Super Typhoon Haiyan's Intensification and Unusually Warm Sub-Surface Waters

By: Dr. Jeff Masters , 6:25 PM GMT on November 13, 2013

Share this Blog
58
+

A remarkable warming of the sub-surface Pacific waters east of the Philippines in recent decades, due to a shift in atmospheric circulation patterns and ocean currents that began in the early 1990s, could be responsible for the rapid intensification of Super Typhoon Haiyan. Hurricanes are heat engines, which means they take heat energy out of the ocean, and convert it to kinetic energy in the form of wind. It's well-known that tropical cyclones need surface water temperatures of at least 26.5°C (80°F) to maintain themselves, and that the warmer the water, and the deeper the warm water is, the stronger the storm can get. Deep warm water is important, since as a tropical cyclone tracks over the ocean, it stirs up cooler water from the depths, potentially reducing the intensity of the storm. When both Hurricane Katrina and Hurricane Rita exploded into Category 5 hurricanes as they crossed over a warm eddy in the Gulf of Mexico with a lot of deep, warm water, the concept of the total heat energy available to fuel a hurricane--the Tropical Cyclone Heat Potential (TCHP)--became one that gained wide recognition. The Pacific Ocean east of the Philippines has the largest area of deep, warm water of anywhere on Earth, and these waters have historically fueled the highest incidence of Category 5 storms of anywhere on the planet. Super Typhoon Haiyan tracked over surface waters that were of near-average warmth, 29.5 - 30.5°C (85 - 87°F.) However, the waters at a depth of 100 meters (328 feet) beneath Haiyan during its rapid intensification phase were a huge 3°C above average, according to Professor I-I Lin of the Department of Atmospheric Science at the National Taiwan University. An analysis by the Japan Meteorological Agency for October showed ocean temperatures 4 - 5°C (7 - 9°F) above average during October (Figure 1). This analysis was from a model. When looking at actual measurements made by the Argo float data in early November, the temperatures in the layer 100 meters below the surface under Haiyan were about 3°C above average, not 4 - 5°C, according to Dr. Lin. As the typhoon stirred this unusually warm water to the surface, the storm was likely able to feed off the heat, allowing Haiyan to intensify into one of the strongest tropical cyclones ever observed.


Figure 1. Modeled departure of temperature from average at a depth of 100 meters in the West Pacific Ocean during October 2013, compared to a 1986 - 2008 average. The track and intensity of Super Typhoon Haiyan are overlaid. Haiyan passed directly over large areas of sub-surface water that were much above average in temperature, which likely contributed to the storm's explosive deepening. While this model showed 4 - 5°C departures from average in October, the actual values were closer to 3°C in early November, according to Argo float data. Image credit: Japan Meteorological Agency.

Why was there such unusually warm sub-surface water?
The sub-surface waters east of the Philippines have warmed dramatically over the past twenty years. According to Pun et al. (2013), "Recent increase in high tropical cyclone heat potential area in the Western North Pacific Ocean", the depth to where ocean temperatures of at least 26°C (79°F) penetrates has increased by 17% since the early 1990s, and the Tropical Cyclone Heat Potential has increased by 13%. The warm-up is due to an increase in the surface winds blowing across the region--the trade winds--which have caused a southward migration and strengthening of the North Equatorial Current (NEC) and the North Equatorial Counter Current (NECC). The strong trade winds have pushed a large amount of water up against the east coast of the Philippines in the past twenty years, resulting in a rate of sea level rise of 10 mm per year--more than triple the global average of 3.1 mm/yr (Figure 2.) This extra sea level rise contributed to the storm surge damage from Super Typhoon Haiyan. Sea level rise data from Legaspi in the Eastern Philippines shows a rise of about 305 mm (12 inches) since 1949. For comparison, global average sea level rose 7.5" (190 mm) since 1901. Part of the rise along the eastern Philippine coast is from tectonic processes--the subsidence of the Philippine plate under the Eurasian plate--but most of it is due to the stronger trade winds piling up warm water along the coast, and the fact that warmer waters expand, raising sea level.


Figure 2. Trend in sea level from satellite altimeter measurements in 1993 - 2010. Black lines are the Sea Surface Height (SSH) in cm from Rio et al. (2009.) Image credit: Qiu, B., and S. Chen, 2012, "Multidecadal sea level and gyre circulation variability in the northwestern tropical Pacific Ocean", Journal of Physical Oceanography 42.1 (2012): 193-206.

Why have the trade winds sped up?
The surface trade winds in the equatorial Pacific are part of the Walker Circulation--a pattern of rising and sinking air along the Equator that the El Nino/La Nina cycle influences. A strong Walker circulation means there is lower pressure over Indonesia, which pulls in more air at the surface along the Equator from the east, increasing the easterly trade winds. As these trade winds strengthen, they pull surface ocean waters away from South America, allowing cold water to upwell to the surface. This is a La Niña-like situation, which takes heat energy out of the atmosphere, putting it into the ocean, keeping global surface temperatures cooler than they would otherwise be. A weakened Walker circulation is the reverse, resulting in weaker trade winds, and a more El Niño-like situation with higher global surface temperatures. As long as the stronger Walker circulation that has been in place since the early 1990s holds, global surface temperatures should stay cooler than they otherwise would be, prolonging the slow-down in global surface warming that has received much attention this year. There may also be a greater chance of super typhoons and higher storm surges affecting the Philippines, due to the warmer sub-surface waters and re-arranged ocean currents. A 2013 paper by L’Heureux et al. notes that the climate models predict that the Walker circulation should weaken (a more El Niño-like situation)--the reverse of what has been observed the past twenty years. The researchers took the observed pressure patterns over the Pacific in recent decades and removed the atmospheric response to the El Niño/La Niña cycle. The resulting pattern they found showed a steady strengthening of the Walker circulation, in concert with global rising temperatures. So, are we seeing a failure of the climate models? Or is the recent speed-up of the Walker circulation a decades-long temporary "speed bump" in the climate system? Time will tell. It is worth pointing out that a just-released paper by British and Canadian researchers shows that the global surface temperature rise of the past 15 years has been greatly underestimated. As discussed at realclimate.org, "The reason is the data gaps in the weather station network, especially in the Arctic. If you fill these data gaps using satellite measurements, the warming trend is more than doubled in the widely-used HadCRUT4 data, and the much-discussed “warming pause” has virtually disappeared."

I appeared on PBS Newshour last night to discuss the linkages between stronger tropical cyclones and climate change, video here.

References
L’Heureux, Michelle L., Sukyoung Lee, and Bradfield Lyon, 2013, "Recent multidecadal strengthening of the Walker circulation across the tropical Pacific", Nature Climate Change 3.6 (2013): 571-576.

Pun, Iam‐Fei, I‐I. Lin, and Min‐Hui Lo, 2013, "Recent increase in high tropical cyclone heat potential area in the Western North Pacific Ocean", Geophysical Research Letters (2013).

Qiu, B., and S. Chen, 2012, "Multidecadal sea level and gyre circulation variability in the northwestern tropical Pacific Ocean", Journal of Physical Oceanography 42.1 (2012): 193-206.

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: 286 - 236

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22Blog Index

Quoting 281. GTstormChaserCaleb:
Severe weather coming?





Wind dynamics are there but no cape or not much that is.
Member Since: Posts: Comments:
Quoting 278. Patrap:
I'm gonna go with the Caymans fo some uncanny reason.


Seems Catastrophic Typhoon Haiyan has kept the "Nagging Naboob's of calamity" wishing for a Cat 5 strike at bay.

Till June Hopefully.

Try the Gumbo, it is outstanding.

..avoid the MCRib, at all costs.


LOL! Stomach explosion afterwards?
Member Since: Posts: Comments:
Quoting 280. KoritheMan:


Gumbo at Pat's house, everyone? ;)
I'll bring tiramisu ;)

Member Since: Posts: Comments:
Did someone miss the severe wind event in South Dade. It is quite breezy out tonight.

I don't buy the weather apps 9 mph wind.
Member Since: March 10, 2006 Posts: 0 Comments: 10034
Quoting 280. KoritheMan:


Gumbo at Pat's house, everyone? ;)


Count me in!
Member Since: March 10, 2006 Posts: 0 Comments: 10034
Severe weather coming?



Member Since: Posts: Comments:
Quoting 278. Patrap:
I'm gonna go with the Caymans fo some uncanny reason.


Seems Catastrophic Typhoon Haiyan has kept the "Nagging Naboob's of calamity" wishing for a Cat 5 strike at bay.

Till June Hopefully.

Try the Gumbo, it is outstanding.

..avoid the MCRib, at all costs.


Gumbo at Pat's house, everyone? ;)
Member Since: Posts: Comments:
How on Earth can you get an East Asian Jet Streak like that in a negative Western Pacific Oscillation??!
Member Since: Posts: Comments:
I'm gonna go with the Caymans fo some uncanny reason.


Seems Catastrophic Typhoon Haiyan has kept the "Nagging Naboob's of calamity" wishing for a Cat 5 strike at bay.

Till June Hopefully.

Try the Gumbo, it is outstanding.

..avoid the MCRib, at all costs.
Member Since: July 3, 2005 Posts: 420 Comments: 127536
Quoting 272. KoritheMan:


I wonder how many people would try to find a way to rationalize it to the US in that kind of pattern. :)
Oh trust me Kori they would find a way to wishcast it to the US.
Member Since: Posts: Comments:
Quoting 272. KoritheMan:


I wonder how many people would try to find a way to rationalize it to the US in that kind of pattern. :)


Don't forget about our friends over at the Cayman Islands.

;)
Member Since: July 2, 2012 Posts: 95 Comments: 9779
Quoting 272. KoritheMan:


I wonder how many people would try to find a way to rationalize it to the US in that kind of pattern. :)

'Once it exits the northeast Caribbean, the Bermuda high is going to turn it west towards Florida. With a monster anticyclone aloft, folks should be prepared for a monster!'
Member Since: July 6, 2010 Posts: 113 Comments: 31417
Chilly out there tonite.
27.5F degrees
believe that's the coldest it's been in a while.
unless it was colder last night.
Member Since: Posts: Comments:
Quoting 271. GTstormChaserCaleb:
14 years ago Wrong-Way Lenny formed in the SW Caribbean Sea.



11 PM Saturday Nov. 3.



The blog would be crazy busy tonight if we had something like a Lenny.


I wonder how many people would try to find a way to rationalize it to the US in that kind of pattern. :)
Member Since: Posts: Comments:
14 years ago Wrong-Way Lenny formed in the SW Caribbean Sea.



11 PM Saturday Nov. 3.



The blog would be crazy busy tonight if we had something like a Lenny.
Member Since: Posts: Comments:
Pattern shift in December will allow for more cold air to come down and if we get a southern storm ride up the east coast bring us some snows if the timing is perfect.
Dec 10-20 seems the most reasonable time frame. Dec 5 could also bean interesting player for first snow date bu we will have to see.
Member Since: Posts: Comments:

Prediction for first inch- Time period on, or between Dec 10-20, a storm may bring more.
Member Since: Posts: Comments:
Quoting 244. DonnieBwkGA:


Need to build up your upper arm strength! ;)


I was thinking the same thing. .25 - .5" doesn't sound like a whole lot to me.

Now 2.5' - 5' does.
Member Since: March 10, 2006 Posts: 0 Comments: 10034
I will release my own first one inch snow prediction in a moment for DC/Baltimore soon.
Member Since: Posts: Comments:
Quoting 265. Doppler22:

We don't want rain, we want snow. And I know you said washi but we want the same thing :p
Only if all that rain was snow
Member Since: Posts: Comments:
Quoting 264. Climate175:
Washi lots of rain for DC and Baltimore on Monday,a 80% chance.

We don't want rain, we want snow. And I know you said washi but we want the same thing :p
Member Since: Posts: Comments:
Washi lots of rain for DC and Baltimore on Monday,a 80% chance.
Member Since: Posts: Comments:
8 killed as mob storms rice shop in Philippines Posted by: Aswathy Published: Wednesday, November 13, 2013,


Manila, Nov 13: Struggle for survival has killed eight people in Tacloban in Philippines today. A huge crowd stormed into a rice warehouse in the city and as a result, a wall collapsed, killing 8 people instantly. There is a shortage of food, safe drinking water, clothes and everything necessary in the Haiyan-devastated Philippines. Police and security agencies guard malls, shops, warehouses and camps to stop angry people from attacking them. There are also reports of armed gangs looting the shops and malls. The crowd took away almost 1 Lakh bags of rice, each bag weighing 50 kgs, authorities reported. According to United nations data, more than 1,00,000 people have died in the typhoon. Haiyan was descibed as one of the most powerful storms ever in the world. UN says it has a huge amount of job to be done in Philippines and Vietnam where the wind caused maximum destructions. "We have not been able to get into the remote communities," UN humanitarian chief Valerie Amos said in Manila. More than 11 million people are said to be affected by the storm. "Even in Tacloban, because of the debris and the difficulties with logistics and so on, we have not been able to get in the level of supply that we would want to. We are going to do as much as we can to bring in more," she said. OneIndia New

Read more at: http://news.oneindia.in/international/8-killed-as- mob-storms-rice-shop-philippines-1340573.html
Member Since: Posts: Comments:
Tropical Storm Narda report is up / Peak intensity was 55kts
Member Since: April 29, 2009 Posts: 75 Comments: 13995
Quoting 64. LargoFl:
the earth over its history has went thru very warm periods and extremely cold periods,today we sit inbetween the very cold periods,so any warming now is a good thing,perhaps slowing down the coming cold period...if human lifespan was not 100 year but several thousand..we would know whats coming.


No, "any warming now is a good thing" is a complete load of bovine excrement. We have built our entire civilization on a relatively stable climate, and ANY threat to that stability should be viewed a lot of concern.

Many companies and government agencies, including the DoD take climate change and it's impacts very seriously. A couple of severe extended droughts in a few key areas is enough to cause global instability. We've already had a small taste of that when Russia shut down it's food exports as a result of the severe drought and fires from a couple years backs.

Considering ice ages and warm periods are induced by as a little as a 2C differential and that often these rapid changes resulted in extinction events counteracts you statement. Sudden changes, regardless of direction, is detrimental to the species existing at that time.

C
Member Since: Posts: Comments:
Sorry if already posted, but apparently an official says its entirely possible that 1,000 American troops could be in the Philippines by the end of the week.
Member Since: Posts: Comments:
Quoting 205. Levi32:


Well, we're assuming that Emanuel's formula for maximum potential intensity (MPI) is without significant errors, and since few storms actually reach their MPI, we have a small sample size, and it could be that Haiyan did strengthen that much due to its thermodynamic environment alone.

I have a hypothesis, though. I think two things helped Haiyan significantly. One is the abnormally strong local Hadley cell (as far as typhoon environments go), due to Haiyan managing to form south of the subtropical ridge at such a late time in the year, within the rising flank of the cell.

The second is Haiyan's very low latitude. I would have to do a formal investigation, but I have gotten the feeling before that, although TCs rarely form south of 10N - when they do, they seem to do very well for themselves. The reason could lie in the weaker Coriolis force, which increases the time necessary for winds to reach gradient balance, and causes a greater radial component to the wind (across isobars as opposed to tangent to them). This could promote eyewall health by increasing low-level convergence and resisting formation of concentric eyewalls that lead to replacement cycles. Haiyan seemed to resist a true replacement cycle right before peaking in intensity. It was during this time that the eye roughly tripled in diameter, but there was no preceding weakening phase.


