Update: Hurricane Earl is passing the Outer Banks of North Carolina,
producing wind gusts in excess of 50 mph along immediate shorelines, but
very little wind just 30 miles inland. The hurricane has encountered
strong winds aloft, which have disrupted its inner core and weakened the
storm. As the hurricane moves north overnight and early Friday, it will
encounter the Gulf Stream and may strengthen briefly again, before
encountering more wind aloft and cooler ocean temperatures.
The track will likely be over the waters southeast of Nantucket, passing
between 50 and 100 miles to the southeast of the Island. There are
indications from numerous guidance products that a void of wind may
develop on the northwest quadrant of the storm, at the time it passes
Nantucket. This void would develop as the storm begins its transition
from tropical to non-tropical. Having said that, wind gusts in excess
of 110 mph will still be present on the southwest and all eastern sides
of the storm center. Additionally, heavy bands of rain developing on
the northwest quadrant of the storm may focus stronger winds aloft,
driving them to the surface.
The end result is to find rain developing at the South Coast between
noon and 2 PM, and the NH Seacoast between 5 and 7 PM, becoming heavier
within 3 hours of starting. Heavier bursts and bands of rain will focus
stronger wind gusts to 39+ mph, primarily along the coastal communities
and those within 30 miles of the coast from the NH/ME border southward.
On Cape Cod and the Islands, the Hurricane Warning remains in effect for
the possibility of drawing these stronger winds to the ground in heavier
rain bursts, as well. In a circumstance like this, the end result is
not the same as it is for a Gloria (1985) or Bob (1991). Instead, we
tend to see damage done rather randomly, where and when the heavier rain
occurs, and especially between 11 PM Friday and 5 AM Saturday.
Occasionally, a storm undergoing non-tropical transition can develop
strong winds on the backside of the circulation. I believe this may be
the case across the far South Shore, Cape Cod and the Islands between 1
AM and 5 AM Saturday. After most of the storm blows from the east, then
northeast...this would come as winds snap direction to blow from the
northwest, on the backside of the storm as it starts to pull away.
Believe it or not, this may bring the greatest threat for damage from
wind for Southeastern MA.
Rainfall amounts will be 3"-6" Southeast MA with urban and poor drainage
flooding, 1"-3" farther inland...less than 1" west of Worcester.
Storm surge of 2'-4' will mean splashover, minor and perhaps pockets of
moderate coastal flooding, though the storm passes with a receding tide.
Rip currents are building now and will continue through the weekend.
Saturday may still feature a 10-20 mph wind from the west, so line
repair may be slightly hindered, but weather will be quiet, and winds
will decrease with fair weather expected Sunday and Labor Day.
Overall - pockets of damage rather randomly dispersed, with a heavier
concentration and more widespread nature on the Outer Cape and Nantucket.