Thursday, October 1, 2015

10/1 Late Week Flooding/Hurricane Joaquin Update

Hurricane Joaquin was upgraded to a category 4 hurricane today with maximum sustained winds up to 135 mph. Fortunately, most of the guidance which once showed an east coast landfall has begun shifting towards the "out to sea" solution first offered by the European. Based on this model swing and the latest observations concerning Joaquin's movement(see last post), I do think the mid-Atlantic will dodge a direct impact. So great news there.
With that said, we are still going to see a lot of rain over the next few days. A plume of deep tropical moisture off the Atlantic will stream westward leading to a band of very heavy rain. 1-3" will be common across the state with as much as 6" along the southern Blue Ridge. The ground is saturated so this will be enough to cause flash flooding concerns along small creeks and streams. All the runoff will also lead to river flooding as well---especially in the Dan, Roanoke, and New Rivers where the heaviest rain is expected.
Another element of this will be the coastal flooding. A strong pressure gradient between Hurricane Joaquin and high pressure over eastern Canada will lead to gusty east-north-easterly winds as high as 30-40 mph through the weekend. This will build seas and allow for the inundation of water across low-lying coastal areas. Coastal flood warnings have been issued accordingly.
Bottom line: If you live along the coast or in any sort of flood plane, have your evacuation route/plans in order. This will still be an impactful event---just not as severe as it would have been with landfalling Joaquin in the mix.