Hurricane Dean

[Stuart Robinson]

Dean was upgraded to a CAT1 hurricane in the 500 AM EDT update

The first Hurricane of the 2007 season.

 

[Justin Turcotte]

The TPC will be sending out the Gulfstream-IV this afternoon for a synoptic surveillance mission. This data will at the least improve initial 00z model conditions and perhaps give us a better idea where Howard Dean is gonna scream next.

Houston NWS isn't totally sold on a Gilbert type track just yet...

LONG RANGE PROGS STILL TRYING TO RESOLVE THE PATH OF DEAN BUT THERE ARE HINTS THAT A TUTT LOW WILL BE MOVING UNDER THE HIGH (SLIGHTLY NORTH/AHEAD OF DEAN) ACROSS THE GULF ON/ABOUT THIS SAME TIME. A BEAR WATCH REMAINS IN PLACE.

 

[John Peters]

Latest GFDL has progged a more "Allen" type track (north of yucatan) and is a little more aggressive in terms of strength projections. As of the 11:00 AM advisory, winds are up to 90 mph and pressure is down to 979 mb (yet HWRF still has the storm remaining below the hurricane threshold throughout the caribbean.

Satellite images show the storm steadily becoming more organized.

 

[Charles Kuster]

Dean continues to strengthen and outflow is looking more and more healthy in all quadrants.

Track is still uncertain, but the deep-layer ridge should steer Dean on a mostly westward track into the western Carribean. After that, I think Dean will take a more WNW track as it reaches the edge of the ridge. As of now, I think it will make a brief landfall in the northern Yucatan and then move towards the Texas coast. It is still too far out to be sure, but I like the guidance offered by the GFDL and the NOGAPS right now.

 

[MClarkson]

yes, the 06z GFDL has a very interesting track. 12z GFS still has the yucatan track. Recon is about to make its first pass, 100 miles out or so.

12z cane models are in... HWRF is back! <900mb and into the southern gulf. GFDL is further into the gulf and <920mb

 

[John Peters]

Reconnaissance aircraft confirmed 970 mb central pressure and 90 mph sustained winds (will probably increase soon in response to pressure drop). This thing is deepening fairly quickly.

Edit: I just nearly lost it after looking at the latest HWRF, which brings it ashore on the northern yucatan with at 887 mb!


GFDL puts it dead center of the gulf as a 913 mb cat 5 with winds of 159 kts, poised to make landfall somewhere in the western Gulf coast!

 

[aaron.burkham]

887 mb, whoa, thats pretty low.

 

[John Peters]

887 mb, whoa, thats pretty low.

Yeah, if (unlikely) dean did indeed achieve an 887 mb central pressure, it would become the second most intense tropical cyclone ever in the atlantic basin. IMO HWRF tends to underestimate central pressure though (model only corresponds 145 sustained winds). I think GFDL's 915-920ish, if not higher would be a more realistic outlook (considering climatology among other factors).


Edit: Winds now to 100 mph (cat 2) as of 5PM AST advisory. Pressure was fluctuating between 974 and 979 mb based on reconnaissance observations.

 

[aaron.burkham]

Im starting to see the track go slightly more to the north, im thinking it might only brush the Yucatan and weaken slightly before entering the gulf and then rapidly strengthen before landfall and quite possibly slow down,
thats my educated guess.

 

[John Peters]

One thing these models may not take into account is eyewall replacement cycles (correct me if i'm wrong). Dean's central circulation currently seems compact - when an eye develops it will probably be small with a tightly wound eyewall. It seems that storms that initially develop this very compact circulation quickly undergo an eyewall replacement cycle and develop a larger eye (Examples: Katrina, Wilma, Ivan).

 

[Brandon Clement]

The upper level low is going to make the decision for Dean. It crosses over Florida then heads across the Gulf before moving in by Houston, Texas. While that is going on Dean will be in the Carribean. 12z Monday seems to be the big point that will determine Dean's final landfall. The GFDL was showing a strong turn north at 12z the past few runs but has since come back towards the other models. I actually think the GFS has handled this thing incredibly and my money is still on the GFS despite that it is not one of the better tropical models. IMO Dean will not be able to maintain a forward speed over 25 all the way through the Yucatan. The Upper level low should have plenty of time to move on shore allowing High pressure from the West to push back in. I would expect Dean to cross the Yucatan then move just a little north of West before catching the SW portion of the High pressure and making a turn almost due West into Mexico.

I love chasing Hurricanes but there is no way I can root for a storm to hit anywhere near La. I hope this thing stays away from the populated cities, La and the oil rigs. The last thing the people along the Gulf Coast, our economy or gas prices need is a major Hurricane in the northern Gulf because all are too vulnerable right now.

The storm looked like it ingested some dry air earlier today and even though maximum winds and the core of the storm has continued to hold its own today I don't see it exploding into a major Hurricane just yet. Once the convection to the South of Dean gets wrapped or Dean finds a good inflow tail from the SE we will see it hover around cat 2 status. Once it moves off a little farther to the West and gets in the extremely warm Carribean waters and gets a larger core by wrapping the convection south of the main circulation Dean is going to go crazy. I think the HWRF and GFL are over doing the strength just a bit (especially the HWRF) but I do think this will be a major hurricane. Unless Dean can maintain speed and the upper level low can either slow down or deepen then I highly doubt we will see a US landfall, much less a direct hit to the Northern Gulf Coast. I wouldn't rule out a cat 5 or a US landfall but I do highly doubt it. IMO, the GFS had this thing pegged a couple days ago outside of a couple throw away runs.

My best guess (and it is exactly that) is about 100 miles south of Matamores, Mx as a Category 3.

