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Major Hurricane Irene live tracking


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Ok yes I agree though the NHC has stated that there is an area of low pressure along the wave.

However it is not a tropical cyclone so somewhere in between. Do the models initialize this as a wave, a low or a tropical depression? Do they input the fact that its just a wave or do they pick a point long the wave and up it to a TD when running the models?

They are initialized according to observations (out there....mostly satellite, ship/buoy, recon, etc.). There is no special treatment for any given system (for the GFS at least) unless it is designated to be of at least TD strength. At that point several possibilities can happen:

- use bogus wind observations if the 06 hour GFS forecast doesn't have a circulation at all

- TC relocation if the 06 hour forecast is displaced

- assimilate the advisory minimum sea level pressure observation

For more information on how it works for the GDAS/GFS, there is a paper coming out in weather and forecast soon (accepted, early release available online):

Assimilation of tropical cyclone advisory minimum sea level pressure in the NCEP global data assimilation system

Daryl T. Kleist

Weather and Forecasting

Volume 0, Issue 0 ( ) pp.

doi: 10.1175/WAF-D-11-00045.1

The GFS had 87L initialized as a 1007 mb low for the 06z run.

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Rough 00Z Recap:

GFS=Greater Antilles/S FL

Euro=Greater Antilles/S FL

HWRF=Greater Antilles

CMC=S of Greater Antilles/Yucatan Channel

UKMET=S of Greater Antilles/Yucatan Channel

GFDL= Little development S of Greater Antilles

GFS ENS=S of Hispaniola/crossing Cuba/Dry Tortugas/W Coast FL

You left out the eventual best part about that one....or the worst....depending on who you are

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You left out the eventual best part about that one....or the worst....depending on who you are

Nah. I tend to not even pay that much attention beyond 144-168 hours, but that's just me...;)

HPC:

DAY-TO-DAY

DIFFERENCES ARE ABOUT AVERAGE STARTING DAY 3/TUE...BUT QUICKLY

BECOME LARGE SURROUNDING THE STRONG AND COMPLEX UPPER TROUGH OVER

THE GULF OF ALASKA...AND ALSO IN THE CARIBBEAN SEA/GULF OF MEXICO

DUE TO INCREASINGLY DIFFERENT TRACK FORECAST FOR THE TROPICAL WAVE

CURRENTLY ENTERING NEARING THE LEEWARD ISLANDS. TO ADDRESS THESE

INCREASINGLY LARGE DIFFERENCES...WILL LIKELY TRANSITION QUICKLY TO

EITHER THE 00Z GEFS MEAN AND/OR ECMWF ENSEMBLE MEAN FOR THE

PRELIMINARY PRESSURES/FRONTS FOR DAYS 3-7. MODELS HAVE TRENDED

SLIGHTLY TO THE RIGHT OF PRIOR FORECASTS WITH THE TROPICAL WAVE

NEARING THE LEEWARD ISLANDS WITH THE 00Z OPERATIONAL ECMWF CLOSEST

TO THE DETERMINISTIC CONSENSUS AND GLOBAL ENSEMBLE MEANS.

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Close staring at morning vis imagery, there doesn't appear to be a closed surface circulation. And the greatest 'turning' in the low cloud elements is located in a couple of places, one well Southwest (almost in the L. Antilles) of most of the convection.

Agrees with the slow developing model theory. I still hope they fly a mission, at least to center the lowest surface pressure. And a closed low could form in the next 6 or 8 hours.

6Z Nogaps LolGaps towards the Panhandle

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This is something to consider if the east coast solution pans out already on top of saturated soil from a couple weeks of heavy rain events in and around I 95 - this has to be one of the most devastating solutions with a 979 cat 1 hurricane or tropical storm passing right along the coast or a few miles inland in addition to the heavy rain pushing all that water inland along the coast through all the inlets -bays etc .- massive flooding from VA to New England - places along the way where the water from the ocean meets the bay - example Long Beach Island in NJ happened in 1962

http://raleighwx.americanwx.com/models/gfs/06zgfsp72252.gif

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Yeah, the global model consensus on a Hispaniola hit or very close brush to the south is strong, and we're nearing 72 hours out. If 97L tracks off of the consensus, I think it's more likely to track south and west of it, but given that we're getting closer in time, there's less and less room for significant track changes. Still, it wouldn't take much shift in the guidance to miss Hispaniola completely.

Also, although the ECMWF and GFS take a very strong TC into FL after the Hispaniola/Cuba landfalls, the models have a notorious tendency to underestimate the weakening of TCs over land, so take the depictions of a post-Hispaniola uber-TC with a grain of salt.

I also recall Emily being modeled to become intense once passing N of the archipelago, too.

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For some reason this storm is reminding me of the track that Dennis took because it just missed Hispanola, and then traversed close to Cuba and eventually hit Havana and then paralleled the west coast of Florida. Could that be a good analog for this storm?

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I also recall Emily being modeled to become intense once passing N of the archipelago, too.

But if I recall correctly, it was primarily just the GFS doing that, at least once it got into this time range. Someone can correct me if I am wrong, though. In this case, pretty much all the models are on board with an intense cyclone - although really all that means is that the environment will be very favorable. Obviously, inner core dynamics and interaction with land which is impossible to determine at this time range (especially without even a LLC to track!) make it impossible to have any true feel for this setup.

It's like others have been saying - the only thing you can say in confidence is that a decent system will probably make it far enough west into the basin to combine with a favorable upper air pattern to threaten the US. How strong and where - who knows? Although I would say you can probably generally narrow down the most likely area as the vicinity of FL, even though the GGEM and ECMWF ensemble do imply a threat as far W as MSY.

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This is something to consider if the east coast solution pans out already on top of saturated soil from a couple weeks of heavy rain events in and around I 95 - this has to be one of the most devastating solutions with a 979 cat 1 hurricane or tropical storm passing right along the coast or a few miles inland in addition to the heavy rain pushing all that water inland along the coast through all the inlets -bays etc .- massive flooding from VA to New England - places along the way where the water from the ocean meets the bay - example Long Beach Island in NJ happened in 1962

http://raleighwx.ame...6zgfsp72252.gif

You do realize, even before the resolution reduction, the effective grid resolution on the GFS is coarse enough that there is no way it can resolve intensity to that fine a level? Especially this far out. The only thing you can really take from the GFS is that the model sees favorable conditions for 97L.

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Granted I have not read all 25 pages with tedious concentration ... SAL is still - imo - having an impact. An "arm" of it is bending around the western semi-circle of any perceived circulation and as elements of this mix with the condensates of the system it creates an over-abundance of seed material, that prematurely dries out the column and not allowing sustained tower activity. That's the theory in a nut shell, but one that pretty much plays out before our eyes every time one of these interacts with that pretty orange-red shimmering stuff we see over at http://tropic.ssec.w...d=splitEW&time=

This "might" be why the models labor any development until about 48 hours from now, because at that time it will finally have passed west of the SAL contaminant.

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But if I recall correctly, it was primarily just the GFS doing that, at least once it got into this time range. Someone can correct me if I am wrong, though. In this case, pretty much all the models are on board with an intense cyclone - although really all that means is that the environment will be very favorable. Obviously, inner core dynamics and interaction with land which is impossible to determine at this time range (especially without even a LLC to track!) make it impossible to have any true feel for this setup.

It's like others have been saying - the only thing you can say in confidence is that a decent system will probably make it far enough west into the basin to combine with a favorable upper air pattern to threaten the US. How strong and where - who knows? Although I would say you can probably generally narrow down the most likely area as the vicinity of FL, even though the GGEM and ECMWF ensemble do imply a threat as far W as MSY.

Yeah, this why I didn't labor the point, because the complexities grow as to "why" that is in this case. The overall improving UVM profile of the Basin means that there could be a few phantoms thrown out there during the next 2 -3 weeks.

I am not sure why the GFS has been so hot on this cyclone; frankly, I don't like its chances until it really clears the SAL that has been interacting with its girthy circulation field. ...another discussion perhaps.

One thing that 97L has in its favor is that its overall mass-field is anomalously large. That helps should an interaction with the big H take place for obvious reason.

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Ok a morning update for those interested.

http://www.examiner....-late-next-week

Note, 99L has emerged along the southern extend of the same TW that has 98L apparently detaching and about to spin into SAL. 98L is around 16N/30W and 99L recently designated - and has it's own floater assigned - is around 10N by slightly W. This southern system - imo - has the better shot given to its further proximity to SAL and that previous activity has "cleared the way" so to speak.

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Excellent discussion linked below - I would put the odds of the GFS/Euro east coast solution 75 % vs. GOM solution 25 % - the Hanna path accuweathers HM has been talking about seems very reasonable right now....

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Note, 99L has emerged along the southern extend of the same TW that has 98L apparently detaching and about to spin into SAL. 98L is around 16N/30W and 99L recently designated - and has it's own floater assigned - is around 10N by slightly W. This southern system - imo - has the better shot given to its further proximity to SAL and that previous activity has "cleared the way" so to speak.

Perhaps so, but the NHC hasnt ran models on invest99 since 4pm yesterday according to their ftp site and they continue to run them for invest98, so I havent put invest99 on my model page yet.

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Perhaps so, but the NHC hasnt ran models on invest99 since 4pm yesterday according to their ftp site and they continue to run them for invest98, so I havent put invest99 on my model page yet.

Yeah am aware that your discussion was probably written well before these recent changes were observed. It was a general note -

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Ok a morning update for those interested.

http://www.examiner....-late-next-week

nice writeup. Given your preferred track of 97L after landfall in FL, do you believe it will have the chance to re-emerge over the Atlantic and regain strength along the coastal plain??

Also, I think you had a typo at the end. I believe you meant to say heavy rain and high winds, not heavy wind and high winds.

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Also, I think you had a typo at the end. I believe you meant to say heavy rain and high winds, not heavy wind and high winds.

About that line (typo notwithstanding), I did appreciate RaleighWx's early heads-up of possible storm/trough interaction and enhancement, something I'd been wondering about. Whether landfall occurs in the eastern Gulf or along the Atlantic coast, a properly placed trough can "funnel" a huge rain event up the east coast. The rain is what I'm in this game for. We've had some drought relief here lately, but stream flows are still low. Five or six inches of rain would be a blessing, wind or no wind.

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nice writeup. Given your preferred track of 97L after landfall in FL, do you believe it will have the chance to re-emerge over the Atlantic and regain strength along the coastal plain??

Also, I think you had a typo at the end. I believe you meant to say heavy rain and high winds, not heavy wind and high winds.

Thanks. It will depend on how strong it gets. If the trough phases with a powerful storm, then we could see a strong gale all up and down the east coast of the US.

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About that line (typo notwithstanding), I did appreciate RaleighWx's early heads-up of possible storm/trough interaction and enhancement, something I'd been wondering about. Whether landfall occurs in the eastern Gulf or along the Atlantic coast, a properly placed trough can "funnel" a huge rain event up the east coast. The rain is what I'm in this game for. We've had some drought relief here lately, but stream flows are still low. Five or six inches of rain would be a blessing, wind or no wind.

YEah, that is what I am watching for too. There are still a good number of ensemble members that still threaten the southeast coast for a direct landfall, so that cant be ruled out. Hopefull the trough and storm can interact in a way to bring nice rains to all in the southeast.

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as long as we dont get any up here you guys can have it all

YEah, that is what I am watching for too. There are still a good number of ensemble members that still threaten the southeast coast for a direct landfall, so that cant be ruled out. Hopefull the trough and storm can interact in a way to bring nice rains to all in the southeast.

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Perhaps circumstantially so for TC's in tihs particular lat/lon, I do see some similarities to Emily when her zygote was in a similar position. She too had a split vorticity field at respective levels and we can clearly see tis occurring again with 97L as it approached the Island.s.

post-904-0-87182900-1313851896.jpg

What this means for 97L's future is not entirely known... As we saw with Emily - and countless other systems in the past - these mid level reflections, while they "look" more impressive tend to not become the dominant center out in time for those systems that actually do overcome hostilities and develop. That stands to reason because meteorologically the TC model is an oceanic/atmospheric virtual couple; any mid level vorticity genesis is not part of that model. It is indeed complex however, as mid level centers some times do "mix" down and get the lower levels involved - it usually takes quite a while for that to take place however, making it probable that the llv center will succeed first once inhibitions are accounted for. ...simple terms.

In about 24 to 36 hours the SAL should be removed from the equation... I believe at those times southwestern low level center is the one to key in on, not the blob of convection associated with the mid level weakly bounded vortex.

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Interesting analysis, I don't agree with your placement of the LLC. Best track puts it around 57W 15N, if it's there at all.

Actually, earlier today, I commented on the vis loop that while there didn't appear to be a closed surface low, the most pronounced turning in the low cloud elements was well Southwest of the largest convective cluster.

I have no idea if Tip's idea that the Southwestern vort will be dominant or not is correct, but there is an observable (by an amateur yet, me) low level maximum in vorticity where Tip has placed it.

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Actually, earlier today, I commented on the vis loop that while there didn't appear to be a closed surface low, the most pronounced turning in the low cloud elements was well Southwest of the largest convective cluster.

I have no idea if Tip's idea that the Southwestern vort will be dominant or not is correct, but there is an observable (by an amateur yet, me) low level maximum in vorticity where Tip has placed it.

If true, this system is in worse shape than Emily ever was

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