Fred fading; halfway point of hurricane season reached

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

Share this Blog
1
+

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

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 1463 - 1413

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39Blog Index

Quoting hydrus:
Charley, Jeanne, David, Belle and the No name in June of 82. Those I will remember for the rest of my life.


What was notable about the 82 storm? Enlighten me.
Member Since: Posts: Comments:
lol, gfs 0000z, 30 hours. Everything looks exactly the same!

Member Since: Posts: Comments:
Quoting homelesswanderer:


I'm not sure yet. Lol. That probably doesn't help much. I'm sorry. :) I'm still in a wait and see. Hoping for a 12, preparing for a 6. Lol.


Funny quote and good, wise words. Can't wait to hang tomorrow. I hope we can just on the 13th as well. Night :)
Member Since: Posts: Comments:
Quoting btwntx08:

well earlier i saw a shear of 100 kts but now its down 80 kts lol



oh wow
Member Since: Posts: Comments:
1458. hydrus
Quoting JLPR:


I have been in a few only
but so far Georges takes the prize :P
Charley, Jeanne, David, Belle and the No name in June of 82. Those I will remember for the rest of my life.
Member Since: Posts: Comments:
I remember nobody could figure out how to pronounce 'Georges'.

I still can't. Was it 'hor-hays'?
Member Since: Posts: Comments:
Quoting homelesswanderer:


I'm not sure yet. Lol. That probably doesn't help much. I'm sorry. :) I'm still in a wait and see. Hoping for a 12, preparing for a 6. Lol.


LOL....yeah I know. I keep thinking it is going to be a 6.....
Member Since: July 2, 2009 Posts: 0 Comments: 2811
Quoting TexasHurricane:


so which one are you going with? 6 or 12?


I'm not sure yet. Lol. That probably doesn't help much. I'm sorry. :) I'm still in a wait and see. Hoping for a 12, preparing for a 6. Lol.
Member Since: Posts: Comments:

AOI

AOI

AOI

AOI
Member Since: October 1, 2007 Posts: 81 Comments: 26511
1452. GetReal
Member Since: Posts: Comments:
1451. JLPR
Quoting hydrus:
Georges was a bad one. I said to you back then I have been through to many to list. Some day I will do that...lol


I have been in a few only
but so far Georges takes the prize :P
Member Since: September 4, 2007 Posts: 36 Comments: 5223
Quoting F4PHANTOM:

Between San Antonio & Del Rio.Supposed to move out to the NE.
Thanks
Member Since: Posts: Comments:
1449. hydrus
Quoting WeatherMSK:
Man sure looks like this thing just to the south east of delmarva penisula is trying to get its act together. Looks almost tropical depression in nature right now, base on local radars.
Yeah, I think that storm is getting better organized. the weather guys might want to stay up and watch this one in case there are any surprises.
Member Since: Posts: Comments:
Quoting F4PHANTOM:

Don't even remember most of them,but there have been many.I look up history and find that I was in a Hurricane or Trop. storm that made little impression. Don't need anymore. But there will always be natures way of venting.


I said almost the same thing the other day. 17 storms and most of them a complete mystery to me. Nver even registered. Weird how a cat 3 crawling over your house will get your attention. Lol.
Member Since: Posts: Comments:
Cloudsat W Gom & E Pac
16, 17
Member Since: Posts: Comments:
Where is the low over Texas, and which way is it moving?
Member Since: Posts: Comments:
Quoting TexNowNM:
Tex,

Good post about Humberto. That little hurricane tore the heck out of High Island. The school and football field were badly damaged, as were some other buildings. (Football is a big deal in Texas.)


I know exactly what you mean, I live in Indiana now (really big on basketball) but I lived in Atlanta Tx for 8 years
Member Since: Posts: Comments:
Man sure looks like this thing just to the south east of delmarva penisula is trying to get its act together. Looks almost tropical depression in nature right now, base on local radars.
Member Since: Posts: Comments:
Tex,

Good post about Humberto. That little hurricane tore the heck out of High Island. The school and football field were badly damaged, as were some other buildings. (Football is a big deal in Texas.)
Member Since: Posts: Comments:
Quoting KoritheMan:


Not surprising, considering DeRidder is in western Louisiana, which was immensely closer to Humberto's center.


oh ok, my bad, I thought you said SW Louisiana, sorry! :P
Member Since: Posts: Comments:
Quoting TexNowNM:


That must have been like walking through water!


