Ida weakens to a tropical storm; tropical disturbance 96E kills 124 in El Salvador

By: Dr. Jeff Masters , 3:20 PM GMT on November 09, 2009

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Tropical Storm Ida is steadily weakening as it hurtles northwards towards the Gulf of Mexico coast. Rains from Ida have already pushed into south-central Louisiana, where radar estimates indicate up to an inch of rain has fallen. Winds along the Gulf Coast of Mississippi, Alabama, and the Florida Panhandle were 20 - 25 mph this morning, and will steadily increase today as Ida draws near. Winds at the Mississippi Canyon buoy 150 miles south of Gulfport, MS were sustained at 45 mph at 8 am EST this morning, with 19 foot waves.


Figure 1. Microwave "radar in space" image of Ida taken at 7:15 am EST on Monday, 11/9/09. The eye is visible as a dark spot, but the eyewall has partially collapsed. The strongest echoes are on the north side of the storm, and Ida's heaviest rains and highest winds will hit the coast tonight, well in advance of the arrival of the center. Image credit: Navy Research Lab, Monterey.

Infrared and visible satellite loops show that wind shear has substantially degraded the appearance of Ida, and there is very little heavy thunderstorm activity in the storm's eyewall. Most of Ida's heavy thunderstorms have been displaced to the north of the storm, due to strong upper-level winds out of the southwest creating 30 knots of wind shear. Water vapor satellite imagery reveals a large area of dry air to the southwest of Ida, and the shear has now driven this dry air deep into the core of the storm, significantly disrupting it. The latest 6:30am EST vortex report from the Hurricane Hunters reported that the eyewall was ragged, and the pressure had risen to 997 mb. A recent microwave satellite image of Ida (Figure 1) shows that the eyewall is weak and has partially collapsed. Ida's most intense thunderstorms are on the north side of the storm, and the heaviest rains and highest winds will hit the coast tonight, well in advance of the arrival of the center.

The intensity forecast for Ida
The intensity forecast models predict that Ida's winds will range between 50 - 65 knots (58 - 74 mph) at landfall. The high wind shear of 30 knots currently affecting Ida is forecast to increase to 40 knots by late afternoon, and 55 knots by midnight. With Ida now over waters near 26°C, which is barely enough to support a hurricane, and with water temperatures decreasing to 23°C near the coast, the combination of high wind shear and cold waters will act to significantly weaken Ida. However, Ida is beginning to transition to an extratropical storm, and it is often the case that during such a transition the winds will gain energy from the process, though that's looking unlikely in this case. I expect Ida's top winds will be in the 50 - 60 mph range along the coast tonight and Tuesday morning. Regardless of Ida's strength at landfall, the storm will be able to dump 4 - 8 inches of rain along the Gulf Coast and well inland. We can't rule out the possibility of an isolated tornado when Ida makes landfall, but the Storm Prediction Center Discussion maintains that the airmass in place over the Gulf Coast is relatively stable, and prospects for an appreciable severe weather threat appear low.


Figure 2. Maximum storm surge (depth of water above ground) for a Category 1 hurricane with 85 mph winds moving north-northeast at 15 mph. Ida is expected to be moving at this speed and direction at landfall, but will be much weaker, so surges will not be this high. Furthermore, the storm will not create this level of surge along the entire coast--the image above is a composite worst-case scenario for all the storms shown by the black tracks with arrows. Image credit: NOAA SLOSH model run for Mobile Bay, 2008 version. Heights are given relative to the NAVD88 datum.

The storm surge forecast for Ida
Storm surge is the other major concern for Ida. With a strong high pressure system anchored over the U.S. today, the pressure difference between this high and Ida is creating a strong pressure gradient that was driving tides 2.5 feet above normal at Shell Beach, LA (on the east side of New Orleans) this morning, one foot above normal at Dauphin Island, AL, and one foot at Pensacola, FL (Figure 3). NHC is now calling for a storm surge of 3 - 5 feet above ground level, which is a reasonable forecast even if Ida weakens further. A large stretch of coast will be subject to very high water levels for an extended period of time today and tomorrow, with battering waves on top of the surge likely to cause a significant coastal erosion event. A particular concern is the western end of Alabama's Dauphin Island, when even a strong tropical storm can cause significant damage to the low-lying, heavily developed barrier island. The tidal range along the Gulf Coast varies by about 1.5 feet between low and high tide, and high tide is near 2 am EST on Tuesday.




