98L and Fred-ex pose little threat

By: Dr. Jeff Masters , 3:21 PM GMT on September 20, 2009

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A tropical disturbance (98L), is located midway between Africa and the Lesser Antilles Islands. This disturbance has lost most of its heavy thunderstorm activity over the past day. Last night's QuikSCAT pass showed an elongated circulation, with top winds around 30 mph. Wind shear is moderate, 10 - 15 knots, and Sea Surface Temperatures are 28°C, which is about 2°C above the 26°C threshold needed to support a tropical cyclone. There is a large amount of dry air to the north and west of 98L, and this dry air has been instrumental in disrupting development of 98L over the weekend.

Wind shear over 98L is expected to remain in the moderate range, 10 - 15 knots, through Tuesday evening, according to the SHIPS model. This may allow the storm to organize into a tropical depression, assuming it can fight off the dry air that surrounds it. Tuesday through Thursday, the SHIPS model predicts shear will increase to the high range, 20 - 25 knots, so it is unlikely 98L will become anything stronger than a weak tropical storm over the coming 5-day period. The models predict that a strong trough of low pressure will turn 98L to the northwest and then north beginning on Monday, with the result that 98L misses the Lesser Antilles Islands by at least 500 miles. NHC is giving 98L a medium (30 - 50%) chance of developing into a tropical depression by Tuesday. It does not appear that 98L will ever threaten any land areas. The GFDL and NOGAPS models develop 98L into a tropical storm; the other models do not.


Figure 1. Morning visible satellite image of Fred-ex (located at the tail end of a cold front draped over the Atlantic), and 98L.

Fred-ex
The remains of Hurricane Fred are still spinning away about 600 miles east of the Georgia-Florida border. Fred-ex's circulation has become ill-defined over the past day, and there has been no increase in heavy thunderstorm activity. High wind shear of 20 - 30 knots is affecting the storm, and there is also quite a bit of dry air interfering with development. The high wind shear and dry air will continue to affect Fred-ex over the next three days, as the storm moves west-northwest at 10 mph. Most of the models show the moisture from Fred-ex moving ashore between northern Florida and North Carolina Tuesday or Wednesday. None of the models develop Fred-ex, and I'm not expecting it to cause any flooding problems when it moves ashore.

Twenty years ago today
On September 20, 1989, Hurricane Hugo continued its steady northwest march at 15 mph towards the Southeast U.S., brushing the Bahama Islands along the way. Wind shear diminished, allowing the hurricane to intensify back to a major Category 3 hurricane with 115 mph winds. Hurricane watches and warnings had not yet been posted for the U.S. coast, but at noon on September 20, Mayor Riley of Charleston went on the air, telling residents of the city that Hugo was a killer. There was a very good chance that Hugo would be South Carolina's worst disaster this century, he said, with a storm surge up to fifteen feet high. Now, while the weather was good and the storm still far away, was the time to board up and get out.


Figure 2. AVHRR visible satellite image of Hurricane Hugo taken on September 20, 1989. Wind shear had diminished, allowing Hugo to intensify to a Category 3 storm with 115 mph winds. Image credit: Google Earth rendition of the NOAA HURSAT data base.

South Carolinans paid attention. Within an hour, residents jammed hardware stores and supermarkets. Traffic on roads away from the coast swelled as people scrambled to flee the arrival of the first major hurricane to strike South Carolina in thirty years--since Category 3 Hurricane Gracie of 1959 slammed into the coast south of Charleston.

At 6 pm, it became official: the Southeast U.S. coast from St. Augustine to Cape Hatteras had been placed under a hurricane watch, meaning that hurricane conditions could be expected within 36 hours. The torrent of evacuees leaving the coast swelled, reaching a million people in all.

