Fred fading; halfway point of hurricane season reached

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

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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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1563. msphar
Fred's is being shredded tonight. How cool is that ?
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1562. JLPR
Quoting GustyinPR:
Im 26 so Marylin, Luis, Bertha, Hortence, Georges even stupid lefty Lenny come to my mind


yep lived through all of those but I don't remember them very clearly
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the man who founded the weather channel has passed away. he was 82 and sunny.
-conan o'brien
Member Since: June 28, 2006 Posts: 24 Comments: 8201
Quoting F4PHANTOM:
http://www.txtornado.net/GFS/wna_10m_gfs_00z.htm#

Check this out. Very interesting.Gfs jumps a low from south of Corpus to east of Houston in 6 Hrs. time. Then senda another low up the coast on the 13th. Any thoughts ?


I haven't seen that yet. Just got done paying bills. But they've been sending one after another. A friend told me they had mentioned multiple vortex. Looks crazy doesn't it.
Member Since: August 15, 2008 Posts: 10 Comments: 3665
Quoting hydrus:
maybe we should establish a troll court to actually prove who a troll and who is exempt.


Best thing ive heard in a while. You made my day, thanks :)
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1558. centex
Quoting ElConando:


There is a point sir. Stormt and his previous incarnations are not forecasters. Unless you are talking about someone else stormt is a doom caster. He hypes up many a storm and 9 times out of 10 nothing happens. He called Danny to become a cat 2. This season. I respect those who don't call for a hurricane when nothing is there yet.
Don't care who started it, blog discounted tropical event and that was wrong period. Anyone who tried to add reason was accused of being troll. This needs to change.
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1557. Seawall
Quoting TexNowNM:
Seawall,

Are you in that "rain shadow" like thing that keeps some from getting KFDM?
Yes, I am, and can't get local channels from Dish because we are so rural.
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Im 26 so Marylin, Luis, Bertha, Hortence, Georges even stupid lefty Lenny come to my mind
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Lost my whole damn house with Rita...scared for Ed.....sprang up awfully fast with a HOT Gomex....just wanted to say...SWLA...read AUDREY

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Georges @ Puerto Rico 1998

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1552. hydrus
Quoting RitaRefugee:
yeah, well i evacuated for Rita, Ike, and Gustav...never again...screw it...my house was ok, i have a well, and I have gas and food....more than a cat 3, i'll go to Alex, but Im home the day after
I almost see some hostility in that post. But I can understand you, point well taken.
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1551. JLPR
Quoting GustyinPR:
"PR is very lucky, for being an island(well actually various islands) in the middle of the ocean it hasn't been visited by hurricanes for awhile"
How old are u JLPR? Its true the 2000's has been a calm decade for PR but the 90's ufffs they were really busy years.


18
and yep the 90s were much more active with quite a few close calls for PR
but so far the 2000s have been relatively calm
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Quoting centex:
Not the point.


There is a point sir. Stormt and his previous incarnations are not forecasters. Unless you are talking about someone else stormt is a doom caster. He hypes up many a storm and 9 times out of 10 nothing happens. He called Danny to become a cat 2. This season. I respect those who don't call for a hurricane when nothing is there yet.
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Quoting JLPR:


yep definitely felt stronger than a TS


Very impressive pic, thank you
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Centex,

I have felt far more comfortable blogging tonight with the skeleton crew that is here, than usual. Sometimes people are mean on this blog and that just isn't okay. Most of the people in my happy little world are nice and I like to keep it that way.

