Erika steadily weakening

By: Dr. Jeff Masters , 7:43 PM GMT on September 03, 2009

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Tropical Storm Erika has weakened steadily this afternoon, and has not generated any sustained winds of tropical storm force (39 mph) at any weather stations in the Lesser Antilles Islands today, according to our wundermap for the region. Erika has dumped some heavy rain on the islands, with 8.03" of rain measured on Dominica over the past two days. The Hurricane Hunters are in the storm now, and have thus far found top winds of 36 mph at the surface and at their flight level of 1000 feet. Radar animations out of Martinique show that the areal coverage and intensity of rain echoes has diminished greatly since this morning, and IR satellite loops also show a major decrease in heavy thunderstorm activity. Visible satellite images (Figure 1) show that the low-level center has become exposed to view, and there is very little heavy thunderstorm activity near Erika's center. Erika is probably just a tropical depression now.


Figure 1. Visible satellite image of Erika showing the exposed swirl of its low-level center southeast of Puerto Rico.

The forecast for Erika
Erika is headed west, in defiance of most of the computer models that predicted a northwest or west-northwest track. Regardless, Erika's track will take the storm into a band of significantly higher wind shear of 25 - 35 knots, Friday through Saturday. Considering that Erika is steadily weakening and is barely alive now, the storm should dissipate by Saturday, and perhaps much sooner. Erika's remains will still be capable of dumping very heavy rains of 3 - 5 inches over the Dominican Republic, Puerto Rico, and the northern Lesser Antilles Islands, and 1 - 3 inches over Haiti and the Southeast Bahamas over the next few days. However, the recent decrease of Erika's heavy thunderstorms makes lower rainfall totals more probable. By Monday, when the remains of Erika should have penetrated through the band of high wind shear over the Greater Antilles, shear may fall low enough to allow redevelopment. This is a scenario offered by the NOGAPS and GFS models. The other models predict quite a bit more shear in the region, and I believe any redevelopment of Erika early next week is unlikely. The GFDL and HWRF models continue to insist that Erika will head northwest, brush off the high shear, and intensify into a Category 2 hurricane five days from now.

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Elsewhere in the Atlantic
A large, strong tropical wave with plenty of spin emerged from the coast of Africa this morning. The wave is not yet generating much in the way of heavy thunderstorms, but has the potential to gradually develop into a tropical depression by early next week. NHC is giving this wave a low (less than 30% chance) of developing into a tropical depression by Saturday. The GFS model continues to predict development of this wave into a tropical depression early next week.

I'll have an update Friday.

Jeff Masters

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Season is over ,how did everyone due on predections?I said 2 storms but we had 5 ,how did everyone else do?
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Quoting TampaSpin:


NO WAY! The GOM becomes even more active late in the season!


ok, but isn't there a lot of shear and troughs this year for things to really develop in the GOM? just curious...
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Quoting Vortex95:
Back in 2005 there was one main troll, i'm sure you can guess who that was...


He was right on one storm though. Although he said all of the storms would do that as well. Erika looks to be going into a period of rapid thunderstorm growth with a little better organization of the MLC.
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Tampa so your thinking along my thinking which kinda scares you doesnt it!!
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Quoting Weather456:
ProduceBoy,

Those were the days when alot of folks here were reasonable, so wishcasters nor downcaster. Even Stormtop got a few systems right back then.

Now we just have two very extremes with few persons like StormW who actually take the time to put together reasoning to come up with an accurate forecast.

I will say this again, Erika indirectly
separated the reasonable bloggers.


Yea, we still have some great knowledgable people on here, but I literally have to ignore 80% of the posts to see post with whorthwhile insight. And I have learned a LOT of things from bloggers/posters on here. I appreciate your time and effort as well!
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Quoting BenBIogger:


Or even end up like the 1993 hurricane season.


dude, 1993 was apart of a very long lasting El Nino....the El Nino of 1991-1994.

The year after that El Nino was 1995 which further reinforce the point.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting GBJane:


Again, s'cuse my knowledge! What is a 'baroclinic entity'? and why do they gain energy from Icelandic low? We get lots of remnants of storms in the Autumn.
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To Reiterate; what an ordeal it must have been for some in the Nature Isle Dominica today and no doubt Guadeloupe/ Antigua. Uninhibited Water from the heavens for hours, However, Knowing the likes of the islands of Dominica and Antigua pretty well, I'd be more concerned for Antigua if the rains keep on coming as they do from what is at least for the moment a downgraded Tropical storm Erika.

Tropical Depression Erika could always gather more symmetry and organisation of convection around its low level center so those in the Virgin Islands and Puerto Rico should not become too complacent just yet.

The blog from Dr. Jeff Masters this morning (2:12 PM GMT on September 03, 2009) was pretty much on the mark as regards the overnight onslaught of rains on parts of the Nature Isle Dominica:
...Erika is hanging together despite strong wind shear, and is bringing high winds and much-needed heavy rain to the Lesser Antilles Islands. Winds on the south shore of Dominica Island were sustained at 37 mph this morning, and 8.03" of rain have been measured at the airport over the past two days. Winds and rain at nearby islands have been less..

Its a major reminder for us and CDEMA also that no matter the type of weather system we should always BE PREPARED especially as we enter the climatological peak of the hurricane season! Blessings!
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Quoting stormpetrol:
Someone might get egg on their faces yet with Erika imo.
It will be interesting to see just how far west it continues,in the short term.
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Quoting TexasHurricane:
well, from a post I saw earlier it looks like the GOM (GULF coast states) is done for the season. So I guess we can all just go off and come back next year......Does anyone else believe this?


NO WAY! The GOM becomes even more active late in the season!
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Quoting Weather456:
ProduceBoy,

years directly after El Ninos can active like 1998, 2003 and 1995.


Yes, just like 1988 (after the large el nino episode in 1987) had hurricane Gilbert, which was a show-stopper! 1998 with Floyd, where everyone evacuated the coast, yes, the years following an el nino episode are quite active. I don't want to be hit by a hurricane, but I do like to watch them. Even Fay last year caused a ton of dammage where I live and work.
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This video will give you an idea on the Coriolis effect:
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Quoting Weather456:
ProduceBoy,

years directly after El Ninos can active like 1998, 2003 and 1995.


Or even end up like the 1993 hurricane season.
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Quoting TexasHurricane:
well, from a post I saw earlier it looks like the GOM (GULF coast states) is done for the season. So I guess we can all just go off and come back next year......Does anyone else believe this?


no, Im still checking my hurricane plans/supplies daily for possible missed things. My view is that its better to be prepared than surprised.

case in point, there was a localized baby boom 9 months after hurricane Ike...people saw the hurricane coming but not the baby lol

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ProduceBoy,

Those were the days when alot of folks here were reasonable, so wishcasters nor downcaster. Even Stormtop got a few systems right back then.

Now we just have two very extremes with few persons like StormW who actually take the time to put together reasoning to come up with an accurate forecast.

I will say this again, Erika indirectly
separated the reasonable bloggers.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
The reason the African wave is moving WNW is the Coriolis effect. The Earth is rotating, and therefore it is an oblate spheroid (like a football with flattned ends). The vector representing true gravity can be decomposed in a component perpendicular to the surface and a component perpendicular to the Earth's axis. The component of true gravity that acts perpendicular to the Earth's axis provides the force that keeps objects at the same latitude.

In the hypothetical case of a perfectly spherical rotating celestial body, all water and air would gather at the equator.

Each component of true gravity has a different effect: the effect of the perpendicular to the surface component is that objects remain tightly on Earth; the effect of the perpendicular to the Earth's axis component is that all objects that are stationary with respect to the Earth remain on the same latitude, rather than sliding to the equator.

The arrow on the outside shows the local direction of a plumb line; the line that is perpendicular to the surface.
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Quoting LPStormspotter:


LOL.. ok Tampa, And Then?


LOL! Thats a trap question that will get me HUNG on this blog....Let's just say i will be tracking whats left of Erika very very close!
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Quoting rareaire:
Im not ignoring you I have even answered your questons. I only have three folks on my ignore list. Takes alot to gain that honor!! I assure you.


ok well good to know, and I seriously doubt I'll end up on your ignore list, we cool?

well im out guys, time for some supper,
take it easy and behave (not that i set a good example).

-Matt
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Quoting tornadodude:


I do agree with you too, to a certain extent, but anyway, I assume I'm on your ignore list now because I quoted someone you don't care for?
Im not ignoring you I have even answered your questons. I only have three folks on my ignore list. Takes alot to gain that honor!! I assure you.
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ProduceBoy,

years directly after El Ninos can active like 1998, 2003 and 1995.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting Hurricane009:
I asked this question earlier, and i dont think i got a response. How do you make your own maps???
Thanks


I use a Paint Program. You cut and Paste and Imaige into the paint program.
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Quoting IKE:
I'd rather it be people RIP-ing Erika then actual RIP's from Erika. Gotta take the bad with the good.


Very well said, I agree!
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Erika did much like Chris in 2006, different path same ending.
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well, from a post I saw earlier it looks like the GOM (GULF coast states) is done for the season. So I guess we can all just go off and come back next year......Does anyone else believe this?
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Quoting Vortex95:
Does anyone know if the vorcacity of the African wave increased?


It has a strong but small vorticity at 850mb, but nothing above 500
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Quoting jeffs713:

They gain strength, but not as tropical entities, but rather as baroclinic entities. Also, they gain energy from the Icelandic Low that is usually positioned near Iceland.


Again, s'cuse my knowledge! What is a 'baroclinic entity'? and why do they gain energy from Icelandic low? We get lots of remnants of storms in the Autumn.
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Quoting Weather456:


its only a hint, not a forecast. Take any long range hints/forecast with a grain of salt.

1 indication is the returning neutral conditions

continued plus AMO

and below normal SLP for march/april 2009


also I never stated any year or years...as every active year was different in its own way.


Actually, you have a great point that I wanted to comment on. If you look at this link:

http://iri.columbia.edu/climate/ENSO/currentinfo/archive/200908/figure2.html

Looking at analog ENSO years, the episode in 1963-1964 is very similar to our current el nino episode. 1963 was a dud year with a persistent trough along the eastern seaboard, while 1964 had 6 major hurricanes (the year after the el nino episode).

Just a thought, and as a long time lurker here, this blog would be SO amusing in a situation like that. I was here in 2005, when there weren't any trolls, and Steve Gregory was here to give us updates inbetween Dr Masters' updates, as storms were blowing up constantly.
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Quoting Vortex95:


Not that it isn't dieing but they are quite annoying.


true
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting Grothar:
Bye all. Have to leave the country for a few days. I am sure you will all miss me. (lol)

Stay well everybody and try and use kind words to each other.


have a great trip!
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Good evening!
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Bye all. Have to leave the country for a few days. I am sure you will all miss me. (lol)

Stay well everybody and try and use kind words to each other.
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Quoting rareaire:


Well said however you and I are not the only ones on this blog. And we have the ignore feature to remove the wasted lines of those that do not contibute anything to the blog. If you wish to wade through it then start stepping ... However many of us do not and if you constantly quote them it defeats the purpose. There are numerous folks who use this feature and would appreciate your not underminding their right to do so! As for me I have 3 folks on ignore. I too am done!


I do agree with you too, to a certain extent, but anyway, I assume I'm on your ignore list now because I quoted someone you don't care for?
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361. IKE
I'd rather it be people RIP-ing Erika then actual RIP's from Erika. Gotta take the bad with the good.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Vortex95,

This is a nice loop of vorticity over the past 5days. It has remain constant with the African wave. It didnt seem to have changed much, but its there.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
Quoting LPStormspotter:


NOPE. I could care less who's on ignore... I thought this was a weather blog. NOT a personality contest. I can tell you if it was some of the GREAT blogger's would be out.. Does it really matter to you? If people say something you personally don’t like.. O well !!!Maybe someone else is interested. I see dumb crap all the time. But there just not worth my time. Soooo I go on to the next interesting post. Ok I’m done.. Just saying. Nothing personal


Well said however you and I are not the only ones on this blog. And we have the ignore feature to remove the wasted lines of those that do not contibute anything to the blog. If you wish to wade through it then start stepping ... However many of us do not and if you constantly quote them it defeats the purpose. There are numerous folks who use this feature and would appreciate your not underminding their right to do so! As for me I have 3 folks on ignore. I too am done!
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Quoting GBJane:


Excuse my lack of knowledge, but do remnants of tropical storms/hurricanes gain strength again as they traverse the atlantic towards the UK despite rapidly decreasing sea surface temperature? And if they do why? They seem mighty strong storms over here, and such huge swells.


Not usually, no. Hurricanes in the past have been close to us as fully fledged hurricanes (Check out Faith and Debbie in the 60s), but usually transition to extratropical storms due to the cooler waters.

They can strengthen but as said, by baroclinic processes. They can sometimes become what we call 'gales' or 'winter storms', though we typically get those in, as you may have guessed, winter. Starting around October, typically worse in El Nino years, mirroring the Nor'Easter conditions.

At their strongest, we can get equivalent Category Three hurricane winds.
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Maybe we will get a +NAO this winter.
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Quoting justalurker:


*spelling bee contest*

can you use it in a sentence please..

preturbation..P-R-E-T-U-R-B-A-T-I-O-N..


What does PREturbation mean? I know PERturbation means, but not PREturbation, is it the state before perturbation?
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Jimena update from Reuters:

"Hurricane Jimena killed an elderly man who drowned when floodwater surged into his home in Mexico's Baja California peninsula, the first casualty of the weakening storm, officials said.

Neighbors found the 74-year-old man's body on Thursday in his home in the small town of Mulege on the peninsula's east coast, close to where Jimena, now graded a tropical storm, passed as it churned into the Sea of Cortes."

R.I.P.
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Quoting Cotillion:


Is the blog sponsored by both C and V?



LOL
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Quoting Floodman:


Trolls will be trolls...The season's over! It's a fish! The shear will get it! The GOM is closed! The Caribbean is closed! South Florida is saved!

Geez, go watch Sesame Street, y'all, and let us be, huh?

We do indeed have a CV wave working it's way this way...


Is the blog sponsored by both C and V?

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Quoting GBJane:


Excuse my lack of knowledge, but do remnants of tropical storms/hurricanes gain strength again as they traverse the atlantic towards the UK despite rapidly decreasing sea surface temperature? And if they do why? They seem mighty strong storms over here, and such huge swells.

They gain strength, but not as tropical entities, but rather as baroclinic entities. Also, they gain energy from the Icelandic Low that is usually positioned near Iceland.
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Quoting TampaSpin:
Here is my thinking as to what happens with TD Erika as she gets ripped from the Shear to the West!

Image and video hosting by TinyPic


LOL.. ok Tampa, And Then?
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Quoting justalurker:
last time i checked, dont we have a wave coming off of africa, am i missing something..season over? huh


Trolls will be trolls...The season's over! It's a fish! The shear will get it! The GOM is closed! The Caribbean is closed! South Florida is saved!

Geez, go watch Sesame Street, y'all, and let us be, huh?

We do indeed have a CV wave working it's way this way...
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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.

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