A very complex weather pattern has developed across the eastern half of the US. A slow moving cold front tapped into Pacific tropical moisture from Marty in the Eastern Pacific, tropical moisture in the Gulf of Mexico as well as a disturbance off the East coast of Florida. This resulted in very heavy rainfall and flash flooding in parts of Alabama, Florida and Virginia on Monday and Tuesday. As shown in the graphic below in areas of red, pockets of 6”+ of rainfall occurred near Tallahassee, FL; Mobile, AL; parts of Western Virginia; Western Pennsylvania, New York and into Maine.
Unfortunately this is the start to a prolonged period of rainfall along the east coast. An additional 0.5’ to around 3” of rain is expected in North Carolina and Southeastern Virginia Tonight and into Thursday as the front gradually moves off the coast on Thursday.
The front becomes nearly stationary along the coast on Friday.
Atlantic moisture will continue to feed north and over the front leading to additional heavy rain for Thursday evening and into Friday. Widespread 2” to 4” of rain is forecast across North Carolina, Virginia, Maryland and New Jersey.
As we approach the weekend, concern increases as Hurricane Joaquin is expected to slowly move west through Thursday Night then take a sharp turn to the north on Friday and strengthen to a Major Hurricane on Saturday.
With the complex interaction of the cold front and Hurricane Joaquin, atmospheric models are showing significant differences in solutions on the path of Joaquin and potential impacts to the US East coast. Thus there is a high degree of uncertainty the forecasts and in the track, strength and speed of Joaquin once it pivots north. The National Hurricane Center currently keeps Joaquin off the east coast for Saturday and brings it onshore near the North Carolina Outer banks Sunday Afternoon. Again there is significant uncertainty and slight shift in the upper level pattern would make a significant difference in how far west Joaquin is able to move.
Heavy rainfall will continue for the Mid Atlantic into the Northeast US for Saturday through Monday with the focus of the front. By Saturday Evening, three day precipitation totals of 5 inches and greater is expected to be widespread across much of North Carolina and Southeastern Virginia.
This widespread heavy rainfall will likely lead to areal, flash and river flooding. In addition, coastal flooding especially in the Chesapeake Bay will be a problem Friday and into the weekend. The graphic below highlights the tidal gauges that have forecasts for minor and moderate flooding as well as the potential for major flooding at the Chesapeake Bay near Kiptopeake, VA.
Those with interests along the east coast especially for the North Carolina Outer banks and into the Northeast are urged to remain in tune for updates and changes in the forecast.
The team at WxIntegrations will continue to provide relevant information and resources to help you better understand and prepare by incorporating weather impacts into your planning and response.