There is one young man who is sometimes on here, who is accused of being a troll, but I think he is just really enthusiastic and lacks "raising." Being unkind is not the way to show anyway how to act. Sorry to be so preachy, but I am a teacher so it comes naturally (lol) and my students are sweet even though they are in 6th grade.
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1547. centex
Quoting hydrus:
Centex-Even a troll with some weather knowledge can estimate with some accuracy what might happen this time of year in the warm G.O.M. And remember, not all the people here are responsible for ferreting out trolls..maybe we should establish a troll court to actually prove who a troll and who is exempt.
Point is reasonable predictions are not accepted. It had some model support and could happen. We should not humiliate anyone who says that is there prediction. Could be you next time. If you disagree just post why, all this troll cramp is real small.
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"PR is very lucky, for being an island(well actually various islands) in the middle of the ocean it hasn't been visited by hurricanes for awhile"
How old are u JLPR? Its true the 2000's has been a calm decade for PR but the 90's ufffs they were really busy years.
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1545. 7544
hi all looks like fred does not want to move or give up just yet looks like hes getting bigger ???? could be good at dmax tonight
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Edouard....TD to Hurricane in 12 hours...dont mess with GOMEX
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1543. hydrus
Quoting RitaRefugee:
GO centex.....anybody here remember Eduaoard? Short sighted Hypercasters missed it....I'm watching GOMEX...fixed my generator tonite....no power SUCKS
Heard that like a giant ear hole man, did 17 days with out the juice.
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1542. JLPR
Quoting jurakantaino:
I remember George so well, my "tormenteras" almost broke and noise was unbearable, sounded like a train. The eye went also on top of us, we went out to get the avocados from our fallen tree, Jeane was almost a hurricane i felt her eyes was broad, calm for about half our, for me it was a category 1 but it wasn't classify at such until it came out by the cooast of Aguadilla in the Mona canal.


yep definitely felt stronger than a TS
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I totally agree with CENTEX but that happens alot in here, and alot of us, like myself, are just trying to be informed so that we can keep our families out of the way of a major storm and facts are, you never know what may happen.
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1540. hydrus
Quoting jurakantaino:
Metropolitan area about 10 minutes from S.Juan, north east
Yes, I know this SanJuan you Speak of. Gracias.
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1539. JLPR
Quoting jurakantaino:
Metropolitan area about 10 minutes from S.Juan, north east


yep exactly =D
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GO centex.....anybody here remember Eduaoard? Short sighted Hypercasters missed it....I'm watching GOMEX...fixed my generator tonite....no power SUCKS
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1537. hydrus
Quoting centex:
Blog warning. Yesterday a so called troll predicted named storm in GOM this weekend. Everyone jumped on him for being a troll and making outrageous claims without any supporting data. Fact, he did present some data and reasoning, while limited it was not off the wall. Shame on you guys/gals for jumping on each trop forecast which does not match NHC at point in time. There must have been over 20 post critical of post and calling names. I think it was more reasonable than most post on this blog. Who is being professional? There is an arrogance to accept only NHC similar caster and trash everyone else, I guess everyone must put percent chance in claims. I guess this one was suggesting greater than 50, NHC now saying less than 30, so we better label them a troll. Sorry for long essay but blog and regulars have a problem too.
Centex-Even a troll with some weather knowledge can estimate with some accuracy what might happen this time of year in the warm G.O.M. And remember, not all the people here are responsible for ferreting out trolls..maybe we should establish a troll court to actually prove who a troll and who is exempt.
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Quoting hydrus:
lol..wheres Carolina? north..south..east..west..
Metropolitan area about 10 minutes from S.Juan, north east
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1535. centex
Quoting ElConando:


was his name Stormt?
Not the point.
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Quoting JLPR:


thank you =]

PR is very lucky, for being an island(well actually various islands) in the middle of the ocean it hasn't been visited by hurricanes for awhile
I remember George so well, my "tormenteras" almost broke and noise was unbearable, sounded like a train. The eye went also on top of us, we went out to get the avocados from our fallen tree, Jeane was almost a hurricane i felt her eye was broad, calm for about half our, for me it was a category 1 but it wasn't classify as such until it came out by the cooast of Aguadilla in the Mona canal.
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Seawall,

