ATL: GRACE - Models

[gatorcane]

For entertainment: the 0Z Crazy Uncle (CMC) takes the remnants of Grace through the NE Caribbean, then across Hispaniola, and then to the NW Bahamas, where it stalls underneath an upper high, strengthens into a TS, and then turns west across central FL as what looks like a TS. Then it gets to the far NE GOM, where it turns N and gets even stronger (992 mb). What a nutty model!

More seriously, let's hope the remnants can give Luis et al some good rains in the NE Caribbean Fri-Sat!

The 00Z ECMWF has essentially the same solution as far as where the remnants ultimately end up but it just keeps the remnants weak. I would be shocked I the CMC verified.

[LarryWx]

Gator et al,
1) It looks like the 12Z GFS as well as recent prior GFS runs take the remnant Grace vortex/moisture faster to the WNW than do the last several runs of the Euro/CMC as implied by Gator. It is already in the SE Bahamas as soon as Sun AM 9/13 on the 12Z GFS. Compare that to the Euro/CMC, which are about 12 hours slower/200 miles further SE. That 12 hours quicker GFS movement is enough to allow the remnants to get caught in a trough off of the SE coast and be easily taken out/stretched out leaving behind little to no vorticity. OTOH, the Euro/CMC (including 12Z CMC), with their slower speeds, doesn't allow the bulk of the remnants to get taken out in time before a blocking high turns the remnants leftward toward FL. I don't trust the CMC at all but it does have the less untrustworthy Euro on its side. This could easily go either way in my mind. Let's watch the speed of Grace. With it having degenerated quickly, I have a feeling the GFS may be onto something with its faster movement. We'll see. Even if the remants do get blocked, the odds of them redeveloping like the 0Z CMC has them are small imo though not near zero.

2) Mucho kudos are deserved by the GFS/Euro/CMC model consensus as regards the degeneration of Grace today!

Edit: 3) The 12Z CMC takes the remnant Grace all of the way to LA/TX border on 9/18 as a weak low. That low SE of FL then is a totally different entity and it never makes it to FL.

4) I'm still rooting for some decent rains for PR and vicinity from the remnants!

[emeraldislenc]

Thanks for your comments. Always interesting!

[LarryWx]

YW, emerald.

Through 78 hours, the 12Z Euro is similarly slower to the 12Z GFS and is similar to recent Euro/CMC runs to this point. So, I'm educatedly guessing that the bulk of the remnants will not get caught in the trough offshore the SE US. Assuming that's correct, let's see if this run keeps it similarly very weak to the 0Z Euro.

[gatorcane]

The 12Z ECMWF has the remnants passing through the Bahamas and Florida and on the way to the Gulf with no development.

[Hurricaneman]

FWIW the 18zGFS has Grace redeveloping off the east coast and landfalling in New England as a TD while I do think anything could be possible I just don't see that happening or even redevelopment

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[gatorcane]

That doesn't look like the remnants of Grace that the GFS sends to New England. The remnants appear to head into Florida.

I am using the 850MB vorticity charts to follow the vorticity.

[Hurricaneman]

That doesn't look like the remnants of Grace that the GFS sends to New England. The remnants appear to head into Florida.

I am using the 850MB vorticity charts to follow the vorticity.

actually it might be a piece of grace doing one of those trough splits

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

[LarryWx]

I agree with Gator. The Grace remnants look to me like they get taken out by a trough on the 18Z GFS well before that just as prior GFS runs did 9/13-4. What does move up to New England is a second piece of energy that develops some 9/17 well off the SE coast and looks like the same piece that the 12Z CMC has that never quite makes it to S FL.

[LarryWx]

The 12Z ECMWF has the remnants passing through the Bahamas and Florida and on the way to the Gulf with no development.

The 0Z Thu Euro, like it did in prior runs, has the remnants of Grace making it to the central GOM on 9/17. This moves to the W GOM 9/18 but stays very weak.

[LarryWx]

For mainly entertainment from the Crazy Uncle:
For the 2nd run in a row, the Crazy Uncle (CMC) redevelops the remnants of Grace just NE of the Bahamas and then later strengthens it into a H that subsequently hits somewhere on the east coast of the CONUS. This 12Z 9/11 run comes ashore just N of Charleston, SC, very early on 9/19 as a 983 mb H. The prior run (0Z of 9/11) skirted the NC/VA coasts with a 978 mb H on 9/19-20.

Follow the 12Z run's 700 mb vorticity here to see that it is obviously Grace related:

http://www.tropicaltidbits.com/analysis ... 0&ypos=685

Note that this model is doing this despite sig. shear always nearby, if not right on top of it. For this reason and because this model is on its own, I don't currently believe it. Is this model not capable of incorporating shear as a negative factor in tropical development chances?
I'm sticking with redevelopment chances into a TC either off of the SE CONUS coast or within the Gulf at only ~10% as of now.