Erika dumping heavy rain on the Lesser Antilles

By: Dr. Jeff Masters , 2:12 PM GMT on September 03, 2009

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Tropical Storm 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, according to our wundermap for the region. The Hurricane Hunters are in the storm now, and have generally encountered top winds of 40 - 45 mph at the surface. They did find one spot of 50 - 65 mph winds, but that was likely due to outflow from a strong thunderstorm, and is not representative of Erika's wind field.


Figure 1. Radar image of Tropical Storm Erika at 9:15am EDT 9/3/09. Image credit: Meteo France.

Erika has improved in organization a bit since last night, but remains weak and disorganized, thanks to about 20 knots of shear at the 200 mb level, as seen on last night's Guadeloupe upper air sounding. Radar animations out of Martinique show plenty of heavy rain moving through the Lesser Antilles, but little organization of the echoes. Satellite imagery shows no low-level spiral bands and little upper-level outflow. Long range radar out of Puerto Rico is beginning to show rain echoes from Erika approaching the island.

The forecast for Erika
The computer models have come into better agreement about the track of Erika, taking the storm west-northwest over Puerto Rico and the Dominican Republic. This track will take Erika into a band of significantly higher wind shear of 25 - 35 knots, Friday through Saturday. Considering that Erika is barely maintaining itself as a tropical storm with 20 knots of shear, the combined effects of the higher shear and the encounter with the high mountains of Hispaniola and Puerto Rico should be enough to cause Erika to dissipate by Sunday. Erika's remains will still be capable of dumping very heavy rains of 3 - 5 inches over the Dominican Republic and 1 - 3 inches over Haiti and the Southeast Bahamas, due to the slow motion of the storm. By Monday, when the remains of Erika should be over the Bahamas, the storm will have penetrated through the band of high wind shear over the Greater Antilles, and shear may fall low enough for redevelopment of the storm. This is a scenario offered by the NOGAPS model, which then takes Erika northward towards North Carolina. The other models predict quite a bit more shear in the region than the NOGAPS, and any redevelopment of Erika early next week remains an iffy proposition. The GFDL and HWRF models continue to insist that Erika will brush off the high shear this weekend, avoid Hispaniola, and intensify into a Category 2 hurricane five days from now. These models have not been giving enough emphasis to how the current shear is affecting Erika, and are being discounted at this time.

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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 are 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 has been consistently developing this wave in its runs over the past few days.

I'll have an update this afternoon.

Jeff Masters

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Quoting justalurker:


why do they even keep wasting gas or tax payers money going over this dead storm?


It's money well spent.
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579. IKE
Now their flying back west, around 65W.

Are they not going to go to 16N and 62W?
Member Since: June 9, 2005 Posts: 23 Comments: 37858
578. JLPR
Quoting Relix:


In truth I think they will change centers again with the new COC, so they may be preparing for that. Next update should be around the same place or something with a similar track.

@justalurker: Do not be so ignorant. This is a storm that will be affecting islands, and I live in one of those. I would prefer they waste their time to keep me up-to date on any changes. Thank you very much.


arrg this system keeps delaying its visit =\
I just want it to pass already xD
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DRY AIR is the KILLING Erika...

I challenge ANYBODY to find sounding near decent tropical systems that have dewpoints of 50-52 at 1000 feet above the surface...

This is insane. Not only is the air dry, but it has been evaporatively cooled apparently...

No WAY air in the tropics in early September should have a temperature of 74.8 at 1000 feet. Think about it this way. The sea surface temperatures in this area according to SHIPS area 29.0 degrees or 84 degrees fahrenheit.

Normally in the atmosphere the temperature drops about 3.5 degrees fahrenheit for every 1000 feet and usually maxes out at about 5.5 degrees/thousand feet in very dry environments (dry adiabatic lapse rate).

In our example there is nearly a 10 degree/thousand feet lapse rate unless the air temperature is cooler than the ocean...which it probably is...

This air is stable stable stable...

Flight height: (~ 922 feet)
Flight temp: 23.8°C (~ 74.8°F)
Flight dewpoint: 10.2°C (~ 50.4°F)
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LOL @ 560. very true!
Member Since: September 14, 2007 Posts: 3 Comments: 3963
Quoting caneluver:
What is up with that track?


the cone does not change for the intermediate advisories - 8 and 2 but the position changes for all updates.

That image you see is the 11am cone but the 2PM position
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Quoting watchingnva:
Image Hosted by ImageShack.us


shes definitely taken on a much better cyclonic look over the last few hours with the banding...

