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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1220. centex
Quoting hydrus:
with all that action on the satellite pic must be good for the drought.
Yes and no. It's still been rather scattered. For example we got 4 inches 40 miles south but none so far in my area. It's still best pattern in long long time and hopeful it will be beginning of end, but they usually end in big floods, that has been the pattern over recorded history.
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Come to Tropics Chat/ Hi everyone! :)
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1218. Patrap
NEXRAD Radar
Brownsville, Storm Relative Mean Radial Velocity 1.45 Degree Elevation Range 124 NMI

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Quoting StormW:


Serious. Maybe addition and division for averaging out steering...but that's about it.


seen
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1216. Patrap
Quoting StormW:
Evening Patrap, and 456!


Hiya StormW...
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1215. hydrus
Quoting Grothar:


You answered and tried. That is the most important thing. Never let anyone demean your attempt at learning.
I am a student before I am anything.
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1213. Patrap
Echo Tops to 50K Plus

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Quoting winter123:
pretty far out, but looks like we may get the classic storm/wave train after all. First of which is fred.

Right, about 2 - 3 weeks behind the "norm", as I was thinking.... wonder if we'll actually get anything else that holds together well, like Bill or Fred, or if we'll get a few more "whingely" [as we put it out here] storms......
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Quoting StormW:
1191. caneluver 9:23 PM EDT on September 09, 2009
Quoting tornadodude:


those topics are entwined like none other btw


No problem, I actually am learning a few things.


I've never used a lick of math in my tropical forecasting.


regardless, I need it at least for my studies, and good evening
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Quoting StormW:
1191. caneluver 9:23 PM EDT on September 09, 2009
Quoting tornadodude:


those topics are entwined like none other btw


No problem, I actually am learning a few things.


I've never used a lick of math in my tropical forecasting.


serious?, BTW good evening
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1207. Patrap


Maybe a seed for the GOM Vort..nasty cells
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1206. hydrus
Quoting Weather456:
all that action on the satellite pic must be good for the drought.
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1205. HadesGodWyvern (Mod)
Japan Meteorological Agency
Tropical Cyclone Advisory #57
DEVELOPED LOW, FORMER DUJUAN (T0912)
9:00 AM JST September 10 2009
=========================================

At 0:00 AM UTC, Developed Low, Former Dujuan (978 hPa) located at 43.0N 164.0E. The low is reported as moving northeast at 45 knots

THIS IS THE FINAL TROPICAL CYCLONE ADVISORY FROM THE JAPAN METEOROLOGICAL AGENCY
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Since nobody had it for me or reed, does anybody have the UKMET model track?
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G'evening!
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1201. Grothar
Quoting hydrus:
#%&*((^%! I will improve.


You answered and tried. That is the most important thing. Never let anyone demean your attempt at learning.
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Patrap, Thanks for the GOM updates. I am scheduled to report back to work 9/15, about 90 miles due east of Brownsville. I'm guessing the guys out there will have an interesting few days ahead of them. Thanks again!
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Quoting centex:
Yes, area where they think development could happen in 48 hours. Not calling for CAT 5 just small chance TD could develop in that area. We are not talking CV time frames in GOM.


Nothing in the GOM for the time being. Maybe later like some models are calling for. To early to tell.



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pretty far out, but looks like we may get the classic storm/wave train after all. First of which is fred.

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1195. Patrap
00 Z Fred Statistical/Simple Models (CLIPER,BAMs,LBAR,other Statistical Models)



00 Z Fred Dynamic Models (More sophisticated models)





00 Z Fred Late Cycle NHC model tracks





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Quoting caneluver:


No problem, I actually am learning a few things.


alright, yeah, I guess I just need refreshed
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Quoting BahaHurican:
Hey, there are some of us that USED to be able to simplify that.... does that mean we're bad people???? lol



I stood outside a short while ago and looking off to the SE I could see the flashes from that complex of clouds. That's as much as maybe, 15, maybe 20 miles away? U wouldn't think u could see lighting from that far...


you can see lightning from probably one hundred miles away if the conditions are right, and if the storms are tall enough
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hmm, it suddenly looks like bill (edit- fred, d'oh!) may be a threat to land. It will dead stall according to GFS, then move due west for days maybe even WSW, due to fujiwara with the wave behind it. My gut was right its likely going to miss the trough now, and a massive high builds behind it.

gfs loop
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Quoting tornadodude:


those topics are entwined like none other btw


No problem, I actually am learning a few things.
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Good Evening!

Tropical Update #25...Fred broke records.. =)
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1189. Grothar
Quoting GeoffreyWPB:


I am better with systems that have formed. Something that does not exist as of now, I have no idea. Sorry.


One of the best answers I have received. I admire your honesty. Thanks!!
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We could sure use the rain in my corner of Orlando, no rain for 6 days hare, and only 1.6" for the entire week before that. If we could just squeeze out a few more good downpours before the rainy season ends...
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Hey, there are some of us that USED to be able to simplify that.... does that mean we're bad people???? lol



I stood outside a short while ago and looking off to the SE I could see the flashes from that complex of clouds. That's as much as maybe, 15, maybe 20 miles away? U wouldn't think u could see lighting from that far...
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1186. centex
Quoting GeoffreyWPB:


Label yellow something that is not there yet, but might be there?
Yes, area where they think development could happen in 48 hours. Not calling for CAT 5 just small chance TD could develop in that area. We are not talking CV time frames in GOM.
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Quoting caneluver:


Good evening! Welcome to the Tropical/Math solving blog....


those topics are entwined like none other btw
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Quoting Grothar:


Which feature is supposed to develop. The upper or the lower?


I am better with systems that have formed. Something that does not exist as of now, I have no idea. Sorry.
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1183. Patrap
GOM GOES-12 Channel 4 (IR)
Loop
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1182. Grothar
Quoting StormW:
Good evening!


Before anyone else gets to you. What is your opinion of the models turning Fred more westerly in a few day? Any validity?
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Quoting StormW:
Good evening!


Good evening! Welcome to the Tropical/Math solving blog....
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Quoting VAbeachhurricanes:
hey man im sorry i gotta go. but go here it should explain all your simplifying needs :)
math help




thanks so much :)
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hey man im sorry i gotta go. but go here it should explain all your simplifying needs :)
math help


Quoting tornadodude:
alright, I got another. link
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1178. Patrap
WV Ch-3 GOM

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1177. hydrus
Quoting Grothar:


Wroooooong. If x=1 and y=1 the answer is 2=1
He was trying to figure a bend in the universe.

Anybody have the latest models on the direction of Fred? Those spaghetti models are too confusing. What is the thinking on long term forecast, please!!!!
#%&*((^%! I will improve.
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Quoting watcher123:


I doubt he knows what a vertical asymptote is if he doesn't know how to simplify that. What is this? Ninth grade algebra? Eighth if you were in the "advanced" class.


well, it is MA 153, one of my classes I take for my meteorology degree. yes I know it is simple, but my brain is fried, and am just looking for some help, which I got, Thanks guys :)
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Quoting Jerrob:
yes, i know.. Im in central fl. we havent had anything for a few days.
Ditto.We have not had our aft. storms the past few days.Kinda miss em!
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1173. Patrap
Late Day Image from earlier

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Quoting centex:
May be about time for NHC to label "yellow" 48HR potential in SW GOM, not what is there now but will be.


Label yellow something that is not there yet, but might be there?
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1171. Grothar
Quoting GeoffreyWPB:
Quicker loading post of the GOM


Which feature is supposed to develop. The upper or the lower?
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hey guys what you think about this



# 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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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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