Frances Advisories

[wxman57]

Those of you watching the models drive it WNW-NW to near 18-20N/51W might want to look at this track from last year:

http://weather.unisys.com/hurricane/atl ... /track.gif

Isabel was well north of where "TD6" is, and the synoptic situation is similar. I see nothing to indicate that it would get ripped apart if it isn't picked up by the trof. Could well go major and turn west but pass north of the Caribbean. In fact, I think it's more likely to turn west than to head out to sea immediately, because that trof will be lifting by the time the storm reaches 20N and the ridge will build back on top. Question is, does it do a "Fabian" or an "Isabel" ahead of the next front?

[Derecho]

779
WHXX01 KWBC 250139
CHGHUR

DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.
PLEASE REFER TO TPC/NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONES.

NATIONAL HURRICANE CENTER NORTH ATLANTIC OBJECTIVE AIDS FOR

TROPICAL DEPRESSION SIX (AL062004) ON 20040825 0000 UTC

...00 HRS... ...12 HRS... ...24 HRS... ...36 HRS...
040825 0000 040825 1200 040826 0000 040826 1200

LAT LON LAT LON LAT LON LAT LON
BAMD 11.1N 35.1W 11.5N 37.7W 12.2N 40.0W 13.1N 42.1W
BAMM 11.1N 35.1W 11.5N 37.4W 12.2N 39.5W 13.1N 41.3W
A98E 11.1N 35.1W 11.5N 38.2W 11.8N 41.2W 12.1N 43.9W
LBAR 11.1N 35.1W 11.5N 38.0W 12.3N 40.9W 13.2N 43.6W
SHIP 25KTS 33KTS 43KTS 52KTS
DSHP 25KTS 33KTS 43KTS 52KTS

...48 HRS... ...72 HRS... ...96 HRS... ..120 HRS...
040827 0000 040828 0000 040829 0000 040830 0000

LAT LON LAT LON LAT LON LAT LON
BAMD 14.0N 43.9W 15.5N 46.7W 16.3N 48.8W 16.2N 51.2W
BAMM 14.0N 42.8W 15.7N 44.9W 16.8N 46.3W 17.9N 48.2W
A98E 12.3N 46.4W 12.6N 50.4W 13.0N 54.1W 13.5N 58.3W
LBAR 14.3N 45.9W 16.3N 49.6W 18.0N 52.2W 18.5N 54.3W
SHIP 61KTS 73KTS 77KTS 77KTS
DSHP 61KTS 73KTS 77KTS 77KTS

...INITIAL CONDITIONS...
LATCUR = 11.1N LONCUR = 35.1W DIRCUR = 280DEG SPDCUR = 15KT
LATM12 = 10.4N LONM12 = 32.1W DIRM12 = 280DEG SPDM12 = 14KT
LATM24 = 10.1N LONM24 = 29.0W
WNDCUR = 25KT RMAXWD = 50NM WNDM12 = 25KT
CENPRS = 1009MB OUTPRS = 1014MB OUTRAD = 200NM SDEPTH = D
RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM




I can never get the NHC model runs to format right. Oh well.

When the header gets a name change, it's a 99.9999999% certainty the first advisory is coming

[wxman57]

Maybe, but I can think of at least 4 reasons why not:

1. Dvorak is only 1.5 = 25 kts. Generaly NHC goes TD at Dvorak 2.0 (30kts)
2. Lack of deep convection near the estimated center (thus the lower Dvorak number)
3. The system is at least 7 days away from any land areas
4. It's hard to really locate an LLC with IR imagery, so they can't really tell if the center is at 11.2N/35W.

So while I don't argue it does have a closed LLC now, convection just hasn't pesisted long enough near the center and the NHC has really no reason to upgrade it in the middle of the night. They'll watch the convection overnight and wait for visible imagery. No rush since it's a week away (at the earliest) from possibly affecting land.

Still, you are right that when they start changing the header to "TD 6" from Tropical Depression Invest they're getting close.

[Thunder44]

Wxman57, check the NRL site and you see 6LNONAME. It's almost a guarntee now they will start issuing advisories by 11pm.

http://www.nrlmry.navy.mil/tc_pages/tc_home.html

[Brent]

It'll be upgraded. The 0z models had come out and initially it still had the invest up.

