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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Quoting weatherbro:


oops...


You get a little credit. Hugo emerged as a cluster and wave on the 9th of September, so you could, theoretically say he was born on 9/9/89. At least you now the year, Good work!!
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Quoting btwntx08:

Link
here u go texashurricane


yep, right on top of us....You see this homeless?
Member Since: July 2, 2009 Posts: 0 Comments: 2811
Quoting StormW:


From my morning forecast:

Based on current motion, current real time shear, and forecast wind shear, as well as still warm SST's , I am not going to rule out further strengthening during the next 24 hours. However, based on the current motion and forecast track, FRED should level off after 24 hours, moving into cooler SST's and increasing wind shear. Based on this, I have to concur with the NHC intensity scheme, though I would not be surprised to see a CAT3 intensity of possibly 5-10 kts higher than the intensity scheme. So there we have it, another one for breaking the rules. Based on the forecast track, I do expect FRED to encounter SWLY wind shear in the next 72 hours or so.

Fred had been moving to the WNW, in response to the first weakness in the subtropical ridge, and has taken on a more NW motion.

expect this motion to continue for the next 24 hours, with a turn more to NNW. By he end of the forecast track period, based on the most recent steering layers forecast maps, and weakening of FRED, I am calling for a motion back to the WNW at around 120 hours, to about a 295 degree heading. I still believe we are going to see, and to the surprise of some, FRED, or what's left of FRED, to make it further west than anticipated before we see a final recurve out to sea.

I do not anticipate any impact to the Lesser Antilles or CONUS based on the consistency of the pattern.

I will continue to monitor the progress of FRED for any significant changes.



Thanks so much StormW
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Quoting btwntx08:


close its has it at the tx/la border


First model I've seen all day. :(
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Quoting Grothar:


Little off on your days, are you not?


oops...
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Quoting btwntx08:


close its has it at the tx/la border


oh, well then I'd say that is pretty darn close...... This suppose to be Saturday?
Member Since: July 2, 2009 Posts: 0 Comments: 2811
Analyst Wx Tropical Update!

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Quoting hurricanehanna:

Heya Surfmom! How have ya been? I think this is our first encounter this season. Waves been good to ya? Maybe light a couple - we have been blessed!


for sure!!! -- but it's not over till......
never enough waves..... be nice if this bit in the gulf just bumped the buoys enough to give the gomex surfers...something... and then dissipates.

I've learned to be careful for what I wish...
been running over to the E.Coast to catch waves...

but w/school on -& polo season fast approaching - no time -- my mermaid light is dimming..I need to ride some waves...would even take cold front waves at this point.
Summer rains were good this year - all horse pastures are thick with gorgeous grass.
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Quoting weatherbro:
It was 20 years ago today, Sargent Hugo taught the band to play...


Little off on your days, are you not?
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Quoting btwntx08:
not good for texashurricane here 18z NAM at 72 hrs


got a link to this so I can see it more close up?
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Quoting iceman55:
btwntx08 .so t.s over me ?

where you at Iceman?
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What an interesting year. I have to admit that it has been a tough forecast pattern so far giving this old weatherman fits particularly the environmental conditions. 5 out of 7 of the analog years on CPC's long range forecast have tropical cyclones impacting the SE Coast and points north with a couple of heavy hitters--Isabel in 03 and Gracie in 59. Yet again, a few of the models hint at development in the SW Atlantic next week. Not so sure the US is off the hook as I have heard in other quarters lately.
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Hey everyone! I am new to this weather chat and to actually talking about weather so don't beat on me that bad :o) . What is going on with Fred? Is he moving north...or west...? To me it looks like he keeps moving west?
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It was 20 years ago today, Sargent Hugo taught the band to play. Guaranteed to raise a smile. He would like you all to sing along. So let me introduce to you. If you remember all these years. Sargent Hugo's Lonely Hearts Club Band!!!
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Quoting iceman55:
so n..h.c follow ukm rigth ????help me


Appears so! How much to the west is still a wait. There should be another trough (or troff)that may swing it further north.
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Quoting all4hurricanes:
Did anyone else think that this could be the first season where all the hurricanes are major?
Were ya been?
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Quoting TexasHurricane:


Mauriceville,TX - about 10-15 minutes from the LA border.


I used to live off Hwy 12 in Mauriceville, tx grew up there but now live in H-town
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Quoting Grothar:


DUDE????????????


haha its been a long day at class :P
Member Since: June 28, 2006 Posts: 24 Comments: 8185
Quoting Autistic2:
Is it too late in rge season for something to spin up in the GOM? I thought that was an June or July thing?


And Septmeber October November
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Quoting tornadodude:


do golden panthers take golden showers?


DUDE????????????
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A Negative NAO means blocking in the Atlantic sets up a semi-permanent Long-Wave Trough in the eastern U.S. Allowing cooler drier air to easily flow out from Canada and re-curve any hurricane. According to the GFS and European models, this should happen sometime next week.

Early Autumn anyone?
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part of Houston/Galveston NWS disussion...

Regarding the nam12 solution...the last several runs have shown a surface
low developing and deepening out near buoy 42002 beginning tomorrow
aftn/evng. It's not totally out of the range of possibility considering
all the models are showing a temporary weakening of the shear aloft
at that time off the Texas coast. But they also increase it again
early Friday. Majority of the models do show various circulations
between now and the weekend...most of which are usually spurious
or short lived convectively induced in such a pattern we are
under. That being said this is typically the peak week of
hurricane season so will never rule anything completely out...but
have a feeling the nam12 is over developing that feature but have
seen weirder things occur. Will just have to watch. If for some reason
something does develop...we'll probably need to pare probability of precipitation down in
the short term as most precipitation will become focused offshore.
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Quoting P451:
168HR GFS - Fred...and friends?

That model shows the Cape Verde Islands being brushed or hit by a storm!
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Quoting BobinTampa:

"BELIEVE THAT THE HEAVIEST RAINFALL WILL BE FOUND ACROSS THE GOLDEN TRIANGLE."


is that called a golden shower???


do golden panthers take golden showers?
Member Since: June 28, 2006 Posts: 24 Comments: 8185
Quoting Grothar:


You don't look old enough to remember that show, or the Flygirls. Besides my wife is a lurker on this blog!! SHHHHHH.


Oh no. Y'all have set Mr Brooks in there going off with the impressions. Lol. That was a great show. :) Wanda was my fav.
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WTNT42 KNHC 092033
TCDAT2
HURRICANE FRED DISCUSSION NUMBER 9
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL072009
500 PM AST WED SEP 09 2009

THE EYE OF FRED HAS BECOME LESS DISTINCT THIS AFTERNOON AS CIRRUS
CLOUDS HAVE OBSCURED THE CENTER. HOWEVER...CONVECTION IN THE
EYEWALL REMAINS STRONG WITH AN OVERALL SATELLITE APPEARANCE
BEFITTING A MAJOR HURRICANE. SATELLITE CLASSIFICATIONS ARE A
LITTLE LOWER THAN SIX HOURS AGO...AND THE INITIAL INTENSITY IS
REDUCED TO 100 KT. FURTHER WEAKENING IS POSSIBLE LATER TONIGHT BUT
A MORE SIGNIFICANT WEAKENING IS EXPECTED BY LATE TOMORROW AS FRED
ENCOUNTERS INCREASING VERTICAL WIND SHEAR AND DECREASING WATER
TEMPERATURES. THESE ENVIRONMENTAL CONDITIONS ONLY GET MORE HOSTILE
AFTER 48 HOURS AND THE SHIPS MODEL ALSO DIAGNOSES DRY MID-LEVEL AIR
NEAR FRED. INTENSITY GUIDANCE IS COMING INTO BETTER AGREEMENT WITH
THE HWRF/GFDL NOW SHOWING A WEAKER SYSTEM THAN EARLIER MODEL RUNS
BY DAY 5. THE OFFICIAL FORECAST IS REASONABLY CLOSE TO A BLEND OF
THE SHIPS/LGEM AND THE PREVIOUS FORECAST. IT WOULD NOT BE
SURPRISING IF FRED DISSIPATED BEFORE THE END OF THE FORECAST
PERIOD.

THE INITIAL MOTION IS NOW 315/11. FRED CONTINUES TO GRADUALLY GAIN
LATITUDE AS SUBTROPICAL RIDGING ERODES TO ITS NORTH. WHILE THERE IS
GENERAL AGREEMENT ON THE HURRICANE TURNING TOWARD THE NORTH AND
DECELERATING IN A DAY OR SO...THERE ARE A VARIETY OF SOLUTIONS
THEREAFTER. AT ONE EXTREME...THE UKMET HAS FRED MISSING A MID- TO
UPPER-LEVEL TROUGH OVER THE CENTRAL ATLANTIC...CAUSING THE CYCLONE
TO STALL SOUTH OF 17N AND EVENTUALLY MOVE WESTWARD UNDER A NEW
RIDGE. A DIFFERENT SOLUTION IS PROVIDED BY THE GFDL/HWRF/NOGAPS
MODELS...WHICH SHOW FRED BEING STEERED QUICKLY NORTHWARD BY THAT
TROUGH AND APPROACHING 30N BY THE END OF THE FORECAST. AT THIS
POINT...THE OFFICIAL FORECAST WILL LEAN ON THE IDEA THAT THE
CYCLONE WOULD EVENTUALLY WEAKEN AND BE STEERED MORE BY THE
LOWER-LEVEL FLOW AT LONG-RANGE...LEADING TO A MORE WESTWARD TRACK
AT THAT TIME. THE OFFICIAL FORECAST IS CLOSE TO THE PREVIOUS
FORECAST AND REMAINS TO THE SOUTHWEST OF THE MODEL CONSENSUS AT DAY
5.

