ATL: TROPICAL DEPRESSION BONNIE - DISCUSSION

[Vortmax1]

Just not getting the "its coming, or wheels are turning, or almost there, or TD in 5 minutes" feeling.

Talking to a few pro mets & looking at some of the reliable models, just don't think this is a big hurricane in the making.[quote][/quote]


I agree...not much of anything in the making here.

[Aric Dunn]

Grace Bay in the Turks and Caicos has a pressure now down to 1007mb... the "center" is passing very close to the area..

any wind info?

low to mid 30s

http://www.wunderground.com/cgi-bin/fin ... 2.090&MR=1
scroll to the bottom

[KWT]

Grace Bay in the Turks and Caicos has a pressure now down to 1007mb... the "center" is passing very close to the area..

Yeah the circulation will pass close to there. High.vis loops do show its pretty weak though but at least this does look the real deal in terms of a LLC this time.

As for the shear, I suspect it'll never totally lose this issue myself though that doesn't mean we can't see decent strengthening, seen plenty of badly sheared 50-70kts systems before.

[Aric Dunn]

So i was thinking and the track and position sort of reminds me of rita more than katrina...

[MWatkins]

One thing to note...while I am not crazy about imminent development at this point (it's not good when supposedly developing systems are shaped like triangles)...the atmosphere along the path is getting a little less stable.

Notice in water vapor imagery that some moisture is starting to poke through the dry layer between 97L and Florida...

http://www.ssd.noaa.gov/goes/east/tatl/loop-wv.html

Not sure if this really means anything...but worth noting.

Also, the system is almost clear of the DR, although eastern Cuba isn't a super friendly terrain to deal with.

Finally, the interaction between the upper low and 97 continues to have my attention. I have been looking at every tropical system in the Atlantic since the early 90's...I had a friend whos uncle worked in the NHC, Frank2 undoubtly knows him, he used to fax me satellite images and NHC stuff all the time (hopefully, I won't get him in trouble 17 years later).

Felix helped me bridge the gap before the pre-internet era...I was at the NHC the day the forecast changed and Chris wasn't a threat anymore...I remember the sense of relief in the building for Puerto Rico.

Anyway, where was I. Oh yeah...

I've been looking at these things in real time for over 15 years, and studying satellite imagery from TC's for almost 20 now...and I have a deep down sense, that I can't explain, that this event isn't quite over yet.

It remains that issue of whether this low will turn into a vent as opposed to a hinderance for development.

With the thermodynamic environment getting a little more favorable, and shear backing off a little, I have to wonder if this system has enough left to develop. My brain says little to no chance of anything significant going up...

But my gut feeling isn't quite sure.

After reading "Blink" last year, I tend to listen to my gut a little more than I used to.

MW

[ConvergenceZone]

I still think it will be a depression and not a wave by the time it hits Florida...

[tolakram]

Hmmm. Inflow looks good?



Am I missing something?

[CalmBeforeStorm]

After looking at the latest visible loops and water vapor loops I see a LLC over the Turks and Caicos with most of the convection sheared to the east and northeast. The center is almost exposed but is at present firing some convection over it. The ULL is now racing west but it will still take some time for it to seperate enough to reduce it's influence. I think it's very much touch and go whether this system survives but if it does for maybe 24 hours it may start developing. As for course, I see just below florida if it stays weak but if it manages to strengthen I see it being kicked up enough by the ULL to threaten firthur up the Florida east coast. Just my opinion.

[alienstorm]

LLC over or near the Turks and Caicos - MLC further east looks to be sheer off. Always the possibility that the MLC in the deep convention could go down to the surface. Don't expect anything major a TD at best.

BTW - secondary wave axis to the SE of this system may develop down the road as well as it moves south and eat of this system.

South Florida to receive rain Thursday evening and most of Friday should be out by Friday evening Saturday morning.

[jasons2k]

Jasons, i'm not sure the conditions will be that good in the Gulf but we shall see, the models are even weaker in the Gulf then they are before Florida.

You're right, and that's one reason why I buy into the weaker, western "Euro" path. I also think it handles the ridge better. Whether the Euro develops the system or not is less important to me than how it handles the ridge placement.

The problem, if it does make it into the Gulf, is then we are talking another 2-3 days away. ULLs rarely behave how they are supposed to and I imagine the placement of those features will verify slightly differently than what we see forecasted right now. *If* this system can distance itself from the ULL to its NW, then ride the periphery of the ridge WNW into the Gulf, then the system could place itself in a favorable environment in a pocket of lower shear. If, and that's a big if, that chain of events can take place, then it could be 'lights out' with the door open for intensification. Further, if that were to occur, I would expect the system to then make the dreaded NW turn around the periphery of the ridge.

