Hurricane Dean

[Keepster]

this could be a very intresting 24hrs

Could is perhaps understatement of the year. It is going to be a dramatic and inevitably tragic day.

Hurricane Dean is bearing down on an island of 2.6m inhabitants, who unfortunately have no-where to go.

Is anyone following the recon? Last set of recordings showed pretty low wind speeds (40mph). Are they heading home?

[crimsone]

yes... I am continuing to follow the recon...

...and I'm pleased to report that now they HAVE turned. lol

http://tropicalatlantic.com/recon/path.cgi...2c-71.78c-71.75

they've come out of the storm in the SW, and are currently travelling in an easterly direction. I'm not sure, but I seem to recall that recon travel in an "X" pattern through the storm, and so I think thay are coming around for the next pass from the SE towards the NW.

Edited August 19, 2007 by crimsone

[Paranoid]

Any news on the windspeeds, the structure looks far too good to be undergoing an EWRC.

Edited August 19, 2007 by Paranoid

[crimsone]

looking at the sattelite back an hour ago, I would have to agree there Paranoid, but I can think of no other way to explain the drop in wind speed. This is another one of those times where KW would be able to give a very useful opinion. lol

Recon are still flying due east on the southern periphery of the storm

Edited August 19, 2007 by crimsone

[Calrissian]

Thanks for the link, watching it now. Out of interest who runs that site, do they stream through the night? They're talking a lot of sense about how the jamaican people don't seem to realise the threat they face from Dean because their media isn't getting fussed about it

Jim Williams runs the site (with a little help), and has been doing the shows for a few years now. The video feed used to be a mere 56k feed, but its now a stable 150k.

His show is on every night when a storm is near, and he also broadcast throughout the day. He uses TV feeds, webcams, charts, etc. You can even give him a call.

Hell, he should be paying me for all this praise

---

Meanwhile...Dean is that little bit closer to Jamaica, and I suspect a real collapse tonight...to perhaps sub 900mb.

Focus on one thing....the warmer sea temps are STILL yet to come.

Calrissian: time for tea

[Paranoid]

On the subject of Sub 900mb, GDFL was showing 899.6mbar on their 18z run.

[Cookie]

an update

Alert Country(s) or Province(s)

Haiti

probability for CAT 1 or above is 85% in about 21 hours

probability for TS is 100% within 9 hours

Jamaica

probability for CAT 1 or above is 85% in about 21 hours

probability for TS is 100% in about 21 hours

the Dominican Republic

probability for CAT 1 or above is 80% within 9 hours

probability for TS is 100% currently

the Cayman Islands

probability for CAT 1 or above is 60% in about 33 hours

probability for TS is 85% in about 33 hours

Cuba

probability for CAT 1 or above is 40% in about 33 hours

probability for TS is 90% in about 21 hours

Mexico

probability for CAT 1 or above is 35% in about 69 hours

probability for TS is 60% in about 69 hours

[kold weather]

There are probably higher winds in there, they've just not been found yet. The fact they've found pressure down as low as it is (offical was 920mbs according to vortex message) suggests also the winds probably haven't yet caught up with the dropping of the pressure, this system is no longer all that small so your not going to see the winds really respond all that fast. Katrina did the same thing, dropped like a bomb then took another 6hrs to start to catch the wind speed up. The fact such low pressure should be found is a very good sign that Dean will be a cat-5 sooner rather then later.

However Dvarok shows that outer eyewall emerging again which wouldn't surprise me given its now over less impressive heat content for the next 6hrs. If its going to start an EWRC it'll be probably be tomorrow morning IMO. Also the development of that outer eyewall could prevent Dean getting much stronger then presently though I think Dean has enough time to ramp winds upto cat-5 status before maybe some slight weakening tomorrow via EWRC...but they are devils to frecast if I'm honest.

Looking at other historical hurricanes lowest pressure recorded in the region was from Allen which got down to 911mbs. I strongly suspect Dean won't go deeper then that, heat content probably can't support unless its under completely perfect condtions, and slight land interactions from Haiti disrupting the north quad a touch won't classify as perfect.

Sub-900mb hurricanes are amazingly rare, there have been 5 in the past, they are the true beasts of the Atlantic and require perfect condtions. However Dean may attempt something close if it gets its timings in regard to EWRC correct, heat content in the W.Carribean would support it and indeed two very close matches, Gilbert and Allen both did make it.

Edited August 19, 2007 by kold weather

[Cookie]

I've stayed up far to late in this thread, I really must go to bed.

Can one you please tell the hurricane not to do anything excting till I get up!

[Paranoid]

Same here, i'm also signing off. Hopefully all the details will be there then.

[crimsone]

Thanks KW.. that explains a lot (as ever )

Recon have just turned agin towards the NW... they're on their way back in - I hope. lol

Edited August 19, 2007 by crimsone

[kold weather]

By the way IF Dean has already started an EWRC, which may be finally happening based on latest IR/Davrok/recon then the lower winds found by recon wouldn't be all that surprising though the pressure is extremely impressive I have to admit and probably means pressure was as low as 915-917mbs before recon arrived around 10-12pm and since the NW eyewall has opened up a little pressure may have rose...but this is all just gossip!