Figure 3. Observed vs. predicted water levels at three coastal stations. Top: Shell Beach, LA (just east of New Orleans); middle: Dauphin Island, Alabama; bottom: Pensacola, FL. The green line shows how high above normal the water is. For Shell Beach, it was 2.5 feet above normal at 9am CST, while it was just over 1.0 feet above normal at the other two locations. Image credit: NOAA Tides and Currents.

Comparing to Hurricane Kate
The last November hurricane in the Gulf of Mexico was Hurricane Kate. Kate struck the Florida Panhandle near Mexico Beach on November 21, 1985 as a Category 2 storm with 105 mph winds. According to Wikipedia, Kate killed five people in Florida and did $300 million (1985 dollars) in damage. Ida will cause relatively minor damage compared to Kate.

Links to follow:
U.S. Severe Weather Page
Wundermap for the Gulf Coast of Alabama.
Long-range radar out of New Orleans, LA.
Navarre Beach, FL webcam.
Coastal observations from the University of South Alabama.
Coastal observations from LSU.

El Salvador floods kill 124
Heavy rains that began on Thursday due to tropical disturbance 96E have killed at least 124 people in El Salvador, with 60 people still missing. The flooding hit the capital of San Salvador and rural areas to the east. The heavy rains were due to tropical disturbance 96E (Figure 4), which formed off the coast of El Salvador on Wednesday, November 4. The counter-clockwise flow of air around the disturbance pulled large quantities of moist, Pacific air over the coastal mountains in El Salvador, dumping heavy rains of up to five inches, according to satellite estimates. The rains must have been much heavier over a small area that the satellite could not resolve. The terrible devastation I'm seeing in news photos indicates much higher rains of perhaps 10 - 15 inches must have fallen in a concentrated area in the mountains.


Figure 4. Satellite image of tropical disturbance 96E, which moved over El Salvador Thursday through Saturday, bringing heavy rains. Also pictured is Tropical Depression Eleven, which intensified into Tropical Storm Ida later that day. Ida was not responsible for the flooding in El Salvador, though it may have helped pull 96E into El Salvador. NASA has a nice zoom image> of 96E from November 5.

I'll have an update on Ida this afternoon.

Jeff Masters

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Quoting Thundercloud01221991:
They have found 70 knts winds at flight level

That's hurricane strength, right? I was never good at conversion from kts to mph! LOL!
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my secretary just gave me a dirty look and closed my office door...s'pose she doesn't like my taste in music...or the volume of it...
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276. IKE
Quoting PalmBeachWeather:
I'm just thankful IKE ..Isn't playing Cashmir


No Zeppelin so far.

I've added a few Waylon Jennings songs in my favorites portfolio on Youtube.

Ida's got one last gasp left in her.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting icmoore:
I have beeen lurking for days as many others have and as I always do when there is a possibility of a big weather event. Just wanted to say thanks to Kman, Ike, and all the others who try to share their opinions on what MIGHT happen, so thanks!


You are more than welcome.
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Quoting IKE:


He was on here all night. Probably snoring...er, sleeping.


please, don't all guys snore? you mentioned the pressure dropping, did you post it? i'll look again.
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Quoting atmoaggie:

Unless they nap or examine their schedules on their laptops in the cockpit...


LOL.I got it! Apparently your post 'flew' over everyone else's head.
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They have found 70 knts winds at flight level
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The Pensacola News Journal got a picture of my van's hurricane flags flying at Pensacola Beach this morning.

Link

When you open the link...click "Show Thumbnails" and you'll see the pictures of the hurricane flags.
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Looks like the turn is coming! She always points the direction she goes....
Member Since: September 2, 2007 Posts: 178 Comments: 20443
Quoting dearmas:
I'm in Tampa and will I hope be closing on a house tomorrow, what kind of effects does anyone see for us?


Lucky you are not in Panhandle area trying to close. Insurance binder for mortgage would not happen... but you should be okay in Tampa
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Think by 2PH she'll be Extra-Tropical?
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Quoting WaterWitch11:
i'm surprised patrap is not on here, I wonder if winds knocked out power?


He was holding the fort down overnight, I would guess he's takin a well deserved nap:)
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Quoting hunkerdown:
Unfortunately that goes for people on both sides of the fence...


That is true. That's why I like to take frequent breaks from the blog whenever the skirmishing starts. With so few systems close to home this year I suppose it was inevitable that when one came along we would see some of what we saw on the blog over the last two days.

Still a great hobby though.
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Quoting icmoore:
I have beeen lurking for days as many others have and as I always do when there is a possibility of a big weather event. Just wanted to say thanks to Kman, Ike, and all the others who try to share their opinions on what MIGHT happen, so thanks!


