Cyclone Sidr slams into Bangladesh

By: Dr. Jeff Masters , 3:34 PM GMT on November 15, 2007

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Tropical Cyclone Sidr made landfall at 1430 GMT in western Bangladesh as a mighty Category 4 storm with 150 mph winds. Sidr is the second strongest cyclone to make landfall in Bangladesh since reliable record keeping began in 1877. The only stronger storm was the 1991 Bangladesh Cyclone, which struck eastern Bangladesh as a Category 5 cyclone. The 30 foot storm surge of that storm killed at least 140,000 people. Sidr is the Arabic word for the jujube tree.


Figure 1. Image of Tropical Cyclone Sidr as a Category 4 storm (928 mb) with 155 mph winds. Image taken at 4:57am EST 11/15/07. The cyclone made landfall at 1430 GMT in the Sundarbans Forest area of Bangladesh, just east of Calcutta, India. Image credit: Navy Research Lab.

Sidr's storm surge
The big killer in Bangladesh cyclones is the storm surge. The triangular shape of Bengal Bay funnels high surges into the apex of the triangle where Bangladesh sits, and the shallow bottom of the bay allows extraordinarily high storm surges to pile up. The maximum theoretical storm surge from a worst-case Category 5 cyclone is thought to be 41 feet in western Bangladesh (Islam, 2006). Sidr's maximum storm surge to the right of where the eye makes landfall is likely to be in the 20-25 foot range. Of critical importance is the timing of landfall with respect to high tide, since there is a 1.5 meter (5 foot) difference between low and high tide in western Bangladesh. According to mobilegeographics.com, high tide is at approximately 1am local time tonight, and Sidr made landfall about halfway between low and high tide. Thus, Bangladesh did have a little luck, as the storm tide could have been about 2-3 feet higher had Sidr hit at high tide.

The coast in western Bangladesh has the Sundarbans Forest, the world's largest forest of mangrove trees. This region is the least populated coastal area in the country, and has been part of a major reforestation effort in recent years. The portion of coast likely to receive the highest storm surge levels of 20-25 feet is virtually unpopulated. However, storm surge levels of 10-20 feet are still likely to affect areas with a population of at least a million, to the east of the Sundarbans forest, and inland from the forest. The last major cyclone to hit western Bangladesh occurred in November 1988. This Category 3 cyclone with 125 mph winds had a 5-10 foot storm surge, and killed 2,000 people.

Hurricane shelters in Bangladesh
Since the Great Bhola Cyclone of 1970, a Category 4 cyclone that brought a storm surge of up to 27 feet and killed an estimated 350,000-550,000 people, Bangladesh embarked on program to build concrete cyclone shelters (Figure 2). After the 1991 cyclone, this process accelerated, thanks in part to foreign assistance. Bangladesh now has over 2500 multi-purpose cyclone shelters that can also be used as primary schools. The warning system in Bangladesh is fairly effective at notifying the population of an approaching cyclone, but many residents choose not to evacuate to the shelters, since most of them are in poor condition with minimum or no maintenance at all (Karim, 2001). In any case, these shelters can accommodate less than 3% of the population of western Bangladesh (Islam, 2006).


Figure 2. A Bangladesh cyclone shelter built after the devastating 1970 cyclone. Image credit: Harry M. Jol, professor at University of Wisconsin, Eau Claire.

The Bangladesh newspaper The Daily Star is already reporting that 300 fishing boats have sunk in Sidr, with 1,000 fishermen missing. While I don't expect we'll see anything approaching the 1991 cyclone with its death toll of 140,000, since Sidr is hitting a relarively unpopulated region of the coast, the storm has the potential to kill several thousand people in Bangladesh. Also of concern is India. The eastern portion of the Calcutta metropolis will receive winds near hurricane force, and these winds could cause major destruction of poorly built housing. Flash flooding from heavy rains could also affect both India and Bangladesh. It's a bad night to be in Bangladesh.

