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.

McAfee virus alert messages
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 Floodman:


That is an excellent question...I'd thought mid-September...anyone with an answer to this question?


Hey Flood; I'd like to know too but not as adept as the younger folks on here who can find the charts and paste them up in a few seconds....... :)

Thanks Atmoaggie...What am I looking at?
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Quoting Floodman:


That is an excellent question...I'd thought mid-September...anyone with an answer to this question?


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Quoting CaribBoy:


lol so where is it supposed to explode again tonight?


North of the Lesser Antilles. Basically drift a little north from where the mid-level turning is at now...
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Quoting DellOperator:


Erika's act 3 possibly? This would make the 3rd sequel to a cloud strip tease tomorrow if she does give rise to towers.

My thoughts exactly!! I can here the music playing now, she is shedding her towers as we speak!! If she doesn't and becomes a remnant low I have a good recipe for crow, I've eaten some and I have only been following for a lil while! LMAO!!
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Quoting flibinite:
It's strange to watch Erika now as it quickly shrinks. It looks like it's finally decoupled from its LLC completely and is making one, last desperate bid to create a new COC just west of Martinique, and using up all its convection and energy in the process.

I'm not sure if it has enough to hang on until D-max (it's looking like it won't), but it sure is interesting seeing it try.

Jo


Very good observation.....Basically a last ditch attempt at life support.
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Quoting weathermanwannabe:


Yup..........Very interesting season so far...So, when is the next wave of MJO sheduled into the Caribbean Basin?


That is an excellent question...I'd thought mid-September...anyone with an answer to this question?
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But then the NAM shows the 40-50 knot westerlies start hitting the new "low"...
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Quoting weathermanwannabe:


Yup..........Very interesting season so far...So, when is the next wave of MJO sheduled into the Caribbean Basin?

Unforeseeable, really. Doesn't look like it will be in the next 2 weeks.
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It's strange to watch Erika now as it quickly shrinks. It looks like it's finally decoupled from its LLC completely and is making one, last desperate bid to create a new COC just west of Martinique, and using up all its convection and energy in the process.

I'm not sure if it has enough to hang on until D-max (it's looking like it won't), but it sure is interesting seeing it try.

Jo
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Tampa, if the storm heads in the direction you have on your map..the storm still will encounter shear?..and it does not travel through DRs mountains, what would be the potential outcome?
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80. You were gone?
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Quoting WEATHERSTUDENTJFV:
Im back!


No you're not...**POOF!**
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Quoting OSUWXGUY:
I think Erika's low level center has headed west, but the upper level vorticity has been left behind.

The steering in the 700-300mb range is RIDICULOUSLY weak.

The 18UTC NAM actually catches on to this.

It takes the low level center and moves it west fairly quickly.

It leaves behind mid-level moisture and some 500 mb vorticity.

The strong divergence aloft continues to kick off thunderstorms, and eventually lowers pressures again forming a weak circulation.

The funny thing is the NAM even shows convection picking up overnight during DMAX!!!


Erika's act 3 possibly? This would make the 3rd sequel to a cloud strip tease tomorrow if she does give rise to towers.
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It would appear that for the next few weeks nothing will get to the caribbean due to the weakening sub tropical ridge. Looks like nothing but hot sun.
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Quoting BurnedAfterPosting:


they havent gone east of 63W yet, so there are no recon obs for the convection in the island yet


True, but according to satellite at 63W, swirl over the island shows southward movement of clouds, or N wind. HH observations show S, SSE wind for 63W. Opposite what it should be if the swirl over the islands had become a LLC.
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Quoting OSUWXGUY:
I think Erika's low level center has headed west, but the upper level vorticity has been left behind.

The steering in the 700-300mb range is RIDICULOUSLY weak.

The 18UTC NAM actually catches on to this.

It takes the low level center and moves it west fairly quickly.

It leaves behind mid-level moisture and some 500 mb vorticity.

The strong divergence aloft continues to kick off thunderstorms, and eventually lowers pressures again forming a weak circulation.

The funny thing is the NAM even shows convection picking up overnight during DMAX!!!


lol so where is it supposed to explode again tonight?
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Quoting TampaSpin:
Sorry i forgot to add the Shear....If Erika stays weak which i fully expect because of high shear. What will remain of Erika should follow this path in my opinion.

Image and video hosting by TinyPic

can ya make Erica look dead, or just erase her with the cool software?
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Quoting kachina:


The one that everyone was talking about here ended in .js which is a java script code. Even McAfee listed it as a false-positive (error) on their part.

If it took the Dell people 4 hours to fix your system, either they are totally clueless or the computer had actual viruses from elsewhere.


The "packed.c.gen" is actually from a trojan...it was unfiortunate that the js compaction routine was called essentially the same thing
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Quoting Floodman:


In all, a truly brilliant plan

wait..I thought that was the standard plan. Pat, isn't that in your Hurricane Survival List? *scratches head*
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Quoting serialteg:


In Puerto Rico lots of people buy prodigious amounts of alcohol and ride it out in stupor.


In all, a truly brilliant plan
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Sorry i forgot to add the Shear....If Erika stays weak which i fully expect because of high shear. What will remain of Erika should follow this path in my opinion.

