Tropical Storm Isaac, Part 2: Isaac Moving Into The Gulf Of Mexico-Hurricane Warnings For Morgan City, LA/MS/AL & FL Panhandle To Destin, FL

[Superstorm93]

Pretty impressive 51 knot dropsonde on the south side of the circulation. It may have gotten to hurricane status briefly.

I'm really liking the 992 mb pressure with 46 knot winds.

L. Eye Character: Poorly Defined

M. Eye Shape & Diameter: Circular with a diameter of 8 nautical miles

[Thunder Road]

Per Wundermaps, the EC is a landfall on Fort Walton Beach at 0z Wed. Min pressure is sub 972.

[Dunkman]

Per Wundermaps, the EC is a landfall on Fort Walton Beach at 0z Wed. Min pressure is sub 972.

I was just looking at that. On that map, it goes from over 992, probably 993, to what I would guess is around 970 or 969 in the 24 hours before landfall. That's pretty damn impressive deepening.

[Scott747]

Moving across the southern end of Gonave Island.

[dan88]

Some particularly heavy precip out there, with recon reporting 78mm/hr convection in a new cell South of Hispaniola.

Edit:

Recon is now flying around the Western edge of Haiti, likely to sample North of the island.

[dan11295]

Isaa would seem to the taking almost the most favorable track possible to maintain strength. Storm is moving so will cross the SW tip of Haiti quickly fairly over a strip that is relatively flat. Then is just appears it will only clip the NE tip of Cuba. Threading the needle pretty much. Sure terrian will still causes some core dispruption, but almost no way it gets "shredded". IMHO anyone in Keys to S FL needs to be prepared for the possibility of a minimal hurricane if the core can remain intact.

[phlwx]

Between the GFS and EC, there isn't a significant difference in landfall -- pretty much near Fort Walton -- GFS is about 9 hours faster on timing than the EC.

Looks like a Tuesday evening/night landfall in the Panhandle -- Fort Walton to Apalachicola -- perhaps as far west as Pensacola.

[phil882]

http://philstropicalweatherblog.wordpress.com/2012/08/25/tropical-storm-isaac-moving-over-hispaniola-and-cuba-heading-for-the-gulf-of-mexico-with-a-us-landfall-looming/

My first track map for Isaac... I agree that its likely not to be significantly affected by land over the next 12-24 hours. In fact, if Isaac can maintain its formative inner core, this intensity forecast might be on the low side before the first landfall in extreme S Florida. The second landfall timing is tricky since the storm will be slowing down, but a track between Panama City and Pensacola seems like a relatively good bet at this time. I think this has a reasonable shot to be our first US major hurricane landfall in 7 years.

[HurricaneJosh]

http://philstropical...ndfall-looming/

My first track map for Isaac... I agree that its likely not to be significantly affected by land over the next 12-24 hours. In fact, if Isaac can maintain its formative inner core, this intensity forecast might be on the low side before the first landfall in extreme S Florida. The second landfall timing is tricky since the storm will be slowing down, but a track between Panama City and Pensacola seems like a relatively good bet at this time. I think this has a reasonable shot to be our first US major hurricane landfall in 7 years.

Omg, love this.

What makes you so bullish Re: the NE Gulf? Scott-- or someone-- posted that map the other day that showed crappy oceanic heat content up there.

[turtlehurricane]

All the convection is currently confined south of Hispaniola, with the only inner core convection being triggered by the mountains. Things aren't as good as those 2 nice convective bands would suggest... we'll have to wait and see if convection fires up northwest of Hispaniola over water. Best case scenario I see for Isaac is 40-50 mph after emergence, naked swirl style. Don't see how this is different than any other time Hispaniola slaughtered a hurricane.

[Ground Scouring]

GTMO radar shows that a small inner core is still intact off Gonave Island, Haiti. Once the system moves off NE Cuba, I see no reason, given the more easterly movement favoring even less land interaction, that steady intensification would not still occur, particularly as the GFS has handled the track and anticyclone fairly well as of late. The only problem is that radar data also indicate a movement around 290°, meaning more direct interaction with Cuba initially.

[Scott747]

I don't think that radar is giving a good representation. On the current heading it may only clip Cuba.

[DaculaWeather]

Key West is already getting hammered well in advance of Isaac: http://www.daculaweather.com/grlevel4/4_byx_br248.php

[Ground Scouring]

I don't think that radar is giving a good representation. On the current heading it may only clip Cuba.

Yeah, normally, I tend to trust radar estimates, so I initially went with my interpretation, though I had some doubts about GTMO’s accuracy relative to that of U.S.-based Doppler-NEXRAD systems, as GTMO has a different form of radar.

[dan11295]

Yea, on satellite unless if really started moving WNW now it may not even clip Cuba. Huge difference between that and spending 8-12 hours over land (some of it mountainous). Both sat/outer fringes of the radar imply heavy rainfall over PAP now, The track, slowdown last night and location of convection has not been good for them at all. Regarding the rain affecting SFL, obviously not directly part of the circulation but interesting to watch nonetheless.

