Some Thoughts and Discussion:
Tropical Storm Hanna to threaten the Southeast US Coast later this week (Friday) as a CAT 1 (My Call) hurricane. At this time South Carolina appears to be the most likely target for landfall on Friday as it moves Northwest from the Bahamas.
The latest water vapor loop of Hanna with the link below, is clearly showing shear and Dry air to the North and NW of the system. Over the next 24 to 48 hours, Hanna will begin to move NW into this Shear and Drier air. Though this shear is forecasted to become less over the next day or two, I think this will hold Hanna to a CAT 1 hurricane as it approaches the SE US Coast.
The warmer waters of the gulf stream, just off the SE Coast will help feed and intensify and maintain the storm to hurricane status. I continue to think the storm's strength will be less than what is now being projected as a CAT 2 hurricane by the NHC for a Friday landfall along the South Carolina coast. My thinking is the shear and drier air will work the storm over enough, to keep it as a minimal hurricane, with Maximum sustained winds between 75 and 85 MPH during landfall.
For The Mid-Atlantic States:
One things for sure, this storm will bring beneficial rainfall to much of the SE and M/A States ! I do see some concerns for flooding over parts of the Carolina's and Virginia, on Friday into Saturday as the storm will dump 4" to 8" of rain over many of these areas, with possibly isolated higher 10" amounts in some areas of the Carolina's.
Further north into MD, DE, NJ, and parts of PA, I'm thinking a general 2" to 4" of rain will be common, with some localized higher amounts. The heaviest rains will fall Friday night into Saturday night for these areas. Windy conditions of 20 to 35 MPH and higher gusts are possible as the storm weakens to tropical storm and depression status. Both an approaching trough from the west, and strong winds aloft, will help accelerate the storm quickly NNE, then NE, into New England for Saturday night into Sunday.
These are my general thoughts as of today. I'll make any adjustments on this forecast by Thursday, if needed. For the Delaware Valley region, look for a more detailed forecast later this week on storm.
In closing, I expect Hanna to make landfall as a CAT 1 Hurricane with winds of 75 to 85 MPH along the South Carolina coast on Friday. My best estimate is between Charleston SC and Myrtle beach.
For the Delaware Valley region, I'm thinking a general 2" to 4" of rainfall, and winds of 20 to 35 MPH and some higher gusts, for Friday night into Saturday night. A more detailed forecast coming later this week.
My Additional Discussion can be found here at EasternUsWx: