ATL: Ex COLIN - Discussion

[Vortmax1]

Vortmax, that is very key, this one is a tough call because its a fine line for sure, if it gains enough latitude now and gets far enough west, its a dead cert for a recurve...IF it takes its time and maybe not strengthen too rapidly then the NE Caribbean and the states down the line is at real threat.

Yes it is and I agree with you KWT.
I was just running through the models.
I think this system will keep me on the edge of my seat!

[tina25]

I am eager to see the pro-mets weigh in on this storms forecast soon.

[KWT]

Its a tough call, I do think a Gulf strike is somewhat unlikely becuase the troughing on the east coast is forecasted to be pretty strong, the set-up aloft to me looks like the type that leads to a risk of a Florida up to say NC risk, after that the flow switches back offshore.

[cycloneye]

18z Best Track

AL, 91, 2010080118, , BEST, 0, 98N, 363W, 25, 1007, LO

ftp://ftp.tpc.ncep.noaa.gov/atcf/tcweb/ ... 010.invest

No upgrade yet.

[KWT]

Pulling up and heading out of the ITCZ, that trend will carry on for the next 24hrs I'd imagine. Still it is quite far south.

Anyway yeah not an upgrade yet but it really is looking like a proper TC right now, its getting that curving look to it right now.

[Aric Dunn]

Pulling up and heading out of the ITCZ, that trend will carry on for the next 24hrs I'd imagine. Still it is quite far south.

Anyway yeah not an upgrade yet but it really is looking like a proper TC right now, its getting that curving look to it right now.

they have and often do upgrade even though the best track has not changed...

[Aric Dunn]

although 9.8 N is a little far south ... satellite image have a convective band going right through the middle of those coordinates.. it is likely more near 11 N

[HURAKAN]

If I ever seen a system looking more like Colin, it's this system!!! If it doesn't get upgraded today or tonight, I think it will be early tomorrow with the push of D-max. The computer models are pretty clustered on a path slightly north of the Lesser Antilles but they believe that a west-northwest motion should begin soon. I would keep a very close eye if I lived in the northern Lesser Antilles, just in case.

[KWT]

although 9.8 N is a little far south ... satellite image have a convective band going right through the middle of those coordinates.. it is likely more near 11 N

Yeah I agree with this post, looks to me like the center is close to 11N, thats where I'd place it right now. This track could well be quite interesting, the models seem to be quite keen on the upper trough becoming fairly potent, maybe enough to lift it out but we shall see...I personally view an East Coast threat though as more likely.

[cycloneye]

From this afternoons San Juan NWS discussion.

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
334 PM AST SUN AUG 1 2010


FCST BETWEEN THU-SAT WILL DEPEND ON THE TRACK AND EVOLUTION OF
WHAT IS LIKELY TO BECOME TD#4 IN THE NEXT 12 TO 24 HRS. MODELS
SHOWING GOOD AGREEMENT WITH A TRACK JUST NORTHEAST OR OVER THE
ISLANDS OF THE NORTHEAST CARIBBEAN. HOWEVER...LARGE SPREAD SEEN
WITH RESPECT TO TIMING OF POSSIBLE EFFECTS WITH THE FASTER 12Z
ECMWF BRINGING ASSOCIATED WEATHER AS EARLY AS THU VS. THE SLOWER
GFS/BAM MODELS (THU NIGHT). UNTIL SYSTEM DEVELOPS A CLOSED SFC
CIRCULATION AND SPEED OF THE SYSTEM CAN BE TRACKED MORE PRECISELY
ANTICIPATE THERE WILL BE MORE ADJUSTMENTS TO THE FCST. EVEN WITH
THE GOOD AGREEMENT WITH THE TRACK FCSTS...USERS ARE REMINDED THAT
AVG TRACK FORECASTS FOUR TO FIVE DAYS OUT ARE IN THE ORDER OF 220
TO 285 NAUTICAL MILES. SO NOTHING IS IN STONE YET. PLEASE REFER TO
PRODUCTS FROM THE NATIONAL HURRICANE CENTER.

[cycloneye]

Pulling up and heading out of the ITCZ, that trend will carry on for the next 24hrs I'd imagine. Still it is quite far south.

