ALERT: Hurricane Isidore forecasted to have at least 150 MPH winds within 72 hours

[newsperson999]

Statement as of 5:00 PM EDT on September 21, 2002

Air Force recon data indicate major Hurricane Isidore has continued to rapidly strengthen and the central pressure has dropped 21 mb in the past 13 hours. A pressure of 946 mb generally corresponds to a maximum wind of about 117 kt. However...the eye is open to the west and there may be a lag in the wind field. Also...dropsonde data indicated about 105 kt surface winds...but winds just a few hundred above the surface have been as high as 130 kt. The three satellite agencies reported a Dvorak satellite intensity estimate of t6.0...or 115 kt...while the 3-hour objective Dvorak T-number was also t6.0. Based on this information...the initial intensity was increased to 110 kt.

The initial motion estimate is 270/3. Recon fix positons since about 12z indicate Isidore has actually remained nearly stationary the past 6 hours...but right over some of the hottest water in the Atlantic Basin. Steering currents remain weak and are forecast by all of the global to remain weak or even get weaker. Isidore remains caught between a mid- to upper-level low east of Florida and one to the west over the Bay of Campeche. A weak and narrow low- to mid-level ridge extends across the northern Gulf of Mexico coast from Florida westward to Texas. Given the relative weakness of this ridge...only 5880 meters at 500 mb...it would not take much of a shortwave trough to erode it and allow Isidore to drift slowly poleward. All of the NHC model guidance...except LBAR...keeps Isidore moving on a slow west or west-southwest track through the forecast period. The AVN and GFDL are very similar in hooking Isidore to the southwest around the western Yucatan Peninsula in 36 to 48 hours. This may be some artifact of terrain interaction which I have ignored for this advisory package since all of the global models show no significant ridging north of isiodre to push the system to southwest. The forecast calls for a slow...less than 6 kt...motion throughout the forecast period with a slight west-northwestward motion after 48 hours as a strong shortwave trough drops down the west side of the broad longwave trough...which is expected to erode the weak ridge over Texas and the northwest Gulf of Mexico and allow Isidore to gain some latitude. However... the slower Isidore moves during the next 36 to 48 hours will determine just how far north and the cyclone will move in the longer time periods beyond 72 hours. The good news is that it appears that Isidore is not going to go anywhere fast. The bad news is that it will remain over very hot water.

The central pressure has dropped 21 mb in the past 13 hours. A typical rapid intensification period. This trend would normally continue for another 12 hours or so...but radar and recon data indicate that the eye is open to the west and that an eyewall replacement cycle may be starting. As such...the official intensity forecast is held below the ships intensity model which brings Isidore to 135 kt in 36 hours and 140 kt in 60 hours. This type of intensification is certainly possible given the low shear...less than 6 kt...and high SSTs...about 30c/86f. However...predicting internal convective changes is nealry impossible so there could be flucuations by as much 10 kt either way from the offical intensity forecast. Some coastal upwelling may weaken the hurricane slightly as it moves west of 88w longitude...but then some restrengtnening is forecast after 48 hours when Isidore is forecast to move back over warmer water.

Forecaster Stewart

forecast positions and Max winds

initial 21/2100z 21.9n 86.2w 110 kts
12hr VT 22/0600z 21.9n 87.0w 120 kts
24hr VT 22/1800z 21.9n 88.0w 125 kts
36hr VT 23/0600z 21.9n 89.2w 125 kts
48hr VT 23/1800z 22.0n 90.3w 125 kts
72hr VT 24/1800z 22.5n 92.5w 130 kts

[Senator Pardek]

From what I've heard, it's an all-or-nothing deal, and he does not take "no" for an answer.

[newsperson999]

one more thing dennis,
do you know why we loose the SAT about 3:15z the past few nights for a few hours? This even happens to the weather channel

[dennis1x]

yep...the satellites are in an "eclipse" for a couple hours due to orbital factors. not sure of the exact specifics.

[catfish1957]

Any chance someone with broadband post the latest strike percentages?

[Dog Gone]

It was written by the enviromental editor, and I'm sure he can't help slipping in his religion.

