ATL: Ex COLIN - Discussion

[CYCLONE MIKE]

Could this just sail due west and head for the Windwards?

I don't think anything can be ruled out for sure, though I do see at least some slight latitude gain occuring at the moment, but I don't think its been WNW in the last 4-6hrs anyway, I think 280-285 right now looks about right but its difficult to tell for me right now for some reason!

That does seem reasonable at the moment. I am looking at the CIMSS site and even if this strengthened all the way to a major hurricane, it would just move due west into the southern Caribbean Sea towards Central America. Things could always change in the medium term (NHC's thinking) though.

The track is showing it getting caught in the weakness between the highs in the ATL and SE US. If it strenghtens should start gaining some latitude if that happens. Now if it weakens in a couple of days and opens back into a wave than I think all bets are off and the remants could easily track westward with the high re-establishing itself.

[Sanibel]

Are are saying the track will help keep oil from coming onshore?

Yes my 6 post friend. It should be nowhere near the spill on the present model tracks.


The off-topic stuff makes too much "noise". They try to keep the info to just scientific discussion of the storm at hand. There tends to be high traffic when something gets going and too much off-topic distracts from good relay of accurate information.

[solomon25]

Ok, thanks Sanibel

[Vortex]

Very interesting Discussion this morning from HPC:


PRELIMINARY EXTENDED FORECAST DISCUSSION

--------------------------------------------------------------------------------



PRELIMINARY EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
855 AM EDT MON AUG 02 2010

VALID 12Z FRI AUG 06 2010 - 12Z MON AUG 09 2010

AS HAS BEEN THE STORY FOR WEEKS...TROUGHING IS EXPECTED TO REMAIN
ACROSS THE NORTHWEST AND NORTHEAST WITH A WARM CORE RIDGE
SANDWICHED IN BETWEEN ACROSS THE SOUTHERN PLAINS. THE ONLY ASPECT
OF THE FORECAST WHICH HAS CHANGED HAS BEEN THE STRENGTH OF THESE
FEATURES...WHICH HAS BEEN INCREASING AS THE SUN ANGLE SLOWLY
LOWERS WITH TIME. THE 06Z GFS/00Z UKMET PROGRESS TROUGHING OUT OF
THE NORTHWEST...WHICH WAS NOT SUPPORTED BY THE REMAINDER OF THE
DETERMINISTIC OR ENSEMBLE MEANS...SO THEIR SOLUTIONS WERE NOT
USED. THE GEFS/ECMWF ENSEMBLE MEANS...00Z CANADIAN...AND 00Z
ECMWF WERE ALL CONSIDERED USABLE WITHIN THE WESTERLIES.
CONFIDENCE IN THIS PATTERN ACROSS THE NORTHERN AND CENTRAL UNITED
STATES IS NEAR TO ABOVE AVERAGE.

ANOTHER WRINKLE IN THE FORECAST IS THE TROPICAL DISTURBANCE NEAR
12N 41W THIS MORNING...WHICH THE DETERMINISTIC GUIDANCE FLING NEAR
OR OFFSHORE THE EAST COAST OF NORTH AMERICA. NONE OF THE
DETERMINISTIC GUIDANCE HAS SHOWN MUCH CONTINUITY WITH THIS SYSTEM
FROM DAY TO DAY. THE ENSEMBLE GUIDANCE WITH THIS FEATURE HAS ALSO
BEEN QUESTIONABLE WITHIN ANY OF ITS 00Z AND 12Z RUNS OVER THE PAST
SEVERAL DAYS...THOUGH THE MULTI-DAY WAVERING IS AROUND A TRACK
WHICH MOVES JUST NORTH OF THE GREATER ANTILLES UP THE BAHAMAS AND
OFFSHORE THE FLORIDA COAST. HOWEVER...THERE ARE A FEW ENSEMBLE
MEMBERS WHICH SUPPORT THE ECMWFS ATTEMPT TO RECURVE THIS SYSTEM
OFFSHORE ATLANTIC CANADA IN A WEEK...BUT JUST AS MANY WHICH MOVE
THROUGH THE FLORIDA STRAITS AND KEYS. THE TROUGH IN THE EAST IS
NOT EXPECTED TO BE STRONG ENOUGH TO CAUSE FULL RECURVATURE...AND
THE COL IN THE FLOW PATTERN SHOULD REMAIN TO ITS NORTH...SO
FLORIDA AND THE GULF COAST ARE NOT IN THE CLEAR. THE WEAKNESS
ALOFT TO ITS NORTH SHOULD SLOW ITS FORWARD MOTION AS IT NEARS
FLORIDA AT THE END OF THE PERIOD. DUE TO THIS TRACK EXPECTATION
AND CONTINUITY FROM THE 16Z CALL ON SUNDAY...THE 00Z CANADIAN WAS
USED AS PART OF THE PREFERENCE. THE 00Z ECMWF HAD TO BE DITCHED
FOR THE 00Z ECMWF ENSEMBLE MEAN AS PART OF THE PREFERENCE LATE IN
THE PERIOD DUE TO ITS QUESTIONABLE HANDLING OF THIS TROPICAL
DISTURBANCE. NEEDLESS TO SAY...CONFIDENCE IS LOWER THAN AVERAGE
IN THIS ASPECT OF THE FORECAST...AND CHANGES MAY OCCUR DURING THE
16Z COORDINATION CALL WITH NHC TODAY.

