ATL: TROPICAL DEPRESSION HENRI (10L)

[wxman57]

The term "organized convection" is ambiguous. Could mean over the center, or banding convection in toward a center, but maybe not convection 100 miles or more from an exposed center. There are many lows that develop across the tropics during the season (closed LLC). We really need a better definition of what defines a TD/TS, or at least some consistency in the naming of systems.

[wxman57]

Yes, it's the "once it gets under the ridge" part that I am curious about. What will happen then?

Possibly a remnant swirl (like Fred) devoid of most convection due to a lack of convergence. Once the ridge starts building, the easterlies will increase to 20-30 kts, so that adds low-level shear.

[HURAKAN]

I think the main difference between Danny and 91L is RECON.

[HURAKAN]

Convection trying to develop again near the LLC.

[HURAKAN]

917
ABNT20 KNHC 061738
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
200 PM EDT TUE OCT 6 2009

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

AN AREA OF LOW PRESSURE LOCATED ABOUT 475 MILES EAST OF THE LEEWARD
ISLANDS CONTINUES TO PRODUCE DISORGANIZED SHOWER AND THUNDERSTORM
ACTIVITY...WHICH IS DISPLACED TO THE EAST OF THE LOW-LEVEL CENTER
DUE TO STRONG UPPER-LEVEL WINDS. CONDITIONS ARE EXPECTED TO REMAIN
UNFAVORABLE FOR SIGNIFICANT DEVELOPMENT AS THIS SYSTEM MOVES
NORTHWESTWARD NEAR 15 MPH. THERE IS A LOW CHANCE...LESS THAN 30
PERCENT...OF THIS SYSTEM BECOMING A TROPICAL CYCLONE DURING THE
NEXT 48 HOURS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER BERG

[cycloneye]

12z CMC has a weak feature moving slowly at the first part and going more faster and moving WSW.

http://moe.met.fsu.edu/cgi-bin/cmctc2.c ... =Animation

[Derek Ortt]

maybe a more realistic scenario is the Bay of Campeche cyclone CMC is spinning up

[HURAKAN]

18 UTC Best Track

AL, 91, 2009100618, , BEST, 0, 177N, 534W, 30, 1007, DB

[HURAKAN]

Convection back over the center

[HURAKAN]

06/1745 UTC 17.7N 53.3W T1.0/1.0 91L


Dvorak doesn't work well with sheared systems

[djones65]

I agree with Aric and Hurakan... this system is a tropical depression in my opinion. The convection has been persistent and close enough to the well defined low level circulation and it deserves to be classified. If we had a reconnaissance aircraft in the system I would wager that it could be a minimal tropical storm. The naming of tropical cyclones is such a subjective decision, but I wish it could be more consistent.

[HURAKAN]

I know that "looks" aren't everything, but tell me it doesn't "look" like a tropical cyclone.

[Nimbus]

There is no elongation to the low level circulation so it could spin up if it overcomes the shear. With a developed system the east coast ridge might have more of a tendency to bridge over. A tropical system develops an anticyclone dome from its outflow.

[Emmett_Brown]

Yup, that's a TC, not doubt about it. Probably wont survive, but it is none the less a TC in my unofficial but correct opinion.

[HURAKAN]

Update:

AL, 91, 2009100618, , BEST, 0, 177N, 534W, 35, 1007, DB

Intensity increased to 35 knots. If it develops, it will be Henri.

[cycloneye]

In that loop it looks like its moving more wnw than nw.

[HURAKAN]

What a fighter. Convection again over the LLC

[Aric Dunn]

In that loop it looks like its moving more wnw than nw.

correct if you look at the steering flow it would suggest a more west north west motion as a deeper system so i have seen it bouncing back and forth all day thus far. everytime convection fires it starts a more wnw motion and when the convection dies and the center is exposed a motion more towards 300 occurs ..

presently the convective burst that is occurring may turn out to be quite impressive..

[djones65]

The latest Marine Weather Discussion from the NHC at 1840 UTC was interesting...
IN THE TROPICAL ATLANTIC AREA INITIALLY THE WINDS WILL BE LESS
THAN NORMAL EXCEPT NEAR THE LOW PRESSURE OVER THE NORTHERN PART
OF THE TROPICAL ATLANTIC WHERE WINDS OF 20 TO 25 KT ARE
FORECAST....HOWEVER CONVECTION HAS INCREASED NEAR THE CENTER AND
A TROPICAL CYCLONE NAY BE FORMING. MORE NORMAL 20 KNOT TRADES
WILL SPREAD OVER THE TROPICAL ATLANTIC WEDNESDAY AND CONTINUE
THROUGH THURSDAY.

The link is: http://www.nhc.noaa.gov/text/MIAMIMATS.shtml

Maybe we will see advisories initiated on Henri in a couple hours?

[HURAKAN]

djones, that's certainly news. Big difference in the wording compared to the TWO at 2 PM.