Miami/New Orleans Hit

[Anonymous]

Well, while I am on the kick, let's talk about Hurricane "Isaac":

TRACK:


TALKING POINTS:

Hurricane Isaac's winds increase all the way into downtown Miami were the intensity peaks at 185 mph/897 mb.

New Orleans landfall cause a 34 foot surge.

[yoda]

We are talking about the strongest winds SUSTAINED in the Atlantic here with only 900 MB? That would be unlikely. And we are suggesting an entire area of no shear, 85 degree plus water temps?

[Anonymous]

The two places you are likely to get MITCH AND 1935 Like storms are...WHERE THEY WERE! Western Caribbean and East of Florida.

I mean, Isabel was not going to weaken below 145 mph in NC unless shear appeared. And it did.

[TS Zack]

Oh Mike,

Do he need some sleep or what!

[Anonymous]

What? What did I do wrong?

[george_r_1961]

Although possible it isnt likely a tropical cyclone would encounter the type of conditions required for an "Isaac" scenario. For a TC to move along a track with high SST's and no shear over such a long period of time would be a fluke. Eyewall replenishment cycles cause rather rapid fluctuations in strength as do the occasional upper level troughs a TC encounters. As far as a storm hitting NC with 145 mph winds that isnt likely either..but certainly not impossible. Storms approaching the mid atlantic coast frequently get dry continental air drawn into their western semicircle, resulting in some weakening and decrease in convection on the western side. The worst case scenario for NC would be a rapidly moving strong TC approaching from the E or ESE. Such a storm would have little oppurtunity to get any dry air entrainment significant enough to cause weakening. This type of scenario in a low shear environment would be disasterous.

[Anonymous]

Well, it is likely that Andrew was 170-180 mph...so I would not at all say that an ISAAC scenario is unlikely.

[george_r_1961]

Are we talking sustained winds or gusts? And Andrew weakened considerably after crossing FL..even though I believe it was still a major when it hit the Gulf Coast.

[Anonymous]

Well, Derek Orrt brought up a good point. Andrew continued to intensify as it came inland. This year, we saw a few major events. Of course, massive hurricanes. But what these showed us, is the damage scale. We saw what a storng and large category 2, a small a fierce category 4, and large and modest category 3, and a modestly sized category 3/4 can do.

So, we have seen massive category 5 damage. Camille, which was 180-200 mph, 1935 Labor Day, which was 180-200 mph, and Andrew which was OFFICALLY 165 mph.

I consider the damage from Andrew not even catastrphic...I consider it cataclysmic. I mean, back after Charley I said "Man, it looks just like Andrew." And then, I looked at Andrew's damage and said "Man...I was wrong." "Charley's damage, while catastrophic, was NOTHING like Andrew."

Therefore, I think Hurricane Andrew was more in the 175-185 mph range. I also feel, while the famed 922 mb is offical, I feel Andrew was probably 920 or maybe 917 mb. I STILL am a little bit skeptical about the true strength of Andrew, even after the upgrade in 2002.

Charley:

Andrew:

As for Andrew weakening CONSIDERABLY, that is not true.
Andrew stayed a major hurricane.

[The Big Dog]

Actually, if you want even more devestation, veer the track through the central Bahamas and make it appear that it's going to miss Florida altogether so that most people let their guards down. Then, at the last minute, turn the storm back to the west after it's too late to evacuate South Florida and the Keys, and bring it in just south of Miami, so the northern eyewall passes through downtown AND catches all the late evacuees from the Keys on US1. That way, you can wash a couple thousand cars right into the Florida Straits.

[Derek Ortt]

Andrew weakened 2 full categories over Florida.

Also, it weakened from 125KT to 100KT in the final 6-12 hours prior to its landfall along the Gulf Coast, which is actually quite typical of major hurricanes in the northern Gulf

[Anonymous]

Andrew weakened from 165 (OR WHATEVER) to 125 mph, then strengthened to 140 mph, and weakened to 120 mph by landfall.

As for the systems weakening in the North Gulf...I find that false.

[yoda]

Andrew weakened from 165 (OR WHATEVER) to 125 mph, then strengthened to 140 mph, and weakened to 120 mph by landfall.

As for the systems weakening in the North Gulf...I find that false.

So, are we saying that we blame it on shear?

[Anonymous]

NORTH GULF STORMS THAT HAVE WEAKENED:

Hurricane Ethel in 1960:
Went from Category 1 (85 mph) to a Category 5 (160 mph) in two advisories. Dry air killed all of the convection and the and the system weakened from 160 mph to 90 mph in one advisory.