[dan11295]

Pressure has really come up per last HH report. Up to 998 mb. Thats a pretty big hit, unsure why they kept winds at 60 mph for 8 am. Will have to see when the pressure rises stabilize.

[DaculaWeather]

Although it doesn't show up yet on the buoy data, Sombrero C-MAN station in the Keys just reported a 61 mph wind gust.

http://www.daculaweather.com/4_buoy_gom_2.php

[DaculaWeather]

Here's the Gitmo radar link if anyone wants it: http://radar.weather.gov/ridge/radar_lite.php?rid=gmo&product=N0R&loop=yes Only one product available. Looks like a WWII relic.

[DaculaWeather]

It looks like it's going to be moving into an area of increasing shear. I was watching the current convective complex over the Key and how it was getting sheared off to the NE.

[Ground Scouring]

The surface trough producing convection off SE FL clearly appears to be a distinct system from Isaac and was largely unseen by the models. I would tend to believe it might enhance shear due to thunderstorm outflow and initially hamper Isaac in its efforts to re-intensify before striking the Keys. Perhaps that’s a primary factor in preventing more substantial intensification, perhaps even limiting Isaac to 60 kt at most before FL, particularly given the small size of the inner core of Isaac. Thoughts?

[DaculaWeather]

I wonder if it may try to form something on it's own. It's already large, over very warm water, and very healthy.

[Ed Lizard]

It looks like it's going to be moving into an area of increasing shear. I was watching the current convective complex over the Key and how it was getting sheared off to the NE.

Base CIMSS shear map does suggest it has gotten a bit NW of its attendant anticyclone, and is experiencing 10 to 20 knots of shear over the center. I assume the anticyclone will try to redevelop over the top, but it would seem an impediment to rapid strengthening even as it initially gets away from land, even if it avoids Cuba.

[DaculaWeather]

The mid levels don't seen to be quite as bad. http://www.daculaweather.com/4_shear_forecast.php

[N. OF PIKE]

Notice that feature in keys developed some nice vorticity and will potentially draw isaac a bit further north over next 12 hours as well as cause a tad more shear. Could be difference between a landfall a bit further north in s florida "could". Models may have under forecast the keys disturbance and thus its potential effects on isaac. Also could isaac slow in next 24-30 hrs more than forecast or is his speed / steering effects pretty high confidence. Have family there, so a tad concernd.

[Ground Scouring]

I am going to go out on a limb and say that the surface trough off the Keys will persist at least over the next 12 hours and prevent Isaac from organizing its small inner core, thereby preventing a hurricane from hitting SE FL. I just have a feeling, based upon synoptic experience and the proximity of the feature to Isaac, that this feature will have a major impact on the intensity as well as the track through early tomorrow, likely resulting in a weaker landfall--60 kt or less--much closer to Miami.

[DaculaWeather]

You can see the kinks in the pressures http://www.daculaweather.com/4_spc_meso_analysis.php

[Baroclinic Zone]

You can see the kinks in the pressures http://www.daculawea...so_analysis.php

Do you think you could refrain from posting a link to your site in just about every post you make?

[wxsmwhrms]

I am going to go out on a limb and say that the surface trough off the Keys will persist at least over the next 12 hours and prevent Isaac from organizing its small inner core, thereby preventing a hurricane from hitting SE FL. I just have a feeling, based upon synoptic experience and the proximity of the feature to Isaac, that this feature will have a major impact on the intensity as well as the track through early tomorrow, likely resulting in a weaker landfall--60 kt or less--much closer to Miami.

It looks to me like that surface trough is a reflection of an upper level low and the associated convection that is pinching off just north of western Cuba. The GFS actually seemed to have a decent handle on this (maybe a hair too far west based on water vapor) and shows it retrograding west southwest away from the system over the next 24-36 hours. You can already begin to see that happening in the water vapor imagery.

Right now I would tend to agree with on the strength, as much because really the models don't show a ton of strengthening until it gets to the Gulf. I am less confident on what you are saying about the movement, because the models seemed to have this more NNW movement over the last 12 hours and given the weakening that has occurred due to the Haiti interaction, and the fact that the convection is much less and being hampered by the fact that the inflow side of the storm is over Hispaniola, I would guess the steering will be more dominated by the low and mid level over at least the next 24 hours which one would think would result in the more WNW-NW movement that the models show.

In any event, this interaction is certainly something to watch today IMO.

[wxsmwhrms]

Looking at visible imagery, looks like the center right now is very close to 20.1N, 74.0W moving maybe a hair E of due NW. Looks like it going to pass by the eastern tip of Cuba here soon.

[Ozarkwx]

Maybe this has been discussed previously, but the tendency to stall out at around H96 is really close to being over water. If the weak steering flow sagged another 50-100 miles south, seems like the problems for the panhandle could escalate quite a bit. Is this a realistic scenario?

Also, not sure what to make of the post landfall track - GFS, et al NNE vs. the EC NW.