ATL: ISAAC - Post-Tropical - Discussion

[JonathanBelles]

Just my opinion, but i'd be willing to say that 94L is a TD and possibly a TS right now. It seems like most the of satellites during the last six hours are trying to dodge the system, but based on distant buoys and the microwave passes that are showing clear circulation. I think we will be waking up to a new NHC warned system.

[Cyclenall]

Anyone think this will get renumbered by 5AM or even 8?

*image removed*

It has been a TD/TS for some time, guessing that NHC is waiting for more sustained convection and that's what we are now getting.

No, it hasn't been a TD or TS yet. To say that is very disrespectful to the NHC. Heck, a few hours ago there were people suggesting that the probabilities for development should be lowered for a lack of convection. A TD or TS isn't a TD or TS until the NHC declares it one. Not only is it disrespectful, but it's irresponsible to undermine the authority of the NHC by saying it's been a TD or TS.

I think we'll have a TD sometime today, so long as the convection can hold on, which it looks like it'll be doing. Really wonder what the NHC is going to do for the intensity forecast. Interesting times ahead. And sleepless nights.

Actually this is false, it can be a TD or TS and the NHC not start advisories for it because they wait until convection sustains or some other minor criteria before pulling the trigger. Various mets have said this and have said the same for 94L. The bolded part: No.

The Weather Network in Canada is even talking about how bad the "I" storms are and did an article on them: http://www.theweathernetwork.com/news/s ... topstories

Man this could be a huge storm and i mean area not so much strength.

I should be because the last 4 "I" storms have been huge and this should continue it based on how it is right now.

[brunota2003]

http://www.ndbc.noaa.gov/station_page.php?station=41040

Buoy is a full 3 degrees west of roughly where the center is (if the ball of convection at 50W is the center)...already winds are starting to go up, only to 15.5 knots (1-minute sustained) so far though.

Any circulation center is due east of this buoy, which is now reporting North winds. From 2 am to 3 am, strongest winds so far have been 21 knots (1 minute peak average).

[somethingfunny]

RENUMBER al94 al09

We get the Best Track updates hookup in the Storm2k chatroom.

[lester]

BEGIN
NHC_ATCF
invest_RENUMBER_al942012_al092012.ren
FSTDA
R
U
040
010
0000
201208210753
NONE
NOTIFY=ATRP
END

[somethingfunny]

[somethingfunny]

Welp, here we go...



This thing is large.

[hurricanes1234]

Tropical Depression Nine forms....expected to become a Category 2 hurricane!

[Shuriken]

Yeeg....budge it two millimeters to the left, and that's a Hurricane Allen cat-5 track...

Welp, here we go...

[somethingfunny]

I'm not a fan of analogs since for every Allen or Gustav or Dennis that's formed in this area and taken this sort of track, there's also a Helene 2000 or an Ernesto 2006. I'm sure this storm will end up being quite like Isaac 2012 and nothing else. But with that being said, I'm very worried about this storm for the Lesser Antilles, Greater Antilles, Florida, and the Southeast US. Stranger things have happened, but I don't think it will be coming towards Mexico or Texas based on everything the models are showing.

[Florida1118]

Yesh...they were not conservative at all with this storm. Bringing it up to near Major strength by day 4.

[USTropics]

POSSIBLE INTERACTION WITH LAND
MASSES OF HAITI AND CUBA...RESPECTIVELY...IS THE PRIMARY REASON
FOR THE LEVELING OFF IN THE INTENSITY.

This part of the discussion definitely caught my attention. Still a long way to go but it's basically inferring that a major is definitely in play if there is minimal land interaction.

[somethingfunny]

Our next frame will have a live visible image. Can't wait to find the LLC on the visible loop.

[somethingfunny]

TROPICAL DEPRESSION NINE DISCUSSION NUMBER 1
NWS NATIONAL HURRICANE CENTER MIAMI FL AL092012
500 AM AST TUE AUG 21 2012

THE LARGE LOW PRESSURE SYSTEM THAT HAS BEEN TRAVERSING THE CENTRAL
TROPICAL ATLANTIC FOR THE PAST FEW DAYS HAS ACQUIRED ENOUGH
ORGANIZED DEEP CONVECTION NEAR THE CENTER TO BE CLASSIFIED AS A
TROPICAL DEPRESSION. THE INITIAL INTENSITY OF 30 KT IS BASED ON A
SATELLITE INTENSITY ESTIMATE OF T2.0/30 KT FROM TAFB AND T1.5/25 KT
FROM SAB. SINCE THE 0600 UTC SATELLITE CLASSIFICATIONS...
CONVECTION HAS CONTINUED TO INCREASE WITH SOME CLOUD TOP
TEMPERATURES COLDER THAN -80C NOTED JUST SOUTHWEST OF THE LOW-LEVEL
CENTER.

THE INITIAL MOTION ESTIMATE IS 270/17 KT. THE DEPRESSION IS LOCATED
SOUTH OF A DEEP-LAYER SUBTROPICAL RIDGE THAT IS FORECAST TO REMAIN
INTACT FOR THE NEXT FOUR DAYS...WHICH SHOULD KEEP THE CYCLONE
MOVING IN A WESTWARD TO WEST-NORTHWESTWARD DIRECTION THROUGH 96
HOURS. BY DAY 5...HOWEVER...THE GLOBAL MODELS ARE FORECASTING A
SHORTWAVE TROUGH TO DIG SOUTHWARD OVER THE SOUTHEASTERN U.S. AND
THE GULF OF MEXICO...WHICH IS EXPECTED TO WEAKEN THE RIDGE ACROSS
FLORIDA AND THE BAHAMAS. THIS SHOULD ALLOW THE CYCLONE TO TURN
NORTHWESTWARD AND SLOW DOWN ACROSS THE NORTH-CENTRAL CARIBBEAN SEA.
THE OFFICIAL FORECAST TRACK IS CLOSE TO THE MULTI-MODEL CONSENSUS
TVCA...WHICH IS A COMPROMISE OF THE FASTER GFS MODEL AND SLOWER
ECMWF MODEL.