Hurricane Carmen in 1974
Went from 150 mph (CAT 4) to 105 mph (CAT 2) and then a CAT 1 by landfall. Dry air weakened it....keep in mind the track, it was also weakened because....IT WAS SCRAPING AGAINST LAND:


Hurricane Lili in 2002
Went from 145 mph (CAT 4) to 100 mph (CAT 2) by landfall. It then hit at 90 mph (CAT 1). Lili was squeezed, and had some shear. She began to intensify just as she made landfall.

Only 3 hurricanes since 1960 on the North Gulf Coast (LOUSIANA) have weakened greatly. Seems to happen every decade or so.

As for Andrew, Hilda, Ivan, Opal, ect. I do not consider those to have GREATLY weakened. Opal went from a strong Category 4 to a Strong Category 3 and Ivan went from a Weak Category 4 to a Weak Category 3. That is not MASSIVE weakening.

[SouthernWx]

Based on the radar and aircraft data I saw, Andrew was still close to cat-4 intensity as the eyewall passed SW of Houma, LA....in a very sparsely populated area of southern Terrebonne Parish.
USAFR aircraft was reporting 950 mb and flight level winds of 125-130 kt around 0330z.

The main reason Andrew weakened to 120 or so before passing inland WSW of Morgan City was interaction with land...as the hurricane crawled parallel near the south-central Louisiana marshes. We were fortunate....if Andrew had been farther east, and moved inland just west of Grand Isle, we'd IMO have witnessed another "Betsy"....central pressure in the 950 mb range and sustained winds of 125-130 mph. With the larger wind field at that time, it's likely greater New Orleans would have experienced wind gusts in excess of 120 mph along with a very destructive storm surge (all across SE Louisiana).

As for Floydbuster's worst case scenario.....I can see a major hurricane taking that track, but highly unlikely it would be a cat-5. Andrew was a freak....the only cat-5 hurricane to ever strike the Florida mainland (1935 hurricane weakened significantly after crossing the Keys; before impacting Cedar Key).

There was a 1947 major hurricane that took a path eerily similar to "Isaac". The monster hurricane blasted ashore over Broward and Palm Beach counties on September 16-17 with sustained winds near 140 mph....winds over 110 mph raked the Florida east coast from Miami to north of Vero Beach (was an extremely large hurricane). A slow mover, the hurricane dropped rainfall by the foot over Southern Florida, but also weakened from cat-4 to a 110 mph cat-2 crossing the Everglades...exiting into the Gulf of Mexico near Naples.

Once in the GOM, the hurricane accelerated toward the WNW and reintensified to a 115 mph cat-3 before moving directly over New Orleans. Gusts were estimated at over 125 mph in the Crescent City (anemometer failed at 98 mph sustained), and 110 mph at Baton Rouge. The storm surge reached 15' along the Mississippi coast.

This was a very destructive hurricane....a repeat today would be catastrophic, both in southern Florida and along the middle Gulf Coast.

[Anonymous]

Yep....THAT HURRICANE HIT CATEGORY 5! It weakened 10 mph before landfall, but Isaac could indeed happen. By the way, The pressure would be more like 910-920 mb. But, winds could be 160-190 mph in that area. There was alot of talk that Frances was gonna become a 170 mph hurricane.

[michaelwmoss]

I am trying to fathom the number of tornadoes well island with an "Isaac" situation

[Derek Ortt]

Opal actually weakened form 130KT to 100KT, it needs to be included

Here are the storms that have weakened in the northern Gulf

Carmen (I wont include Ethel because it likely wasnt even close to cat 5 anyways), Anita (came in as a 4), Allen, Elena, Kate, Andrew, Opal, Bret, Lili, Ivan

Now, lets look at the classic canes that didnt weaken before NGOM landfall

Eloise, Frederic, Alicia, Georges

there is an onvious difference between the two. Also, cannot use the land factor as these storms either intensified or maintained despite interacting with land

[Stratosphere747]

Bret and Allen were southern GOM storms...

[Anonymous]

Derek:

Anita: PEAK OF 150 MPH, hit at 150 MPH----NOT ON LIST, AND IT HIT MEXICO Not the North Gulf Coast

Elena: It was a Category 3 at it's peak, and hit as a Category 3.....NOT ON LIST

Allen: DID indeed weaken, but not the North Gulf Coast.---NOT ON LIST

Bret: Again Derek...NOT NORTH GULF COAST, and Weakened from a modest Cateogry 4 to a modest Category 3, NOT ON LIST

Kate: Only dropped 10-15 mph, Not on LIST

Andrew: I would not at all consider Andrew having FELL APART

Opal: Only dropped one Category---NOT ON LIST

Ivan: Only dropped one Category, NOT ON LIST

So, the list is:
Ethel----CATEGORY 5 DOWN TO CATEGORY 1
Carmen---CATEGORY 4 DOWN TO CATEGORY 1
Lili-------CATEGORY 4 DOWN TO CATEGORY 1