Right now, Isaac has a bit of a center organization problem... wind shear of about 10-20 kts from the south has displaced the storm's surface center from its mid-level center, which is going to make intensification a bit more difficult since it can't efficiently transfer the ocean's heat energy throughout all levels of the storm. Also, at present it is still having a bit of a problem with dry air. There is almost no convection at all on the storm's southwest side, and it only has one well-established outflow channel, in the north quadrant. Also, the ocean's heat content is only in the moderate range ahead of the storm.
For comparison, Katrina had no wind shear whatsoever (0-5 kts for 4 days straight,) it passed directly over a giant eddy in the Gulf's loop current which supplied it with some of the warmest waters in the entire Atlantic, plus it was perfectly vertically-stacked, and had excellent outflow channels on all four sides of the storm. All of these factors aided in its explosive intensification.
Basically, any news outlet that is trying to say that Isaac is going to be another Katrina is crazy right now. This storm has way too many factors that are inhibiting its intensification potential right now. Unless something changes fast, we're looking at a category 1 or 2 hurricane by landfall. Isaac is a HUGE storm, though, with tropical storm-force winds extending up to 205 miles from the center, so the storm surge potential is going to be a bit higher than a normal storm of this intensity, but it shouldn't be a catastrophe... definitely a billion-dollar disaster, but not a repeat of Katrina.
EDIT:
Strike everything that I just said. All day, this storm was struggling with organizational problems, with its low-level center out of alignment with the mid. But within the last 30 minutes, the low-level center just took a huge jump to the north and is now directly underneath the mid-level center and the deepest convection. Recon is reporting that pressure has dropped by 3 mb since the last update, and winds have increased from 60 to 70 mph. The storm is rapidly building an eyewall, and its western outflow is beginning to improve as well. So, yeah, strike absolutely everything that I just said. This storm is rapidly organizing, and will almost certainly be a hurricane by tomorrow morning. The wind shear is still an inhibiting factor, but some of the latest model runs are now taking it up to category 3 before landfall. The worst of these forecasts is the HWRF computer model, which brings Isaac all the way up to a 150 mph category-4 hurricane with a 936 mb center at landfall. The official NOAA forecast is for a category-2 hurricane with winds around 100-105 mph hitting the central Louisiana coast. I highly doubt the HWRF's worst-case scenario of another Katrina will happen, but either way it's definitely not good.
I dont think it will be stronger than Category 2.Dry air and shear will limit intensity.
Katrina was a Catagory 2 when it hit New Orleans. Don't argue with me since I study weather currents and preassure systems. Also by the way, the levees are 4 feet too short for the predicted storm surge.
Somehow, despite the central pressure dropping by another 10 millibars to 979 mb, a pressure usually associated with weak category-2 or strong category-1 hurricanes, Isaac is still a tropical storm.
The storm's still having too many organizational problems for it to intensify significantly before landfall. I'm now about 90% sure that we're just going to have a category-1 hurricane at landfall.
The storm surge potential with this storm is going to be significantly higher than with your average hurricane, though, due to Isaac's enormous size. It's a situation similar to Ike and Irene. Most Cat 1 hurricanes usually only carry a surge potential of maybe 4-5 feet, while Isaac is likely to have surge topping the 10-12 ft range in a few locations because of the sheer volume of ocean under it. And also due to this storm's huge size, it will not weaken as quickly as a typical hurricane would. This means that there will be significant rains, flooding, and winds hundreds of miles inland from its landfall site.
UPDATE:
Isaac has finally made it to hurricane status. Reconnaissance aircraft finally found a surface wind of 75 mph at about 12:19 this afternoon. It's about damned time. This morning, the pressure was all the way down to 976 mb, typical of a category-2 hurricane, but it was still a tropical storm with surface winds of only 70 mph despite hurricane hunters finding winds of up to 102 mph at flight level. In my 16 years of watching hurricanes, I have NEVER seen a tropical storm with a pressure as low as 976 mb. Usually it only takes a pressure of about 990 mb to make it to hurricane status.
Anyway, again, although this is still only a minimal hurricane, this storm is no joke. This is going to be a major storm surge event. NOAA's hurricane research division is currently rating the destructive potential of Hurricane Isaac's storm surge as a whopping 4.1 out of 6. For comparison, Hurricane Gustav of 2008, a strong category-2 hurricane, was rated as a 4.2 on this same scale, and produced a storm surge of 14.5 feet on the southern Louisiana coast.
Another thing to worry about is that Isaac has now slowed its forward speed down from 13 mph to 10 mph, as the steering currents are weakening. This is a HUGE storm (almost 400 miles wide,) and therefore was already going to be a significant wind and rainfall event, but now it is expected to make landfall very slowly too. This means an exceptionally higher potential for flooding. Current rain forecasts are calling for up to 10-20 inches of rain being possible in most of Eastern Louisiana and southern Mississippi. So even if the winds aren't going to be a huge issue, this is going to be a disastrous flood event, and likely a multi-billion-dollar disaster.
Remember, Hurricane Irene of last year was also only a category-1 hurricane at landfall. And just look at the damage that it caused...
Originally posted by gforce1994 Don't argue with me since I study weather currents and preassure systems.
I 555 kPa'ed your dad's ass
EYE CAHN'T SPELLZ
Originally posted by cjd Remember, Hurricane Irene of last year was also only a category-1 hurricane at landfall. And just look at the damage that it caused...
Good thing the RNC won't be requesting tax dollars to fix it.