ATL: KATIA - Post Tropical - Discussion

[ronjon]

00z CMC Takes TD 12 dangerously close to the SE US.

http://raleighwx.americanwx.com/models/ggem/00zggem500mbHGHTPMSLtropicalGGEMLoop.html

[senorpepr]

it's already TS Katia

Wonder if this one is gonna curve or not. Gotta follow this. Thx for the updates.

Do not spread false information, or at least back up these claims.

Per the ATCF, it's still a depression:

AL, 12, 2011082906, , BEST, 0, 93N, 257W, 25, 1009, TD,
ftp://ftp.nhc.noaa.gov/atcf/tcweb/inves ... 011.invest

[Thunder44]

Honestly, my gut feeling considering all the model errors and biases, this will track closer to the NE Leeward Islands. But then recurve out to sea, somewhere between the US and Bermuda. But that's just a gut feeling.


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The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.

[cycloneye]

This morning's discussion of 12 by Rob of Crown Weather.

The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.

http://www.crownweather.com/?page_id=4557

Tropical Depression #12:
Tropical Depression #12 has developed to the south of the Cape Verde Islands this morning. This depression is expected to slowly strengthen over the next few days as it encounters some easterly wind shear. Even with the easterly wind shear, environmental conditions should be favorable for strengthening throughout this week; therefore, I expect TD #12 to become Tropical Storm Katia by tonight or early Tuesday and then reach hurricane strength by late this week.

Tropical Depression #12 is tracking due west at a forward speed of 15 mph. This system is currently located to the south of a ridge of high pressure which will weaken somewhat over the next couple of days as a upper-level low pressure system tracks across the central Atlantic. This, in turn, will cause TD 12 to track west-northwestward from later tonight until about Wednesday. After Wednesday, that upper level low pressure system will weaken and the ridge of high pressure will strengthen to the northeast of the storm thus causing it to remain on a west to west-northwest track through the end of this week.

Looking much further out, the dynamical and global operation model guidance currently forecast that this system will eventually turn to the northwest and north missing the Lesser Antilles by a good distance, but possibly threatening Bermuda in about 10 days from now. The ensemble members of the GFS and European model guidance tell a different story, however.

The GFS ensemble guidance forecasts that TD 12 will track just north of the Lesser Antilles around next Monday. From there, the GFS ensemble forecasts that this system will track to the east of the Bahamas around next Wednesday and then the ensemble guidance becomes much less uncertain with some of the members forecasting a track north and northeastward to Nova Scotia with other ensemble members forecast a westward track into the Gulf of Mexico.

The European ensemble guidance also forecasts a close brush to the northern Leeward Islands around next Monday and then split on the potential track with some members taking it northward towards Bermuda and other members forecasting a west-northwest track towards the Bahamas in 10 days.

Needless to say, it is way too early to be confident or certain on any one forecast track. The GFS operational model is biased with forecasting tracks that take systems into the open Atlantic too quickly. I do think there are a couple of possibilities: The first is a track that takes this system about a couple of hundred miles north and east of the northern Leeward Islands next Monday and then impact Bermuda by late next week. The other possibility is that this could conceivably head towards the Caribbean and miss the upper level trough of low pressure that is forecast over the western Atlantic in 8 to 10 days from now. The track model guidance is slowly trending towards that direction and I will continue to closely monitor these model trends. Right now, I am leaning towards a track that eventually takes this very close to, if not right over the northeastern Caribbean next weekend followed by a turn to the north and a threat to Bermuda and the Canadian Maritimes late next week into next weekend.

[CourierPR]

Bastardi tweets look for the models to trend west with this system.

[KWT]

Judging by the models and the fact systems often get a little further west then the initial forecasts, that may not be a bad call Thunder.

Stronger upper high on the 00z CMC but looks like a frontal system off the E.coast , notice how there is constant lows forming along the wave/frontal system stretching into the NW Atlantic.