Links to follow for Sidr
Dhaka, Bangladesh current conditions
Calcutta, India current conditions

References

Islam, T., "Integrated Approach to Cyclone Wind Analysis and disaster planning for the Benladesh coast," Ph.D. Dissertation, Texas Tech University, December 2006.

Karim, N., (1999) Options for cyclone protection: Bangladesh context".

Paul, A., and M. Rahman, "Cyclone Mitigation Perspectives in the Islands of Bangladesh: A Case of Sandwip and Hatia Islands", Coastal Management, 34, Issue 2 April 2006, p, pp 199-215.

Jeff Masters

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402. RaptorWitness
7:01 AM GMT on November 23, 2007
Although there is some debate, the name "Sidr"(cedar) can apparently refer to any number of plants of an evergreen or aromatic type. In the Qur'an, however, the Cedar of Lebanon is the usual reference for a "Sidr," not the Jujube. [Link 1] [Link 2]
401. Floodman
3:42 PM GMT on November 16, 2007
New blog
Member Since: August 2, 2006 Posts: 10 Comments: 9922
400. groundswell
3:40 PM GMT on November 16, 2007
Be careful surfing a lot in cold water-One day I went it was 18 degrees outside and sunny with water temp at 38 degrees. I had to slide on the ice to get to the shorebreak, which was 3 foot frozen ice mush, with a north wind of 15 knots-water got in my ear & froze...so, over time and surfing in cold conditions, I grew bones in the center of my ears which causes ringing, and at times, blockage. Doctors won't operate because the area is so delicate, if they make a mistake, I will have lost my equilibrium forever.
Member Since: August 28, 2006 Posts: 0 Comments: 381
399. LakeShadow
3:39 PM GMT on November 16, 2007
hey jpritch thanks for the article! I realize the numbers are just getting in. However,I expected to wake up this morning and find much higher numbers, and thats less discouraging.
Member Since: August 10, 2007 Posts: 3 Comments: 2134
398. NEwxguy
3:29 PM GMT on November 16, 2007
397. jpritch 3:27 PM GMT on November 16, 2007
Link

"At the height of the fish drying and processing season, tens of thousands of fishermen and their workers were reportedly working on remote islands off the coast. Their fate remained unknown, but a number of fishermen were confirmed dead."

It sounds like there wasn't really any effort to get the fishermen to safety. Also, there are reports from several islands that only foreigners and nationals with airline tickets were allowed to leave.

I heard a report this morning some of the islands were completely inundated,I think the early damage reports and death toll are just the tip of the iceberg.
Member Since: September 6, 2007 Posts: 878 Comments: 15734
397. jpritch
3:27 PM GMT on November 16, 2007
Link

"At the height of the fish drying and processing season, tens of thousands of fishermen and their workers were reportedly working on remote islands off the coast. Their fate remained unknown, but a number of fishermen were confirmed dead."