 

[John Peters]

The upper level low is going to make the decision for Dean. It crosses over Florida then heads across the Gulf before moving in by Houston, Texas. While that is going on Dean will be in the Carribean. 12z Monday seems to be the big point that will determine Dean's final landfall. The GFDL was showing a strong turn north at 12z the past few runs but has since come back towards the other models. I actually think the GFS has handled this thing incredibly and my money is still on the GFS despite that it is not one of the better tropical models. IMO Dean will not be able to maintain a forward speed over 25 all the way through the Yucatan. The Upper level low should have plenty of time to move on shore allowing High pressure from the West to push back in. I would expect Dean to cross the Yucatan then move just a little north of West before catching the SW portion of the High pressure and making a turn almost due West into Mexico.

I love chasing Hurricanes but there is no way I can root for a storm to hit anywhere near La. I hope this thing stays away from the populated cities, La and the oil rigs. The last thing the people along the Gulf Coast, our economy or gas prices need is a major Hurricane in the northern Gulf because all are too vulnerable right now.

The storm looked like it ingested some dry air earlier today and even though maximum winds and the core of the storm has continued to hold its own today I don't see it exploding into a major Hurricane just yet. Once the convection to the South of Dean gets wrapped or Dean finds a good inflow tail from the SE we will see it hover around cat 2 status. Once it moves off a little farther to the West and gets in the extremely warm Carribean waters and gets a larger core by wrapping the convection south of the main circulation Dean is going to go crazy. I think the HWRF and GFL are over doing the strength just a bit (especially the HWRF) but I do think this will be a major hurricane. Unless Dean can maintain speed and the upper level low can either slow down or deepen then I highly doubt we will see a US landfall, much less a direct hit to the Northern Gulf Coast. I wouldn't rule out a cat 5 or a US landfall but I do highly doubt it. IMO, the GFS had this thing pegged a couple days ago outside of a couple throw away runs.

My best guess (and it is exactly that) is about 100 miles south of Matamores, Mx as a Category 3.

great post Brandon, i agree with your analysis

Recent runs seem to be favoring the full-blown Yucatan landfall rather than the "Allen" brush-by. I also think HWRF and GFDL are overestimating landfall intensity, though I wouldn't rule out a cat 4 landfall just yet. Dean will have a good deal of higher SSTs and likely decent outflow between Jamaica and the Yucatan.

As for the US/Gulf, we will almost certainly dodge the bullet if the storm makes a more southerly landfall and has more distance to dissipate over land. The further north this thing goes, the stronger it is going to be as it emerges into the warm Gulf waters - the less of a turn to the N it is going to need to make a US landfall.

My *rough* estimates would be: 110mph as it enters the Caribbean, 115-125 mph across Jamaica, and then 135-155 onto the Yucatan.

 

[Brandon Clement]

great post Brandon, i agree with your analysis

Recent runs seem to be favoring the full-blown Yucatan landfall rather than the "Allen" brush-by. I also think HWRF and GFDL are overestimating landfall intensity, though I wouldn't rule out a cat 4 landfall just yet. Dean will have a good deal of higher SSTs and likely decent outflow between Jamaica and the Yucatan.

As for the US/Gulf, we will almost certainly dodge the bullet if the storm makes a more southerly landfall and has more distance to dissipate over land. The further north this thing goes, the stronger it is going to be as it emerges into the warm Gulf waters - the less of a turn to the N it is going to need to make a US landfall.

My *rough* estimates would be: 110mph as it enters the Caribbean, 115-125 mph across Jamaica, and then 135-155 onto the Yucatan.

I am not ruling out a cat 4 landfall by any means. I actually think a strong 4 is a good chance when it hits the Yucatan. I also think it could easily get back to a 4 in the Gulf but I said 3 just because most major hurricanes weaken some just before landfall. I'm not sure this holds up as well along the Mexico coast as well as it does along the La/Ms coast and the forward motion of Dean wont give much time to weaken before landfall.

Again, this is a long way out and usually the safest place you could be 5+ days out is where the GFS is predicting landfall but I am really confident in the GFS being pretty close for Dean.

 

[Blake Michaleski]

I was wondering how much tropical chatter would have to take place to get Brandon talking...

As Brandon mentioned, I love chasing 'canes we sure don't need one on the upper gulf coast... Mobile is still recovering as is the MS Coast. There are places in teh FL panhandle that are still recovering from Ivan.

With the oil refinery fire in Pascagoula today and fear over this storm, we're already going to see prices rise some tomorrow. Then if Dean decided to take a more northerly track we'll be hurting bad with teh gas prices.

 

[Jeff Snyder]

I am not ruling out a cat 4 landfall by any means. I actually think a strong 4 is a good chance when it hits the Yucatan. I also think it could easily get back to a 4 in the Gulf but I said 3 just because most major hurricanes weaken some just before landfall. I'm not sure this holds up as well along the Mexico coast as well as it does along the La/Ms coast and the forward motion of Dean wont give much time to weaken before landfall.

Again, this is a long way out and usually the safest place you could be 5+ days out is where the GFS is predicting landfall but I am really confident in the GFS being pretty close for Dean.

I seem to remember a lot more hurricanes that are severely interrupted (inner core disrputions) as they cross the Yucatan and are unable to regain their strength than otherwise. There are many cases of storms crossing smaller land masses (e.g. Cuba) and reintensifying quickly thereafter (e.g. Dennis in 2005), but I can't think of too many major hurricanes that spent >6 hrs of land crossing the Yucatan that were then able to reach their previous intensity (or within 20 kts of that intensity). Just my limited experience, though!