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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has anybody noticed the L marked 1010mb on the GOM? press on NWS

Link
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Quoting Floodman:
Here's the GFDL at the end of the current run:



The CMC taking her into Georgia????
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Erika still has a few tricks up her sleeve... Im not sure exactly where she's going (I dont think she is too sure either) But I think she's going to be creating her own line to follow. its going to be the Erikagap model
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Quoting DellOperator:


Be back in a bit. Got some papers to comb through. Lots of printing going on.

Well, if you're still here. Dad is on his way to run the Miata at Birmingham - Barber Motorsports.
Another new (to him) track...
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Quoting KEEPEROFTHEGATE:


GOING GOING ...
24 Hours and she is history. She may make a comeback early next week.
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AL062009 - Tropical Depression ERIKA

being called a td by RAMMB Link
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Quoting KEEPEROFTHEGATE:


GOING GOING ...


You've got about 5 hours for her to be gone, then Erika is back in her comfort zone for another night.
Wash, Rinse, Repeat....
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Quoting futuremet:


I never seen a storm developed this much COCs before lol.


Somehow indicative of the great red spot Jupiter has had for who knows how long.
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I am actually quite BORED with Erika - Def more interested in the more impressive wave south of Cape Verde.. not a lot of convection but massive vorticity and lots of momentum with it moving WEST...

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Quoting palmasdelrio:
Is a flare-up of thunderstorms tonight out of the question? Yesterday Erika looked really bad but at night it picked up quite a bit.


I think that she's going to flare up at night again, and you will see some reorganization. I think the biggest thing that's been killing her is the sun. During the day, there is a ton of solar energy driving the wind sheer. At night, the air rapidly cools, the atmosphere stabilizes and the sheer stops (or drops off significantly). Also, it's at that time that the warm air in the storm begins to cool down. Water vapor condenses (as seen in the water vapor loops at night) and all of the latent heat from the day is released within the storm. Keep an eye on the storm just after sunset. Just like Tera Ried or Lindsay Lohan, Erika is wild at night and a total wreck during the day.
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Quoting Floodman:


Okay, enough Aggie lovefest...LOL

Must be a tea-sip...
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Quoting Floodman:


Okay, enough Aggie lovefest...LOL


LOL

10-4 Floodman :)
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Quoting IKE:


Severely.

I've been following storms on here for 4, maybe 5 years. Never seen one do, daily, what this one has.


I agree IKE! Never have i seen a system nearly stall in this location......it really hasn't moved 100 miles in 2 days. Weak steering is mostly the cause.
Member Since: September 2, 2007 Posts: 178 Comments: 20439
Quoting IKE:


Severely.

I've been following storms on here for 4, maybe 5 years. Never seen one do, daily, what this one has.


I never seen a storm developed this much COCs before lol.
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Quoting atmoaggie:

Yeah, your not alone in that regard.
Howdy.


Be back in a bit. Got some papers to comb through. Lots of printing going on.
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Quoting TampaSpin:


Thats the case with all females.....LOL




You are 100% correct.. We just let the men think other wise..
Member Since: August 15, 2009 Posts: 0 Comments: 90
cyclo degenisis in all its glory
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AOI

AOI

AOI

AOI


The HH pictures will be updated on my blog.. the single No was all that was required to stop it.
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Quoting atmoaggie:

Yeah, your not alone in that regard.
Howdy.


Okay, enough Aggie lovefest...LOL
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My husband plots storms and the wobbling of Erica looks like Hurricane Hazel?????? Can Erica do that?
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Quoting btwntx08:
she's blowing convection on the east in the last few frames


So...and that means what?
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750. IKE
Quoting KEEPEROFTHEGATE:


GOING GOING ...


Severely.

I've been following storms on here for 4, maybe 5 years. Never seen one do, daily, what this one has.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting DellOperator:


I guess not. Forgot to day Howdy to a fellow Aggie. Sorry bout that.

Yeah, your not alone in that regard.
Howdy.
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Quoting lurkn4yrs:




At this point neither. She is doing what she wants to do...


Thats the case with all females.....LOL
Member Since: September 2, 2007 Posts: 178 Comments: 20439
GOING GOING ...and it's foul.
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Quoting atmoaggie:

Possible they did an 18Z that hasn't been distributed yet, but don't hold yer breath.


I guess not. Forgot to day Howdy to a fellow Aggie. Sorry bout that.
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Even the SHIPs does nothing with it for 48 hours until it gradually strengthens Erika.
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Quoting Magical:
Gee...let's see....NHC or blog...which shall we trust?




At this point neither. She is doing what she wants to do...
Member Since: August 15, 2009 Posts: 0 Comments: 90
The Bermuda High keeps pushing West some yet.....No way Erika goes much North yet. Erika is still positioned on the SouthEast corner of the HIGH......you can see it on this LOOP! Secondly the ULL located near the Eastern tip of Cuba is disapating and what is left is moving WNW.
Member Since: September 2, 2007 Posts: 178 Comments: 20439
thank you for the great answers, I feel a little smarter now (lol)

back to lurking.
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Quoting DellOperator:


Crap. I was hoping they would make exceptions for this event and send more up.

Possible they did an 18Z that hasn't been distributed yet, but don't hold yer breath.
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Quoting btwntx08:
720: If u keep saying huh to my comment then i get rid of u


Ok.
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it's finally started to rain in st barts. i was beginning to wonder if we'd see anything.
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Here's the GFDL at the end of the current run:



The CMC:



And GFS:



Interesting spread on track AND intensity...wonder how the 18Z models will look?
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Gee...let's see....NHC or blog...which shall we trust?
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Good afternoon folks

It looks like Erika is still having problems with her COCs and is now developing a new one. This seems to be her 5th COC so far. Hopefully this will be the last one.
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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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