It sounds like there wasn't really any effort to get the fishermen to safety. Also, there are reports from several islands that only foreigners and nationals with airline tickets were allowed to leave.
Member Since: June 28, 2007 Posts: 0 Comments: 291
396. LakeShadow
3:20 PM GMT on November 16, 2007
B-lo fans are experts at primetime tailgating....right from work to the parking lot. Pick up an order of wings along the way...
Absolute worst rush hour traffic in the world...even for you, NE!
Member Since: August 10, 2007 Posts: 3 Comments: 2134
395. Bonedog
3:20 PM GMT on November 16, 2007
Lake yes the clipper is going to tack the southern route past us. Most models have it weakening as it does. Looks like the precip will be because of the dynamical forcing thats already present in the atmosphere. Basically snow showers for the inland areas and possible Lake Effect bands if the winds are right.
Member Since: July 14, 2005 Posts: 14 Comments: 7418
394. NEwxguy
3:19 PM GMT on November 16, 2007
Any way getting back to weather,looks like we're slipping into a quiet period for the upcoming week,the clipper this weekend is staying far south and weak.
Member Since: September 6, 2007 Posts: 878 Comments: 15734
393. LakeShadow
3:18 PM GMT on November 16, 2007
Bills are notorious for losing primetime games. Its our speciality.
Member Since: August 10, 2007 Posts: 3 Comments: 2134
392. NEwxguy
3:17 PM GMT on November 16, 2007
Hey,Lake,since its a Sunday night game,I assume the tailgating will start early,fans should be in good shape by game time.
Member Since: September 6, 2007 Posts: 878 Comments: 15734
391. LakeShadow
3:17 PM GMT on November 16, 2007
So whats happening with this clipper? Bone...are the models still taking it southeast?
Member Since: August 10, 2007 Posts: 3 Comments: 2134
390. Bonedog
3:16 PM GMT on November 16, 2007
LOL NE you just jinxed Boston LOL
Member Since: July 14, 2005 Posts: 14 Comments: 7418
389. NEwxguy
3:14 PM GMT on November 16, 2007
lol,************zipping his mouth shut*********
Member Since: September 6, 2007 Posts: 878 Comments: 15734
388. NEwxguy
3:13 PM GMT on November 16, 2007
385. Bonedog 3:09 PM GMT on November 16, 2007
I dont follow football much but will say this..

it seems like New England's year for all sports.

I hope Miami's record is never broken but I do know it will happen.

I honestly don't see them going undefeated,but in realty its not important.And it really does seem to be Boston's year,our Pro soccer team is playing the championship game this weekend,for all I know a Bostonian is winning the checkers championship.
Member Since: September 6, 2007 Posts: 878 Comments: 15734
387. LakeShadow
3:12 PM GMT on November 16, 2007
I dunno even the Sabres managed to win against the Bruins, so maybe not ALL NE teams are doing well...

He;s been saying great things about B-lo because we're AWESOME!!!

:0P
Member Since: August 10, 2007 Posts: 3 Comments: 2134
386. NEwxguy
3:10 PM GMT on November 16, 2007
Lake,he's been saying nothing but great things about Buffalo,I wish he would do some trash talking for once
Member Since: September 6, 2007 Posts: 878 Comments: 15734
385. Bonedog
3:09 PM GMT on November 16, 2007
I dont follow football much but will say this..

it seems like New England's year for all sports.

I hope Miami's record is never broken but I do know it will happen.
Member Since: July 14, 2005 Posts: 14 Comments: 7418
384. LakeShadow
3:08 PM GMT on November 16, 2007
If Brady's head got any bigger, we'd be calling him Mr. Mackey, mmmmkay?
Member Since: August 10, 2007 Posts: 3 Comments: 2134
383. LakeShadow
3:06 PM GMT on November 16, 2007
I'm sorry NE who has the bigger bubble???
Member Since: August 10, 2007 Posts: 3 Comments: 2134
382. Bonedog
3:06 PM GMT on November 16, 2007
nature takes care of it self Lake.

some might not make it but most will
Member Since: July 14, 2005 Posts: 14 Comments: 7418
381. LakeShadow
3:04 PM GMT on November 16, 2007
Thats the thing, bone, I'm not sure if there was any higher ground to go to.
Member Since: August 10, 2007 Posts: 3 Comments: 2134
380. NEwxguy
3:04 PM GMT on November 16, 2007
378. LakeShadow 3:01 PM GMT on November 16, 2007
Hey NE...ready to end that winning streak?