In the U.S. Virgin Islands, the aftermath of Hugo became desperate as widespread looting erupted on St. Croix, forcing President Bush to send 1,100 troops. Wunderground member Mike Steers was there, and relates this story: "Surviving the aftermath was the real challenge. The lack of power, water, communications of any kind, and the crime and looting was the real test. After about a week of digging out of the remains of the house and neighborhood I was able to venture out on my motorcycle to see what had become of my job. On the way, I personally witnessed the looting and lawlessness. I even saw a National Guard truck backed up to what was a appliance store and the guardsmen were helping themselves to washers and dryers. Never mind that there was no power to run them. When I got to the seaplane ramp, I saw the total destruction that is depicted in one of the photos I sent. On my way home, there was a small local grocery store I had usually gone to, and I was going to stop in and see how the owners were doing. There was a band of youths in the process of carrying out everything that was not nailed down. From the back, out ran a rastaman with a machete saying he wanted my motorcycle. Needless to say, I gunned it and got back to my house as soon as possible. My neighbors and I set up our own armed 24-hour security checkpoint to protect ourselves. It was about a week later that the first of the giant C-5s flew over, sent by President Bush to start to restore order..."


Figure 3. Newspaper headline from the Virgin Islands Daily News after Hurricane Hugo, detailing the looting problems on St. Croix. Image scanned in by Mike Steers.

Jeff Masters

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Quoting futuremet:
Initially, the CFS expected the Caribbean to shut down in October...



Later in the period as you can see on the CFS shear map forecast... you can see the arrival of a rather strong subtropical yet towards the beginning of 2010.

Also, latest ENSO trends are still showing a moderate El Nino still persisting...



There's a good chance that we might be experiencing some unusual SVR WX down in the S for quite sometime and I won't be surprised that some state(s) might have wished to received to receive a couple tropical disturbances than to experience a tornado, large hail, etc... which can be localized but with higher damage potential than a hurricane due to El Nino.
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Quoting JLPR:


1997 doesn't agree with you
but yep unless something changes I don't see much
now if the MJO comes then things are different =P



Yea,
I'm aware that there are October storms in El Nino years but it tends to be where the seasons shuts off.

Member Since: July 24, 2005 Posts: 407 Comments: 19076
choi whan dissipated >:O grrr no invests
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Quoting futuremet:


Yes, the MJO will cause a significant swing in tropical cyclone activity during October. I was puzzled over the past weeks of why the CFS is expects anomalously high shear in the western Caribbean when an MJO will move into the area. A planetary scale pattern like the MJO have synoptic and mesoscale features embedded in it. The preliminary CFS forecasts for October were not initializing the wind shear/MJO relationship properly. Surface convergence at the surface often creates a positive feedback of upper high pressure systems in the upper air. Those unusually high SSTs we have been seeing in the Bahamas and the GOM are working their way to the Caribbea--so we can expect this to kick some activity. Hopefully a potent ridge will set up across the east CONUS, and steer these systems west....I doubt that will happen, however.


That does not sound good for me, Grothar, and everyone in South Florida. What do you think the chances are of a RI like WIlma down there again FutureMet?
Member Since: October 8, 2008 Posts: 14 Comments: 4553
Quoting Tazmanian:



me too


Did an extensive report on the last season (2008-2009)

An example is this tropical cyclone report on Severe Tropical Cyclone Hamish (17U)


Member Since: July 24, 2005 Posts: 407 Comments: 19076
:P noaa saysa no tropical formation in 48 hrs.
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September 20 and no worries in the tropics.
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Quoting KEEPEROFTHEGATE:
tropical cyclone activity not expected during next 48 hrs


Yea that was the shortest discussion in a while
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tropical cyclone activity not expected during next 48 hrs
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Quoting KEEPEROFTHEGATE:



cv season is almost shut as well very calm



yes it is most likey overe
Member Since: May 21, 2006 Posts: 5091 Comments: 114728
Quoting JLPR:


1997 doesn't agree with you
but yep unless something changes I don't see much
now if the MJO comes then thing are different =P


the MJO wont help not in EL Nino years
Member Since: May 21, 2006 Posts: 5091 Comments: 114728



cv season is almost shut as well very calm
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early oct. should be a good kickoff
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Quoting futuremet:
Initially, the CFS expected the Caribbean to shut down in October...




yup



there is no way this year we will get pass 10 storms or even if we even make that
Member Since: May 21, 2006 Posts: 5091 Comments: 114728
501. JLPR
Quoting Weather456:
Even though we could get another named storm or so, it is rather difficult to get named storms in October during El Nino years, atleast from my experience.