That seems to make sense to me as well, as storms like Ivan in the Atlantic also have formed at relatively low latitudes and yet managed to put on quite a show in the MDR.
Member Since: Posts: Comments:
Quoting 257. allancalderini:
Washi you are funny,you always make my day with those pics.
They say "a picture tells a thousand words" or emotions something like that...
Member Since: Posts: Comments:
Quoting 255. washingtonian115:
"sees second picture"
Washi you are funny,you always make my day with those pics.
Member Since: Posts: Comments:
Looks like a surface circulation might be developing near 12N/79W according surface observations.
After looking at coverage of the devastation of the Philippines last night on CNN, if I never see or hear about a typhoon or hurricane again it will be too soon, a very sad and tragic situation!
Member Since: Posts: Comments:
Quoting 252. TropicalAnalystwx13:
As far as temperatures are concerned, expect a modification across most of the East United States as the arctic high shifts eastward and dissipates and a new one in the Gulf and Caribbean builds north. As Scott and others have pointed out, we might see a rain event across the Southeast as a disturbance forms and tracks northeast. It shouldn't be that big of a deal. Meanwhile, in the West, cold will be building once again as an upper-level trough breaks off from the Polar Vortex and dips southeast. Heavy snow is possible across portions of the Intermountain West. Though its southeastward progression will be blocked initially by the aforementioned high, a change in the pattern (PNA going positive, NAO going negative) should allow for it to amplify and bring much cooler weather just before Thanksgiving.

Watch for severe weather in Arkansas and surrounding states with this trough (see SPC outlook)?


"sees second picture"
Member Since: Posts: Comments:
Quoting 171. JupiterKen:
Apologies if this has been previously posted. Before and after pics Tacloban.
Link


Looks like a lot of the well built structures held their ground
Member Since: September 6, 2007 Posts: 0 Comments: 6057
Riverside, California (Airport)
Updated: 3:53 PM PST on November 13, 2013
Clear
88 °F
Clear
Humidity: 8%
Dew Point: 19 °F

Corona CA to my SW tied the National high at 95F
Member Since: Posts: Comments:
As far as temperatures are concerned, expect a modification across most of the East United States as the arctic high shifts eastward and dissipates and a new one in the Gulf and Caribbean builds north. As Scott and others have pointed out, we might see a rain event across the Southeast as a disturbance forms and tracks northeast. It shouldn't be that big of a deal. Meanwhile, in the West, cold will be building once again as an upper-level trough breaks off from the Polar Vortex and dips southeast. Heavy snow is possible across portions of the Intermountain West. Though its southeastward progression will be blocked initially by the aforementioned high, a change in the pattern (PNA going positive, NAO going negative) should allow for it to amplify and bring much cooler weather just before Thanksgiving.

Watch for severe weather in Arkansas and surrounding states with this trough (see SPC outlook)?


Member Since: July 6, 2010 Posts: 113 Comments: 31417
Quoting 241. beell:


Where is the cyclonic curvature in the jet streak?

It's not extreme by any means, but it appears to have the most cyclonic curvature in the vicinity of the Korean Peninsula. Divergence as analyzed by CIMSS seems also to support that the jet streak had noticeable cyclonic curvature.

Member Since: Posts: Comments:
Quoting bappit:

It is a fallacy, generally, to cite any one factor as the cause of events like this. If the thermodynamics had not been there then the ventilation would have been supporting a weaker storm. I'll accept for the sake of argument that if the ventilation had not been there, then the thermodynamics would have supported a weaker storm. (Actually, I dunno. Wish you cited a source.)

People have to pose their questions clearly when dealing with complex situations. Demanding simple answers is a mistake, pure and simple.


Indeed. The World Meteorological Organization, while saying are rising sea levels and warmer SST's are "aggravating" the impact of storms like Haiyan, they also said "Extreme events include super typhoon Haiyan, one of the most intense in history that smashed into the Philippines last Friday, it said. The WMO said, however, that it was impossible to blame climate change for individual storms.