I was actually inside during the time of that rainstorm. Wasn't about to venture out in that, didn't want to get soaked. :P
Member Since: Posts: Comments:
Quoting homelesswanderer:


Just watched the locals. On totally opposite sides of the scale of course. But yeah I wanted to comment on Carey. I remember how he was about Allison. Lol. I cringe when he says somethings not coming here. Lol. Believe it or not Greg's calling for more chance of development this time.


so which one are you going with? 6 or 12?
Member Since: July 2, 2009 Posts: 0 Comments: 2811
Quoting tornadodude:


From Wiki-
link
Louisiana and Southeast United States

Tracking through the state as a weakening tropical storm, Humberto produced light to moderate winds across southwestern Louisiana. Gusts officially peaked at 43 mph (69 km/h) in the state, although an unofficial reading of 55 mph (89 km/h) was reported in Vinton.[23] Heavy rainfall occurred across the area, reaching a peak of 8.25 inches (210 mm) in DeRidder.[27] The rainfall triggered minor river flooding, and the Vermilion River in Lafayette reached a crest of 0.94 feet (0.29 m) above flood stage. Storm surge was minor in the state, peaking at 2.13 feet (0.65 m) in Cypremont Point;[28] no beach erosion was reported.[19]

Widespread freshwater flooding occurred in Beauregard Parish, leaving homes in DeRidder flooded. High water across the southwestern portion of the state resulted in the closure of several roadways, including U.S. Route 171 and various state highways. Isolated wind damage was reported, particularly near the Texas border, with some trees and power lines blown down. A total of about 13,000 power customers lost electricity in southwestern Louisiana.[19] After the circulation dissipated, the remnants of Humberto spawned several tornadoes across portions of South Carolina and North Carolina and caused widespread damage in some locations. Numerous tornadoes were reported,[29] though none caused injuries or fatalities.[30]


Not surprising, considering DeRidder is in western Louisiana, which was immensely closer to Humberto's center.
Member Since: Posts: Comments:
1437. hydrus
Quoting JLPR:


yep that's right
Georges was a bad one. I said to you back then I have been through to many to list. Some day I will do that...lol
Member Since: Posts: Comments:
1436. JLPR
Quoting KoritheMan:


There are also indications that the shear will ease a bit, particularly further south, beyond five days. Need to watch this.


yep Fred has his F name
the feared F name so he could surprise us all xD
Member Since: September 4, 2007 Posts: 36 Comments: 5223
Quoting KoritheMan:
Humberto was a non-event for southeast Louisiana, save the 5 minute rainstorm that produced 1-2 inches of rain. That was awesome.


From Wiki-
link
Louisiana and Southeast United States

Tracking through the state as a weakening tropical storm, Humberto produced light to moderate winds across southwestern Louisiana. Gusts officially peaked at 43 mph (69 km/h) in the state, although an unofficial reading of 55 mph (89 km/h) was reported in Vinton.[23] Heavy rainfall occurred across the area, reaching a peak of 8.25 inches (210 mm) in DeRidder.[27] The rainfall triggered minor river flooding, and the Vermilion River in Lafayette reached a crest of 0.94 feet (0.29 m) above flood stage. Storm surge was minor in the state, peaking at 2.13 feet (0.65 m) in Cypremont Point;[28] no beach erosion was reported.[19]

Widespread freshwater flooding occurred in Beauregard Parish, leaving homes in DeRidder flooded. High water across the southwestern portion of the state resulted in the closure of several roadways, including U.S. Route 171 and various state highways. Isolated wind damage was reported, particularly near the Texas border, with some trees and power lines blown down. A total of about 13,000 power customers lost electricity in southwestern Louisiana.[19] After the circulation dissipated, the remnants of Humberto spawned several tornadoes across portions of South Carolina and North Carolina and caused widespread damage in some locations. Numerous tornadoes were reported,[29] though none caused injuries or fatalities.[30]
Member Since: Posts: Comments:
Quoting KoritheMan:
Humberto was a non-event for southeast Louisiana, save the 5 minute rainstorm that produced 1-2 inches of rain. That was awesome.


That must have been like walking through water!
Member Since: Posts: Comments:
Quoting JLPR:


seems possible
the bad thing is that it could try to regenerate on the hotter waters that are close to the islands


There are also indications that the shear will ease a bit, particularly further south, beyond five days. Need to watch this.
Member Since: Posts: Comments:
Quoting Gumluvr:


Yeah, I live North of Beaumont in a little town named Kountze. It is about 30 minutes from Homeless. Where did you live in Texas before you moved??? Believe it or not, Greg is actually trying to do better this year. He really did a poor job last year. I agree, he is usually a big downcaster. Maybe, that is why Cary does the same. :(


Just watched the locals. On totally opposite sides of the scale of course. But yeah I wanted to comment on Carey. I remember how he was about Allison. Lol. I cringe when he says somethings not coming here. Lol. Believe it or not Greg's calling for more chance of development this time.
Member Since: Posts: Comments:
Gumluvr,

Of course I know where Kountze is. We have actually considered moving there instead of to old family homestead because Kountze is out of storm surge territory. After looking at the new Noaa storm surge maps, Kountze is looking even better.