This may be a stupid comment and may make no difference but looking outside earlier the lower clouds were moving wsw and now they are moving nne and the thunder is starting again. Rain is still steady but no breeze. I am located on the island nw of were you are saying the new center is located.
Member Since: July 20, 2007 Posts: 0 Comments: 107
Member Since: October 1, 2007 Posts: 81 Comments: 26511
Quoting Floodman:


A real bore until you got a few drinks in him...he was writing Antigone at the time and all he could talk about incest and funreals...boring, really


LOL Man I'm in love. Thanks for the chuckle. Erika's making me go bald here so it's really appreciated. :-D
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Quoting Relix:


LOL @ Track


They don't adjust the track @ 2pm just the location of the center. Usually it is on track and goes unnoticed however, that is grossly off track.
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In regards to Erika, I am perplexed.. center of whatever circulation there is has been identified as 16.6 N and 64.7W.. while strongest center of storm is about 15.5 N and 63.5W Why is and has COC if there really is a center of circulation or low located so far from where the strongest part of the storm is?
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BR>LOL @ Track


She would have to do a pretty neat trick to follow that, wouldn't she? I wonder how many tricks she's got left?
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Quoting StonedCrab:


illegitimi non carborundum


LOL...youre funny for a megalomaniac
Member Since: August 2, 2006 Posts: 10 Comments: 9922
Quoting IKE:
Memo to NHC: I never saw any winds near 40 mph from recon....with the naked swirl. I'm not sure I saw a 30 mph wind.


From NHC to IKE

We never even noticed you on the plane?
Member Since: October 1, 2007 Posts: 81 Comments: 26511
Quoting IKE:
Memo to NHC: I never saw any winds near 40 mph from recon....with the naked swirl. I'm not sure I saw a 30 mph wind.


there were def. no 40s...i think i saw 3 32's north of the swirl, but thats it...lol
Member Since: September 7, 2005 Posts: 7 Comments: 1494
562. Relix
Quoting violetprofusion:
This is my first season of really following storms, so bear with me here:

I think there's some exuberance and hyperbole, naturally, when you witness something from afar and it doesn't jibe with your expectations. I've seen a few comments to the effect of "This is the weirdest storm I've ever seen" or "In all my years of tracking, Erika takes the cake for being bizarre."

Is Erika really that weird? I'm completely and totally untrained--I'm just a nerdy type who thinks weather is cool--and I know that Erika is bucking the model guidance and inexplicably clinging to life. Is this really a good example of an oddball storm? Or are people exaggerating a little about her weirdness (due to the fact that she's the main event in the Atlantic right now and you might as well speculate about something?)

Just curious about how some of the more experienced/knowledgable folks feel about this - I guess even if it's not been terribly active so far, 2009 is an interesting season to learn about storms, huh?


Last year Tropical Storm Fay was similar. This one is about to take the cake from it though =P
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Quoting pearlandaggie:
540. allegedly, yes! ;)


Same here. Don't Over Work.

Hehe
Member Since: May 31, 2007 Posts: 0 Comments: 189
i see they are sticking with the swirl...lol...interesting, and im loving the forecast track...ne to hit the next point?...lol
Member Since: September 7, 2005 Posts: 7 Comments: 1494
557. Relix
Quoting JLPR:


lol! xD
probably going back down to Ponce on the next update


In truth I think they will change centers again with the new COC, so they may be preparing for that. Next update should be around the same place or something with a similar track.

@justalurker: Do not be so ignorant. This is a storm that will be affecting islands, and I live in one of those. I would prefer they waste their time to keep me up-to date on any changes. Thank you very much.
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Quoting Weather456:


since 5am, no rain, the heaviest showers are staying east of us but thankfully some will trickle in eventually and no soak us to cause flooding which is the best scenario.


basically, just a thunderstorm..
Member Since: August 18, 2009 Posts: 0 Comments: 157
This is my first season of really following storms, so bear with me here:

I think there's some exuberance and hyperbole, naturally, when you witness something from afar and it doesn't jibe with your expectations. I've seen a few comments to the effect of "This is the weirdest storm I've ever seen" or "In all my years of tracking, Erika takes the cake for being bizarre."

Is Erika really that weird? I'm completely and totally untrained--I'm just a nerdy type who thinks weather is cool--and I know that Erika is bucking the model guidance and inexplicably clinging to life. Is this really a good example of an oddball storm? Or are people exaggerating a little about her weirdness (due to the fact that she's the main event in the Atlantic right now and you might as well speculate about something?)