"The jury is still out on whether tropical cyclones will become more frequent in the future," Jeremiah Lengoasa, deputy WMO Secretary-General, told a news conference.

He pointed to wide uncertainties about how they form."


The last sentence says it all. We are a long way from understanding any individual tropical cyclone, let alone a cyclone season, as this year in the Atlantic Basin made abundantly clear. Anyone trying to connect AGW with Haiyan has no scientific basis to validate such a statement.

Link to WMO statement
Member Since: Posts: Comments:
Quoting 200. PalmBeachWeather:
Never

I am tired of the bickering. There should be more posts removed on the anti-denialist side, but they shouldn't bother doing that if they don't get rid of the baiting by the denialists.
Member Since: Posts: Comments:
troughs at 138 and 240..
Member Since: Posts: Comments:
I think tonight will be the first night that I go into the teens over night. TWC and my local news forecasted a low of 27 for tonight. It is 27 now and the sky is clear and the winds are calm. I wouldn't be surprised if we go down to 20 or under.
Member Since: Posts: Comments:
The last post will be on the CBS Evening news in the next few minutes.
Member Since: July 3, 2005 Posts: 420 Comments: 127536
Massive Iceberg Drifting Off Coast Of Antarctica May Be A Problem

Posted: 11/13/2013 4:20 pm EST



A massive iceberg drifting from Antarctica could spell disaster for international shipping lanes if it floats too far away from the continent.

So, to track the estimated 270-square-mile iceberg, the Natural Environment Research Council awarded an emergency grant of 50,146 pounds (about $80,000) to Grant Bigg, a geography professor at the University of Sheffield in the United Kingdom. The funds will be used to help predict the path of the giant iceberg, which broke off Antarctica's Pine Island Glacier in July.

According to BBC News, Bigg explained that the iceberg began floating away from the glacier sometime in the last couple days. Earlier, during Antarctica's winter, the floe remained affixed to the larger part -- likely due to sea ice and cold winter temperatures.

"It often takes a while for bergs from this area to get out of Pine Island Bay but once they do that they can either go eastwards along the coast or they can … circle out into the main part of the Southern Ocean," Bigg told BBC.

As The Australian points out, news of the iceberg drifting has sparked a flurry of size comparisons -- from the entirety of Singapore to eight times the area of Manhattan.



NASA scientists first noticed a massive crack across Antarctica's Pine Island glacier in November 2011. (Photo by Universal History Archive/UIG via Getty Images)


The iceberg is the first of its size to break off from the island since 2001. While researchers do not expect the iceberg to cause any environmental issues when it melts, the massive piece of ice could interfere in international trade, depending on which way it floats.

Initial predictions hold that the iceberg will follow the Antarctic Coastal Current toward the Ross Sea before it eventually reaches the Southern Ocean, the research grant states. Scientists will use algorithms to forecast where the iceberg will float over the next six months, the period of time covered by the grant. The iceberg's lifetime is expected to span several years.
Member Since: July 3, 2005 Posts: 420 Comments: 127536
Quoting 242. TropicalAnalystwx13:

We got a dusting on all surfaces sans the road. The snowflakes started off small but got really large and heavy. Some locations around here picked up .25-.5" of snow...WOW!

I spent all morning digging out.


Need to build up your upper arm strength! ;)
Member Since: Posts: Comments:
243. beell
Outflow is to the west of Haiyan and then north and back east into the entrance region of a zonal jet which rapidly increases in velocity from north to south-divergence aloft into the streak. The entrance region of the zonal jet extends from at least 110E to 140E

Member Since: Posts: Comments:
Quoting 240. DonnieBwkGA:
Thanks for the answers y'all!

I know the satellite presentation degraded between Guiuan and Tacloban. It's too bad there is not an observation from Guiuan but that's a very small thing compared to the devastation there.

TropicalAnalyst did you get any snow accumulation?

