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.

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 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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The main system remains stationary and is not moving westward. I include thunderstorms and a MLC included as the storm as well and this low level center moving westward is showing signs of weakening now. Also the storm is finally showing signs of inflow and not just convective flareups without any backup which a feeder band is, its a backup for the thunderstorm activity, it feeds moisture and heat into the storm and allows the debris clouds to not affect the center of circulation causing possible dry air.
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Quoting TriniGirl26:


HOT on this end of the Caribbean chain...lol...she heading south and she's still afraid to visit trinidad...i wonder what voodoo they worked?!?!?
LOL. Cher, they put the gris gris on her yeah..
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Quoting stormpetrol:
I just sense an angry tone by the NHC because Erika is going against the forecast track. This thing is west bound and whether it degenerates or remains weak, it is still a flood threat for Haiti/DR.

LOL! Cheerleader a particular forecast track doesn't alter the actual track the storm takes even if the forecaster is the NHC.

These things are good at humbling the best of forecasters.
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Quoting Beachfoxx:
Something sparkly!


I'm just going to leave it alone.. good to see you up and around again...
Member Since: October 1, 2007 Posts: 81 Comments: 26516
617. a break?? what's that? LOL
Member Since: September 14, 2007 Posts: 3 Comments: 3963
Quoting alpha992000:


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


**tips hat**

Nothin' to it...I got a million of 'em...
Member Since: August 2, 2006 Posts: 10 Comments: 9922
Something sparkly!
Quoting Orcasystems:
I finally figured out what Erika is doing...and all of the married members here will recognize it.. we should have caught it earlier... She is window shopping.. that explains the track. Now the questions is what is she shopping for.. and whats it going to cost.
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Quoting stormpetrol:
I just sense an angry tone by the NHC because Erika is going against the forecast track. This thing is west bound and whether it degenerates or remains weak, it is still a flood threat for Haiti/DR.


I bet they are reliving Roxanne of 1995. That worked them over pretty well.
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Quoting watchingnva:


what island are you on again...

Montserrat 16.74N, 62.19W and the rain has started pouring down.
Member Since: July 20, 2007 Posts: 0 Comments: 107
Quoting pearlandaggie:
431. what is it when you're at work but not *working*? LOL

lentesco off??


A Break????? Don't know where you are from but since afew here are using foriegn languages, let me add in another dead language,commonly known as just plain english,that it is usually peceeded by coffee or smoke.
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I finally figured out what Erika is doing...and all of the married members here will recognize it.. we should have caught it earlier... She is window shopping.. that explains the track. Now the questions is what is she shopping for.. and whats it going to cost.
Member Since: October 1, 2007 Posts: 81 Comments: 26516
The way the track looks maybe they all went to lunch and left an intern in charge, somebody is going to get yelled at after lunch. lol
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The Paul Hebert Box?????
LOL
Quoting Floodman:


Wait, wait...you want to die in a box? Funny and morbid...
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Quoting TheCaneWhisperer:
What are the conditions down the line in the Caribbean?


HOT on this end of the Caribbean chain...lol...she heading south and she's still afraid to visit trinidad...i wonder what voodoo they worked?!?!?
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I just sense an angry tone by the NHC because Erika is going against the forecast track. This thing is west bound and whether it degenerates or remains weak, it is still a flood threat for Haiti/DR.
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I don't want them to stop monitoring anything that even looks like a storm during the peak of hurricane season, in the middle of hurricane alley, and that is near to populated land... until there is absolute certainty that it has dissipated.

Monitoring storms like this so they can alert us in a timely manner should they unexpectedly intensify is EXACTLY what we pay those smart people in the big building to do for us. If the particular storm does not develop that certainty does not mean that it was a waste of money monitoring it.

What are some of you people thinking?
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Quoting StonedCrab:


illegitimi non carborundum
LMAO...C'est vrais/Veritas

Sorry for the delay, I had to step away to feed my swine flu stricken son a chicken sandwich. BTW you have the BEST avatar IMO..
Guess it shoulda been ham. :P

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Quoting OSUWXGUY:
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)



Bingo! We spoke about that yesterday but mainly noted the dry air layer located a little higher.

Erika did this cloud shed yesterday. This pulse style organization may continue to cycle keeping the momentum up for the LLC. This could definitely allow this to "slip" under most of the hostile environment aloft, especially for the near term shear expected to occur.

