Loc: Orlando, FL
Tropical Storm Ophelia Weak and Getting Weaker
Sat Sep 17 2011 09:08 AM
Update, Thursday, Sept. 22, 2011 - 1230PM
Strong southwesterly windshear has fully exposed the low level center of Ophelia. The high winds reported well to the northeast of the center are a result of convective collapse and have little association with the cyclonic circulation of the system. At 22/16Z, The low level swirl of Ophelia was located near 13.3N 48.0W and it was moving due west. Strong windshear should continue and keep Ophelia as a weak system - IF it can survive the shear as the disrupted cyclone heads to the west and west northwest. Its possible that Ophelia could lose tropical cyclone classification in a few days and become an open wave, but it is also fair to mention that Maria encountered the same strong shear and managed to survive it.
Update, Wednesday, Sept. 21, 2011 - 6AM
The trend of weaker storms this year continues with Ophelia, as it heads westward.
It is expected to remain relatively weak, and indeed even remain under shear for the foreseeable future.
The official forecast takes Ophelia near the northern Leeward islands on Sunday, and then it begins to get more uncertain, the NHC is going with an assumption that the strong ridge to the north weakens and it gets pulled to the north, if that were to occur, it is very unlikely Ophelia would approach the US. The other alternative is that is misses the weakness and continues westward. The odds are now favoring the former, though.
Either way Ophelia will likely remain a weak, sheared system that may never get very organized.
Update, Tuesday, Sept. 20, 2011 - 1145PM
Tropical Storm Ophelia formed Tuesday evening near 12N 40W and movement is to the west at about 8 knots. Ophelia is still slowly organizing so some centerpoint adjustments are possible. Convective consolidation is weak at best and westerly windshear remains to the north so additional intensification will be slow to occur. Ophelia is almost 1,600 miles to the east southeast of the northern Leeward Islands. Upgrade was based on an area of 35 knot winds to the north of the apparent center, but the satellite presentation is certainly a long way from that of a classic TS.
The former Invest 99L has flared up again near 17N 58W, and a new tropical wave is located in the far eastern Atlantic near 12N 21W at 20/03Z.
11:00 AM Update 20 September 2011
The wave 98L in the Central Atlantic is close to becoming a depression or storm today, and likely will form later today or tomorrow.
It is still expected to go generally westward and with the relatively strong high pressure to the north and the weak nature of the system, odds favor it to continue into the Caribbean, after which it could vary, but it's slightly favored to stay weak and cross further west into the Caribbean and possibly Central America.
Aircraft recon is tentatively scheduled to approach the wave tommorrow if it continues to develop. Those in the Leeward islands in the Caribbean should watch this wave, it is likely to be Tropical Storm strength as it nears the islands.
7:00 AM Update 19 September 2011
This morning attention is being drawn toward 98L as it has become the dominant system with chances for development now up to 60%. 97L is no longer being tracked and 99L has weakened again with chances now at 0%.
It will need to be monitored into through the week into next week, especially by those in the Eastern Caribbean. Beyond that is too soon to tell, although odds slightly favor it staying in the Caribbean. It, like many other systems this year, will probably remain weak or not be all that organized.
10:45 AM Update 18 September 2011
There appears to be a pattern change approaching in about a week that may keep the newly tracked invests (At least one of them) south into the Caribbean into next week. All waves currently have less than a 33% chance of forming in the next two days, but one or two of them likely will form at some point.
If it were to approach the eastern Caribbean (Antilles) it would be late this week. Beyond this, the odds still favor it staying in the Caribbean all the way to central America, but these are still weak and could change.
Of the 3 invests, 98L is the most likely to be the one to watch.
The first half of September saw a few tropical storms, along the coast, and a few storms and two hurricanes that recurved away from the US, with Maria running into eastern Newfoundland.
So what's next after this? Not all that much, the general air in the Atlantic is fairly stable vertically which is not conductive for development (and when it does occur it tends to shear or tilt systems as has happened with most of the storms this year).
However, there is an area in the eastern Atlantic (97L) that could develop over the next week or so (30% chance right now). Early indicators is that it may tend to stay much further south and weak and move through the Caribbean all the way into Central America, but this will likely change and should be monitored by those in the Eastern Caribbean during the week.
Edited by Ed Dunham (Thu Sep 22 2011 12:51 PM)