ATL: KATIA - Post Tropical - Discussion

[TYNI]

Lot of possibilities with this one. "Know the cone..."



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[cycloneye]

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.

15N-50W is the benchmark position for the NE Caribbean to be affected or not by a system. Looking at where it is so far south right now,I have it below that position,unless a big weakness opens up.

[cycloneye]

12z CMC ends run at 21N-60W.

http://moe.met.fsu.edu/cgi-bin/cmctc2.c ... =Animation

[x-y-no]

He may exaggerate a bit most of the times, but JB just posted on Twitter about TD#12... "Still think GFS is missing pattern. Typhoon hits Japan from south Thur into Fri, teleconnection 6-10 days later would have central US trof".

Dont know about you guys, but i find it very interesting.

Well ... it's a good test of his WPAC/ATL teleconnections concept.

[ROCK]

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.

15N-50W is the benchmark position for the NE Caribbean to be affected or not by a system. Looking at where it is so far south right now,I have it below that position,unless a big weakness opens up.

I agree Luis...at 10N this is such a low lat....we will have to watch it today and tonight to see if she is really taking a WNW course...

I am guessing 1005ish mb right now. Current steering

http://tropic.ssec.wisc.edu/real-time/d ... oom=&time=

[x-y-no]

This is what I mentioned earlier. them models the past few runs have been a little too aggressive with this mid to upper low and the effect of it seems to be lessening with every run.

from the 11am discussion

"THIS FEATURE SHOULD CAUSE THE
TROPICAL CYCLONE TO TURN TOWARD THE WEST-NORTHWEST WITHIN THE NEXT
DAY OR SO. LATER IN THE FORECAST PERIOD...GLOBAL MODELS SHOW THE
WEAKNESS IN THE RIDGE SHIFTING WESTWARD AND THIS SHOULD PREVENT THE
CYCLONE FROM MOVING SIGNIFICANTLY POLEWARD DURING THE FORECAST
PERIOD. THE OFFICIAL TRACK FORECAST IS SIMILAR TO THE PREVIOUS ONE
AND ON THE SOUTHERN SIDE OF THE GUIDANCE ENVELOPE. "

One thing I find confusing - the official forecast track has TD12 gaining 8 degrees latitude during the forecast period. Isn't that "moving significantly poleward?"

[Jevo]

12z GFS 10 days out.. A threat to shipping

[rainstorm]

http://moe.met.fsu.edu/cgi-bin/gfstc2.c ... hour=168hr

dont buy into the out to sea scenario just yet.

the 7 day clearly shows a huge high building over the NE with POS NAO.

[KWT]

Should be a recurve on the 12z CMC, however its not a total certainty on that run to be fair.

[Jimsot]

Doesn't look too bad right now butn i do agree with the others that given the set-up aloft the models are probably being over-agressive.

Something similar happened with Earl last year, the models bombed it too quickly and in truth it didn't really get going till further west, thus it also got further west.

IMO still needs close watching in at least NE Caribbean, Bermuda and E.Canada based on the models at the moment...and that may well not be all as well...

This does remind me a lot of Earl. Everyday last August we would use the StormCarib 'closest point' tool with each new set of NHC FCT PTS and every run Earl got closer and closer. It eventually did 'turn' mostly right over us on Anguilla. I much prefer fish storms.


A little late in turning

[gatorcane]

12Z Euro started running, initalization looks good:

[KWT]

I suspect like the NHC this gains a fair amount of latitude in the next 48-72hrs, maybe getting to 13-14N, normally as the system pulls itself together and gets to the stage that TD12 is at now they tend to pick up latitude unless there is some very potent upper blocking aloft, which is not the case right now. That motion may well be followed by more of a bend west IF the system is still not all that strong by that point.

[Gustywind]

000
AXNT20 KNHC 291749
TWDAT

TROPICAL WEATHER DISCUSSION
NWS NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT MON AUG 29 2011

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS OF
SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST FROM THE
EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED ON SATELLITE
IMAGERY...WEATHER OBSERVATIONS...RADAR...AND METEOROLOGICAL
ANALYSIS.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
1745 UTC.

...SPECIAL FEATURE...

T.D. TWELVE IS CENTERED NEAR 9.8N 27.5W AS OF 29/1500 UTC...OR
ABOUT 405 MI...650 KM SSW OF THE SOUTHERNMOST CAPE VERDE ISLANDS
MOVING W AT 13 KT. ESTIMATED MINIMUM CENTRAL PRESSURE IS 1008
MB. MAXIMUM SUSTAINED WIND SPEED IS 30 KT WITH GUSTS TO 40 KT.
PLEASE SEE THE LATEST INTERMEDIATE PUBLIC ADVISORY UNDER
AWIPS/WMO HEADER MIATCPAT2/WTNT32 KNHC AND THE FULL
FORECAST/ADVISORY UNDER AWIPS/WMO HEADER MIATCMAT2/WTNT22 KNHC
FOR MORE DETAILS. SCATTERED MODERATE TO ISOLATED STRONG
CONVECTION IS MOSTLY W OF THE CENTER FROM 4N-13N BETWEEN
22W-33W. ENVIRONMENTAL CONDITIONS ARE CONDUCIVE FOR GRADUAL
INTENSIFICATION OF THIS SYSTEM OVER THE NEXT COUPLE OF DAYS.

[BigA]

Looks to be moving a bit north of due west per latest visble imagery. Also in no hurry to organize rapidly.

[wxman57]

major shift in the 12z GFS run ... especially noting the weakness and the trough

Here's a graphic showing the 7-day position from the 06Z and 12Z GFS. 12Z is in purple. It's about 65nm southwest of the 06Z run, but still has it passing well NE of the Caribbean. Not sure I'd identify that as a major shift.



At 10 days, the 12Z GFS (Purple lines) is a good bit faster than the 06Z and about 290nm farther north, plus a little bit farther west for the recurve point. This shift may be significant, as that it indicates "Katia" may impact the Canadian Maritimes a day earlier than the 06Z run. Also note the quite different pattern across the eastern U.S. on the 12Z vs. the 06Z run.

[wxman57]

Oh, and using GARP and visible Meteosat every 15 min, I calculated a 3-hr movement (15Z-18Z) toward about 319 deg at 10-11 kts.

[KWT]

Shift is also quite signifcant for Bermuda as well Wxman57, that track would put it very close to that island.

Of course from 10 days out, its a bit silly trying to even make that sort of call!

[gatorcane]

Out through 120 hours so far, the 12Z Euro is much faster and slightly more south of the 00Z run.

[Aric Dunn]

the CMC just like the GFS is now kicking that low that develops in the wake of Irene out almost 2 whole days faster which allows for in the CMC case ridging to build in... the end of run seems as though it gets trapped.

[jhpigott]

Out through 120 hours so far, the 12Z Euro is much faster and slightly more south of the 00Z run.

I presume that means it is showing a little more ridging over the top of TD12 at least through 120 hours?