Anyway yeah not an upgrade yet but it really is looking like a proper TC right now, its getting that curving look to it right now.

they have and often do upgrade even though the best track has not changed...

The majority of the time, the signal that they upgrade a system is when the renumber set comes out.But they also have upgraded without doing that by issuing a regular first advisory or issuing a special first advisory so we will see what happens between 4:30-5:30 PM.

[bvigal]

Its a tough call, I do think a Gulf strike is somewhat unlikely becuase the troughing on the east coast is forecasted to be pretty strong, the set-up aloft to me looks like the type that leads to a risk of a Florida up to say NC risk, after that the flow switches back offshore.

KWT, can you show us dummies what you mean when you say it "looks to me like"? I'm really hoping to learn something here.
Thanks!

[scotto]

2 Questions?

- When a low 'closes' will there be a flare-up of convection over the center or it's perimeter?

- Is it the rotation that may cause 91L to lift out? The stronger the rotation the more north it moves?

Thanks

[KWT]

The sun is just on its way down near where 91L is, looking pretty good at the moment it has to be said, seems to be drawing from quite a wide region. I've gotta admit I think this one may not take too long to get going once the LLC becomes strongly established.

The ECM/SHIPS do seem to hint at a shear zone being present between 96-120hrs which could weaken the system, so thats something to watch as well...

[srainhoutx]

Sunset in the Central Atlantic...

[dixiebreeze]

Conditions at 31007 as of
1700 GMT on 08/01/2010:

Note: This report is more than two hours old Unit of Measure: English Metric Time Zone: Station Local Time Greenwich Mean Time [GMT] British Summer Time [GMT+1] Eastern Greenland [GMT-1] Azores [GMT-2] Western Greenland [GMT-3] Atlantic Standard [GMT-4] US/Eastern Standard US/Central Standard US/Mountain Standard US/Pacific Standard Alaska Standard [GMT-9] Hawaii-Aleutian Standard [GMT-10] Samoa Standard [GMT-11] International Date Line West [GMT-12] Western European [GMT+0] Central European [GMT+1] Eastern European [GMT+2] Moscow [GMT+3] USSR Zone 3 [GMT+4] USSR Zone 4 [GMT+5] USSR Zone 5 [GMT+6] USSR Zone 6 [GMT+7] China Coast [GMT+8] Japan Standard [GMT+9] Guam Standard [GMT+10] GMT+11 International Date Line East [GMT+12]
Click on the graph icon in the table below to see a time series plot of the last five days of that observation.

Air Temperature (ATMP): 78.6 °F
Water Temperature (WTMP): 79.3 °F
Atmospheric Pressure (PRES): 29.83 in
Wind Speed (WSPD): 15.0 kts
Wind Direction (WDIR): ESE (120 deg)

Data from this station are not quality controlled by NDBC

[HURAKAN]

Looking at the loops, I would pull the trigger at 5 pm. But since I don't work at the NHC and they tend to be more conservative, I would expect upgrade at 11 pm or 5 am.

[wx247]

If they don't upgrade at 5 pm, unless there is a major change I would imagine they would hold off until 5 am. Just my $.04 worth...

[Aric Dunn]

Looking at the loops, I would pull the trigger at 5 pm. But since I don't work at the NHC and they tend to be more conservative, I would expect upgrade at 11 pm or 5 am.

yeah they said either 5 or 11 but could be 5am as well .. its not really exactly a huge deal at this point..

[Portastorm]

When a low pressure system closes off, yes, generally the convection will consolidate around the center. However, every tropical system is different and you can have a closed low with little convection and you can have no closed low with a lot of convection.

As to 91L lifting out ... that depends on the atmosphere around it and the influence of various high pressure and low pressure systems. You have to think three dimensional and realize that the more developed a system becomes, the higher in the atmosphere it is, and the more prone it then becomes to the influences of wind currents at mutiple levels.

There are much smarter people than me on here who can opine better, I'm sure.

2 Questions?

- When a low 'closes' will there be a flare-up of convection over the center or it's perimeter?

- Is it the rotation that may cause 91L to lift out? The stronger the rotation the more north it moves?

Thanks