TD INGRID: Discussions & Images - Last Advisory

[Ed Mahmoud]

It's moving but the ridge is more lax with this one. My eye wants to say an Antilles track. I wonder what role the weaker ridge will play in forcing development? Track will depend on where the center forms in that broad circulation. I guess we can assume further north in a lax scenario.

Wait 24 hours.

Lesser Antilles or Greater Antilles?

Or both? Or Netherland Antilles.

[Sanibel]

Ah, let's wait til tomorrow. 2007 is very tough to predict. But obviously a more north track is more possible in September climatology.

[HURAKAN]

Something that makes foecasting development a very difficult task is that a tropical disturbance may take a few days to go from a disorganized area of convection to a tropical depression, but the jump from an area of disturbed weather to depression will occur in about 24 hours.

Meaning, you have a system that has spent 3 days as a disturbance and in the next 24 hours it looks to continue that way. Then you suddently see the system organize into a cyclone. We saw that occur with Dean and Félix.

[Sanibel]

I think I see the center coming together in the very northern convection blob at 11N-39W

[HURAKAN]

Latest:

[flwxwatcher]

This sure is a big system and big systems sometimes take awhile to get organized but when they do things can happen quickly. It will be interesting to watch this system this week.

[windstorm99]

According to jeff masters he expects 91L to in position to threaten the northern islands.

Tropical wave in the mid-Atlantic (91L)
A strong tropical wave near 10N 38W, about 1000 miles west-southwest of the Cape Verdes Islands off the coast of Africa, is headed west to west-northwest at 10-15 mph. This system (91L) has the potential to develop into a tropical depression later this week. This morning's QuikSCAT pass showed a broad, elongated circulation and top winds of 25 mph. Satellite loops show some disorganized clumps of heavy thunderstorm activity. The disturbance is under about 15 knots of wind shear. Shear is forecast to remain near 15 knots over three days, which may allow some slow development. Later in the week, shear is expected to drop below 10 knots, and this could lead to a better chance of development. Both the HWRF and GFDL models predict that this will be a hurricane five days from now. This seems over-aggressive, given the wave's current state of disorganization, and the shear forecast. I think the earliest this would become a tropical depression is Wednesday.

A large extratropical storm over the mid-Atlantic between Europe and the U.S. is expected to pull 91L on a more northwesterly track by mid-week. This would put 91L in a position to threaten the northern Lesser Antilles Islands seven days from now.

[DESTRUCTION5]

How in the Heck can this thing recurve on its current position? I mean all I see is a soon to be depression crusing along at a Lat that I have not seen a Nov trough reach..

[Blown Away]

What's the current thinking? Does 91L move out to sea or near the Islands? Where does the GFS long range model take 91L? THe GFDL seems pretty drastic w/ the right turn rate now.

[Ed Mahmoud]

Former 90L- Just watched the Bastardi video, he admits he thought this would already be a cyclone by now, and he isn't quite as bullish, but with front dropping into Texas bringing Northerly winds to Western GOMEX, and shear relaxing, he says it is still possible. Not big ticket, apparently.

Former 92L- Will be in a favorable area when it reaches Bahamas, hasn't named a target, says storms should start increasing tomorrow. May be big ticket.


91L- Will enter Caribbean, but at higher latitude than Dean/Felix due to weakening of South American heat low with progression into Fall. No target yet, but he implied could be big.


JB also pointed out that while he was overdone on intensity of Gabrielle, he doesn't know anyone else who picked up as early as he did on it, and he is 3 for 4 calling "rabbit out of the hat" (Barry, Erin, Gabrielle) development.


Don't want to get any more detailed than that, hate to violate copyright on the AccuWeather PPV.

[StormWarning1]

:idea:

I think I see the center coming together in the very northern convection blob at 11N-39W

If you go to the NRL site and enlarge the satellite pic of 91L, you can see the low level center near 9.5N and 39W. Look at the low level clouds around this area and you can see the circulation.

[tolakram]

Floater:

http://hadar.cira.colostate.edu/ramsdis ... at1_0.html

from

http://www1.cira.colostate.edu/ramm/rms ... PICAL.html

I hope they keep the old version of this page active, I really dislike the java loops.