***POP*** the sound of Bufflo bubble bursting
Member Since: September 6, 2007 Posts: 878 Comments: 15734
379. Bonedog
3:02 PM GMT on November 16, 2007
Glad you like it Lake.
Member Since: July 14, 2005 Posts: 14 Comments: 7418
378. LakeShadow
3:01 PM GMT on November 16, 2007
Hey NE...ready to end that winning streak?
Member Since: August 10, 2007 Posts: 3 Comments: 2134
377. Bonedog
3:01 PM GMT on November 16, 2007
yea nature has a way of taking care of itself. The tigers probably got to high ground and bedded down under a bush.
Member Since: July 14, 2005 Posts: 14 Comments: 7418
376. LakeShadow
3:00 PM GMT on November 16, 2007
hey bone thanks again for those links. the SPC hourly Mesoscale is great. The Lake effect tools are also great. I'm glued.
Member Since: August 10, 2007 Posts: 3 Comments: 2134
375. NEwxguy
2:58 PM GMT on November 16, 2007
Ahh,you floridians should be up here on New Year's day for the annual dip into Boston Harbor,so refreshing.
Member Since: September 6, 2007 Posts: 878 Comments: 15734
374. aspectre
2:58 PM GMT on November 16, 2007
281 AussieStorm "How often does this site update as Cyclone Guba is still listed as a Tropical Storm yet our Bureau of Meteorology has it now classified as a Category 3 Cyclone."

An American tropical cyclone must have sustained winds of greater than 119kph/74mph to be labeled as a Cat.1 Hurricane

However the Australian Bureau of Meteorology doesn't classify cyclones by sustained winds but rather by maximum gusts. An Australian cyclone with maximum gusts between 170kph-224kph is labeled as Category3. ie Even if an Australian cyclone has sustained winds under 119kph/74mph, it would be labeled as Cat.3 by the Australian Bureau of Meteorology if it has gusts over 170kph/105mph.

Since it's possible for cyclones to have sustained winds under 74mph while having gusts over 105mph,
and since this site is written primarily for an audience familiar with American labels,
an Australian Cat.3 Cyclone would be labeled as if it were an American TropicalStorm until that Australian Cat.3 Cyclone's sustained winds exceed 119kph.
Member Since: August 21, 2007 Posts: 0 Comments: 4860
373. Zaphod
2:57 PM GMT on November 16, 2007
The tigers have survived cyclones for millenia -- they'll probably do OK this time too.

I'll be surprised if the final human toll doesn't rise significantly as people migrate back toward the sea.
Zap
Member Since: October 5, 2005 Posts: 15 Comments: 3239
372. Beachfoxx
2:50 PM GMT on November 16, 2007
Bone,

Either way... it makes me cold just thinking about it!

Have a good one.... Later!
Member Since: July 10, 2005 Posts: 157 Comments: 29384
371. Bonedog
2:50 PM GMT on November 16, 2007
Later Geek and Beach
Member Since: July 14, 2005 Posts: 14 Comments: 7418
370. Bonedog
2:49 PM GMT on November 16, 2007
its a northern thing Beach. Most of our best surf happens in the winter. ESA even has a contest in Febuary up here because the surf is more consistant.

Haven't done it in a while though (winter surfing) my body can't take it. I usually get maybe 1 or 2 sessions in but only if its phenominal. In the winter I usually stick to the heavy clothing and strap the snowboard to the roof and head up Vermont or Colorado way.
Member Since: July 14, 2005 Posts: 14 Comments: 7418
369. Beachfoxx
2:49 PM GMT on November 16, 2007
Gotta run!

Have a Niceville Day!

TTYL
Member Since: July 10, 2005 Posts: 157 Comments: 29384
368. HurricaneGeek
2:47 PM GMT on November 16, 2007
OK guys, I am staring not to breath well again. So I am going to say bye. I BBL
nice chatting!
Member Since: May 10, 2007 Posts: 110 Comments: 7039
367. LakeShadow
2:47 PM GMT on November 16, 2007
Even so, there's not going to be a 100,000 plus count like there was in the past. I thinks thats great that Bangledesh has done a better job protecting its people. The actual storm damage and devestation left to properties and wildlife is another story. Still waiting to hear about the Bengal Tigers. anyone know anything?
Member Since: August 10, 2007 Posts: 3 Comments: 2134
366. HurricaneGeek
2:46 PM GMT on November 16, 2007

Cutie PaTootie!
---
Never heard that one before..LOL :')
Member Since: May 10, 2007 Posts: 110 Comments: 7039
365. Beachfoxx
2:45 PM GMT on November 16, 2007
Bone,

That makes me hurt just thinking about it!
Member Since: July 10, 2005 Posts: 157 Comments: 29384
364. HurricaneGeek
2:45 PM GMT on November 16, 2007
WOW bonedog!!
Member Since: May 10, 2007 Posts: 110 Comments: 7039
363. Beachfoxx
2:45 PM GMT on November 16, 2007
*LOL* Bone, its a matter of perspective!

