Tropical Atlantic
Isaias as of 4:00am, had max sustained winds of 110mph, min central pressure of 963mb, track north-northeast at 15 mph. as of 7:20 this morning he had max sustained winds of 120 mph, min central pressure of 959mb, tracking north-northeast at 16 mph.
ISAIAS has
gone through two R.I. (Rapid Intensification) periods where sustained winds
increased by at least 35 mph within 24 hours. So, as I’ve been indicating, Isaias
has reached Category 3 status (major hurricane). But this should be his peak,
now he should weaken a bit because of that increasing wind shear and dry air ahead
of landfall. But he is
still expected to be a strong category 2 hurricane at landfall. Isaias is a rather small storm; generally tropical
storm force winds extend 125 miles from the center with hurricane force winds
reaching 25 miles from its center.
The track
forecast is virtually unchanged, with a landfall somewhere right around
midnight close to Pensacola FL. Isaias’s
inner core is now coming into radar range
The only big
chance is that the surge forecast has been nudged up a bit.
The tornado
risk tomorrow in the Southeast has been expanded.
Isaias will
bring areas of heavy rainfall to the central U.S. Gulf coast and much of the
Southeast through the weekend. Considerable flash and urban flooding, along
with significant river flooding, will be possible in those areas.
What
about impacts up in our region.
Here’s a
look at the surface/radar chart.
There is an upper-level
low west of Isaias over Texas. We also have a strong ridge sitting off the
Southeast Coast. This setup means Isaias
will come due north and start to really speed up. This is also going to shove
all that tropical moisture northward into the Tennessee Valley and then up the
coast into the northern Middle Atlantic. The center of what left of Isaias,
looks to pass over the Delmarva
Peninsula. Because of the fast forward motion of this storm, it will rapidly weaken
and lose its tropical characteristics. So, our region is not going to be
dealing with a tropical storm. I know there are some social media sites hyping
that tropical storm idea, but that is simply not the case. But we will see some remnant moisture. How far
north that moisture can get will be limited. As we’re going to see a ridge of high-pressure
setup in Southeast Canada. At the same time that upper-level low is also going
to come north and east, staying just west and north of Isaias’s track.
The core of the heavier tropical moisture will stay over Maryland, Delaware into Southern New Jersey and the Delmarva. So, much of New York State and Northern and Central New England, won’t see too much tropical rain out of this.
General
rainfall amounts from Sunday morning to later Monday morning.
Rain will be
moving southwest to northeast across the region.
For Southern Pennsylvania, Maryland, Delaware, New Jersey, Long Island and maybe New York City. 1.5 to 2.5 inches of rain is possible. Across Southern New England (including the Cape and offshore islands), southern Hudson Valley, Northeast into Central Pennsylvania 0.5 to 1.5 inches. North and west of there into the Central Hudson Valley, Catskills and south and east of the Mohawk Valley 0.25 to 0.50 inches of rain, those north and west of there will see 0.25 or less inches. These rainfall amount will be a combination of the remnants of Isaias and the upper-level low.
As for as winds, Sunday into early Monday, winds look to be 10-25 mph with a chance for some higher gust. The farther south, the stronger the wind. Monday afternoon into Tuesday will see all of this move away with clearing developing west to east. Then on Tuesday into Wednesday a cold front will come through. Then on Thursday a warm front will lift through, followed by another cold front for Friday into Saturday.
