With one much-talked about but lackluster tropical wave failing to produce, a creepy Carolina creature crawls coastward...
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The tropical wave being monitored near Hispanola effectively fell apart
in the last 12 to 18 hours, now just a smattering of thunderstorms.
The interaction with land over the Dominican Republic seems to have
been simply too much for the already struggling wave to handle, with
its surface circulation still unable to develop with consistency, the
mid-level circulation degrading rapidly, and a chunk of tropical
moisture and energy advecting northward, away from both centers. This
has left the area of lowered pressures now drifting north, north of the
Dominican, but absent of deep moisture aloft and therefore absent of
any thunderstorms. The ironic twist is that the surface circulation
now appears better developed on visible satellite shots and surface
reports than it ever did when the wave had deep convection - just a
matter of the timing not lining up at the surface and aloft. It should
be noted that there is still plenty of opportunity for this system to
regenerate in the coming few days over the warm waters as it re-absorbs
deep moisture already streaming toward it in an inflow band from the
south, but it's certainly not going to be a player for us or anyone
else in the immediate future.
The shell game comes with the circulation that has developed, as expected, off the Carolina coastline. For awhile today, this tight storm center was looking darn good on IR satellite imagery, with cold cloud tops consolidating near the center. It was at that point that the National Hurricane Center issued their statement:
SATELLITE IMAGES INDICATE THAT THE LOW PRESSURE SYSTEM CENTERED
ABOUT 250 MILES...400 KM...SOUTHEAST OF WILMINGTON NORTH CAROLINA
IS ACQUIRING SOME TROPICAL CHARACTERISTICS. THIS SYSTEM COULD
BECOME A TROPICAL OR SUBTROPICAL CYCLONE LATER TODAY OR TONIGHT AS
IT MOVES WESTWARD OR WEST-NORTHWESTWARD. THE LOW IS ACCOMPANIED BY
WINDS OF UP TO 65 MPH...100 KM/HR...TO THE NORTH AND NORTHWEST OF
THE CENTER. REGARDLESS OF DEVELOPMENT THIS SYSTEM WILL BRING
STRONG WINDS...COASTAL FLOODING...HIGH SURF...AND DANGEROUS RIP
CURRENTS TO PORTIONS OF THE U.S. EAST COAST DURING THE NEXT COUPLE
OF DAYS. SEE STATEMENTS FROM LOCAL NATIONAL WEATHER SERVICE
FORECAST OFFICES FOR ADDITIONAL INFORMATION AND WARNINGS. AN AIR
FORCE HURRICANE HUNTER AIRCRAFT IS SCHEDULED TO INVESTIGATE THE
SYSTEM THIS AFTERNOON.
$$
FORECASTER PASCH/BERG
The winds may have surprised some, but indeed it not only matches up with satellite derived estimates, but nearby buoys have all been impressive, with Diamond Shoals the most impressive with continued gusts to 45 mph, hour after hour, and seas to 12.5 feet on a 12 second period - those are some nasty waves! There are issues with whether this actually becomes tropical, however, which focus on whether it meets the criteria. For now, there's question in my mind as to whether deep convection can persist around the center, thereby making it a symmetric, warm-core system. It's over water that's running 78-82 degrees - marginally warm enough for development - but the abundance of dry air that's visible to the east of the circulation center has squashed the hopes of more than one cyclone this year, and is already playing games with this Carolina Creature. Not only did IR satellite imagery show a rapid drop in deep convection when the dry air entrained to the core, but visible satellite imagery also showed this dry air penetrating all the way to the ground, and as of this writing, even wrapping into the north side of the circulation. Working in the storm's favor is the tight circulation that will try to protect itself with a small core of deep convection, but I have to say that the abundance of dry air may be damning to this storm.
The real point here is that it doesn't make much difference. If this thing went tropical, the only differences are these: it'll have a number or name, the media will suddenly care (right now nobody cares given the economic news), and the winds *may* pull a bit tighter to the center, since right now they're very non/sub-tropical by being removed by hundreds of miles - hence the highest gusts at Diamond Shoals when the actual center is due east of Savannah, Georgia. So, meteorologically, it's the impact a strong cyclonic circulation has that will make a much bigger difference. It's the tropical moisture feed that's been off the Carolinas for a few days, the northern breakaway piece of tropical moisture and energy from the Hispanola wave, and more than anything else, the pressure gradient between the Carolina low and the New England (soon to be Nova Scotia) high that will result in continued wind. The onshore flow should gust as high as 50 mph all the way north to Southern NJ by the end of Thursday as the band of easterly low level jet moves northward, but this is PRESSURE GRADIENT produced, not tropical. If it weren't for the autumn high, this would be a totally different story. With great agreement that the center of this creature will go into the Carolina coast Thursday evening, and given the abundance of dry air around it, and cool air that will soon advect into it in the lower levels on developing ageostrophic flow and the cool air firmly in place across the Northeast, this is going to have a very tough time becoming truly tropical. If it can maintain a core of convection, it may earn itself a sub-tropical classification, but the wind mechanism that will cause high surf, beach erosion, and some coastal flooding for the Mid-Atlantic is decidedly non-tropical in nature.
Of course, when you slam tropical air into non-tropical air, you get rain. Lots of rain. And that's what's headed to areas farther north, with a diminishing but still gusty gale force wind to the South Coast of New England.
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