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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A number of wunderground users with the McAfee virus protection software installed were alerted yesterday that a possible Trojan virus existed on our web pages. After an investigation of the issue, we have determined that this is a false alarm. It appears McAfee updated their virus files yesterday, and included in their list of suspected viruses JavaScript web pages that compressed using the packer compression system used by wunderground. We've changed the compression technique used on our web pages, and hopefully this will eliminate the bogus McAfee alert messages.

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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Quoting nrtiwlnvragn:


While the NHC has stopped issuing public advisories, they are still tracking the system. They updated the 06Z position and updated models. It is still an active system but now basically treated as an "invest".


do they still send HH ?
Member Since: August 18, 2009 Posts: 0 Comments: 157
Shear and land interaction will finish her off. I believe by Sat. end of this weekend at latest she'll be completely died out.
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Quoting aquak9:
quick question- NHC sez their last update on ExEricka was at 11pm last night...

Do ya'll think she warrants more output from the NHC?


NHC says last advisory 'unless regeneration occurs'. Well, she's regenerating, now, but 35 knts of shear and interaction with Hispaniola or PR could finally finish her off.
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Quoting aquak9:
quick question- NHC sez their last update on ExEricka was at 11pm last night...

Do ya'll think she warrants more output from the NHC?


While the NHC has stopped issuing public advisories, they are still tracking the system. They updated the 06Z position and updated models. It is still an active system but now basically treated as an "invest".
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NHC was quick to declare Erika a remnant low. (I thought it would be one at 5 or 11 this morning). But they declassified it last night. This entity shall be watched until it completely dissipates.

Pre-95-L slowly organizing as it heads west....

and ANOTHER invest in the Pacific. Already up to the "L" storm there (Linda). [the next one would be Linda]
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Quoting StormW:


It does..everyday Stef! :)


Awe. Ya makin' me blush. :) Lol.
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Yes I agree Ex-Erika looks good right now but when we get going through the day and she hits that shear plus D-min! I think she'll be back to slowly dying then will go ahead and die so in short it's a nice temporary show but not impressed. Watch as we go through the day and you'll see no comeback for Erika(JMHO).
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Quoting aquak9:
G'morning to all..I had written off the Erickas yesterday...keep forgetting what DMax can do to a wannabe storm.


Quoting OSUWXGUY:


All storms feel the influence of DMIN/DMAX due to the influence of long wave/short wave radiation at the cloud edges.

During the day, sunlight (short wave radiation) is bombarding the cloud tops/edges causing a slight warming. This slight warming makes the environment slightly more stable during the day and the thunderstorms are not quite as deep.

During the night, there is no sunlight (shortwave radiation) obviously, so the emission of longwave radiation by the clouds at the cloud tops/edges is the dominate process cooling the environment near the clouds, making it more unstable and causes stronger storms with higher cloud tops.


For a weak system like Erika, or other invests, a slight change in the environment's instability can be an important factor in getting thunderstorms to form and to help organize a system.

In a well developed storm, the structure of the storm is such that there is always strong convergence at the surface which fuels thunderstorm activity. However, if you watch major hurricanes a lot, their cloud tops in general are higher during the night than during the day (think red instead of black on the AVN loop). Both are still significant convection, but one is slightly stronger.

Obviously, going over a rocket fuel warm eddy like Katrina did, throw all this DMIN/DMAX crap out the window...
Member Since: August 18, 2009 Posts: 0 Comments: 157
Quoting stormpetrol:
well i got up early and took a peak at Erika, kinda nice looking for a remnant low, i said it before and i'll say it again i wonder if someone will get egg on their faces regarding Erika.


Probably. Maybe it will star with you.
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Told you...

She won't die unless we get the stakes and holy water... (or would that be holy dust?)
Member Since: August 23, 2008 Posts: 7 Comments: 5300
Quoting aquak9:
quick question- NHC sez their last update on ExEricka was at 11pm last night...

Do ya'll think she warrants more output from the NHC?


FWIW. I do. Wasn't not having just one circulation one of her problems before? Now it seems she does have one. If that's a LLC I'd say she's probly back to TS. But I think they'll wait til she stays that way during the day to do anything about it. Sigh. Would love to know now though. Lol
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Quoting Lizpr:
wow she realy does'nt want to die


I agree. Looking better than ever this morning. Wish DMAX did that for me. Lol. Good morning all.
:)
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Quoting StormW:


Good morning.


got my nice pot of coffee brewing this morning waiting for your 8am update, so i can have something to important to read this morning.
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1281. aquak9
quick question- NHC sez their last update on ExEricka was at 11pm last night...

Do ya'll think she warrants more output from the NHC?
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1280. aquak9
G'morning to all..I had written off the Erickas yesterday...keep forgetting what DMax can do to a wannabe storm.
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1279. RJT185
Morning Yinz!
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1277. Lizpr
wow she realy does'nt want to die
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Good morning y'all...
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good morning stormW and Weather 456.
Member Since: August 18, 2009 Posts: 0 Comments: 157
Good Morning all

Tropical update
Member Since: July 24, 2005 Posts: 407 Comments: 19076
00Z GFS..am i seeing this right? sure i dare to say it *loop* for erika..

Link
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1271. LMCid
Quoting stormpetrol:
well i got up early and took a peak at Erika, kinda nice looking for a remnant low, i said it before and i'll say it again i wonder if someone will get egg on their faces regarding Erika.


I remember your comments... yesterday in PR governor said school and business would operate as usual. When eggs fly he might need to be as fast as Bush with the shoes....
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95L coming soon to a theater near you..



Member Since: August 18, 2009 Posts: 0 Comments: 157
Quoting BahaHurican:
Morning everyone. [anyone???? lol]

he problem with ur point (and I do get it, and can understand why u have come to ur conclusion) is that the steering has changed since StormW wrote that. Specifically, the weakness that all the models were picking up on has basically filled in; the trough that was expected to influence Erika didn't have the impact that was expected. IF things in the larger environment had worked out as initially expected, I think we would have seen the results expected by NHC.

The problem in my view is with NHCs ability to forecast intensity. If Erika had indeed intensified as expected by several of the main models, it would not have been slowly meandering along as it neared the Antilles. That would have brought it into the position where it could be picked up by the trough. Then it wouldn't have mattered much what the strength of the storm was after that point.

Erika and storms like it would make good study cases in an effort to improve intensity forecasts. There were obviously some atmospheric dynamics involved which we don't understand enough to program them accurately into the models.


Morning Baha -

That has to get the blog award as the most coherent post at this hour, ever! I might be able to understand it in about an hour....

Actually, you make an excellent point. All the dynamic models still want to develop Erika and pull her almost due north. Even the stastical models are starting to want to move her remains north. This has been a nightmare for the models(although the statistical have done pretty well)

06z statistical...



06z Dynamic...

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good morning

i see erika is under limited sheer now, helping her increase convection over DMAX, but she will be going thru 35 kts of shear later today and tomorrow, with DMIN approaching soon, that might be the last cycle for her..but if she can make it thru based on NHC to SE bahamas, possibilities are still there for development..

Member Since: August 18, 2009 Posts: 0 Comments: 157
well i got up early and took a peak at Erika, kinda nice looking for a remnant low, i said it before and i'll say it again i wonder if someone will get egg on their faces regarding Erika.
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Seems quiet in here this morning.... lol wonder why?


Have a great day!
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Good Morning y'all. What I wouldn't give for a visible right now. She's finally taken a hurricane shape. For lack of a better word. Lol. Do MLC'S do that?
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Morning everyone. [anyone???? lol]

Quoting centex:
Here is my question to stormw, not pinging him I respect him more than any of you guys. Just showing this was NHC thinking also on 8/31.

Quoting centex:
Ok, but doesn't that assume we have a TD at minimum?


Not really...the flow is basically the same right now at the shallow and mid layer level.

He is saying no matter how weak it would pull N. This is the big problem with models, NHC and many on this blog.
he problem with ur point (and I do get it, and can understand why u have come to ur conclusion) is that the steering has changed since StormW wrote that. Specifically, the weakness that all the models were picking up on has basically filled in; the trough that was expected to influence Erika didn't have the impact that was expected. IF things in the larger environment had worked out as initially expected, I think we would have seen the results expected by NHC.

The problem in my view is with NHCs ability to forecast intensity. If Erika had indeed intensified as expected by several of the main models, it would not have been slowly meandering along as it neared the Antilles. That would have brought it into the position where it could be picked up by the trough. Then it wouldn't have mattered much what the strength of the storm was after that point.

Erika and storms like it would make good study cases in an effort to improve intensity forecasts. There were obviously some atmospheric dynamics involved which we don't understand enough to program them accurately into the models.
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It's 5:30 am and is starting to rain on st. croix. It seems Erika is trying to get her act together. I welcome the rain but not the damaging winds. We have been in a drought for a long time. Showers has been on and off and heavy at times. There were only a few thunderstorms during midnight.