We are north of Orangefield and south of I10, so surge is a huge concern. I guess when we do move back to Texas we will go back to the old land. I know how Patrap feels about New Orleans. Home is home.
Member Since: Posts: Comments:
1429. JLPR
Quoting Tazmanian:



and the more N it gos the higher the wind shear get i all so noted on that map of 80kt of wind shear


yep some pretty bad shear in the area
Member Since: September 4, 2007 Posts: 36 Comments: 5223
1428. JLPR
Quoting hydrus:
I remember you said you went through Georges.


yep that's right
Member Since: September 4, 2007 Posts: 36 Comments: 5223
1427. JLPR
Quoting KoritheMan:


The low- and upper-level circulations are already decoupled, as per microwave satellite data.

I think that Fred will weaken quickly than the NHC is predicting. It would not surprise me to see Fred make it as far south as the northern Leeward Islands.


seems possible
the bad thing is that it could try to regenerate on the hotter waters that are close to the islands
Member Since: September 4, 2007 Posts: 36 Comments: 5223
Humberto was a non-event for southeast Louisiana, save the 5 minute rainstorm that produced 1-2 inches of rain. That was awesome.
Member Since: Posts: Comments:
A little info on Humberto...

Hurricane Humberto developed extremely rapidly on September 12, 2007, before making landfall along the southwestern Jefferson County, Texas coast as a Category 1 hurricane early on the morning of September 13, 2007.

Humberto made history due to its rapid strengthening from a tropical depression the morning of September 12, 2007, to a hurricane early on September 13, 2007, as no other hurricane has ever strengthened so quickly close to landfall. After making landfall between High Island, TX, and Sea Rim State Park, TX, the hurricane then tracked northeastward across Jefferson and Orange counties, impacting the Golden Triangle metropolitan area of Beaumont, Port Arthur, and Orange. This area had been severely damaged by Hurricane Rita just two years earlier. Although a small hurricane with a very tight wind field, Humberto caused considerable wind and flood damage across Jefferson and Orange counties, with numerous trees and power lines blown down along with some damage to structures. The storm knocked out power to 120,000 customers in the area. Damage estimates across Southeast Texas from Humberto were around $60,000,000.

Humberto continued northeastward across southern Newton county, crossing the state line into western Calcasieu and Beauregard parishes, and causing additional wind and flood damage along its path. The storm weakened as it moved further northeastward, moving across Vernon, Rapides, and far northwestern Allen parishes during the afternoon hours on September 13th, before exiting the area.

Member Since: July 2, 2009 Posts: 0 Comments: 2811
1421. hydrus
Quoting JLPR:


nope I expect an exposed center tomorrow =]
I remember you said you went through Georges.
Member Since: Posts: Comments:
Quoting JLPR:


shear is trying to remove the convection but Freddy keeps fighting trying to keep its convection
but these 20 to 40kts of shear should do their job soon



and the more N it gos the higher the wind shear get i all so noted on that map of 80kt of wind shear
Member Since: Posts: Comments:
Quoting JLPR:


nope I expect an exposed center tomorrow =]


The low- and upper-level circulations are already decoupled, as per microwave satellite data.

I think that Fred will weaken quicker than the NHC is predicting. It would not surprise me to see Fred make it as far south as the northern Leeward Islands.
Member Since: Posts: Comments:
1418. hydrus
Quoting F4PHANTOM:

Gale force winds in Houston 2-3 days before landfall with flooding.
you are correct. There have been many tropical cyclones that people have never heard of.
Member Since: Posts: Comments:
1416. JLPR
Quoting hydrus:
Fred looks like he is ready to charge. Don,t think he will though.


nope I expect an exposed center tomorrow =]
Member Since: September 4, 2007 Posts: 36 Comments: 5223
1414. hydrus
Quoting JLPR:
Freddy is looking annular lol xD
Fred looks like he is ready to charge. Don,t think he will though.
Member Since: Posts: Comments:

Viewing: 1463 - 1413

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39Blog Index

Top of Page

About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.

Local Weather

Partly Cloudy
78 °F
Partly Cloudy