Invest Thread

[Iceberg]

I am sure Dean(to be) will get his own thread soon, latest ships takes it to 67Kt by 120 hrs, with the other 06Z tropical models taking it pretty much as before, with GFDL taking it down to sub 980 again.

Organisation is getting a lot better.

The latest Sat I can find shows that convection is nicely wrapping and building around the closed centre shown by QuikScat.

No Dvorak ratings yet, Winds seem to be around the 20-25Kt mark so certainly nowhere near a TS yet.

[Iceberg]

Quick addition: HWRF 06Z takes this to a 940mb low now entering the Carib.

[Iceberg]

The kids are asleep so pardon my playing.

Ocean Heat content is really going to be the fuel under this thing, so I've plotted a likely (taken from all todays models) course.

As you can see it's only really after Day 3 (wednesday) that he's likely to get any real shot of a hurricane.

IMO

Blue = a CAT 1 at best realistically.

Green = CAT 1/2.

Yellow = CAT 2/3

To really get a CAT 4 or 5 it needs to get in touch with the oranges and reds, obviously a host of other factors come into play as well, such as SAL, Shear etc.

BTW Met 9 is available and updated very frequently at

http://oiswww.eumetsat.org/SDDI/cgi/listIm...121330#controls

The tropical models all really anticipate real strengthening after day 3 atm.

Edited August 12, 2007 by Iceberg

[kold weather]

Yeah thats a good post Iceberg though the lapse rates do also have an important part as obviously does the shear in the set-up and the air moistness though your rough guide does roughly work out based on average condtions.

not much change right now in terms of the structure of 90L. There does appear to be some weak outflow occuring in the northern quadrant and convection is still well organised and so I suspect a tropical depression is pretty close by, maybe as soon as the next 12hrs I dare say. Air seems to be pretty moist around the system with any SAL starting to mix out right now and shear doesn't appear to be a problem presently. Track over the next few days should be roughly west though recent models do want to take it slightly WSW tomorrow which is possible given the strong high to the north of the system. As it tracks westwards it should enter increasingly warmer waters that can support stronger cyclones, esp if it takes a more southerly route and I wouldn't be that surprised if it becomes a major, indeed Geroges got upto 155mph on a similar track just east of the Windward Islands. I'm not going to be that agressive simply because its too far into the future.

In terms of tonights models, both the GFS and the UKMO take it into the Caribbean. THe GFS and all its based models have been taking it constantly through the Caribbean sea in recent runs and its a trend that needs to be watched given the GFS ha sbeen fairly consistant on that and ther eis a strong high t othe north of the system right now. As for the UKMO run it should be noted that the run starts the low at 33W which is way too far west and means it would pick up about 1-2 degrees of latitude then the UKMO is forecasting, tohugh that would still put it in the north of the Caribbean.

It should be noted though that such a long deep westerly track is extremely rare and as such the tracks suggested by the models should be used with catuino past 72hrs given they do have a westerly bias past that range.

The 12z ECM will be very interesting, esp if does track further south like the GFS.

IF the GFS is right then the system is going to track through some amazing heat content values, the like which under decent atmospheric condtions could give strong category-4/5 hurricanes and would cause large damages to the Yucatan and be a threat to Mexico and Texas...however thats a very very long way away and I think the GFS may be overdoing the upper high a little too much.

So it does look very likely we will have a long tracked system to watch which is likely to be a large threat somewhere down the line, exactly where I'm not sure, track probably closest to Georges 1998, at least in the next 5-6 days, then watch for a possible shortwave to open a breif weakness. If its to pull too the north it'll be then. If it doesn't then its gonig to head for the powergrounds of the W.Caribbean...

I'd also say its got a good shot at a major hurricane, esp if it takes the southerly route. Dean here we come!