OTHER THAN SOME MODEST NORTHEASTERLY VERTICAL WIND SHEAR FOR THE
NEXT 24 HOURS OR SO...ENVIRONMENTAL CONDITIONS ARE EXPECTED TO BE
QUITE FAVORABLE FOR INTENSIFICATION TO OCCUR. DURING DAYS 2-3...THE
VERTICAL SHEAR IS FORECAST TO BE THE WEAKEST AND WATER TEMPERATURES
THE WARMEST...AND THAT IS WHEN THE MOST SIGNIFICANT STRENGTHENING
SHOULD OCCUR. AT DAYS 4 AND 5...POSSIBLE INTERACTION WITH LAND
MASSES OF HAITI AND CUBA...RESPECTIVELY...IS THE PRIMARY REASON
FOR THE LEVELING OFF IN THE INTENSITY. THE OFFICIAL INTENSITY
FORECAST CLOSELY FOLLOWS THE TREND OF...BUT IS LOWER THAN...THE
SHIPS AND LGEM INTENSITY MODELS...ESPECIALLY AT DAYS 3 AND 4.

AN AIR FORCE RESERVE RECONNAISSANCE AIRCRAFT WILL INVESTIGATE THE
CYCLONE THIS AFTERNOON.

FORECAST POSITIONS AND MAX WINDS

INIT 21/0900Z 15.2N 51.2W 30 KT 35 MPH
12H 21/1800Z 15.3N 53.8W 35 KT 40 MPH
24H 22/0600Z 15.7N 57.2W 40 KT 45 MPH
36H 22/1800Z 16.0N 60.5W 50 KT 60 MPH
48H 23/0600Z 16.3N 63.6W 65 KT 75 MPH
72H 24/0600Z 16.9N 69.3W 80 KT 90 MPH
96H 25/0600Z 18.0N 74.0W 95 KT 110 MPH
120H 26/0600Z 20.0N 77.3W 95 KT 110 MPH

$$
FORECASTER STEWART

I bolded the parts that seemed most interesting to me. We'll see about that vertical shear... I've seen plenty of situations where the northeasterly vertical shear never lets up as predicted... but TD Nine does not look like a sheared system to me at all.

And this is from the Hydrometeorological Prediction Center:

PRELIMINARY EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER COLLEGE PARK MD
342 AM EDT TUE AUG 21 2012

......

VALID 12Z SAT AUG 25 2012 - 12Z TUE AUG 28 2012
THE GFS BECOMES QUESTIONABLY FAST WITH A
SHORTWAVE TROUGH CROSSING THE PLAINS ON DAY 5 AND THUS IS NOT
PREFERRED COMPARED TO THE BETTER SUPPORTED ECMWF SOLUTION. FOR
DAYS 6-7/MON-TUE...GENERALLY PREFER THE ECMWF ENSEMBLE MEAN
BLENDED SLIGHTLY WITH THE OPERATIONAL ECMWF FOR AMPLITUDE. THIS
APPROACH IS ALSO USED FOR THE TRACK OF TD NINE CURRENTLY NEARING
THE CARIBBEAN SEA...WHICH WAS COORDINATED WITH THE NHC YESTERDAY
AFTERNOON TO REACH SOUTHERN FLORIDA BY DAY 6/MON.

[JTD]

The track and forecast discussion by Stacey Stewart are very concerning and omninous to say the least. To jump to nearly a category 3 on the first advisory has to be pretty near unprecedented. Recall that 111 mph is a cat 3. I also recall that most hurricane strikes on Florida are from the SE direction...or is it SW?

Also of note is that this thing literally seems to be exploding on satelite right now in my opinion.

In any event, the Carribbean Island friends are our top concern and priority right now. Possible rough times ahead for those great people.

Most significant threat faced since Irene in my personal opinion.

[summersquall]

[GCANE]

Nice flare before sunrise very close to the LLC.

http://www.ssd.noaa.gov/PS/TROP/floater ... imated.gif

http://rammb.cira.colostate.edu/product ... 210145.jpg

http://www.nrlmry.navy.mil/tcdat/tc12/A ... .100pc.jpg

Looks like it was a short-duration, rotating hot-tower.

Should start to see core get up to 12km level during the day today.

Yesterday's boundary-layer cap has been broken.

http://rammb.cira.colostate.edu/product ... 1208210040

A moderate 300mb PV anomaly is to the south of the LLC which may have some effect on strengthening.

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

[KWT]

Wow well that is an agressive forecast, much more agressiver than the global models would suggest, though they are now back on board with strengthening.

This track is a really hard one to call as is intensity, if only because 1 degree difference in eventual location may make the difference between a weakening TS/TD over Hispaniola heading out towards Cuba, or a 3/4 hurricane close to the NW Caribbean and curving up towards the Gulf.

Either way...I'm a smelling a possible record breaking storm on storm2k...

[Shuriken]

Now we get to see if the 200mb cap stays popped.

Lotta hurr-fans be howling if this over-night poof doesn't have a follow-up.

Ernesto already pulled that stunt.

Even if it's for real, don't be surprised if there's a good six-to-twelve hour period of quiescence before the next blow-up.

[KWT]

Well the first step has been made, in that we actually do have a Tropical Cyclone to follow, now we'll have to see how it evolves from here on.

Going to be such a close call for Hispaniola, I think the system will weaken due to it even if it doesn't make a landfall, regardless of whether its north or south of the island.