Image and video hosting by TinyPic
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Quoting BoroDad17:
From HH observations, swirl by convection is clearly MLC, since they are at approx. 1000 ft altitude, they are in lower level, which is still being governed by naked swirl off to the west.


they havent gone east of 63W yet, so there are no recon obs for the convection in the island yet
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Quoting justalurker:
look famialiar tropical storm chris in 2006


Great post! I guess PR's hurricane shield works lol! I will still keep my eye on Erika: she likes to play dead at this time of day.
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Quoting btwntx08:

no it was tampaspin who calle out claudette


Well, a lot of people, but stormno was constantly pointing out that our attention had to go to the GOM while we were busy on Bill. Wasn't a one man job, granted.
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From HH observations, swirl by convection is clearly MLC, since they are at approx. 1000 ft altitude, they are in lower level, which is still being governed by naked swirl off to the west.
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Quoting hydrus:
It would be cool to have Shear velocity and direction observations in all sectors of a storm,but on a more detailed analysis.


Maybe a Google Earth app where you can steer the storm 360 degrees with Z axis and live info (shear, vorticity, Hurricane Hunter data, divergence and convergence, steering maps, etc) around it...
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I think Erika's low level center has headed west, but the upper level vorticity has been left behind.

The steering in the 700-300mb range is RIDICULOUSLY weak.

The 18UTC NAM actually catches on to this.

It takes the low level center and moves it west fairly quickly.

It leaves behind mid-level moisture and some 500 mb vorticity.

The strong divergence aloft continues to kick off thunderstorms, and eventually lowers pressures again forming a weak circulation.

The funny thing is the NAM even shows convection picking up overnight during DMAX!!!
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look famialiar tropical storm chris in 2006 = erika 2009



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Quoting atmoaggie:

You mean the eastern Caribbean graveyard of tropical systems? (Weird year. Weirder than other mod Nino years)


Yup..........Very interesting season so far...So, when is the next wave of MJO sheduled into the Caribbean Basin?
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60: I advise against that.
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Has anyone noticed Stormno has been quite on the money this season?

He called out Claudette, said Ana and Bill were going to be non-factors, and repeatedly put forks into Erika until she died. I missed his take on Danny, though.
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Quoting CZMDM:
Funny how they are calling that virus a hoax. My wife's computer got infected yesterday afternoon and it took 2 two hour sessions talking with Dell to get it them removed.


The one that everyone was talking about here ended in .js which is a java script code. Even McAfee listed it as a false-positive (error) on their part.

If it took the Dell people 4 hours to fix your system, either they are totally clueless or the computer had actual viruses from elsewhere.
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Quoting GBJane:
Hi all, I'm new here too! Really fascinated with hurricanes and tropical storms, have been visiting this site for a while now. My meteorological understanding is limited, but am learning! Just been battered by remnants of TS Danny - Wow! Live in the Channel Islands (UK) near France. We often get the remnants of hurricanes this time of year. How do you guys survive the real thing? Remnants are bad enough!


I'm living in the Netherlands (Europe) and we have the same trouble with the remnants from Danny!
It's really stormy out here!

I did live in Florida for about 3 years and I went in 2004 through Charley, Frances and the very strange Jeanne who made a looping.

Maybe it sounds stupid, but every time it get stormy over here i'm affraid that something will happen, even it isnt that powerfull as the Hurricanes I have been through though.
I guess it can be traumatic when you have been through 3 hurricanes :)
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Quoting hurricane23:
Thought i'd repost again incase that blogger is still looking for his answer in regards to windshear impacting what was erika.


I think wind differences through the troposphere need to be looked at throughout various layers to really see where the strongest vertical wind shear exists within the troposphere. Just because it seems low between the cloud base (850 hPa) and the cirrus level (200 hPa and above) doesn't mean it's not stronger within some intermediate layer.

I really wish some of the intermediate layers were readily available online for viewing.

adrian

It would be cool to have Shear velocity and directional observations in all sectors of a storm,but on a more detailed level.
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Quoting BurnedAfterPosting:


What was Erika?

NHC still is classifying her as a named system


Not for long if the present hostile situation all around erika continues.
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Quoting weathermanwannabe:
Thanks Dr; it was a coin flip yesterday but it looks like all of the nessesary ingredients have not panned out in favor of Erika over the past 24 hours......Looking more like a slow death in the Eastern Caribbean.

You mean the eastern Caribbean graveyard of tropical systems? (Weird year. Weirder than other mod Nino years)
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Quoting mkmand:

true this season has been really lame


Given the death and destruction that can be generated durning H-Season, a "lame" season is a good season for all concerned.
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Quoting mkmand:

true this season has been really lame


Uh...don't tell that to families who have lost loved ones!
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Quoting NRAamy:
Precisely when it's forecasted to go ga-ga over Puerto Rico.

I thought it was gonna go goo-goo...


It could go poof also, or meh...
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what is it with this storm and throwing out its centers. it is throwing them out faster than the winds the HH can find in the storm.
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Quoting GBJane:
Hi all, I'm new here too! Really fascinated with hurricanes and tropical storms, have been visiting this site for a while now. My meteorological understanding is limited, but am learning! Just been battered by remnants of TS Danny - Wow! Live in the Channel Islands (UK) near France. We often get the remnants of hurricanes this time of year. How do you guys survive the real thing? Remnants are bad enough!


In Puerto Rico lots of people buy prodigious amounts of alcohol and ride it out in stupor.
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Precisely when it's forecasted to go ga-ga over Puerto Rico.

I thought it was gonna go goo-goo...
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Quoting jipmg:
im getting tired of hurricane season, nothing at all has come by, I just want some nice cold fronts

true this season has been really lame
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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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