsula.

Rainfall Forecast

Where bands of rain and thunderstorms stall, rainfall totals could be locally higher, triggering additional flash flooding and flooding of creeks, streams, and some small rivers into the weekend.

(MORE: We're Entering the Prime Time for Flash Flooding)

Flood watches remain in effect for portions of North Carolina and Virginia.

A flood watch is also in effect for southeastern Florida, including the Miami and West Palm Beach areas into Saturday evening where rainfall totals of 2 to 4 inches are possible.

This wet pattern will last until at least early next week, especially across the Southeast. The mid-Atlantic and Northeast will likely experience drier conditions by Tuesday.

(MAPS: 7-Day U.S. Rainfall Forecast)

Several cities in the mid-Atlantic states are on notable rain streaks through Saturday, including:

  • Wilmington, Delaware: 10 straight days with at least a trace of rain
  • Baltimore (BWI Airport): 8 straight days with measurable (at least 0.01 inch) rain
  • Washington (Reagan National Airport): 8 straight days with measurable rain.

With rain forecast through at least Saturday, Reagan Airport may at least tie its fourth longest precipitation streak in records dating to 1941. Their record long streak is 15 straight days from Apr. 27 - May 11, 2016. 

Needed Rainfall in the Southeast

This rainfall has been beneficial in central and southern Florida, as well as parts of Georgia and South Carolina, where drought conditions have recently developed.

As of May 8, more than 26 percent of the Sunshine State was in moderate drought, but as of May 15, just under 15 percent of Florida remained in at least moderate drought. A portion of South Florida, however, is still in severe drought but that area has shrunk as well, according to the U.S. Drought Monitor.

Thirty percent of Georgia and roughly one-quarter of South Carolina, mainly in the southern parts of each state, are also in drought. 

Drought conditions as of May 15, 2018.
(U.S. Drought Monitor)

Miami only measured 0.37 inches of rainfall in February, 1.88 inches below average for the month. This dry trend was exacerbated in March, when Miami only picked up 0.19 inches, compared to the average rainfall for March – 3 inches.

(MORE: What to Watch Out For and Look Forward to in May)

This dry pattern began to shift in late April in parts of Florida, but there appears to be hope for a wetter pattern as the wet season commences.

Flooding Reports

Multiple basements were reported flooded in Hutchinson and Mt. Lebanon, Pennsylvania, Wednesday, some with up to 3 feet of water. Water had entered garages in Frederick, Maryland, Wednesday, just one day after severe flash flooding prompted water rescues in the city.

Since Sunday morning, parts of the Florida Peninsula and the Florida Keys have picked up over 5 inches of rain. 

A band of heavy rain on the west side of the Atlanta metro area prompted a pair of streets to close in Lithia Springs, Georgia, Wednesday. 

Over 6 inches of rain flooded out a culvert east of Toccoa, Georgia, Wednesday, leaving approximately 70 residents unable to leave or reach their homes, according to Stephens County Emergency Management.

Flooding led to lane restrictions on sections of Interstate 95 in the Philadelphia metro early Thursday morning, near exit 20, between exits 23 and 25, and also northbound at the Interstate 476 interchange in Leiperville.

Lane restrictions were also in place early Thursday morning for a section of Interstate 76 eastbound in Montgomery County, Pennsylvania between exits 328 and 330.

The higher terrain of western North Carolina flooded from heavy rainfall and additional runoff Friday afternoon, including in the Boone and Asheville, North Carolina areas. Spots in Watauga County have had almost 10 inches of rain since Tuesday night. 

At least two mudslides have been reported in this area: one in Blowing Rock and another in Foscoe, North Carolina. 

Rivers were moving rapidly in some parts of western North Carolina as seen here in Foscoe: 

Indian Creek, West Virginia, just across the border from Blacksburg, Virginia, escaped its banks Thursday evening and was flowing across Route 219 near Salt Sulphur Springs. 

A flash flood near Roanoke, Virginia, swept away some small debris and toppled a small tree. 2 feet of rapidly flowing water were reported following 4.32 inches of rain in 4 hours. Flooding has been reported in Virginia Beach where more than two inches of rain has fallen since early Thursday afternoon.

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