361. HurricaneGeek 8:42 AM CST on November 16, 2007
*LOL* Depends on Dew Point! ROFLMCPO
---
LMAO...now I know what "ROFLLM_ _ O" means. Whats the CP mean?
LOL


Cutie PaTootie!
Member Since: July 10, 2005 Posts: 157 Comments: 29384
362. Bonedog
2:43 PM GMT on November 16, 2007
Geek as long as the waters not frozen we can surf.


I personally have been in 34 degree water with 10* outside air temp, winds at 20knts making the windchill -9. Get about 15 minutes in water 30 in the truck with heaters blasting. We rotated that way for 8 hrs of great surfing. BTW it was snowing at the time also
Member Since: July 14, 2005 Posts: 14 Comments: 7418
361. HurricaneGeek
2:42 PM GMT on November 16, 2007
*LOL* Depends on Dew Point! ROFLMCPO
---
LMAO...now I know what "ROFLLM_ _ O" means. Whats the CP mean?
LOL
Member Since: May 10, 2007 Posts: 110 Comments: 7039
360. HurricaneGeek
2:41 PM GMT on November 16, 2007
Ok thanks Beachfoxx. I thing it has to be less then half your body temperaure ouside. So If you body temperature is 98.6. It has to be like 48-49 or so.

Us here is do for snow. We got it once in 1977. I was not born yet. BUT it DID SNOW IN MIAMI>>>FLORIDA. NOT OHIO. Jan 19, 1977
Member Since: May 10, 2007 Posts: 110 Comments: 7039
359. Beachfoxx
2:41 PM GMT on November 16, 2007
Lake,

I have heard 508 deaths from Sidr, but as you said reports are just coming in. Slowly.
Member Since: July 10, 2005 Posts: 157 Comments: 29384
358. Bonedog
2:40 PM GMT on November 16, 2007
thats from a northerners point of view


here it is from a southerners


florida in winter


northeast in winter



notice the diffrence
Member Since: July 14, 2005 Posts: 14 Comments: 7418
357. Beachfoxx
2:40 PM GMT on November 16, 2007
356. HurricaneGeek
How cold can you surf?


*LOL* Depends on Dew Point! ROFLMCPO
Member Since: July 10, 2005 Posts: 157 Comments: 29384
356. HurricaneGeek
2:38 PM GMT on November 16, 2007
How cold can you surf?
Member Since: May 10, 2007 Posts: 110 Comments: 7039
355. Beachfoxx
2:38 PM GMT on November 16, 2007
Geek, not real sure but I do know it varies depending on Dew Point.
Member Since: July 10, 2005 Posts: 157 Comments: 29384
354. LakeShadow
2:38 PM GMT on November 16, 2007
That article said that the death toll was only at 425. I know they are probably still counting, but considering past cyclones in that region and the size and power behind Sidr, I think thats amazing that there are so few deaths! I expected in the thousands...
Member Since: August 10, 2007 Posts: 3 Comments: 2134
353. NEwxguy
2:37 PM GMT on November 16, 2007
Winters haven't been to bad the last couple of years,haven't had any of those wind chille days -20 to -30,I think were due this year.
Member Since: September 6, 2007 Posts: 878 Comments: 15734
352. HurricaneGeek
2:36 PM GMT on November 16, 2007
Uh oh. Frozen Hair Is Never Good.

How cold does it have to be to see your breath?
Member Since: May 10, 2007 Posts: 110 Comments: 7039

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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.