ROTH

[SeminoleWind]

Very interesting Discussion this morning from HPC:


PRELIMINARY EXTENDED FORECAST DISCUSSION

--------------------------------------------------------------------------------



PRELIMINARY EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
855 AM EDT MON AUG 02 2010

VALID 12Z FRI AUG 06 2010 - 12Z MON AUG 09 2010

AS HAS BEEN THE STORY FOR WEEKS...TROUGHING IS EXPECTED TO REMAIN
ACROSS THE NORTHWEST AND NORTHEAST WITH A WARM CORE RIDGE
SANDWICHED IN BETWEEN ACROSS THE SOUTHERN PLAINS. THE ONLY ASPECT
OF THE FORECAST WHICH HAS CHANGED HAS BEEN THE STRENGTH OF THESE
FEATURES...WHICH HAS BEEN INCREASING AS THE SUN ANGLE SLOWLY
LOWERS WITH TIME. THE 06Z GFS/00Z UKMET PROGRESS TROUGHING OUT OF
THE NORTHWEST...WHICH WAS NOT SUPPORTED BY THE REMAINDER OF THE
DETERMINISTIC OR ENSEMBLE MEANS...SO THEIR SOLUTIONS WERE NOT
USED. THE GEFS/ECMWF ENSEMBLE MEANS...00Z CANADIAN...AND 00Z
ECMWF WERE ALL CONSIDERED USABLE WITHIN THE WESTERLIES.
CONFIDENCE IN THIS PATTERN ACROSS THE NORTHERN AND CENTRAL UNITED
STATES IS NEAR TO ABOVE AVERAGE.

ANOTHER WRINKLE IN THE FORECAST IS THE TROPICAL DISTURBANCE NEAR
12N 41W THIS MORNING...WHICH THE DETERMINISTIC GUIDANCE FLING NEAR
OR OFFSHORE THE EAST COAST OF NORTH AMERICA. NONE OF THE
DETERMINISTIC GUIDANCE HAS SHOWN MUCH CONTINUITY WITH THIS SYSTEM
FROM DAY TO DAY. THE ENSEMBLE GUIDANCE WITH THIS FEATURE HAS ALSO
BEEN QUESTIONABLE WITHIN ANY OF ITS 00Z AND 12Z RUNS OVER THE PAST
SEVERAL DAYS...THOUGH THE MULTI-DAY WAVERING IS AROUND A TRACK
WHICH MOVES JUST NORTH OF THE GREATER ANTILLES UP THE BAHAMAS AND
OFFSHORE THE FLORIDA COAST. HOWEVER...THERE ARE A FEW ENSEMBLE
MEMBERS WHICH SUPPORT THE ECMWFS ATTEMPT TO RECURVE THIS SYSTEM
OFFSHORE ATLANTIC CANADA IN A WEEK...BUT JUST AS MANY WHICH MOVE
THROUGH THE FLORIDA STRAITS AND KEYS. THE TROUGH IN THE EAST IS
NOT EXPECTED TO BE STRONG ENOUGH TO CAUSE FULL RECURVATURE...AND
THE COL IN THE FLOW PATTERN SHOULD REMAIN TO ITS NORTH...SO
FLORIDA AND THE GULF COAST ARE NOT IN THE CLEAR. THE WEAKNESS
ALOFT TO ITS NORTH SHOULD SLOW ITS FORWARD MOTION AS IT NEARS
FLORIDA AT THE END OF THE PERIOD. DUE TO THIS TRACK EXPECTATION
AND CONTINUITY FROM THE 16Z CALL ON SUNDAY...THE 00Z CANADIAN WAS
USED AS PART OF THE PREFERENCE. THE 00Z ECMWF HAD TO BE DITCHED
FOR THE 00Z ECMWF ENSEMBLE MEAN AS PART OF THE PREFERENCE LATE IN
THE PERIOD DUE TO ITS QUESTIONABLE HANDLING OF THIS TROPICAL
DISTURBANCE. NEEDLESS TO SAY...CONFIDENCE IS LOWER THAN AVERAGE
IN THIS ASPECT OF THE FORECAST...AND CHANGES MAY OCCUR DURING THE
16Z COORDINATION CALL WITH NHC TODAY.

