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

Share this Blog
2
+

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

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 478 - 428

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14Blog Index

Quoting Wetagain:
The report of dauphin island bridge being closed was premature. Just rode it and the causeway. Wind driven spray on roadway - for now. D I police confirmed town does not close it- state calls and tells them to. No info as yet from state to close. Was pretty gusty tho that high up in a suv.


Just wondering if you could get to the west end of the Island..... I have heard that it was under water already....

Taco :0)
Member Since: Posts: Comments:
Is the needel going to move again to the W, because every time there is a new NHC update ,it has.
Member Since: Posts: Comments:
My prediction after looking at the water vapor loop provided by NOAA and the Gulf Infrared Satellite loop. I must say that it appears that the storm has already turned North.

I forecast somewhere between Mobile, AL and Crestview, FL. But, it looks to be close to the AL/FL line to around Gulf Breeze area.
Member Since: Posts: Comments:
Quoting mattkenton:
Here in Pensacola it's still off and on wind gusts and rain. Nothing serious yet. Hoping that Ida threads the needle between Mobile and here so that we at least get a good reason to drink.


That needle you speak of is where a lot of us live. It even has a name... Baldwin County.
Member Since: Posts: Comments:
Ha! Ill have to admit, the NHC definitelt beat me on this one. I usually trust them actually, but this history of forecasting appeared as if they were way behind.

Apparently I was dead wrong, lol, I should stick to being in more of a agreement with the NHC like I usually do.

Looks like Ida's rapidly exapanding circulation is gonna throw some impressive squalls my way torward the west coast, maybe some isolated tornados and mcroburst issues with that big squall.
Member Since: Posts: Comments:
200 PM EST MON NOV 09 2009

PANHANDLE FLORIDA

PENSACOLA RAIN 66 64 94 NE7 30.02F FOG
PENSACOLA NAS RAIN 69 65 86 NE15G22 30.01F FOG
MILTON NAS LGT RAIN 66 63 90 E10 30.05F
CRESTVIEW LGT RAIN 65 64 97 NE8 30.06F
VALPARAISO LGT RAIN 68 63 83 NE13G22 30.00F
MARY ESTHER LGT RAIN 67 65 91 E18G25 29.99F
DESTIN CLOUDY 67 63 87 NE15G24 30.00F
PANAMA CITY LGT RAIN 69 64 84 E14G24 30.02F
TYNDALL AFB LGT RAIN 68 66 94 E7 30.01F
APALACHICOLA LGT RAIN 71 65 81 E14G22 30.02F

COASTAL ALABAMA

GULFPORT LGT RAIN 71 62 73 E17G25 29.98F
PASCAGOULA RAIN 67 63 87 E14G20 30.01S
MOBILE RAIN 64 63 94 E10 30.03F
GULF SHORES RAIN 70 69 95 E7 30.00F
PENSACOLA RAIN 69 65 86 NE15G22 30.01F FOG
PANAMA CITY LGT RAIN 68 66 94 E8 29.99F
APPALACHICOLA LGT RAIN 71 65 81 E14G22 30.02F

COASTAL MISSISSIPPI

BILOXI LGT RAIN 68 63 83 E16G25 29.99F
PASCAGOULA RAIN 67 63 87 E14G20 30.01S
GULFPORT LGT RAIN 71 62 73 E17G25 29.98F

SOUTHEAST LOUISIANA

N.O. AUDUBON N/A 71 63 75 MISG N/A
N.O. INTL ARPT CLOUDY 72 62 71 E16G24 29.97F
N.O. LAKEFRONT CLOUDY 71 64 78 NE21G31 29.97F
SLIDELL CLOUDY 73 60 63 E14G28 29.99F
BELLE CHASSE CLOUDY 72 62 71 NE14G23 29.96F
BATON ROUGE CLOUDY 70 62 76 NE8 30.01F
SALT POINT N/A 68 65 90 VRB5 29.96F
BOOTHVILLE LGT RAIN 69 66 90 E24G37 29.89F FOG
HOUMA CLOUDY 72 64 78 NE23 29.96F
Member Since: Posts: Comments:
The report of dauphin island bridge being closed was premature. Just rode it and the causeway. Wind driven spray on roadway - for now. D I police confirmed town does not close it- state calls and tells them to. No info as yet from state to close. Was pretty gusty tho that high up in a suv.
Member Since: Posts: Comments:
Quoting VIPForecastor:


Actually there is alot of difference in the two. Water vapor shows the vapor as observed from space and can identify both tropical and subtropical jet streams. It includes dry air vs moist air. Dry air being indicated in brown.

Radar on the other hand sends UHF radio pulses to a limited range. Thus, there has to be some every few hundred miles. They can detect how heavy and the velocity of a cell. The way it works is the echo of the pulse is read.

One more: there can be attenuation of the radar beam by an area dense with hydrometeors, giving a distorted view, or none at all, of precip beyond the high density stuff.
Sometime today, there may be features visible on the New Orleans long range radar, not visible via Mobile's radar because of this.

