Monday, June 25, 2018

Excessive rain and flooding on East Coast USA

While wildfires have been burning in the western United States, areas of the Eastern United States have seen excessive rainfall the last month or so. There is a nice overview of the excessive rainfall in the Eastern United States in this June 25th article from the Washington Post (limited free articles per month due to pay wall. I really liked the article and for this reason I am sharing the article here.The article, by Tim Craig and Angela Fritz provides a nice overview of the recent heavy rains, a map, some photos, and interviews with those affected. For those of you who do not subscribe to the Washington Post and have some free articles left, I hope that you take the time to read the article. For those of you who are unable to view the article, I apologize.

What is on my mind as I think about areas of the East Coast which have seen heavy rains is that while the East Coast is seeing a lot of rain, areas out west are seeing a drought, see the areas in red and dark red on the map below.



Wildfire season is underway out West and wildfire activity is starting to ramp up. See for example these articles by Bill Gabbert of Wildfire Today: June 22nd on new fires in Oregon and June 25th on the Pawnee Fire in Lake County California; an ABC News video update on 52 wildfires burning in the USA and finally an NBC News report on preparations by various agencies to fight summer wildfires.

Back to the excessive rainfall in areas of the East Coast USA.

Knowing that I was sharing an article from the Washington Post with limited free views per month, I wanted to have some other information to share with you about the recent rains in areas of the East Coast. So I looked to the National Weather Service Middle Atlantic River Forecast Center. Here is today's Graphical Daily Briefing from the NWS Middle Atlantic River Forecast Center (MARFC). note the map (30 Day Rainfall Departures from average). The areas in purple (30 day rainfall greater than 75 percent above average) are in Virginia, West Virginia, Pennsylvania and Maryland. That is a lot of rain. I have heard various news reports over the last month of areas of flooding, mud slides, etc. I have been living on the East Coast USA my whole life, and this amount of rainfall is extraordinary.  Of course not all of the MARFC forecast area has shared in this excessive rainfall, some areas are close to average. Note the areas with less than average 30 day rainfall in extreme northern New Jersey, adjacent areas of New York, and northern Pennsylvania.



I called up my friends at the Middle Atlantic River Forecast and told them about the article that I am posting today. I asked my friend from MARFC for a representative River that has seen excessive flooding. First he made a point of telling me the Potomac River Basin had seen excessive rains recently, but not recent enough to show on their hydrographs (shows recent and forecast river levels as measured by a gage). The River he told me that had seen major flooding late last week is the Rapidan River near Culpepper Virginia.

There is a gage on the Rapidan near Culpepper Virginia, you may access information about the Rapidan near Culpepper including a hydrograph showing river levels measured by the gage for the last five days. I have copied today's hydrograph for you so that you may see the major flooding of last week, 23.7 feet above flood stage. Depending on when you are accessing this article, the hydrograph you see online will be different. Anyway. note in the graph below that the Rapidan started at about two feet late in the day on Wednesday, June 20th, rising to 23.7 feet by Friday, June 22nd. River levels had dropped below flood stage by Saturday June 23rd. If you look at historic crests on the Rapidan at Culpepper page from MARFC (click more information, not yet updated as I write this) you will see that the June 22nd flood of the Rapidan is in the top ten.


Finally, I wanted to give you an idea of rainfall that occurred in Virginia for the 24 hour period ending on June 22nd, so I went to the CoCoRaHS, Collaborative Rain, Hail, and Snow Network. Volunteers from around the USA record rain, snow, and hail data and send it to CoCoRaHS daily around 7:30 AM. This precipitation data is used by the National Weather Service and others. I refer to CoCoRaHS data frequently to get an idea of rainfall in my State and other areas I am interested in. I found a nice map for you showing rainfall in Virginia on June 22nd. As I understand it, the rainfall is for the preceding 24 hours. A CoCoRaHS reporting station near Culpepper VA recorded 4.24 inches of rain with Madison VA, to the west of Culpepper recording over 6 inches of rain during the same period.

No comments: