Fred fading; halfway point of hurricane season reached

By: Dr. Jeff Masters , 1:40 PM GMT on September 10, 2009

Hurricane Fred peaked in intensity yesterday afternoon, attaining Category 3 strength with 120 mph winds. 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 the data record. However, this type of system would have been difficult to document before satellite pictures began in the 1960s.

Fred's glory is past, and the storm is on a downslide now, thanks to moderate wind shear of 15 - 20 knots and dry air eating into the hurricane's southwest side. The shear and the dry air will increase over the next few days, with the shear rising above 40 knots by Monday morning. Sea surface temperatures (SSTs) will also cool to near the 26.5°C threshold needed to sustain a tropical cyclone. The combination of high shear, dry air, and cool SSTs will likely kill Fred by Tuesday.

Figure 1. Hurricane Fred at peak strength, 8:55am EDT UTC 9/9/09. At the time, Fred was a Category 3 hurricane with 120 mph winds. Image credit: NASA.

Elsewhere in the tropics
An upper-level low pressure system has moved over Texas and is expected to spawn a surface low pressure system along the Texas Gulf of Mexico coast on Friday. This low will probably have characteristics of both a tropical and extratropical storm. The surface low is likely to move northeastward and move ashore near the Texas/Louisiana border region on Saturday or Sunday. There will be some high wind shear to the west of the low (shear is currently a high 25 knots), so it is uncertain whether this low will be capable of developing into a tropical cyclone. Regardless, this storm will bring heavy rain capable of causing flooding--and help alleviate the exceptional drought conditions over Southeast Texas.

Early next week, we should be alert for tropical storm development over the waters between the Bahamas and North Carolina, along an old frontal zone. None of the reliable models are forecasting tropical storm development in this area or in the Gulf of Mexico, though.

Figure 2. The climatological halfway point of the Atlantic hurricane season is today, September 10.

Halfway point of hurricane season
September 10 marks the halfway point of the Atlantic hurricane season. Despite a late start (Tropical Storm Ana did not form until August 15, the latest start to a hurricane season since 1992), our number of storms has been near average. An average Atlantic hurricane season has 5 named storms, 3 hurricanes, and 1 intense hurricane by the midpoint of the season. So far this year, we've had 6 named storms, 2 hurricanes, and 2 intense hurricanes. A better measure of hurricane activity that takes into account their destructive power is the Accumulated Cyclone Energy (ACE) index. ACE for an individual storm is computed by squaring the maximum sustained winds of the storm at each 6-hourly advisory, and summing up over the entire lifetime of the storm. As of 5am EDT this morning, the seasonal ACE tally was 37.5. This number should rise to around 40 by the end of the day, thanks to the presence of Hurricane Fred. Over the period 1950 - 2005, the average ACE index for a half-season was 51, so 2009 ranks about 20% below average for the halfway point of the season. But when compared to the hurricane seasons we've been having since the current active hurricane period began in 1995, this year has been quite inactive. Between 1995 and 2008, the average ACE index for the halfway point of the season was 72. Thus, 2009 is about 45% less active than what we've been accustomed to over the past 14 years.

We've been lucky this year that the steering currents have aligned to keep our two major hurricanes, Bill and Fred, out to sea. What will the rest of the season have in store for us? I'll present an analysis on Friday.

Twenty years ago on this date
On September 10, 1989, the strong tropical wave that had moved off the coast of Africa the previous day acquired an organized circulation at the surface and began building a concentrated area of heavy thunderstorms near its center. A new tropical depression, the 12th of the season, was born. Moving westward at 20 mph, the depression brought strong, gusty winds and heavy rain showers to the Cape Verdes Islands as it passed to the south. Forecasters at the National Hurricane Center predicted that the steadily organizing tropical depression would strengthen into a tropical storm within the next day or two. The next name on the list of Atlantic tropical storm names for 1989: Hugo.

Figure 3. AVHRR visible satellite image of Tropical Depression Twelve taken on September 10, 1989. Image credit: Google Earth rendition of the NOAA HURSAT data base.

Jeff Masters

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Quoting TampaSpin:

AOI and tropial Update

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AOI and tropial Update
Member Since: September 2, 2007 Posts: 179 Comments: 20521
1911. hydrus
Quoting BobinTampa:
Good morning everyone. Always sad thinking back to 8 years ago and what took place. Never forget that day.

I never forget, today just makes it worse..:(

Member Since: September 27, 2007 Posts: 1 Comments: 26127
It is a sunny, warm day in Charleston
I just stepped outside to listen to the Bells Tolling.

For all of us, but particularly those of you who lived in New York and family members of those who were lost in the Towers, the Pentagon and aboard the 4 Planes, you are in my heart and prayers.

I thank those who serve in the armed forces of so many countries and have participated in the battle against terrorism.
It is much appreciated.

Member Since: August 19, 2008 Posts: 6 Comments: 2490
1909. IKE
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1908. Buhdog

looks like some rotation of the swfl coast...any chances here?
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1907. Bonedog
quick look at the bouy data does show a surface circ with the NJ system. alot of 35knt gusts and some higher.