Edited August 12, 2007 by kold weather

[crimsone]

TROPICAL WEATHER DISCUSSION

NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL

205 PM EDT SUN AUG 12 2007

A 1008 MB LOW...ASSOCIATED WITH A VIGOROUS TROPICAL WAVE...IS

LOCATED OVER THE FAR EASTERN ATLANTIC OCEAN ABOUT 150 NM SOUTH

OF THE SOUTHERNMOST CAPE VERDE ISLANDS NEAR 12.5N25W. VISIBLE

IMAGERY SHOWS THE LOW-LEVEL CIRCULATION PARTIALLY EXPOSED TO THE

E OF A CONVECTIVE MASS FROM 10N-14N BETWEEN 25W-30W.

OVERALL...THIS SYSTEM HAS IMPROVED IN ORGANIZATION OVER THE PAST

24 HOURS AND A TROPICAL DEPRESSION COULD FORM LATER TODAY OR

TOMORROW AS THE LOW MOVES WESTWARD AT 15-20 KT.

[tinybill]

here it comes!!

[Iceberg]

The 7.00 image does indicate that he's a little lopsided, however convection has just started to flare up in the 7.30 image to the east, I favour this will be TD4 in the morning.

Re the ocean heat content it does of course depend upon the speed of the system, fast speed less heat needed, slow more needed.

A hit on Florida is looking more unlikely now I think, but it's still a way off

Matt

[crimsone]

000

ABNT20 KNHC 122121

TWOAT

TROPICAL WEATHER OUTLOOK

NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL

530 PM EDT SUN AUG 12 2007

A LOW PRESSURE AREA...ASSOCIATED WITH A TROPICAL WAVE...IS LOCATED

OVER THE FAR EASTERN ATLANTIC OCEAN ABOUT 175 MILES SOUTHWEST OF

THE SOUTHERNMOST CAPE VERDE ISLANDS. STRONG UPPER-LEVEL EASTERLY

WINDS HAVE KEPT THE SYSTEM FROM BECOMING BETTER ORGANIZED THIS

AFTERNOON. HOWEVER...ONLY A SMALL INCREASE IN ORGANIZATION WOULD

RESULT IN THE FORMATION OF A TROPICAL DEPRESSION AS THE LOW MOVES

WESTWARD AT ABOUT 20 MPH.

Question..... : if this thing gets into the carribean, is there any chance of it going north into the GoM, and back out into the atlantic, or is it a fairly certain thing that it would make a full and final landfall in the US somewhere and die?

Edited August 12, 2007 by crimsone

[kold weather]

Can't make a long post this morning as I've got stuff to do!

90L still looking very well organised, last night vis. shots showed an exposed LLC just to the east of the convection, so waiting for the new images soon to see if thats still the case. Given the strength of the convection still present and the fact its been presistant with the convection and the fact it does have a LLC if Sat.images show that the LLC is no longer as exposed it'll be upgraded to TD4 very soon.

Models generally taking it west though the GFDL loses the system at 06hrs so not sure what you can read into that. Other models are still creating a fairly powerful hurricane heading into the Caribbean with the GFS landfalling over the Yucatan then getting into the BOC and hitting Mexico...I myself would follow that track but plump for a further north landfall over Texas right now. IF it does take the track through the western Caribbean it could become a very powerful system.

[Iceberg]

I am less convinced about this feature now.

GFDL has backed away a bit( and didn't develop it zilch earlier!) from it and ECM now nolonger develops it at all (although it does develop some of the other waves leaving Africa.).

Thankfully it's now viewable from the central atlantic sat, so updates are every 30 mins.

Convection looks good, but the problem is the amount of shear, On ECM this destroys the system and on other models the system is really effected by it..

On balance this should still develop, but there is probably a 20% chance now that it will die in the next 72 hours.

PS I'd say there was a 95% chance of it not re-entering the Atlantic as any kind of tropical influence.

[kold weather]

Latest Quikscat shows the LLC is still present though not quite as strong as previously, its now around 29.5-30.5W and around 12N.