Water vapor by satellite obviously does not have this issue.
Member Since: Posts: Comments:
Quoting TheCaneWhisperer:


Looking at post 448, you'll notice it's taken that turn a little ahead of schedule. Those are recon verified center locations. It's getting stronger too.


You're right. Didn't examine that one too closely first time around. Thanks for the insight.
Member Since: Posts: Comments:
Quoting taco2me61:


Figured that had already happened.... An a other thing is back in May 30th we had a extropical storm
to hit Dauphin Island and here it is the end of hurricane season
and we have another one hitting as close.....

Kinda funny how this all played out this year....

Taco :0)


I had that same thought! The bridge is still open as of 10 minutes ago, however. Won't be for long.
Member Since: Posts: Comments:
Here in Pensacola it's still off and on wind gusts and rain. Nothing serious yet. Hoping that Ida threads the needle between Mobile and here so that we at least get a good reason to drink.
Member Since: Posts: Comments:
This does look to be a little bigger in the TS-force wind area. Caveat: This product depends on some persistence between the time of satellite pass and production of this product. Can be off in a fluid situation such as Ida with much latency in the satellite data.

Member Since: Posts: Comments:
Any speculation on flooding in the big easy? TWC shows water will build up in that area.
Member Since: Posts: Comments:
Quoting StormChaser81:


what a difference looking at the water vapor and the radar, almost looks like different storms.


Actually there is alot of difference in the two. Water vapor shows the vapor as observed from space and can identify both tropical and subtropical jet streams. It includes dry air vs moist air. Dry air being indicated in brown.

Radar on the other hand sends UHF radio pulses to a limited range. Thus, there has to be some every few hundred miles. They can detect how heavy and the velocity of a cell. The way it works is the echo of the pulse is read.
Member Since: Posts: Comments:
Quoting stormy2008:
Conditions at 42363 as of
(1:00 pm CST)
1900 GMT on 11/09/2009:

Wind Direction (WDIR): NNE ( 30 deg true )
Wind Speed (WSPD): 56.3 kts
Air Temperature (ATMP): 69.1 °F
Water Temperature (WTMP): 72.7 °F
Dew Point (DEWP): 64.0 °F

Wind picked back up...reminder that the anemometer is 122 meters up...(I forgot that tidbit earlier)
Member Since: Posts: Comments:
Quoting atmoaggie:

Nice, simple page.
(Not a jab at you, TampaSpin, you have a nice, heavyweight page)


Hey no jab here.....all is appreciated...love the live stuff....great job
Member Since: September 2, 2007 Posts: 178 Comments: 20439
Quoting Ossqss:
Big picture loop. I must be getting tired with monitor multitasking. I am seeing a smiley face on the first image of the loop. LoL

http://www.atmos.washington.edu/~ovens/loops/wxloop.cgi?wv_east_enhanced+12

With a scary, freaky, clown-face, yeah I see it.
Wish I could find the GFS precip forecast I saved a couple of years ago that had a great big green question mark spanning TX to Minnesota, Missouri to Colorado...
Member Since: Posts: Comments:
Conditions at 42363 as of
(1:00 pm CST)
1900 GMT on 11/09/2009:

Wind Direction (WDIR): NNE ( 30 deg true )
Wind Speed (WSPD): 56.3 kts
Air Temperature (ATMP): 69.1 °F
Water Temperature (WTMP): 72.7 °F
Dew Point (DEWP): 64.0 °F
Member Since: Posts: Comments:
Quoting KeyWestwx:
Just a FYI- our winds in Key West were 25-35 for the last day. Ida just spit on us and dried out our already rain deprived island. Damn her!!!!



FYI. Cactus is the new Orange in Florida, didn't ya hear?
Member Since: Posts: Comments:
Quoting wxfreqrs:
DR MASTERS
I live in pascagoula
I have a DAVIS PRO 2 in my back yard
I post real time obs to the web here
http://myweb.cableone.net/wxfreqrs/
feel free to use any the data
also here
http://www.wunderground.com/weatherstation/WXDailyHistory.asp?ID=KMSPASCA4

Nice, simple page.
(Not a jab at you, TampaSpin, you have a nice, heavyweight page)
Member Since: Posts: Comments:
Just a FYI- our winds in Key West were 25-35 for the last day. Ida just spit on us and dried out our already rain deprived island. Damn her!!!!
Member Since: Posts: Comments:
Big picture loop. I must be getting tired with monitor multitasking. I am seeing a smiley face on the first image of the loop. LoL

http://www.atmos.washington.edu/~ovens/loops/wxloop.cgi?wv_east_enhanced+12
Member Since: Posts: Comments:
Yes actually working here running the Austin office. Like you watching this play out as well. Maybe we can meet there if things pan out.
Member Since: Posts: Comments:
Quoting hurricanejunky:
Looking at the right feeder band that extends down to Cuba, the convection flareup is impressive. Looks like it's moving N or slightly east of N to me too BAP.



