Fred rapidly intensifies; new wunderground storm surge section launched

By: Dr. Jeff Masters , 1:51 PM GMT on September 09, 2009

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Hurricane Fred put on an impressive burst of intensification overnight, and is now a major Category 3 hurricane with 120 mph winds. However, Fred is not a threat to any land areas for at least the next week. Satellite imagery of Fred shows the spectacular signature of a classic Cape-Verdes type major hurricane, with a prominent eye, well-developed low-level spiral bands, and high cirrus clouds denoting excellent upper-level outflow on three sides. It is quite unusual to have such a powerful system so far east in the Atlantic, and Fred is only the third major hurricane to exist east of 35W. Fred is also the strongest hurricane so far south and east in our data record. However, this type of system would have been difficult to document before satellite pictures began in the 1960s.


Figure 1. Visible satellite image of Hurricane Fred at 10:30am EDT 9/9/09. Fred was a Category 3 (120 mph winds) at this time.

The forecast for Fred
Wind shear through Thursday morning is expected to stay in the low range, 5 - 10 knots, and ocean temperatures will be about 1 - 2°C above the threshold needed for tropical cyclone formation. Given these conditions, plus such factors as the temperature at 200 mb and the amount of moisture between 700 mb and 500 mb, this morning's run of the SHIPS model computes that the Maximum Potential Intensity (MPI) Fred can reach tonight is 140 mph (121 knots), which would make it a Category 4 hurricane. This is the strongest a hurricane can get in this region of the atmosphere. Very few hurricanes ever reach their MPI, and it will be interesting to see how close Fred gets to this mark.

Shear will rise to the moderate range, 15 - 20 knots, Thursday through Friday, then increase to the high range, 20 - 40 knots, Saturday through Sunday, thanks to a strong trough of low pressure traversing the North Atlantic. This should weaken Fred to a tropical storm five days from now. The trough will also pull Fred to the northwest and then north. Most of the models foresee that this trough will not be strong enough to fully recurve Fred to the northeast and out to sea. However, another strong trough of low pressure is forecast to traverse the central Atlantic about eight days from now, and this trough should be strong enough to recurve the storm northeastward out to sea. The odds of Fred making it all the way across the Atlantic to threaten land areas appear low at this time.

Elsewhere in the tropics
A weak front is expected to move off the Texas coast Friday and linger along the coast for several days. Beginning on Friday, we will need to watch the Western Gulf of Mexico for possible development of a tropical cyclone along this front. Any storm that develops would likely move northeast or north-northeast and impact Louisiana and northern Texas coast. The models are less enthusiastic this morning about developing such a storm than they were in previous runs, and there will be some high wind shear to the west for a potential tropical system to contend with.

New wunderground storm surge section launched
The Weather Underground is pleased to announce the release of the Internet's most comprehensive hurricane storm surge web pages. The new storm surge section provides more than 500 detailed, zoomed-in storm surge maps from the official storm surge model used by the National Hurricane Center--the Sea, Lake, and Overland Surge from Hurricanes (SLOSH) model. I've created SLOSH model worst-case flood maps for Category 1, 2, 3, 4, and 5 hurricanes for the entire U.S. Atlantic coast, plus Hawaii, Puerto Rico, the Virgin Islands, and the Bahamas. Zoom-in maps of fifteen important cities such as Miami, New York City, Boston, Tampa, and Corpus Christi are included. To help coastal residents see how past storms have affected their region, the wunderground storm surge pages also include SLOSH model animations of the surge for more than 40 historic storms--from the Great Colonial Hurricane of 1635 to Hurricane Ike of 2008. You can access the new storm surge web pages.from our Tropical/Hurricane page, on the right side of the page under my blog box. I encourage all coastal residents along the U.S. coast to take the time to familiarize themselves with the storm surge risk where they live.


Figure 2. Sample water depth inundation image (left) and storm tide image (right), created using NOAA's SLOSH model. These Maximum of the "Maximum Envelope of Waters" (MOM) plots are for Tampa Bay, Florida, for a mid-strength Category 4 hurricane (sustained winds of 143 mph) hitting at high tide.

How to interpret the storm surge images
There are two sets of images available. The first set, titled "Maximum Water Depth", shows the water depth at each grid cell of the SLOSH domain. Thus, if you are inland at an elevation of ten feet above mean sea level, and the combined storm surge and tide (the "storm tide") is fifteen feet at your location, the water depth image will show five feet of inundation. The second set of images, titled "Maximum Storm Tide", shows how high above mean sea level the sum of the storm surge plus the tide reaches. Over the ocean, the storm tide and water depth images will show the same values. The storm tide images contain no information about how deep the water will be inland, and are generally less useful than the water depth images. All of these Maximum of the "Maximum Envelope of Waters" (MOM) images were generated for high tide, and thus show worst-case inundation scenarios for mid-strength hurricanes of each Saffir-Simpson Category (Category 1, 2, 3, 4, and 5). Category 5 hurricanes have never occurred in the Mid-Atlantic or New England regions, so there are no Category 5 images shown there. No single storm will be able to cause the level of flooding depicted in the SLOSH storm surge images along the entire coast. A sample set of storm surge images for a Category 4 hurricane hitting Tampa Bay is shown in Figure 2. Black lines mark the coastline, and also delineate the grid the SLOSH model used. There may be storm surge present outside the boundaries of the grid, so pay attention to where the grid boundaries are. Also, if you see a high surge modeled for a narrow waterway that goes right up to the edge of the grid boundary, don't believe it. The model puts an artificial barrier at the grid boundary, and the surge is piling up against this non-existent barrier. Empty brownish grid cells with no coloration show where no inundation is computed to occur. St. Petersburg becomes two islands in a worst-case scenario Category 4 hurricane, as shown by the brown areas surrounded by colored areas of storm tide (this did occur during the Great Gale of 1848, a Category 4 hurricane that hit the city). The tide level is marked at the bottom of the color legend, and is 1 foot in this example. The left "maximum water depth" image shows how high above each grid cell the storm tide reaches. The storm tide--the combination of the storm surge plus the 1 foot high tide--reaches as much as 27 feet above mean sea level (pink colors) near downtown Tampa (right-hand "maximum storm tide" image). The amount of inundation inland is controlled by the elevation of the land. Some of the inland regions near downtown Tampa being inundated by the 27-foot storm tide are at an elevation of 19 feet, so as much as 8 feet of inundation will occur at those locations (dark blue colors in the left-hand "maximum water depth" image). Interstate highways are the thick grey-green lines, and smaller highways are shown as dark green and light green lines. If a road is inundated by storm surge, it will not appear. County boundaries are shown in red.

Twenty years ago on this date
On September 9, 1989, satellite imagery detected a strong tropical wave with plenty of spin and heavy thunderstorm activity moving off the coast of Africa, just south of the Cape Verdes Islands. The satellite analyst at the National Hurricane Center duly noted the tropical wave, the 35th such wave to move off Africa that year, in his tropical weather discussion. No one could suspect that the routine-looking tropical wave would eventually grow to become Hurricane Hugo--the costliest Atlantic hurricane of all time.

Jeff Masters

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Member Since: Posts: Comments:
Quoting tornadodude:


well from my limited understanding, it looks like you should pay attention to the isobars,the tighter they are, the more wind there is and also the numbers that state the millibars, the lower the number, the more intense


Ok. Thanks. There are no lines or numbers on what it shows coming our way so I guess that's a good thing. :)
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Quoting iceman55:
i hope not hard shi?


well, it's not going to be easy,i'd say the hardest will be the math xD
Member Since: June 28, 2006 Posts: 24 Comments: 8185
Quoting homelesswanderer:
How do you tell what intensity these models are showing. Never could figure that out. Unless it was bright red or something and you know its bad. Still not clear on the colors in between.

Link


well from my limited understanding, it looks like you should pay attention to the isobars,the tighter they are, the more wind there is and also the numbers that state the millibars, the lower the number, the more intense
Member Since: June 28, 2006 Posts: 24 Comments: 8185
You all wanna see something crazy look at the BAM models on my website.......don't think i have ever seen an extreme like that.
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How do you tell what intensity these models are showing. Never could figure that out. Unless it was bright red or something and you know its bad. Still not clear on the colors in between.

Link
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Quoting iceman55:
thank


no problem, penn state has an excellent meteorology program
Member Since: June 28, 2006 Posts: 24 Comments: 8185
Quoting btwntx08:

i hope so if anything develops i don't expecr it to be no stronger than a 45 mph storm at least


Yeah, that's what he also said.
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Monroe
Member Since: June 28, 2006 Posts: 24 Comments: 8185
Well iceman, the only one in Louisiana is Monroe
Member Since: June 28, 2006 Posts: 24 Comments: 8185
Quoting btwntx08:

did i see the word brownsville in here yep yes i did btw hello homelesswanderer


Hi BT. Yeah thats what he said. Still hoping it will mean rain for those who need it and nothing else.
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Quoting iceman55:
go uno in new orleans


well the closest one to you I found is in Monroe
Member Since: June 28, 2006 Posts: 24 Comments: 8185
Quoting BA:


Anyone who just "wants a storm to track" obviously doesn't live on the coast. I live right on the coast and a storm is the last thing I want to worry about tracking...


I don't live right on the coast. But I know what you mean. I come here to make sure I know if one is coming my way. And to learn more about these things. But I get called a wish caster for asking questions about my area. Oh well they can call me what they want. I don't find it unusual at all for someone who's been thru one to ask if another may come. It's not wishing it will.
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Quoting iceman55:
new models come soon


Bet they shift West and not as far north....IMO
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Quoting iceman55:
go uno in new orleans


ok, hang on a second man
Member Since: June 28, 2006 Posts: 24 Comments: 8185
1394. BA
Quoting homelesswanderer:


Yes it is if it has to be. There is still unfinished business from last year. I know no one on here wants a land falling major cane but just one to track. I feel a lot better if they don't exist at all. Here's a sobering reason why...

Remains Found, Thought to be Missing From Ike
David Ingram

Story Created: Sep 9, 2009 at 8:17 AM CDT


Link


Anyone who just "wants a storm to track" obviously doesn't live on the coast. I live right on the coast and a storm is the last thing I want to worry about tracking...
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Quoting iceman55:
cool.can u give more info what to look for i,m go next year???


well, where do you want to go?
Member Since: June 28, 2006 Posts: 24 Comments: 8185
gfs 00z run very interesting is now at 150hrs developing what appears to be another TC farther south than Fred.
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Quoting iceman55:
Meteorology rigth ?


most definitely :)
Member Since: June 28, 2006 Posts: 24 Comments: 8185
Quoting homelesswanderer:


Just that the shear may weaken long enough to allow development. And some of the models were showing development east of Brownsville and everything would drift northward toward us. He's not expecting any serious development but a lot of rain. But not on the same scale of Allison. Thank God.


You're welcome. :)
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Quoting WatchingThisOne:


Yup, thank god all those CV storms didn't roll across the Atlantic into the Eastern seaboard or the GOM.

Fred is dead (or wake me up if he comes back to life). And that never ending series of troughs rolling off the east coast suggests that might be it for CV storms.

Watching GOM now. Hopefully that will remain problematic for serious storm development. 2010 is plenty soon enough for the next bad land-falling storm.


Yes it is if it has to be. There is still unfinished business from last year. I know no one on here wants a land falling major cane but just one to track. I feel a lot better if they don't exist at all. Here's a sobering reason why...