Iceberg the models are probably starting too far east as the NHC has the system at 28W, and if the models are based on that then there is nothing there so of course they are not gonig to show anything much, the ECM by the way does form a tropical storm from it and hits S.Florida with it at 240hrs.

Shear however is not probably the ture problem for this system, like 99L its the foward speed which is at least 20mph if not more and at such speeds conbined with easterly shear its going to have to work hard to form a decent LLC though unlike 99L it does appear to have one right now. Until we get a decent vis. imagery of the system its gonig to be hard to tell whether the system still has an exposed LLC. IF its tucked underneath the convection, an upgrade is likely shortly, probably in the next 6hrs unless ther eis a major change.

Development was always likely to be slow given low heat content present, however its currently the foward speed that is causing problems for it to become a tropical system. As I said before I think NHC could have upgraded a few hours ago but they are probably waiting for a vis.loop to get a better idea of where about the circulation actually is. Either way given the drier air to its west, fast foward motion so slow development will be the name of the game till the Caribbean.

Edited August 13, 2007 by kold weather

[Iceberg]

The problem is the mass of convection is a lot further West and is trying to form a new LLCC, not very well though due to the strength of the LP situation further east., Dvorak has increase to 1.5 (a boarderling TD). So naming could be soon, I am still far less convinced though.

Matt

[Iceberg]

Scrub what I've just said They do finally have floater 1 over http://www.ssd.noaa.gov/goes/flt/t1/loop-vis.html

Visual loop shows that convection is still very uncentred but it has covered the centre of a good LLCC and this will almost certainly be TD4 today with D ratings of 2.

I am not convinced by the forward speed, although this will certainly help to make any shear stronger in it's effect which is probably happening hear.

Exact location is 31.2, 11.8.

[Iceberg]

Well 90l has now official gone to TD 4, so will move to it's own thread.

but for this thread we now have 91l......

[crimsone]

Either the NHC has made a mistake, or we have TD4! (no mention of td4 in the other products right now, or in the description when you click on it... maybe that changed by the time I managed to save the screendump. lol)

http://www.nhc.noaa.gov/gtwo_atl.shtml

Edit: Too late! lol

Discussion on TD4 here

Edited August 13, 2007 by crimsone

[Iceberg]

The track for Invest 91L Ships take this to a Hurricane at 96 hrs.

[kold weather]

91L may need some very close watching given wher eit is right now. Its still rather disorganised thanks to the ULL however its easing now a touch as the ULL heads westwards. Convection and also moisture is clearly no problem and as the shear weakens ther eis scope for development and quick development at that as well.

Convection is farly unorganised but with a borad low in the deep convection overnight it wouldn't take much at all to form a LLC in such a set-up and it could develop quite rapidly under pretty high heat content profiles. Models take it generally towards S.Texas however areas a good 15- miles north/south ma need to watch because the system may develop a LLC in a place not expected by the models which will shift the actual track. Not sure i'd go quite as high as the SHIPS mind you but it may be one of those quick TS spin-ups that do occur...it could well be a TD in the next 12-18hrs though and could wlel become a tropical storm

Even if it doesn't develop 4-6 inches of rainfall could still cause some issues, there is plenty of moisture so even if it doesn't form into anything noteable it may well be quite a rain-maker.

Edited August 13, 2007 by kold weather

[tinybill]

are we going to start calling it now alo4

http://forecast.mssl.ucl.ac.uk/shadow/trac...namic/main.html

Caribbean island right in line for this one then on to the gom

[crimsone]

TD4 (previously Inv 90L) has it's own thread here

[kold weather]

Invest 91L doesn't appear to have developed much more though convection is slowly becoming more organised as the ULL drifts away to the west wit hthe shear slackening all the while it does need lose watching over the enxt 24hrs IMO. the invest is progged ti have 30kts winds already give the powerful nature of the convection still firing up. As the ULL moves away t othe west there should be a weakness open up which will allow 91L to head NW towards Texas from the look of the models. If it does develop it'll very likely be a totally lop-sided system given the ULL presence on the western side so if it does develop the system would have most of its 'weather' on its E side so that where the heaviest rainfal and highest winds are likely. In such a set-up it doesn't take much organisation to get moderate TS strength winds, in effect this and Barry aren't all that different in terms of how it developed though obviously there are track differences.