Nice to see you...you have mail, btw
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I'm just thankful IKE ..Isn't playing Cashmir
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Ha, Ha, Ha...instead of quoting AwakeInMarylands last post, just copied the funny part:

On Pensacola Beach, Glenn Wickham stood on the roof of a three-story house, securing metal shutters on a window as his crew moved furniture from the lower stories to the upper floors. They were hired by a homeowner who wasn't taking any chances after his property was one of the few to survive Hurricane Ivan, which came ashore in 2004 as a Category 3 storm.

"We doing all this out of an abundance of caution — I really don't think this is going to be anything," Wickham said.

Dan Conell took shelter in a beach pavilion so he could watch the churning Gulf water as heavy rain fell. The Kansas City, Mo., resident, in town for a conference, was seeing the ocean for the first time.

"This is amazing," he said. "It is beautiful."

Burt Waters, a Pensacola native, stood nearby with his grandson and said he wasn't worried about Ida.

"I've been through Erin with 180 mph winds and then there was Ivan — we call that one Ivan the terrible," he said.

Still, some beach businesses put protective plywood on their windows and emergency officials planned to close bridges coming on and off the beach when winds picked up later Monday.

Read Burt Waters quote! Wikipedia says Erin peaked at 100. Ivan was waaaaay worse than Erin ever was and it did not even have 180 mph winds. I am still LMAO!
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Quoting Seastep:


Max was 65.5mph and they haven't been to the N or in the NE quadrant yet where winds are usually higher.


oh...ok.

I'm a lurker and love to learn stuff from this site. Thanks for helping us out!
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261. A4Guy
Anyone on here think Ida is NOT the last named storm of the season (in other words...another storm or twoto come)?

I was surprised we had Ida..thought we were done last month
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Quoting Tropicaddict:


with it being only 64 mph why would they put up hurricane warnings???


Max was 65.5mph and they haven't been to the N or in the NE quadrant yet where winds are usually higher.
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Quoting BurnedAfterPosting:
OMG so some of us were wrong, SO WHAT!!!!


How about you handle it like StormW is and telling us we weren't crazy for thinking what we did?

Nope instead you have to act like a little kid; pointing out when someone is wrong is so childish


+1
Member Since: April 26, 2009 Posts: 3 Comments: 3667
Quoting IKE:
Center appears near 27.5N and 88.5W. Looks like it's moving due north. Last advisory had it at 26.5N and 88.5W.


I feel an eastern turn coming in the next 8 hours.
Member Since: September 6, 2009 Posts: 2 Comments: 3759
Quoting IKE:


I'm not saying they would, but the pressure has dropped and usually it takes the winds awhile to catch up.


oh ok...that makes sense. Where do you see landfall being, Ike? What do you think South MS will get???
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256. IKE
Quoting WaterWitch11:
i'm surprised patrap is not on here, I wonder if winds knocked out power?


He was on here all night. Probably snoring...er, sleeping.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting StormW:


Could be some rain, maybe a tad bit more wind than right now. I'm west of you, in Palm Harbor. I'll look and post some stuff.


Thanks. The house is in Wesley Chapel, also I have a little boy with Swin Flu that needs to go back to the doctors and I don't want to take him out in the rian, may need to try and get him in today.
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254. Skyepony (Mod)
Quoting IKE:
56 knots
(~ 64.4 mph)


That would be something if it made a cane again and the NHC had to put hurricane warnings back up again after they lowered them.


I was thinking the same thing. next recon pass samples the winds on the NE side. If it keeps blowing up.. looks possible.
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Quoting IKE:
56 knots
(~ 64.4 mph)


That would be something if it made a cane again and the NHC had to put hurricane warnings back up again after they lowered them.

Are you trying to tell us something IKE? ;)
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252. beell
Not over yet, and I had Apalachicola last night as my guess. But in any event, probably human nature for some of us to try to one-up the NHC on landfall. Even when the data would seem to indicate otherwise. No fun going with the easy out!

That said, we can always cite this for Ida-from the NHC Discussion this morning...

THE TRACK OF THE SURFACE CENTER OF IDA IS LOSING SIGNIFICANCE IN
TERMS OF THE EFFECTS OF THIS STORM
. STRONG WINDS COVER A LARGE
AREA OF THE GULF OF MEXICO AND THE ASSOCIATED RAINS ARE MOVING WELL
AHEAD OF THE CENTER. THIS SHOULD CONTINUE TO BE THE CASE AS IDA
WEAKENS AND BEGINS TO LOSE TROPICAL CHARACTERISTICS.
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251. IKE
Quoting Tropicaddict:


with it being only 64 mph why would they put up hurricane warnings???