Are you in that "rain shadow" like thing that keeps some from getting KFDM?
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Quoting centex:
Blog warning. Yesterday a so called troll predicted named storm in GOM this weekend. Everyone jumped on him for being a troll and making outrageous claims without any supporting data. Fact, he did present some data and reasoning, while limited it was not off the wall. Shame on you guys/gals for jumping on each trop forecast which does not match NHC at point in time. There must have been over 20 post critical of post and calling names. I think it was more reasonable than most post on this blog. Who is being professional? There is an arrogance to accept only NHC similar caster and trash everyone else, I guess everyone must put percent chance in claims. I guess this one was suggesting greater than 50, NHC now saying less than 30, so we better label them a troll. Sorry for long essay but blog and regulars have a problem too.


was his name Stormt?
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1530. Gumluvr
Quoting TexNowNM:
Gumluvr,

O-field is on a salt dome, thank God! Everybody, almost, got water except O-field. Some of the homes in the school district took water, and down the main road water came up from the bayou over the road, but no homes in O-field itself had water. It is pretty darn scary when you look at a map and see that area in the middle still dry, but water all around. It was weird! Mom and Dad didn't even have water get out of the banks of the drainage ditch by their house but most of the rest of the south part of the county flooded. An old survey mark (I mean old!) on my uncles land is 17 feet. That is pretty high for that part of Orange county.

According to the NOAA maps, we could get 10 feet on top of us with a cat 5 or a hurricane with a big enough wind field. That makes Kountze look reeeeealy nice!


Wow! Thanks for letting me in on that info. I really need to go check out that new slosh map. Glad your family was high and dry.
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1528. hydrus
Quoting Progster:
Delaware bay bouy near Cape May.

Must be tough on the Lewes Cape May Ferry this eve...

Link
Yes, I hope she stayed home.
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1527. centex
Blog warning. Yesterday a so called troll predicted named storm in GOM this weekend. Everyone jumped on him for being a troll and making outrageous claims without any supporting data. Fact, he did present some data and reasoning, while limited it was not off the wall. Shame on you guys/gals for jumping on each trop forecast which does not match NHC at point in time. There must have been over 20 post critical of post and calling names. I think it was more reasonable than most post on this blog. Who is being professional? There is an arrogance to accept only NHC similar caster and trash everyone else, I guess everyone must put percent chance in claims. I guess this one was suggesting greater than 50, NHC now saying less than 30, so we better label them a troll. Sorry for long essay but blog and regulars have a problem too.
Member Since: Posts: Comments:
yeah, well i evacuated for Rita, Ike, and Gustav...never again...screw it...my house was ok, i have a well, and I have gas and food....more than a cat 3, i'll go to Alex, but Im home the day after
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1521. JLPR
Quoting hydrus:
lol..wheres Carolina? north..south..east..west..


Northeast
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Well channel 12 said pretty much rain event tomorrow and lots saturday for sure. Then goes to oh yea fred's out there and then a wet day for us tomorrow and saturday
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Delaware bay bouy near Cape May.

Must be tough on the Lewes Cape May Ferry this eve...

Link
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1518. JLPR
Last images of Fred before the blackout

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1516. hydrus
Quoting JLPR:


Carolina
lol..wheres Carolina? north..south..east..west..
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Quoting hydrus:
I use to love math. Until they put a nifty page of calculus in my face...aaaarrrrgggghhhh!!!!


haha yuck!!! oh well :P
Member Since: June 28, 2006 Posts: 24 Comments: 8201
Quoting TexasHurricane:


oh,ok - sorry

channel 6

Watching Low Near Brownsville....



Low pressure is slowly becoming better organized near Brownsville this evening. This low will likely move slowly to the north-northeast and has some potential for some development. It is possible that it could become a tropical depression or tropical storm in the next 24-36 hours. The low should move inland near Freeport Saturday with widespread heavy rains spreading into our area. In fact through Sunday, rainfall totals to near 10 inches will be possible in isolated spots. With plenty of clouds, temperatures will be below normal for afternoon highs.


thanks, I try to learn on here to keep up with any storms since rita. I don't like for them to sneak up on us at all. Sometimes I know alot more from trying to learn and stay informed on this blog than I do from any news channel, of course I do appreciate all of our news channels.
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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.