[kold weather]

91L starting to take on a more organised look since my last post, its still not there just yet but i think we may have a pretty quick former here given the high temps of the gulf right and the steady reduction of shear. Could well be a depressio by tonight based on the increasingly decent look it has right now. Other then that not much to talk aobut but silll the real threat of a TS into Texas, maybe evn a fairly strong TS if it gets going well today.

[kold weather]

Looking very close to tropical depression strength now and maybe even tropical storm strength given the deep convection is returning again. i expect a tropical depression tonight followed by a rapidly developing tropical storm tomorrow. Its hard to tell how much this could develop. Its under some pretty slack condtions right now though its heading NW slowly. As I've stated shearis decreasing and ther eis huge amounts of moisture so powerful convection is present and importantly there is some very impressive heat content so we could see a rapid former with a weak upper high forming close by in the wake of the ULL as it moves out to the west.

Latest info shows how close the NHC are to upgrading it:

000

ABNT20 KNHC 141505

TWOAT

TROPICAL WEATHER OUTLOOK

NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL

1130 AM EDT MON AUG 14 2007

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

THE NATIONAL HURRICANE CENTER IS ISSUING ADVISORIES ON RECENTLY

UPGRADED TROPICAL STORM DEAN...LOCATED ABOUT 1490 MILES EAST OF THE

LESSER ANTILLES.

SATELLITE IMAGES AND SURFACE DATA INDICATE THAT THE AREA OF LOW

PRESSURE IN THE SOUTH CENTRAL GULF OF MEXICO IS GRADUALLY BECOMING

BETTER ORGANIZED AND A TROPICAL DEPRESSION COULD BE FORMING. A

RECONNAISSANCE AIRCRAFT IS SCHEDULED TO CHECK THE AREA THIS

AFTERNOON. THIS SYSTEM IS EXPECTED TO MOVE TOWARD THE

WEST-NORTHWEST OR NORTHWEST AT 10 TO 15 MPH. ALL INTERESTS IN THE

NORTHWESTERN GULF OF MEXICO...INCLUDING THE SOUTHERN TEXAS AND

NORTHEASTERN MEXICO COASTAL AREAS...SHOULD CLOSELY MONITOR THE

PROGRESS OF THIS SYSTEM...AND BE READY TO TAKE ACTIONS. TROPICAL

STORM WATCHES OR WARNINGS COULD BE PROMPTLY REQUIRED FOR A PORTION

OF THE COAST.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE

NEXT 48 HOURS.

[Gray-Wolf]

I've been watching 91L 'bloom' also. Due north isn't out of the question for it's drift and at 15mph it'll have plenty of time to become better organised before any landfall. Dean may be the main focus but I think it worth watching the Gulf also.

[dvdfjojo]

I've been watching 91L 'bloom' also. Due north isn't out of the question for it's drift and at 15mph it'll have plenty of time to become better organised before any landfall. Dean may be the main focus but I think it worth watching the Gulf also.

Especially as there will be little warning or preparation time if she does decide to go bang tonight. Definitely worth a close watch.

[summer blizzard]

Wecould see something akin to Albert last year, it formed very quickly and while it only lasted 24 hours, a hurricane watch was issued due to rapid development.

It was all quite ammusing actually...

TROPICAL STORM WARMINGS HAVE BEEN TAKEN OFF

I was thinking good for the people of Florida...

HOWEVER A HURRCANE WARMING HAS NOW BEEN ISSUED

I'm there thinking, wtf, its only been around a day.

lol.