And the models do not know how to handle this shallowness she is maintaining.

Defiant to the end, just like a Furian.

Your thoughts?

DellOP
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Quoting toasterbell:
I love how it has to go NE to hit the next forecast point! *giggles*

LOL
Member Since: August 2, 2006 Posts: 10 Comments: 9922
just lost my power temp, you sure erika isnt in SLFA NOW..Raining cats and dogs here..
Member Since: August 18, 2009 Posts: 0 Comments: 157
Quoting StonedCrab:


Thanks,
Mihi est compositum in taberna mori


Wait, wait...you want to die in a box? Funny and morbid...
Member Since: August 2, 2006 Posts: 10 Comments: 9922
It is rotating over the Lesser Antilles islands. I don't know why the HH would not investigate this area.
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601. Relix
Quoting JLPR:
it sure looks like a new center is forming
near 16.5N 62W
convection from the south moving west and convection from the east moving NE
its rotating lol xD
Link


I am quite sure they are going to change the center again at 5, but probably degrade it as tropical storm as well.
Member Since: August 3, 2006 Posts: 0 Comments: 2741
WXHead, I don't mean to sound like an idjit, but what do HAM radio operators do? Heck, I've got a CDL and still never learned to use a CB, so that's not an area I know anything about (not that I don't want to).
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599. JLPR
it sure looks like a new center is forming
near 16.5N 62W
convection from the south moving west and convection from the east moving NE
its rotating lol xD
Link
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Quoting StormChaser81:
I a lost for words its heading west, but if you look at the track forecast map there saying its going to head northeast then WNW. That naked swirl there saying is erika. looking at the visible it would have to turn any minute now, that doesnt make any sense.



Read post #569
Quoting sandyoaksea:
There are some very good antivirus softwares that are "freeware" and imho are better than McAffee.

Anyone use Avast or AVG?

So...for SE FL, looks like a non eventful season....too early of course and of course not a real "educated" weather person, but I am learning my Davis Pro that was a gift for my boyfried after Frances, Jeanne and Wilma....nothing to use it for, but certainly am going to keep watching. Thanks for all the info guys and gals :)


I use AVG Free. Been using it for years, and recommend it highly to all my friends.
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596. Relix
Quoting KEEPEROFTHEGATE:
T.S 06L
Weakening Flag : ON
Rapid Dissipation Flag : FLAG


And so it begins its descend to nothingness =P
Member Since: August 3, 2006 Posts: 0 Comments: 2741
Quoting tbrett:

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.


what island are you on again...
Member Since: September 7, 2005 Posts: 7 Comments: 1525
Im at a lost for words its heading west, but if you look at the track forecast map there saying its going to head northeast then WNW. That naked swirl there saying is erika. looking at the visible it would have to turn any minute now, that doesnt make any sense.

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593. Lizpr
hmm for some reason I think it will be like Ana not even rain.
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Erika has to have the record when it comes to center relocation, only Matthew 2004 I know had about 3.
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Quoting Floodman:


LOL...youre funny for a megalomaniac


Thanks,
Mihi est compositum in taberna mori
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Doncha just love the latest TWO? LOL
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584. AVG is working well on my old laptop. it doesn't use a tremendous amount of system resources.
Member Since: September 14, 2007 Posts: 3 Comments: 3963
GFDL develops Erika into cat 2, as well as HRWF. These are the latest model runs.

(golf clap)

Fool me once, your fault. Fool my twice....
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T.S 06L
Weakening Flag : ON
Rapid Dissipation Flag : FLAG
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Must be a very shallow moist boundary layer... Dewpoints at the surface in the islands are in the 70s
Member Since: Posts: Comments:
There are some very good antivirus softwares that are "freeware" and imho are better than McAffee.

Anyone use Avast or AVG?

So...for SE FL, looks like a non eventful season....too early of course and of course not a real "educated" weather person, but I am learning my Davis Pro that was a gift for my boyfried after Frances, Jeanne and Wilma....nothing to use it for, but certainly am going to keep watching. Thanks for all the info guys and gals :)
Member Since: Posts: Comments:
Note to self.. upload new pic.. then post.... always upload first..then post
Member Since: October 1, 2007 Posts: 81 Comments: 26516
What are the conditions down the line in the Caribbean?
Quoting IKE:
Now their flying back west, around 65W.

Are they not going to go to 16N and 62W?


Sure, but first....
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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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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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