[timeflow]

Here are the steering currents... looks like it sees a storm or two coming in from the SE, but whatever it is gets absorbed in the noise of time...

http://www.nco.ncep.noaa.gov/pmb/nwprod ... loop.shtml

[KWT]

Given the expectation of a 2/3 by the time it gets to 55W, I suspect Crownweather's first option seems more probable, I'd be amazed if it misses...even Irene as a Td/TS could escape that weakness...doubt a near Major hurricane will...

[cycloneye]

Still easterly shear is affecting it. The weak it stays more west applies here right?

[CourierPR]

Joe Bastardi tweets that the models will trend west and we may have another east coast threat in 10-15 days.

[GCANE]

There are some new ionospheric disturbances underway again.

This may be a good chance to test my theory on intensity modulation as it tracks across the pond.

Here is a current view of the D-region absorption of RF energy due to a C-class solar flare underway.

[Thunder44]

00z CMC Takes TD 12 dangerously close to the SE US.

http://raleighwx.americanwx.com/models/ggem/00zggem500mbHGHTPMSLtropicalGGEMLoop.html

The CMC/GGEM has a large cut-off low centered over the Tennesse Valley, that could actually draw this storm towards the East Coast. It could happen with +NAO/+PNA pattern forecasted. But the GGEM is pretty much junk, at this range.

[LarryWx]

I'm currently going with a 90% chance for a recurve E of the continental US vs. the ~83% climo chance
of a storm that forms east of 50W not hitting the continental US. This is keeping in mind the strong model consensus of less than the normal amount of western ATL/Bermuda high pressure and consistent GFS recurves well E of the US. This is in sharp contrast to the GFS runs showing a US hit starting on 8/15 and having a US hit from Irene every run from that point. Moreover, keep in mind that these early GFS runs ended up too far west. IF it were to either develop more slowly than the models suggest and/or move WSW while in the E ATL, I'd then likely reduce the recurve chance from 90%.

[KWT]

Not to mention its at total odds with the GFS/ECM, which at this range tend to be the two models that need to be most closely watched.

[DelrayMorris]

Joe Bastardi tweets that the models will trend west and we may have another east coast threat in 10-15 days.

I don't think I can take another week of this hype without completely losing my mind. All this does is scare people. Why can't anyone ever just say "there's another tropical depression WAY out in the Atlantic but we really won't know where it's possibly going for a week or so" Why are Americans so in need of always having a disaster - something TERRIBLE getting ready to or just happening to us?

Sorry, I've been fighting with someone on another board about what saying "Irene's FURY" and "Cataclysmic Hurricane Irene" does to people, but I think they thrive on the drama.

I once saw an elderly woman run over by a crowd of panicked people in Wal-Mart when they brought out a pallet of water. Because of Hurricane Ernesto 2006. Yes, we needed to prepare. No, we didn't need to be terrified.

[KWT]

LarryWx, yeah sounds fair enough, mind you its pretty hard to move WSW when your already at a very low latitude.

Does look like its getting a little sheared at the moment to be fair.

[GCANE]

Here's the latest core-temp profile I could find.

Max temp at 12km which is expected for a normal TC.

During the previous TCs, I have seen this get compressed down to about 8km altitude.

[LarryWx]

Joe Bastardi tweets that the models will trend west and we may have another east coast threat in 10-15 days.

1) Keep in mind that JB very often says this kind of thing. How often do you hear him say the opposite? Also, all he says is that it MAY then be a threat. That's not really committing to anything, regardless.

2) JB was not as much of a guru on Irene as he leads us to believe. Initially, he had it as a big FL
threat per his tweets.

[LarryWx]

Not to mention its at total odds with the GFS/ECM, which at this range tend to be the two models that need to be most closely watched.

Agreed. The CMC is generally an inferior model. I'm still going with a 90% chance of a recurve east of the continental U.S. The western Atlantic is forecast to be pretty void of the high pressure needed to bring a TC far enough west.

[LarryWx]

Bastardi tweets look for the models to trend west with this system.

JB says this with many storms....no big deal for him to say it here.