ROTH

Wow seems as if forecast is still up in the air as far as will it get picked up fully or not.

[KWT]

The track is showing it getting caught in the weakness between the highs in the ATL and SE US. If it strenghtens should start gaining some latitude if that happens. Now if it weakens in a couple of days and opens back into a wave than I think all bets are off and the remants could easily track westward with the high re-establishing itself.

Yeah thats fair enough. I think the NHC track looks a little too far to the north at 120hrs, lets see if the weakness actually comes off as strong as some of the models expect.

[Vortex]

I think one very viable option that now must be considered is the fact this system in about 60-72 hours will encounter shear from the SW on the order of 30-35kts...I would not be surprised to see the LLC become exposed and head off towards the WNW either over the northern Leewards or just to the North...

Then it gets interesting...as long as there is some reflection at the surface you have a system that gets steered w/wnw much like the EURO indicated for days and finds itself in the bahamas under much improved atmospheric conditions...If this verifies then of course FL to to the Carolinas would need to play close attention..

***After looking at all the models this does seem reasonable almost as much so as the forecasted track.

[Vortmax1]

I'm happy to see the upgrade. I think most of us were expecting it at 11am.
I was called away but I have now read Stewart's discussion.

The part about the forward speed of the Depression is what I was thinking about earlier. I know a lot of scenarious are currently in play but this thing could just possibly never get past TS status the whole way and not be much of a problem for anyone.
So the ECM could be correct!

[KWT]

Vortex, its certainly an interesting possible thing that could happen, of course if there is one thing I never put too much faith into on the models it is things like upper shear...

The thing that goes against that idea is the ECM has a *very weak* system but still recurves it. If the trough is deep enough it'll even lift out a strong wave feature, so we will have to watch what happens, though I do have my doubts the trough is quite as strong as progged, at least during its first attempt.

[KWT]

msbee, yeah it could end up being a rather close call for the far NE Caribbean, most of the models end up to the NE and if this is a weak system it'd just lead to a breezy day with some showers on that sort of track.

Of course needs to be watched still though I agree!

[Vortex]

12Z GFS brings system right through the northern leeward islands...


http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_066l.gif

[KWT]

The GFS seems to indicate some pretty hefty shear tears this one apart around 20N...the TUTT looks like its going to be the main player perhaps for the entire season...

Anyway that doesn't mean these runs will be right regarding to the possible shear aloft but we will see....got a decent amount of time still before that happens, easily enough time for Colin.

[tgenius]

So I haven't seen on the discussions very much, have the new Para-GFS runs worked out or are they still being a bit flaky with things?

[Gustywind]

TD4 pointing at the horizon well east of the Lesser Antilles on this sat pic...

[Gustywind]

Tropical Depression 4 forms in Atlantic
Mark Avery, Lead Meteorologist, The Weather Channel
Aug. 2, 2010 10:56 am ET
Tropical Depression 4 has formed in the central Atlantic, located 1365 miles east of the Lesser Antilles and moving west-northwest at 17 mph. This tropical depression could quickly become Tropical Storm Colin by tonight. Right now, the forecast track takes this system into the western Atlantic, avoiding the islands of the Caribbean and the Bahamas mid to late week. The track could easily change so stay tuned!

East of the tropical depression, another strong tropical wave continues to produce thunderstorms and bears watching as well.

[KWT]

Won't be long Gustywind before it reaches the dry air aloft, will see how well TD4 cane mix it out but should have enough time to become Colin I'd have thought.

[mascpa]

MsBee - I visited your beautiful island this past Tuesday. Phillipsburg is a delight! I also think of my many friends in the islands during the hurricane season.

[Gustywind]

Won't be long Gustywind before it reaches the dry air aloft, will see how well TD4 cane mix it out but should have enough time to become Colin I'd have thought.

Yeah KWT but hope that Colin won't make a travel in Lesser Antilles. Let's wait and see.

[KWT]

Yeah true Gustywind, though to be honest I do think there probably will be enough distance to be ok if the current models are correct...besides by that time it'll be heading inbto the jaws of that powerful TUTT...and the GFS/ECM really do kill it off in that time....can't ignore when those two models come together.

[Vortex]

appears to be moving slightly North of due west last several hours at clip around 20mph....IMO I would not be surprised and to an extent I expect this system too come trough the area from the middle Leeward islands North...I think it will be moving to quickly to develop much and I now think its reasonable to expect a passage either side of Guadeloupe probably as a TD at worst with some squally weather/gusty winds...