Looking at post 448, you'll notice it's taken that turn a little ahead of schedule. Those are recon verified center locations. It's getting stronger too.
Member Since: Posts: Comments:
DR MASTERS
I live in pascagoula
I have a DAVIS PRO 2 in my back yard
I post real time obs to the web here
http://myweb.cableone.net/wxfreqrs/
feel free to use any the data
also here
http://www.wunderground.com/weatherstation/WXDailyHistory.asp?ID=KMSPASCA4

going to be close on land fall here no more than 20 miles to the east of my location IMHO

Don Arnold
Pascagoula Ms
wxfreqrs@cableone.net
Member Since: Posts: Comments:
Just wonderin. Is this the last hurrah of the season or will other systems pop up before 2009 is put to bed.
Member Since: Posts: Comments:
Looking at the right feeder band that extends down to Cuba, the convection flareup is impressive. Looks like it's moving N or slightly east of N to me too BAP.

Member Since: Posts: Comments:
Quoting JUSTCOASTING:
How you been Rare ? staying busy ?
Yes business has been good here. Im on a holding pattern right now waiting to see if their sending us south for the holidays or not, lol How about you?
Member Since: Posts: Comments:
Member Since: Posts: Comments:
Wind direction starting the swing-around at 28.160 N 89.220 W

Member Since: Posts: Comments:
Quoting mobilehurricane:
DI bridge already shut down for the event?


Figured that had already happened.... An a other thing is back in May 30th we had a extropical storm
to hit Dauphin Island and here it is the end of hurricane season
and we have another one hitting as close.....

Kinda funny how this all played out this year....

Taco :0)
Member Since: Posts: Comments:
Still putting out cold cloud tops, but in a fairly small area:

Member Since: Posts: Comments:
Quoting taco2me61:
I did figure that Dauphin Island would get slamed as it moved towards Mobile Bay..... Now I understand that they are not letting anyone back on the Island....

Taco :0)
DI bridge already shut down for the event?
Member Since: Posts: Comments:
ok...gotta bounce...gonna pick my yard up today since we are supposed to be bombarded with rain for the next 2...
Member Since: Posts: Comments:

Member Since: Posts: Comments:
I did figure that Dauphin Island would get slamed as it moved towards Mobile Bay..... Now I understand that they are not letting anyone back on the Island....

Taco :0)
Member Since: Posts: Comments:
How you been Rare ? staying busy ?
Member Since: Posts: Comments:
Quoting catastropheadjuster:


Yes they are. I wonder where my friend Ron is Floodman. I figured he would be on today. Well he was earlier for a minute or two.

Sheri
He sent me some paperwork yesterday but he is as usual not available when you need him, lol Just make a mistake on a file or bring one in high and he's easily to reach just answer the phone, lol
Member Since: Posts: Comments:
Wow...watching TWC...the footage of the waves is awesome
Member Since: Posts: Comments:
Quoting BurnedAfterPosting:
based on radar looks like she is moving slightly East of Due north

Drak is right, that hole in the middle is not the center, it is easy to get fooled into that being the center, it is not and recon verifies that it is not


I'll need a few more frames to convince me.
Member Since: Posts: Comments:
435. drj27
looks like fwb and destin will be ok just what i think
Member Since: Posts: Comments:
Really surprised Keeper isn't here...love reading those posts...
Member Since: Posts: Comments:
based on radar looks like she is moving slightly East of Due north

Drak is right, that hole in the middle is not the center, it is easy to get fooled into that being the center, it is not and recon verifies that it is not
waiting on the coastal flooding in Charleston, hopefully the bad bands won't be during high tide...when it already floods here...
Member Since: Posts: Comments:
Surfs building. http://piercam.net/
Member Since: Posts: Comments:
Quoting bingcrosby:
Clearly a defined eye on radar.


The hole on radar is not the surface center. It could be the mid level center. The vortex position is southwest of the hole on the radar. Refer to post 419 (the picture).
Member Since: Posts: Comments:
The noon news in New Orleans is predicting (predictably) a local non-event, except for some flooding on the coast and perhaps on the North Shore of Lake Pontchartrain. It looks to be dry here, and the real worry was the possibly closing of the outfall canal gates plus heavy rain but that looks unlikely now. But my kids are ecstatic to be home. The miss their old North Dakota snow days.
Member Since: Posts: Comments:
428. srada
Good Afternoon everyone..Just watched that Bastardi video posted in the blog and I of course live on the coast of NC in Wilm..usually he is hyped up about noreasterns but he is really calling for a bad storm our way if the low of IDA vamps up according to the UKMET model..I just hope everyone keeps safe along this storms path
Member Since: Posts: Comments:

Viewing: 478 - 428

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14Blog Index

Top of Page

About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

Local Weather

Mostly Cloudy
64 °F
Mostly Cloudy