I may by the way have gotten things a little wrong in my last post by the way, Deans a touch further west then I thought, which places him pretty much in the lower heat content right now---that would explain quite nicely why its undergoing a new attempt at an eyewall replacement cycle and unlike last time it may have time to complete it before heat content rises again.

Very latest images show NW quadrant is open which may explain why the pressure is so low yet winds that have been found so far aren't that noteable. IF its another attempt at an EWRC then pressure should rise a little next vortex.

Honestly speaking, its been so long since I've tracked a cat-4/5 (last one was Rita since I missed Wilma!!!) that I'm a touch rusty!

Edited August 19, 2007 by kold weather

[crimsone]

Thanks for the further info KW That explains the situation very clearly

Recon are heading back in this vey moment... they may well be approaching the eyewall in the next set of HDObs. In this set 83 kts (30 sec) is the highest flight level wind the've found... but they are still some way out from the middle yet.

edit: Recon have just crossed the eye again... this time around they've similarly extrapolated a repeated pressure of between 917 and 918 mb, but found windspeeds of only 108 kt (30 sec... 111 kt for 10 sec) on the way back out of the eye heading to the NW

Edited August 19, 2007 by crimsone

[kold weather]

Extrap pressure of 917mbs just found, impressive but winds at flight level still are only 110-117kts which supports just 105-110kts at the surface...or cat-3 winds!

By the way I forgot to mention this, with outer eyewalls it slackens the pressure gradient of the storm (thats why they get bigger once EWRC are done generally) and so while the pressure currently between 917-920mbs would norrmally support cat-5 but in this case as the pressure gradient isn't very tight the winds are more spread out through the developing eyewalls and so the winds reported aren't quite so high, hence why systems going through EWRC tend to see lower winds despite low pressures.

Latest pass just found 122kts at flight level, supports 110kts at the surface, still obviously way lower then the previous strength of 130kts, EWRC really helping to peg those winds down....but with a pressure that low once its sorted that issue out it could become very strong indeed with a quick ramp-up.

Finally, highest winds were found in the outer eyewall, suggests that may be starting to become the more dominant which is a good indicator that the EWRC is well on its way.

Edited August 19, 2007 by kold weather

[crimsone]

One of the flight level winds after exiting the eye was 120 kt... not that changes anything much.

the latest vortex message completes the recon (if I recall).

000

URNT12 KNHC 190119

VORTEX DATA MESSAGE AL042007

A. 19/01:05:20Z

B. 16 deg 04 min N

071 deg 13 min W

C. 700 mb 2370 m

D. 100 kt

E. 138 deg 012 nm

F. 223 deg 105 kt

G. 126 deg 005 nm

H. 918 mb

I. 11 C/ 3048 m

J. 17 C/ 3029 m

K. 15 C/ NA

L. CLOSED

M. CO

N. 12345/ 7

O. 0.02 / 1 nm

P. AF302 0704A DEAN OB 12

MAX FL WIND 118 KT N QUAD 23:36:00 Z

MAX FL WIND OUTBOUND 123 KT NW QUAD 01:11:00

MAX FL WIND OUTBOUND IN OUTER EYEWALL

Minimum central pressure down 2 mb to 918 mb... max flight level wind at 123 kt, found in the outer eyewall. Eye is concentric and closed. Surface winds estimated (90% of flight winds) at 100 kt.

edit: Recon have turned due South West... possibly they will make the same two passes again in reverse? Otherwise, I have no idea where they are heading! - http://www.tropicalatlantic.com/recon/path...5c-72.15c-72.15

Edited August 19, 2007 by crimsone

[kold weather]

Right I'm out of here, will see what sort of shape Dean is in early tomorrow, I think the one we do know is Dean's hurricane force winds are expanding, quite noteable on recon that nearly all even some way out from the eye have been hurricane force.

As I said with max winds found in outer eyewall, its becoming the dominant one which suggests EWRC is occuring right now (thats the final proof thats needed!) and that its probably about 50% done, now we need to watch the inner eyewall erode and replaced by the new one, pressure should rise about 10-15mbs while doing this, thats what normally occurs. Timing of this may just save Jamaica from really severe winds unless it hurries up with this process BUT the wind field now is so large that the hurricane force winds extend some way out according to recon. Dean's getting fatter!

(ps, SHIPS takes Dean upto 143kts by 36-48hrs)

Edited August 19, 2007 by kold weather

[crimsone]

Absolutely... very large it seems. I'm in two minds whether or not to follow recon for a while longer and see what they're up to, but I must admit I'm a bit sleepy myself now. It's been a fun evening.. thanks peeps (especially KW... where would we be without you? I for one would be a bit confused. lol )

[Mad Murdoch]

thank for the updates kw... nite

[crimsone]

Yep... recon are heading back in again... I don't think I have the energy to follow another couple of passes.

edit: I may well be mistaken about it's location, but I think they've just found 89 kt (30 sec... 93 kt for 10 sec) in the outer eyewall on the way in... it will be interesting (if I'm right about that) to compare with what they find when they pass through the inner eyewall... but we won't know for another 10 mins.