1997 doesn't agree with you
but yep unless something changes I don't see much
now if the MJO comes then things are different =P
Member Since: September 4, 2007 Posts: 36 Comments: 5223
Yeaaaaaaaaa no yellow circles
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Quoting Weather456:
Even though we could get another named storm or so, it is rather difficult to get named storms in October during El Nino years, atleast from my experience.



yes it is
Member Since: May 21, 2006 Posts: 5091 Comments: 114728
Quoting JLPR:
where is Freddy?


and what is left of 98L


looks like we are going into a quiet time in the Atlantic Ocean
with nothing to watch... ehh ..nice.. that will give me some time to concentrate on other stuff =P
ya may be like that for the next 10 to 14 days by then it will be early oct
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Quoting Weather456:
Even though we could get another named storm or so, it is rather difficult to get named storms in October during El Nino years, atleast from my experience.


True....very true...

Let us wait and see 456.
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Quoting Weather456:
I cannot wait until the Southern Hemisphere Season starts. You can track up to 30 cyclones between the SW, SE, and SW pacific Basin.



me too
Member Since: May 21, 2006 Posts: 5091 Comments: 114728
Even though we could get another named storm or so, it is rather difficult to get named storms in October during El Nino years, atleast from my experience.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
494. JLPR
where is Freddy?


and what is left of 98L


looks like we are going into a quiet time in the Atlantic Ocean
with nothing to watch... ehh ..nice.. that will give me some time to concentrate on other stuff =P
Member Since: September 4, 2007 Posts: 36 Comments: 5223
Initially, the CFS expected the Caribbean to shut down in October...

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Good evening...
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Bring me the cold weather this winter! Highs in the 60's in south Florida are the best!
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Quoting JLPR:


umm xD
That would be Caribbean =]


someone's on top of his game tonight haha
Member Since: June 28, 2006 Posts: 24 Comments: 8201
o thnx storm ur always helpful :)
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Quoting will40:


MJO up?


Yes, the MJO will cause a significant swing in tropical cyclone activity during October. I was puzzled over the past weeks of why the CFS is expects anomalously high shear in the western Caribbean when an MJO will move into the area. A planetary scale pattern like the MJO have synoptic and mesoscale features embedded in it. The preliminary CFS forecasts for October were not initializing the wind shear/MJO relationship properly. Surface convergence at the surface often creates a positive feedback of upper high pressure systems in the upper air. Those unusually high SSTs we have been seeing in the Bahamas and the GOM are working their way to the Caribbea--so we can expect this to kick some activity. Hopefully a potent ridge will set up across the east CONUS, and steer these systems west....I doubt that will happen, however.
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grrrrrrrr.. lol jk
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483. JLPR
Quoting Hurricane009:
The USA will be safe unless something forms in the Carabbean Sea


umm xD
That would be Caribbean =]
Member Since: September 4, 2007 Posts: 36 Comments: 5223
i feel ignored :(
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mjo?
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I cannot wait until the Southern Hemisphere Season starts. You can track up to 30 cyclones between the SW, SE, and SW pacific Basin.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
474.

not to great :P
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Quoting IKE:
They don't even mention remnants of Freddie anymore...I think he's finally RIP...finally.

HIGH SEAS FORECAST
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
2230 UTC SUN SEP 20 2009

N OF 30N W OF 72W NE WINDS 20 KT. SEAS LESS THAN 8 FT.
.24 HOUR FORECAST WINDS LESS THAN 20 KT. SEAS LESS THAN 8 FT.
But is Fred really dead? Can it be? Only Fred knows !
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Funny how that Carib. loop makes it look like So. Fla. is stormy...but in actuality...
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What is the outlook for the rest of the season? Do you feel the US will be threatened in any way?
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466. GeoffreyWPB
probably from the ull near belize, nothing at the surface.


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472. JLPR
98L's 850mb vorticity is splitting into two

Member Since: September 4, 2007 Posts: 36 Comments: 5223
Quoting futuremet:
It seems October will be more active than September.


MJO up?
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iv'e been watching the carribean 4 the past couple of days it has been disturbed ever since the barbados... mabe some development?
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It seems October will be more active than September.
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466. GeoffreyWPB

Yea maybe a thunderstorm or two
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Doesn't look to bad down there...
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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.