Just curious about how some of the more experienced/knowledgable folks feel about this - I guess even if it's not been terribly active so far, 2009 is an interesting season to learn about storms, huh?
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540. allegedly, yes! ;)
Member Since: September 14, 2007 Posts: 3 Comments: 3963
Quoting lurkn4yrs:
Omg! I'm gonna need another shot of cuban coffee to keep up with this storm...
more like tequila but im at work haha!
551. IKE
Memo to NHC: I never saw any winds near 40 mph from recon....with the naked swirl. I'm not sure I saw a 30 mph wind.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting Dakster:
Sophocoles?

How was he in person, I've only read about him.


A real bore until you got a few drinks in him...he was writing Antigone at the time and all he could talk about incest and funreals...boring, really
Member Since: August 2, 2006 Posts: 10 Comments: 9922
Quoting IKE:
...AIRCRAFT RECONNAISSANCE FINDS CENTER OF POORLY-ORGANIZED ERIKA FARTHER SOUTHWEST...
2:00 PM AST Thu Sep 3
Location: 16.6N 64.7W
Max sustained: 40 mph
Moving: W at 9 mph
Min pressure: 1008 mb


LOL!


why do they even keep wasting gas or tax payers money going over this dead storm?
Member Since: August 18, 2009 Posts: 0 Comments: 157
Quoting TampaSpin:
492. DellOperator 1:44 PM EDT on September 03, 2009
Quoting TampaSpin:
We might actually have a true established LLC finally near St. Johns island...
Quoting TampaSpin:
We might actually have a true established LLC finally near St. Johns island...






That bright swirl you are mentioning is the mid level swirl. Surface circulation out ran its upper structure it was trying to rebuild. A repeat performance Erika put on yesterday.



I don't think so i think the swirl that came out was just one of the two and the stronger has taken over....look at the lower level clouds.....they are being pulled in toward the Certain i mentioned....Could be wrong...JMO


im seeing the same thing as you...and the radar is seeing the rotation as well...
Member Since: September 7, 2005 Posts: 7 Comments: 1494
547. JLPR
Quoting Relix:


LOL @ Track


lol! xD
probably going back down to Ponce on the next update
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I love how it has to go NE to hit the next forecast point! *giggles*
Member Since: August 21, 2008 Posts: 0 Comments: 8
544. IKE
It's moved .3S and 1.2W in 3 hours.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting Orcasystems:


I can cheat also.. I have a webpage I post them onto.. makes it easier.. no size limitations.


OOOOOOOOOH! See how you are. I already checked out your web-site. Good work! Seriously, I enjoy your graphics.
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is it just me...or does the satellite image make it look like the storm is splitting into two pieces? has that ever happened?
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Quoting pearlandaggie:


Hey PearlandAggie, are you in Freeport today at work? I noticed you had mentioned this the other day.
Member Since: May 31, 2007 Posts: 0 Comments: 189
Quoting watchingnva:
Image Hosted by ImageShack.us


shes definitely taken on a much better cyclonic look over the last few hours with the banding...



So, just got home... she is reforming her center again??? Looks like the current center is racing to the west and a new one if forming in the thunderstorms and the radar out of the Antilles is picking up on the rotation... or is that just at the mid-levels?
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1007.9mb is as low as their going to find with the naked swirl from the looks of it...with most winds 30mph or lower in the area...

i want to see what obs the get from the island area...
Member Since: September 7, 2005 Posts: 7 Comments: 1494
536. Relix


LOL @ Track
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@456 5am update, read that already..oops
Member Since: August 18, 2009 Posts: 0 Comments: 157
534. IKE
...AIRCRAFT RECONNAISSANCE FINDS CENTER OF POORLY-ORGANIZED ERIKA FARTHER SOUTHWEST...
2:00 PM AST Thu Sep 3
Location: 16.6°N 64.7°W
Max sustained: 40 mph
Moving: W at 9 mph
Min pressure: 1008 mb


LOL!
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting justalurker:
good afternoon 456

checking your update now, staying dry?


since 5am, no rain, the heaviest showers are staying east of us but thankfully some will trickle in eventually and no soak us to cause flooding which is the best scenario.
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Quoting thegoldenstrand:
How is it that the low that has been reported is so far to the west of the blob called Erika. This girl is not in very good shape.


I agree! Oprah is in better shape!
Member Since: October 30, 2007 Posts: 0 Comments: 270

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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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