[BigA]

My eyes hurt, but I think I notice two things. One is that the northern convection is building, even as we approach DMIN (I do not understand DMIN and DMAX; I wish someone would explain it, but not necessarily in this thread)

Second, I sort of see two areas of turning, one with the big northern mass of convection (which I think may be a proto-cdo, and I mean this in the very early sense) and a second near 9.5 N, 39W.

[wjs3]

BigA:

Great question--as a lot of people are using Dmin and Dmax here.

Mods, can this question be split over to the "Got a Question" Forum? I can at least get us started over there.

WJS3

[MWatkins]

d-min and d-max (which, by the way are not terms I have ever seen before seeing them on this board)...are terms refering to the convective maximum and minimum times of day for tropical systems.

The theory is that tropical systems are less convectively active when the temperature differences between the upper and lower troposphere are the least (ie...mid afternoon when heating occurs)...and more convectively active (more thundestrorms, higher colder cloud tops) when the temp differences are greatest (early in the morning before sunrise)...due to radational cooling of the upper troposphere)

I am guessing d-min refers to diurnal minimum and d-max refers to diurnal maximum.

Please note, however, that each tropical system is different and the diurnal min/max pulses may not line up with the time of day theory.

Also...I do not know what if any role this plays with weak/disorganized systems over water.

MW

[windstorm99]

[HurricaneMaster_PR]

TPC 2:05pm Discussion

AN ACTIVE TROPICAL WAVE IS ALONG 40W/41W S OF 16N. THIS SYSTEM
WAS SLIGHTLY ADJUSTED AHEAD BASED ON SATELLITE IMAGERY AND THE
POSITION OF THE SFC LOW ALONG THE WAVE AXIS...WHICH IS NEAR
9N41W WITH 1010 MB. IT IS PRODUCING A LARGE AREA OF CLOUDINESS
AND THUNDERSTORMS. THIS SYSTEM IS GRADUALLY BECOMING BETTER
ORGANIZED AND HAS THE POTENTIAL TO DEVELOP INTO A TROPICAL
DEPRESSION DURING THE NEXT COUPLE OF DAYS AS IT MOVES WESTWARD
TO WEST-NORTHWESTWARD AT 10-15 MPH.

[AJC3]

d-min and d-max (which, by the way are not terms I have ever seen before seeing them on this board)...are terms refering to the convective maximum and minimum times of day for tropical systems.

The theory is that tropical systems are less convectively active when the temperature differences between the upper and lower troposphere are the least (ie...mid afternoon when heating occurs)...and more convectively active (more thundestrorms, higher colder cloud tops) when the temp differences are greatest (early in the morning before sunrise)...due to radational cooling of the upper troposphere)

I am guessing d-min refers to diurnal minimum and d-max refers to diurnal maximum.

Please note, however, that each tropical system is different and the diurnal min/max pulses may not line up with the time of day theory.

Also...I do not know what if any role this plays with weak/disorganized systems over water.

MW

Mike,

Based upon my experience in FL, the diurnal/nocturnal instability min/max would be more pronounced when it comes to weaker systems. After all, it has a significant effect on run-of-the-mill nocturnal showers off our east coast - they also tend to proliferate at night and weaken during the day (even outside of the sea breeze subsidence zone). With much stronger systems (canes), I think the more latent heat that convection is releasing into the ambient air mass in the vicinity of a system, the less significant the diurnal/nocturnal effects would be.

[punkyg]

http://www.ssd.noaa.gov/goes/east/catl/rb-l.jpg
I think that 91L is getting better organized.
just look at it now and look at it at 5am
I'm thinking we'll have a tropical depression maybe on wednesday.


any one still believe this will make it to the carribean or into the western atlantic and to the east coast or ou to see.

[MWatkins]

Thanks Tony. I wish I had thought about that a little more...the cooler the atmosphere is aloft, the further a rising, saturated air parcel can go up before it reaches an environment of equal temperature.

In a strong hurricane with a tight, warm inner core and the evacuation of mass aloft is optimal, it makes sense that the diurnal issue would become less of a contributer...

MW