Remains Found, Thought to be Missing From Ike
David Ingram

Story Created: Sep 9, 2009 at 8:17 AM CDT


Link
Member Since: Posts: Comments:
Quoting iceman55:
matt u in college right???


yeah I am
Member Since: June 28, 2006 Posts: 24 Comments: 8185
Quoting iceman55:
new models come soon


yessir
Member Since: June 28, 2006 Posts: 24 Comments: 8185
Quoting homelesswanderer:


Just that the shear may weaken long enough to allow development. And some of the models were showing development east of Brownsville and everything would drift northward toward us. He's not expecting any serious development but a lot of rain. But not on the same scale of Allison. Thank God.


ok,thanks
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Quoting TexasHurricane:


I didn't catch either.....what did he say?


Just that the shear may weaken long enough to allow development. And some of the models were showing development east of Brownsville and everything would drift northward toward us. He's not expecting any serious development but a lot of rain. But not on the same scale of Allison. Thank God.
Member Since: Posts: Comments:
gotta love doing laundry :P so, fred is weakening a little, eh?
Member Since: June 28, 2006 Posts: 24 Comments: 8185
Quoting homelesswanderer:


I caught Gregs. Did you see what channel 12 said? I missed that one.


I didn't catch either.....what did he say?
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Quoting homelesswanderer:


Shear is our friend. :)


Yup, thank god all those CV storms didn't roll across the Atlantic into the Eastern seaboard or the GOM.

Fred is dead (or wake me up if he comes back to life). And that never ending series of troughs rolling off the east coast suggests that might be it for CV storms.

Watching GOM now. Hopefully that will remain problematic for serious storm development. 2010 is plenty soon enough for the next bad land-falling storm.
Member Since: Posts: Comments:
Link
To NASA pic today of Hurricane Fred
Member Since: August 25, 2009 Posts: 20 Comments: 6785
Quoting tornadodude:
hello everyone


Hi Matt.
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#

UN reports ‘weak to moderate’ El Nino in Pacific

By BRADLEY S. KLAPPER, Associated Press Writer Bradley S. Klapper, Associated Press Writer – Wed Aug 19, 11:06 am ET

GENEVA – A “weak to moderate” El Nino weather system has developed in the tropical Pacific Ocean and could create unusual weather patterns around the world through March, a U.N. agency said Wednesday.

The condition, which is linked to warmer surface temperatures in the central and eastern Pacific Ocean during the latter months of the year, is already being associated with an intense drought in south Asia, said Rupa Kumar Kolli, of the World Meteorological Organization.

But he noted that sea surface in the equatorial Pacific is less than 1 C (1.8 F) warmer than normal. The El Nino will also likely mean a weak Atlantic hurricane season this year, he said.

“This is a weak to moderate event,” Kolli told reporters.

“This particular event is nowhere close to the strength of the 1997 El Nino,” he added, referring to the weather system 12 years ago that was linked to hundreds of deaths and billions of dollars in losses around the world.

Kolli said it was difficult to predict all of the possible effects of the current El Nino, but said conditions could be drier than normal in eastern Africa. He said national meteorological bodies around the world would be monitoring the consequences in their regions.

The El Nino was first observed in June and July, and estimates indicate it will continue into the first quarter of next year, he said.

“Beyond that, the model predictions are not reliable,” Kolli added
# Daniel Swain Says:
September 9th, 2009 at 2:44 pm

…no, not on vacation; just very busy. I will have a full update by later tomorrow night, I promise! Not much going on attm. The current weak to moderate El Nino event, which has stagnated and not become much stronger in recent weeks, is likely to begin to strengthen again in the near future. A strong Kelvin wave is propagating eastward in the Pacific, and I expect this to give all Nino regions a good 0.5 C bump in the next 1-3 weeks. A strong EL Nino is lookling slightly less likely than earlier in the summer, but still remains a distinct possibility. More later.
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Quoting iceman55:
homelesswanderer not next year .


Yeah. I know it. Sigh.
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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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