--------------
Sent from Iphone 3GS
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Ericka is my type of girl, unpredictable kinda fickle, always keeps you guessing, changes the way she looks, has the boys talking about her.
Keeps me on my toes with this type of gal,
any comments?
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Somebody sure does love to get dressed up and go out at night!!

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Hmmmm? I don't know if she still has a llc but she finally seems to have only one. Lol. And these are the coldest cloud tops I've seen her produce yet. I'm not too sure what is meant by the following but it seems shes still a nasty bit of weather to be dealt with. Yuck! Some are in for a rocky night. Lol. Now she's even rounding off instead of the elongated shape. Anyway...

THE ASCAT PASS
FROM 0204 UTC SHOWS WINDS TO 25 KT CONFINED TO THE NE
QUADRANT...WITH SHIP C6OM8 NEAR 22N65W CONFIRMING THESE WINDS
ARE STILL OVER 25 KT IN THE NE QUADRANT AT 0600 UTC
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Quoting apocalyps:


Wise words my friend


Fail.
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Quoting apocalyps2:
Maybe Erika just will survive coming days,drifting west.And 2-3 days from now she will have a much better environment.


Wise words my friend
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Thanks, Kerry, btw... lol.
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Quoting centex:
Here is my question to stormw, not pinging him I respect him more than any of you guys. Just showing this was NHC thinking also on 8/31.

Quoting centex:
Ok, but doesn't that assume we have a TD at minimum?


Not really...the flow is basically the same right now at the shallow and mid layer level.

He is saying no matter how weak it would pull N. This is the big problem with models, NHC and many on this blog.


In Storms defense, when he said it didn't matter because the shallow and the mid layer are basically the same..." They were at that time almost exactly the same. So that's why he said whether it was weaker or did strengthen it would go the same way. The steering was the same at both levels at the same time. If the steering levels were different then he probably would've said, if it strengthens it'll go this way if it doesn't it'll go that.
At least that's how I understood it.

Now, having said all that, I agree with you that this storm has not done what it should from the get go. And we may have not liked or agreed with the models or forecasts. However, it wasn't the models or the forecasters or the NHC who were wrong. They were doing what they do best. (And I'm glad they do.) Nope it was not them. It was Nature. As frustrating as it is. Nature doesn't go by the models. There's a saying, "There are no straight lines in nature." You can't know what will happen. Nature's a wild and wonderful and sometimes dangerous thing. And we don't have all the answers yet. And the day we do she'll change the questions. Lol, Erika, you're making us all nuts! And now she's up to her old tricks again. Lol.
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convections in the NE carib seem to be moving northeastward...
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Erika just doesn't know when to give up, does she?
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Sorry, didn't see your post, msphar... hopefully you can see what I meant in iceman's radar image, as it will soon be gone and I don't know how to save a time sequence like that.

But no, I have no idea at all, thought the spaced pulses going into the east side of Claudette from the ocean east of Jacksonville really reflected the radar waves strongly, so if it's some sort of energy pulse it's *very* dense and powerful. I can't believe that it's an actual "physical" thing like chaff or silver iodine, either, as it just suddenly displays for a few minutes all along its path, then dissipates pretty quickly, like tonight.

If that was even anything tonight.

Again, I'm not dogmatic about being right here, but almost all the forecasting this year has been wrong, outside of general direction, and everyone's scrambling to try to explain why each of the storms is doing this and doing that.

Thanks for responding, though, and sorry I didn't see your question sooner, as it looks like I've scared everyone else to bed. :P

Jo
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1249. msphar
I'm fading g'nite
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Last thing, then I'll try to leave you alone. If this a "pulse" of some kind, what happens after it. Well, the last two nights what seems to have happen is, any convection moving into the area the pulse hit evaporates, for the most part, and if you'll look at the radar loop from PR, right below St. Croix, all the convection moving north toward St. Croix has stopped.

It does look like remnant Erika is trying to wrap around itself about 100 miles southwest of that spot, though. It will be interesting to see. Hopefully the PR radar won't go out on us.

Note: Look on iceman's PR radar loop Link rather than Patraps, as it runs longer and the "pulse" and convection "destruction" is more "obvious".

Jo
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1247. msphar
Hey Jo, I'll take your offer. Do you have a concept for how this sort of modification is being effected ?
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About JeffMasters

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