FORECAST POSITIONS AND MAX WINDS

INITIAL 09/2100Z 14.8N 33.3W 100 KT
12HR VT 10/0600Z 15.8N 34.0W 95 KT
24HR VT 10/1800Z 17.0N 34.6W 90 KT
36HR VT 11/0600Z 17.8N 34.7W 80 KT
48HR VT 11/1800Z 18.3N 34.4W 65 KT
72HR VT 12/1800Z 19.5N 33.5W 50 KT
96HR VT 13/1800Z 21.5N 34.5W 40 KT
120HR VT 14/1800Z 23.5N 37.0W 25 KT

Who has been saying more westerly????
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"BELIEVE THAT THE HEAVIEST RAINFALL WILL BE FOUND ACROSS THE GOLDEN TRIANGLE."


is that called a golden shower???
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Data Time:2009-Sep-09 1700 EDT
Lat/Lng:Lat: 14.8 Lng: 33.300
Wind Speed:115 (sustained) 150 (gusts) mph
Pressure:960 mb
Category:H3
Heading:Northwest
Bearing:-62.6 degrees
Forward Speed:13 mph
Hurricane Radius:25 miles
Tropical Radius:100 miles
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Quoting tanman63:


Actually, in the past 100 years, 4 cyclones have made it to the U.S. that where 'alive' 100 miles in the vicinity of where Fred is, just in September :)

Well I stand corrected, I was just looking at the historical data posted on wunderground yesterday of the storms/hurricanes that formed within 200 miles of where Fred formed, not where it is now and could not find one reaching the US, I'm not arguing & you could could absolutely be correct, just going by what was posted on this site yesterday.
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676. JLPR
low to PRs northeast has some decent winds with it
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5PM NHC track lookss very similar to the 12z CMC model run.
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000
WTNT32 KNHC 092033
TCPAT2
BULLETIN
HURRICANE FRED ADVISORY NUMBER 9
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL072009
500 PM AST WED SEP 09 2009

...FRED WEAKENS A LITTLE...BUT STILL A MAJOR HURRICANE...

AT 500 PM AST...2100 UTC...THE CENTER OF HURRICANE FRED WAS LOCATED
NEAR LATITUDE 14.8 NORTH...LONGITUDE 33.3 WEST OR ABOUT 595 MILES...
955 KM...WEST OF THE SOUTHERNMOST CAPE VERDE ISLANDS.

FRED IS MOVING TOWARD THE NORTHWEST NEAR 13 MPH...20 KM/HR. A
GRADUAL TURN TOWARD THE NORTH-NORTHWEST AND NORTH WITH A DECREASE
IN FORWARD SPEED IS EXPECTED OVER THE NEXT COUPLE OF DAYS.

MAXIMUM SUSTAINED WINDS HAVE DECREASED TO NEAR 115 MPH...
185 KM/HR...WITH HIGHER GUSTS. FRED IS A CATEGORY THREE HURRICANE
ON THE SAFFIR-SIMPSON HURRICANE SCALE. ADDITIONAL WEAKENING IS
FORECAST DURING THE NEXT 48 HOURS.

HURRICANE FORCE WINDS EXTEND OUTWARD UP TO 30 MILES...45 KM...FROM
THE CENTER...AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO
115 MILES...185 KM.

ESTIMATED MINIMUM CENTRAL PRESSURE IS 960 MB...28.35 INCHES.

...SUMMARY OF 500 PM AST INFORMATION...
LOCATION...14.8N 33.3W
MAXIMUM SUSTAINED WINDS...115 MPH
PRESENT MOVEMENT...NORTHWEST OR 315 DEGREES AT 13 MPH
MINIMUM CENTRAL PRESSURE...960 MB

THE NEXT ADVISORY WILL BE ISSUED BY THE NATIONAL HURRICANE CENTER AT
1100 PM AST.

$$
FORECASTER BLAKE/BERG
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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.