I'm not saying they would, but the pressure has dropped and usually it takes the winds awhile to catch up.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting kmanislander:
Wow, I didn't know hanging out with me was such a bad thing LOL.

You guys take this too seriously LOL
Unfortunately that goes for people on both sides of the fence...
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I have beeen lurking for days as many others have and as I always do when there is a possibility of a big weather event. Just wanted to say thanks to Kman, Ike, and all the others who try to share their opinions on what MIGHT happen, so thanks!
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Quoting FSUCOOPman:


Yeah, as far as how bad we get it here, it's still kind of a wait and see game...unofortunately. When it makes that bend East will be important.

I just don't think it's a good idea to put the kids out in that mess all day. It's not like we have a bunch of snow days to worry about where missing ONE day of school will greatly impact things.

Of course, I'm biased for two reasons...

1. I don't want to work much tomorrow. (i'll still have to work some, regardless)
2. It'll give me a chance to fully test my COOP efforts.


I agree about putting the kids in harms way. Too many times, I've seen school districts wait until the last possible minute to call off classes, only to have their buses stuck in the middle of weather systems. Either keep them at the school for the sake of safety purposes, or be proactive in your decisions, but never put children in harms way. Just plain stupid.

Unfortunately, that's the frame of mind with many administrators. They don't want to jump the gun and look like a fool for being proactive. Instead, they play the wait and see game and typically get caught with their pants down. See what happened to NOLA with that approach and frame of mind, eh?

Anyways, nice to see someone else in here from the Tally area. Good luck getting your chance to put your COOP plan into action!
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i'm surprised patrap is not on here, I wonder if winds knocked out power?
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246. IKE
Center appears near 27.5N and 88.5W. Looks like it's moving due north. Last advisory had it at 26.5N and 88.5W.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting IKE:
56 knots
(~ 64.4 mph)


That would be something if it made a cane again and the NHC had to put hurricane warnings back up again after they lowered them.


with it being only 64 mph why would they put up hurricane warnings???
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244. Skyepony (Mod)
Recon hit Center ~27.45N 88.4W, flight level winds 71 knots
( ~ 81.6 mph), surface 56 knots (~ 64.4 mph), 991mb (extrapolated)
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Well the way this season has gone Ida would be the perfect storm to end the season with.
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Ike - Yeah. Will be interesting to see what they find as far as winds to the N and NE of center.
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Quoting dearmas:
I'm in Tampa and will I hope be closing on a house tomorrow, what kind of effects does anyone see for us?
A strong cold front. rain and some gusty winds.
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Post#212: That would bring, IMO, more severe weather to the Tallahassee area, and was kind of what I was thinking. I was also in the wayyyy right camp. on this to begin with, though...

To hard to pinpoint exact locations with that forthcoming bend. A few fractions of a degree early or late makes a huge difference in what happens over this way.
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Tampaspin, I respect your forecast but it will not make that drastic of a turn. NHC is right on with this one!
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236. IKE
56 knots
(~ 64.4 mph)


That would be something if it made a cane again and the NHC had to put hurricane warnings back up again after they lowered them.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Pressure is down and winds are up. Odd. Ida still packing a punch.
Member Since: August 14, 2008 Posts: 0 Comments: 137
wow... so much moisture...
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When is Conch season again?? Answer...when I am in town...I will be in your neck of the woods this spring Kman..maybe get a pint and watch the chickens...
Member Since: October 1, 2007 Posts: 0 Comments: 551
Quoting divdog:
you reamed me like a child yesterday for saying i thought your forecast was wrong. If you are gonna dish it out then be man and take it. You are just down right nasty to anyone who disagrees with you. You need a better attitude.


Gotta agree with you. Some on here need to Man-up.
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I'm in Tampa and will I hope be closing on a house tomorrow, what kind of effects does anyone see for us?
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Quoting LACajunKid:
Glad to see there are others in here from Tallahassee along with me.

I doubt Leon County will close schools early today. Possibly tomorrow, but I doubt that too. The kids are already going to be off on Wednesday, so that makes things a bit easier.


Yeah, as far as how bad we get it here, it's still kind of a wait and see game...unofortunately. When it makes that bend East will be important.

I just don't think it's a good idea to put the kids out in that mess all day. It's not like we have a bunch of snow days to worry about where missing ONE day of school will greatly impact things.

Of course, I'm biased for two reasons...

1. I don't want to work much tomorrow. (i'll still have to work some, regardless)
2. It'll give me a chance to fully test my COOP efforts.
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For your listening pleasure while blogging...WAIL Key West- Classic Rock for the Keys...plus live local weather...
Link
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Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

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