Tropical Storm/Hurricane Isaias continues to move up the coastline. Very heavy rain continues to be the main threat from this storm. The heaviest rain may fall over a period of just a few hours.
The trend has been for the heaviest rain to fall slightly further west than yesterday’s model runs. Some models are predicting amounts as high as 5-7 inches of rain in some spots! The heaviest rain will fall between 11AM and 3 PM Tuesday.
The peak winds will occur around 1-2 PM. Gusts around 35-50 MPH are forecast by the latest GFS in the PHL area.
Here are the latest models with their rainfall totals –
The latest National Blend of Models (NBM version 4.0 ), often correct for QPF values, has even greater amounts—
The latest NAM NEST model has the heaviest rain more westward—
The Canadian Global (GDPS) is also a bit westward with higher amounts—
The German ICON model has a similar precip forecast—
So a generalized very heavy rain event is expected