Edited August 19, 2007 by crimsone

[crimsone]

a couple of assumptions about inner/outer eyewalls, based on what KW said and my interpretation of what the HDObs say...

Extrapolated pressure is still around 917/918... but one reading on this last pass recorded 916.2 mb.

93kt was the highest wind on the way in... and nothing after it is remotely close... on the way out, it seems to record the speeds (again my interpretation of the structure... I may be wrong) as being about 109 kt (30 sec) for the inner eyewal, and then 126 kt (30 sec) for the outer eyewall. A flight level wind of 129 kt (10 sec) was found on the way out.

This pass was from the SW to the NE. If I'm correct in the assumptions of the winds being found in the respective inner/outer eyewalls, it would seem that the outer eyewall is becoming very much dominant, and the inner one is fading quite well.

Edited August 19, 2007 by crimsone

[MAF]

and some more info Crimsone

THE MINIMUM CENTRAL PRESSURE JUST REPORTED BY AN AIR FORCE RESERVE

RECONNAISSANCE AIRCRAFT WAS 920 MB...27.17 INCHES.

Source NOAA

[crimsone]

Yes... just picked up on the latest vortex message Mick... thanks - though the vortex message is saying 918 again(Advisory 24 now says the same thing).

000

URNT12 KNHC 190235

VORTEX DATA MESSAGE AL042007

A. 19/02:09:00Z

B. 16 deg 10 min N

071 deg 30 min W

C. 700 mb 2384 m

D. 93 kt

E. 219 deg 010 nm

F. 305 deg 092 kt

G. 220 deg 012 nm

H. 918 mb

I. 8 C/ 3050 m

J. 16 C/ 3049 m

K. 15 C/ NA

L. CLOSED

M. C25

N. 12345/ 7

O. 0.02 / 1 nm

P. AF302 0704A DEAN OB 18

REMNANTS OF INNER EYWALL E040/10/8

MAX FL WIND OUTBOUND 130KT NE QUAD 02:14:00 Z

That says it all really.... and also says that I shouldn't be so unsure of myself and my thoughts. lol... I refrained from saying that the inner eyewall looked practically non-existant on the way in, but there it is from recon theirselves... "REMNANTS OF INNER EYWALL E040/10/8". Also... they are no longer saying concentric, they are now giving the eye as circular and 25 nautical miles wide (28.75 miles as most of us know it), suggesting that the EWRC is quite near completion.... we will see with one last vortex message a bit later - if it is soon to be complete, it was pretty quick by any standards!

NHC have genously dropped the wind speed by just 5 MpH to 145 MpH... no doubt they are expecting the speeds to pick up again (they are already going by the recon over the last few hours), as do we all.

Recon are about to turn towards the SE for another pass (NE to SW), presumably then returning to base.

Edited August 19, 2007 by crimsone

[crimsone]

Recon's just passed through the eye again... though still haven't fully exited the eyewall on the other side... they found a minimum pressure of 917.5 mb and maximum flight level winds of 115 kt (30 sec)

[crimsone]

000

URNT12 KNHC 190352

VORTEX DATA MESSAGE AL042007

A. 19/03:17:20Z

B. 16 deg 14 min N

071 deg 50 min W

C. 700 mb 2383 m

D. 112 kt

E. 322 deg 025 nm

F. 057 deg 118 kt

G. 320 deg 031 nm

H. 919 mb

I. 6 C/ 3049 m

J. 18 C/ 3050 m

K. 15 C/ NA

L. CLOSED

M. C25

N. 12345/ 7

O. 0.02 / 2 nm

P. AF302 0704A DEAN OB 23

MAX FL WIND 130 KT NE QUAD 02:14:00 Z

REMNANTS OF INNER EYEWALL E060/16/13

Recon finding an increased surface wind speed at last, a slight rise in pressure, and again, remnants of the inner eye.

...recon are now heading home, and I think that really is it for me tonight!

Edited August 19, 2007 by crimsone

[Iceberg]

Vortex Data Message

--------------------------------------------------------------------------------

000

URNT12 KNHC 190447

VORTEX DATA MESSAGE AL042007

A. 19/04:17:00Z

B. 16 deg 17 min N

072 deg 05 min W

C. 700 mb 2391 m

D. 108 kt

E. 046 deg 014 nm

F. 128 deg 122 kt

G. 047 deg 020 nm

H. EXTRAP 920 mb

I. 7 C/ 3046 m

J. 18 C/ 3046 m

K. 15 C/ NA

L. CLOSED

M. C23

N. 12345/ 7

O. 0.02 / 1 nm

P. AF302 0704A DEAN OB 28

MAX FL WIND 122 KT NE QUAD 04:10:50 Z

INNER EYEWALL REMNANTS OPEN NNE AND E030/18/15

SLP EXTRAP FROM 700 MB

Not much pressure drop to say it's gone through an ERC.

Thanks for everybody that stayed up, made good reading.