Thursday, October 10, 2013

Update on the Prolonged Coastal Storm

Radar Image as of 10 PM

A slow moving coastal storm continues to slowly move northward bringing occasional rounds of rain, gusty winds, and tidal flooding to the region. Early this evening, the center of the low was off of the North Carolina coast. Modeling continues to suggest that the system will move further north, before being pushed back to the south by an area of high pressure over New England. This process, to push the system back to the south, will occur over a period of several days and that means a prolonged period of damp and dreary weather. 

Peak wind gusts so far have been in the 20 to 30 MPH range across the interior with wind gusts in the 40 to 50 MPH range along the coast, particularly in Southeastern New Jersey and Delaware. Dewey Beach observed a 50 MPH wind gust early this morning and Lewes observed a 49 MPH wind gust this afternoon. Ocean City observed a 44 MPH wind gust, Cape May Harbor observed a 42 MPH wind gust, and Tuckerton observed a 41 MPH wind gust this morning.  Wind gusts from now through much of Friday will be in the 15 to 25 MPH range inland with gusts in the 30 to 40 MPH range along the coastline.

Rainfall totals so far have been greatest south of Philadelphia and in Central Pennsylvania. The heavy rain occurring this evening in Central Pennsylvania was not indicated by the majority of model guidance and it has come as “surprise”. In fact, the rain has been heavy enough across the Susquehanna Valley to result in flooding. You can see some tropical characteristics combining with the easterly flow on the radar tonight. In addition, the models are struggling to key in on the dry air in the middle and upper portions of the atmosphere northeast of Philadelphia and the models have been too wet here so far. The area of high pressure in New England has been fighting the northeast progression of the moisture.

Radar is estimating as of 10:00 PM, that 0.50” to 2 inches of rain has fallen in much of Delaware with the lowest amounts in Northern New Castle County. Generally, 0.50” to 1.00” of rain has fallen south of the Atlantic City Expressway in New Jersey. Then near Lancaster, 1.50” to 3.00” of rain has fallen. Elsewhere, amounts have been under 0.50”. 

The major modeling suggests additional rainfall amounts of 0.50” to 2.00” through Monday. While much of the region has seen occasional rain and drizzle this evening, we will have to see if a Vort-Max causes any heavy rain to blossom in our region late tonight and early Friday Morning as some of the modeling suggests. Interestingly enough, the latest run of the RPM is showing steady rain in the Susquehanna Valley and occasional rain/drizzle in the Delaware Valley during the daytime hours on Friday. The RPM so far has been one of the more reliable models for this event. With that said, some heavier pockets of rain are still quite possible on Friday in the Delaware Valley.

Meanwhile, the persistent northeast wind will continue to create repeated rounds of coastal flooding at the time of high tide. Locally, this continues to be the main concern. Widespread minor coastal flooding is expected around the time of high tide with some pockets of moderate coastal flooding possible. Several reports of coastal flooding continue to come in from the shore points. Beach erosion and high surf will also continue through the weekend.