[Derek Ortt]

http://www.nwhhc.com/atl062004forecast.html


This should not threaten land through the next 5 days

[Thunder44]

http://www.weatherunderground.com/tropi ... ublic.html

[Brent]

Tropical Depression Six Discussion Number 1

Statement as of 11:00 PM EDT on August 24, 2004

Satellite imagery shows that the cloud pattern associated with the
strong tropical wave over the eastern Atlantic has become better
organized over the past several hours...with an increase of deep
convection near the low-level circulation center. Therefore the
system is being numbered at this time. There is pronounced
upper-level outflow to the North...East...and south of the
center...but outflow is limited to the east. Analyses from the
University of Wisconsin CIMSS indicate weak vertical shear along
the projected path of the cyclone to about 50w longitude. Farther
west and north...the shear may increase as suggested by the latest
200 mb forecast from the GFS model. Therefore strengthening may be
inhibited late in the forecast period...although this is highly
uncertain.

Initial motion is slightly north of west at around 15 kt. Dynamical
model predictions indicate a weakening of the mid-tropospheric
ridge to the north of the tropical cyclone over the next several
days...due to the incursion of a trough into the central Atlantic.
This trough is at rather high latitudes however...so it is not
likely to play a direct role in steering the tropical cyclone.
Notwithstanding...the track guidance generally shows a slowing of
the forward speed and a turn toward the northwest later in the
forecast period. The NHC track forecast follows this scenario...but
is a little to the south and faster than most of the models in view
of the current motion which seems to be accelerating to the west
as we speak.

Forecaster Pasch

forecast positions and Max winds

initial 25/0300z 11.2n 36.0w 25 kt
12hr VT 25/1200z 11.8n 38.2w 35 kt
24hr VT 26/0000z 12.4n 40.7w 40 kt
36hr VT 26/1200z 13.0n 43.0w 45 kt
48hr VT 27/0000z 13.8n 45.1w 50 kt
72hr VT 28/0000z 16.0n 48.5w 60 kt
96hr VT 29/0000z 18.0n 51.0w 70 kt
120hr VT 30/0000z 20.0n 53.0w 70 kt

[TS Zack]

They bring it North!! Very Uncertain!

[wxman57]

Never try to introduce logic to the NHC forecast methodology...

[rainstorm]

sounds good

[wxman57]

However, the NHC also doesn't think that trof to the north will actually pick it up and carry it out to sea. I think the track may be similar to either Isabel or Fabian of last year. NW turn then W-WNW for a while then NW-N turn ahead of the next front. Odds are it'll be east of the U.S. coast, but you can't rule out an east coast hit yet.

[vbhoutex]

Never try to introduce logic to the NHC forecast methodology...

Sorry, but I had to laugh as I was reading your post just as they upgraded!!!How ironic!!!! The email literally came in as I was reading your post, which made all the sense in the world based on past performance.

[KatDaddy]

Now what is this! Talk about hyping up uncertainty. This takes the cake. Its going to move NW but the trof will not likely play a role?? I am missing something here with the Disc. so Der, MWatkins, or Dortt please clear the confusion from the TPC Disc.

TIA



Dynamical model predictions indicate a weakening of the mid-tropospheric
ridge to the north of the tropical cyclone over the next several
days...due to the incursion of a trough into the central Atlantic.
This trough is at rather high latitudes however...so it is not
likely to play a direct role in steering the tropical cyclone.

[TerryAlly]

Track highly uncertain. Historical tracks show a scatter shot

[Thunder44]

I think they NHC means is that they don't think the trough is going to take this out to sea. All the trough will do erode the ridge to it's north, alowing the storm to take a more poleward motion for awhile, until the ridge builds back south and east.

[Derek Ortt]

their discussion says it should move into a weakness in the ridge (actually better 2 ridges. Maybe not a strong trough, ut a TC tales the path of least resistanc,e which is trhough any weakness in a ridge

[Rieyeuxs]

If the trough is not going to take it and it's moving North of the islands, I'm getting the stronger feeling that everyone's hinting at the SE coast... Am I wrong?

[weatherlover427]

You can't say it's a fish this far out (at least not for sure 100% no matter what) with this much uncertainty in the air. The storm just formed for Pete's sake and some of you are already declaring it to be worthless. This makes no sense.

[flyingphish]

Geeez...Forget the Freak'in Trough. Maybe a Good Insurance Policy if system will not exit ....NW ramp at 58W. This is a fish. Give it up! Should be a pretty one though.