But residents of the Big Easy should disregard the quotes from the experts in this article at their own peril.

[newsperson999]

No point..they will change...it's all up in the air..

[rwfromkansas]

It also is moving more northwest (well, the NHC says west, but I disagree).....it has stopped its southwest jog.

[newsperson999]

No point..they will change...it's all up in the air..it looks like its a little north of the most recent forecast track

[rwfromkansas]

The peak is in early September. However, the last couple years (at least last year) were late seasons.....not really getting going good until October IIRC.

[dennis1x]

SamAdams,

This is a pointless debate as you are incredibly wrong. Waters in the gulf are at their warmest of the year at the end of September. Texas is usually spared because most storms either go west into Mexico or make a full turn toward the north and hit a east-west border (northern gulf).

Ramble on but there is a strenghtening hurricane in the gulf, its not going to go away with the clock strikes midnight on the 25th.

[catfish1957]

New Orleans is the worst place in the U.S for Huricanes.

1. -5ft. elevation

2. water on 3 sides in some areas. Missisppi (2) Lake Ponchatrain.

3. Traffic configuration designed by an engineer after a week on Bourbon street.

A fast moving category 5 would kill more than the Falveston Huricane of 1900.

[rwfromkansas]

It is basically hovering over a spot of some of the warmest water....no doubt this sucker is going to strenthen even more. It may drop a bit as it interacts more with the Yuc., but it is far enough to the north it should not be affected hardly at all from that, perhaps a SLIGHT weakening. Now, if it decides to start heading southwest and stall in the BOC and interact with lots of land masses before heading north to Texas, which the latest AVN shows, then it may start some bigtime weakening before strenghtening again to probably a Cat 3 before hitting Texas.

[catfish1957]

I haven't seen the satelite run recently, but that north jog may just be a wobble.

[dennis1x]

catfish,

beyond 72 hours, strike probabilities are fairly meaningless.

in 3 days the storm will be somewhere between the east coast of mexico and the yucatan.

after that there are 3 most likely possibilities:

1. the strength and momentum of Isidore will prevent a turn toward the north and continue west into Mexico

2. an approaching front will be strong enough to curve the storm towards the north and east.

3. if the storm does begin a turn north/ne, but not until late then Texas could be at risk.

[newsperson999]

Another thing about New Orleans is that the hurriance would have to come from a SE direction for Max damage..the winds would be NNE puching all the water in the lake south..If the storm hits moving 360 degress just west The winds will be from the south..if the storm hits east into MS the city would be on the Weaker side of the storm(ie camile)

Hurricane andrew was almost a nightmare and a worst case storm...worst case would be a Cat 4-5 hitting miami..then hitting New Orleans from the SE..well the worst of the storm went a tad south of Miami thanks to a last minute jog..and it hit west of New Orleans.

[Dog Gone]

Most of the computer models indicate that you are wrong, so why don't you just assume this is an aberration? But to preach that people shouldn't be concerned about a storm that will be Category 4 with strong indications of hitting the Gulf Coast is reckless at best.

I could use other words to describe it.

[NELSON111]

Well...strong storms do influence their environment. The best example you listed was Gilbert. It traveled at a 290 for most of its life due to the fact it built a ridge to it's north. However, storms will react to the mesoSCALE:-) environment when the trf is strong enough....especially if they are in weak steering flow. What will (or should) eventually turn Izzy to the north is a building ridge over Florida/Eastern GOM. this ridge looks like it will be oriented N/S so the steering will turn it north. The only thing left to determine is how far west does it drift before it gets pushed north by the ridge. Think the eastern GOM is off the hook now...and it could drift into Central Mexico before the ridge develops...or it could really slow down and wait 3 days or so and then move N into Central Louisianna.

[rwfromkansas]

or La.

[catfish1957]

As I previously stated, if this storm continues to grow to category 4/5, fronts/troughs will have little bearing on this storm on a mesoclinic scale.

[Dog Gone]

The models show that a hurricane coming from the SW would inflict the most damage on New Orleans.

To see why, click link here.