We got a dusting on all surfaces sans the road. The snowflakes started off small but got really large and heavy. Some locations around here picked up .25-.5" of snow...WOW!

I spent all morning digging out.
Member Since: July 6, 2010 Posts: 113 Comments: 31417
241. beell
Quoting 184. 1900hurricane:

I am very aware of that jet streak, but it's influence on the situation is somewhat diminished by a few things. First, the core of Haiyan is over 10* latitude from the jet streak. Additionally, upper level riding (the same upper level ridge that was slightly shearing Haiyan the day before) is separating Haiyan's outflow from the right entrance region of the jet streak. Your chart above even features convergent streamlines along the ridge and between the features. The divergent area associated with the jet streak doesn't even start until about the latitude of Taiwan, and the cyclonic curvature of the jet streak somewhat compromises the amount of divergence associated with it as well (not as much as in the image below, but you get the picture).



Yes, an excellent upper air environment is needed in addition to an excellent thermodynamic environment in order to produce and sustain a tropical cyclone of Haiyan's caliber. You're not getting such a storm without either. However, the influence that jet streak had on Haiyan's upper level environment was very small.

Interesting note on Raymond by the way. I remember you mentioning that very thing earlier. I look forward to what that study concludes.


Where is the cyclonic curvature in the jet streak?
Member Since: Posts: Comments:
Thanks for the answers y'all!

I know the satellite presentation degraded between Guiuan and Tacloban. It's too bad there is not an observation from Guiuan but that's a very small thing compared to the devastation there.

TropicalAnalyst did you get any snow accumulation?
Member Since: Posts: Comments:
Quoting 234. DonnieBwkGA:


Thanks! Would a pressure of 960 mb 15 miles from the eye support a Cat 5 rating?

There's no inherent pressure range for a Category 5. In the database, the pressure for past storms ranges from a questionable 972 millibars (Ethel '60) to an insane 882 millibars (Wilma '05). It's likely that Haiyan had a crazy pressure gradient, though the idea of this being a sub-900mb system by the point of landfall (in Leyte) would probably not be accurate given the measurements they observed. It's very possible it was sub-900mb as it hit Guiuan, however.
Member Since: July 6, 2010 Posts: 113 Comments: 31417
Quoting 234. DonnieBwkGA:


Thanks! Would a pressure of 960 mb 15 miles from the eye support a Cat 5 rating?
That's a good question and the reason for debates over if Haiyan was or wasn't as strong as thought :\
Member Since: August 1, 2011 Posts: 28 Comments: 7896
Quoting 231. DonnieBwkGA:


How far were they from the eye?
Quoting 234. DonnieBwkGA:


Thanks! Would a pressure of 960 mb 15 miles from the eye support a Cat 5 rating?

I may have to look at the coastal pressure profiles I worked up in ArcGIS for Camille, Andrew, Ike, Charley, and Katrina. I know that the pressure tends to change the fastest right at the eyewall, perhaps right at the inner edge of the eyewall where winds are the fastest.

Technically there is no pressure number to look for when trying to decide cat5... it's all about the gradient. But I would imagine that, operationally-speaking, we have a range of values that are typically seen in storms of that intensity.
Member Since: September 28, 2002 Posts: 5 Comments: 3167
236. HadesGodWyvern (Mod)
though JTWC dropped development for 90W..

Japan Meteorological Agency
Tropical Cyclone Advisory #34
Gale Warning
TROPICAL DEPRESSION 36
6:00 AM JST November 14 2013
======================================

South China Sea

At 21:00 PM UTC, Tropical Depression (1004 hPa) located at 12.3N 114.8E has 10 minute sustained winds of 30 knots. The depression is reported as moving west at 16 knots.

Dvorak Intensity: T2.0

Forecast and Intensity
=======================
24 HRS: 12.3N 109.9E - 40 knots (CAT 1/Tropical Storm) South China Sea
Member Since: May 24, 2006 Posts: 50 Comments: 44697

Viewing: 286 - 236

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22Blog 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.