Going to be a cold windy rainy day here
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I agree BT... also the NHC's AOI is down there as well...
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Any talk on the GOM this morning Storm:W
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1904. Bonedog
P451 Im in NJ also =) goofy must be quite a sight down there on the Shore
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Re: Post 1846
Looks like an eye o'head. No buoy update since 1250 GMT. Storm tracks are to WNW to NW so center of Circ. headed towards Cape May. Winds here gusting to 17+ kts @ Bradley Beach to 35kts in Point Pleasant. Both Stations near the beach. High tide also coming. Sand blowing off beach since early pm yesterday.
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1899. Bonedog
BTW the phase diagrams for the system of NJ right now all show warm core, LOL Seems extratropical to me too darn chill to be tropical. Also no organized convection to speak of, Just a plain ol fall gale with a cold chilly windswept rain.

Does have a nice wind with it though. All beacuse of the strong High to our north its a pressure gradiant wind not storm induced. Should be a fun afternoon as the center starts to pass by.
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1898. Bonedog
I hear ya Storm still keeping my fingers crossed for October. Dont need one sneaking up the Yuc on me
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1897. IKE
NORFOLK, Va. (AP) - Frank Batten Sr., who built a communications empire that spanned newspapers and cable television and created The Weather Channel, died Thursday. He was 82.

Batten, the retired chairman of privately held Landmark Communications and a former chairman of the board of The Associated Press, died in Norfolk after a prolonged illness, Landmark Vice Chairman Richard F. Barry III said.
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Quoting StormW:

Don't have any track info for you right now, but, I think it will continue to organize, albeit it's gonna be a slow process.

Ok, thank you.
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1895. Bonedog
Rita would be eerie. Have been in a few situations like that, actually puts fear into you because all of a sudden you realize what beast your dealing with
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1891. Bonedog
Thanks =)

Hopefully things get better for you. I can imagine how busy you have been. Started off quiet enough.
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Can you imagine being on a ship and the sun coming out and winds going calm just offshore of'd be like what the heck?
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1888. Grothar
Sorry, quote function not working.

Just hit refresh and go back to the quote, I am having a similar problem. Usually works when you hit refresh.
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Hey Storm, what do you think of the wave that exited the African coast?
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1886. Bonedog
Hey Storm. Been very good Sir.

Been busy as all heck. Got my EMT Cert and have been working for my town at night and doing the normal job during the day.

Hows things on your end?
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Quoting TheCaneWhisperer:

I never said it was out of the question. If you go back to post 1800 and 1801 I actually agree with the scenario for Fred but, the post you questioned of mine had nothing to do about any specific storm rather a persistent pattern. I really don't care for the debate, keep my posts in context.

i am not sure, but I think my point is being missed all together.

point is: mother nature is an opportunist.. el Niño, recurves etc etc only lessens mother natures # of opportunities for a land strike, it doesnt eliminate them.

I don’t believe I was taking u out of context, maybe with fred but not with the entire season rational.
At this point is just agree to disagree, no need to get upset about it.

Anyway, im out for now..
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1884. Bonedog

Nice Ol Nor'Easter

NE1 and its a month early.
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1882. Bonedog
gotta love a good gale =)

raining heavy, its windy and cold. I love the NE this time of year LOL
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Quoting caneluver:

I see your a Packers fan. I will forget your smart a@#ness since I am a big fan myself. Can't wait until we play the Vikes.

I never knew you Packer fans were so eagar to get beat LOL! No worries, it will happen soon enough, Oct. 5th to be exact! Go Vikings!
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Blog Update
Reflector site for those at work, includes Dr. Masters & Weather456, daily update.




Member Since: October 1, 2007 Posts: 81 Comments: 26525
even thought it's insignificant, it does have a friggin eye!
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1875. jpsb
Quoting StormW:
Anyone know the significance of this?

Ahhh, low pressure just past by?
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The GOM low shows no signs of development at this time.
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Quoting TheCaneWhisperer:

I never said it was out of the question. If you go back to post 1800 and 1801 I actually agree with the scenario for Fred but, the post you questioned of mine had nothing to do about any specific storm rather a persistent pattern. I really don't care for the debate, keep my posts in context.

Post is not in context if you are looking at current information. You are looking at past trends.
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Nothing happening in the Gulf off TX,
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If that's the case then there you have it. It does resemble Hannah but this is stronger. The one thing I must continue to point out is that it is cold and damp here - not warm and sticky as every TS I've known has given us regardless of calendar date. It just has the look and feel of a winter gale and not a tropical system.

Sorry, quote function not working. Obviously, then, it's a hybrid system. Cold air with no one minute sustained winds is a gale. Other features are more tropical in character.
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Quoting CandiBarr:

the females dont look like recurves to me, not at all. personally I am not gonna count storm "one" as it doesnt have actual name.

and the models had fred doing backflips two days ago we believed them then. why is it now out of the question that it would trend west over north or northeast?

I never said it was out of the question. If you go back to post 1800 and 1801 I actually agree with the scenario for Fred but, the post you questioned of mine had nothing to do about any specific storm rather a persistent pattern. I really don't care for the debate, keep my posts in context.
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Quoting Hurricajun:
I hate to ask, but is that in the GOM?

stalled weak surface trof in the gulf might eventually bring TX some flooding rains in a few days.Pressure in the area are quite high.
Member Since: May 14, 2006 Posts: 8 Comments: 13857
area of disturbed weather off the african coast could become invest 97L . That is if the area off the us east coast is not designated today
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Looking at the loop that this image comes from, the eye like feature in the centre, which would have caused the drop in pressure and wind speed, only forms at the end of the loop, so it's probably a very recent development.

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Dr. Masters co-founded wunderground in 1995. He flew with the NOAA Hurricane Hunters from 1986-1990. Co-blogging with him: Bob Henson, @bhensonweather

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