So that's my concern and has been for the last couple of days. I think the potential is there...otherwise it'll be just a sheared blob the whole way to Brownsville or Corpus, with maybe a teaser at the end like TD#2.

But, FWIW, I still just don't see any way this will be another Erin and hit the east coast of FL and then a 2nd landfall in the FL Panhandle.

[srainhoutx]

HPC had some interesting thoughts as well this afternoon in their Final Extended Update...

GULF COAST...
THE TROPICAL DISTURBANCE JUST NORTH OF HISPANIOLA IS EXPECTED TO
CROSS THE GULF OF MEXICO EARLY IN THE PERIOD. THE WESTERN SIDE OF
A PERSISTENTLY STRONG SOUTHEASTERN RIDGE ALOFT COULD BE DENTED BY
AN UPPER LEVEL LOW PRECEDING THE DISTURBANCE...WHICH THE GFS AND
ITS PARALLEL RECURVE THE FARTHEST EAST/NORTHEAST...WHICH HAS LED
TO NHC TRACK GUIDANCE SUCH AS THE GFDL AND LBAR TO LIE STILL
FARTHER EAST/NORTHEAST...WELL EAST/NORTHEAST OF ALL OF THE CURRENT
GLOBAL DETERMINISTIC AND ENSEMBLE GUIDANCE. THE 16Z COORDINATION
CALL WITH NHC YIELDED POINTS WITHIN THE NORTHEAST FRINGE OF THE
OVERALL 00Z MULTI-MODEL ENSEMBLE SPREAD WHICH COMPROMISE BETWEEN
THE WESTERN GLOBAL GUIDANCE AND THE EASTERN TROPICAL CYCLONE TRACK
MODELS. A PERSISTENT LACK OF ECMWF ENSEMBLE SUPPORT FOR THIS
SYSTEM CALLS INTO QUESTION HOW STRONG OF A FEATURE WILL ACTUALLY
MATERIALIZE IN THE GULF OF MEXICO FROM THIS DISTURBANCE. IF THE
SYSTEM FORMS INTO A TROPICAL CYCLONE...THE HEAVY RAIN THREAT WOULD
LIE ACROSS THE NORTH-CENTRAL GULF COAST. IF THE SYSTEM REMAINS
WEAK AND DISORGANIZED IN THE SURFACE PRESSURE PATTERN...THERE
WOULD BE ENHANCED SHOWER ACTIVITY ALONG THE TEXAS COAST VERY EARLY
NEXT WEEK. HENCE...CONFIDENCE IS LOW IN THE FORECAST ACROSS THE
CENTRAL AND WESTERN UNITED STATES GULF COAST FROM THIS WEEKEND
INTO EARLY NEXT WEEK. SEE THE LATEST TROPICAL WEATHER OUTLOOKS
FROM NHC CONCERNING THIS FEATURE.

[Kludge]

"weaker, further west....weaker, further west.....weaker, further west"

Wake me up when it crosses 80W and Texas is in the cone.....

Gotcha, Jason. Agreed. I'm setting your alarm clock for Monday at 00z.

[KWT]

Indeed ULL's are right little blighters to forecast, we could in theory go from it being hostile to actually helping the system.

tolakram, all the inflow is seemingly going into the convection just to the east instead.

[StormClouds63]

It won't increase past 50% at 8 p.m. (EST) If anything, it may go down to 40%. It's not dead yet, but it's still badly sheared and very disorganized.

[HURAKAN]

It's a bird!!! lol

on a sad note, thunderstorms are exploding over Haiti

[KWT]

It won't increase past 50% at 8 p.m. (EST) If anything, it may go down to 40%. It's not dead yet, but it's still badly sheared and very disorganized.

No reason the NHC takes it down to 40%, we have proof of a LLC of sorts and its got convection over the center...we've seen MANY syastems be upgraded from similar states when there is obvious proof of a circulation...take Danny last year as a great example, it looked terrible for a good part of its life.

[Weatherfreak000]

Convection firing closer to the center. it's definitely improving.

[Ivanhater]

Looks to still be on a wnw movement. Elongated low pressure area gives the illusion of moving SW

[rockyman]

I've been out of the loop since noon and just checked the visible loops...97L looks significantly better organized than it did 5 hours ago...the circulation is becoming more pronounced and the convection is almost covering the "center"

[ConvergenceZone]

Yea, I don't think it's quite dead yet either, but if it it's going to improve, it needs
to do it quickly, and not just improving with a burst of convection for 2 or 3 hours either.