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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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 Elena85Vet:


Downgrade likely but not death. Fine silverware to be replaced with plastic sporks.


lol
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Subject to change......

AL 06 2009090318 BEST 0 166N 647W 30 1008 TD
Member Since: September 23, 2005 Posts: 14 Comments: 10875
Quoting sonofagunn:
Erika seems like a good example to observe shear tearing apart a storm. You can easily see the lower level center forging ahead while shear is pushing the higher levels further and further away.



But im pretty sure the higher levels shouldnt be spinning after the center has moved away. Unless it left a spin in the atmosphere.
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00
WHXX01 KWBC 031823
CHGHUR
TROPICAL CYCLONE GUIDANCE MESSAGE
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1823 UTC THU SEP 3 2009

DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.
PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE
AND SUBTROPICAL CYCLONE INFORMATION.

ATLANTIC OBJECTIVE AIDS FOR

TROPICAL CYCLONE ERIKA (AL062009) 20090903 1800 UTC

...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...
090903 1800 090904 0600 090904 1800 090905 0600

LAT LON LAT LON LAT LON LAT LON
BAMS 16.6N 64.7W 17.3N 66.7W 18.1N 68.6W 18.7N 70.5W
BAMD 16.6N 64.7W 17.2N 65.9W 17.8N 67.0W 18.3N 67.9W
BAMM 16.6N 64.7W 17.1N 66.2W 17.7N 67.7W 18.1N 68.9W
LBAR 16.6N 64.7W 17.1N 66.3W 18.0N 67.8W 18.8N 69.2W
SHIP 30KTS 30KTS 33KTS 35KTS
DSHP 30KTS 30KTS 33KTS 34KTS

...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...
090905 1800 090906 1800 090907 1800 090908 1800

LAT LON LAT LON LAT LON LAT LON
BAMS 19.4N 72.5W 19.9N 75.8W 19.9N 78.5W 19.7N 80.6W
BAMD 18.7N 68.7W 19.5N 70.4W 20.7N 72.3W 22.3N 74.3W
BAMM 18.6N 70.1W 19.2N 72.2W 19.5N 74.0W 20.1N 75.6W
LBAR 19.5N 70.5W 20.0N 72.8W 20.1N 75.5W 20.3N 78.3W
SHIP 38KTS 46KTS 52KTS 62KTS
DSHP 35KTS 43KTS 48KTS 58KTS

...INITIAL CONDITIONS...
LATCUR = 16.6N LONCUR = 64.7W DIRCUR = 275DEG SPDCUR = 10KT
LATM12 = 16.4N LONM12 = 62.4W DIRM12 = 291DEG SPDM12 = 6KT
LATM24 = 16.3N LONM24 = 61.2W
WNDCUR = 30KT RMAXWD = 120NM WNDM12 = 35KT
CENPRS = 1008MB OUTPRS = 1011MB OUTRAD = 125NM SDEPTH = M
RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM

$$
NNNN

TD Erika.
Member Since: August 23, 2008 Posts: 7 Comments: 5300
676. IKE
Quoting TropicalGenesis:
Looks like the eye is passing over San Juan right now. Sun is out! Calm winds. LOL


LOL.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting OSUWXGUY:


Between the westerly shear at 200 forecast to build in, and the dry air. One thing is for sure, she's going be fighting an uphill battle the whole way. Forgetting the shear for a second, I just don't see a way you can moisten an environment this dry. Downdraft will continually disrupt the circulation and prevent organization.

All that said, the low/area of strong 850 vorticity will probably stick around for quite a while unless it goes directly over Puerto Rico or Hispaniola.

She's could be a thorn in our side for another week...


I concur. Even though, it doesn't take much forcing to steer that shallow swirl. It is probably safer to watch the typical cumulus cloud overall direction that is in the mean flow rather than take heed with model solutions.

When are the next Skew-T charts coming out for Puerto Rico?
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Erika seems like a good example to observe shear tearing apart a storm. You can easily see the lower level center forging ahead while shear is pushing the higher levels further and further away.
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Quoting IKE:


Unless recon heads to 16N and 62W...and then finds something....fat-lady is clearing her throat.


Yup, all she's doing is thrashing about in the Caribbean playing hide and seek.

Still... while I don't think she'll amount to much in the next 48 hours, *if* she does manage to survive dry air, shear and mountains (as in, have some sort of remnants - it'd be a borderline miracle if she was anything more than that), then could be interesting to see if she spins up in a better environment. If one is still there by that time.
Member Since: August 23, 2008 Posts: 7 Comments: 5300
Looks like the eye is passing over San Juan right now. Sun is out! Calm winds. LOL
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Quoting IKE:


Unless recon heads to 16N and 62W...and then finds something....fat-lady is clearing her throat.


Downgrade likely but not death. Fine silverware to be replaced with plastic sporks.
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669. IKE
Quoting OSUWXGUY:


Between the westerly shear at 200 forecast to build in, and the dry air. One thing is for sure, she's going be fighting an uphill battle the whole way. Forgetting the shear for a second, I just don't see a way you can moisten an environment this dry. Downdraft will continually disrupt the circulation and prevent organization.

All that said, the low/area of strong 850 vorticity will probably stick around for quite a while unless it goes directly over Puerto Rico or Hispaniola.

She's could be a thorn in our side for another week...


I have a question....a true tropical storm wouldn't be going through DMIN and DMAX like Erika is doing, would it? I've read on here tropical storms and hurricanes aren't influenced by DMIN and DMAX? True?
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting btwntx08:
take a look on radar guys clearly a center is relocating it self and that too weak erika thing should be once everything is clear


Huh?
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Orca, once per page please!
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Looks like it's time to say goodbye to Erika. There is no convection near the center and no convergance at all coming in towards the center. At 5 it will be downgraded to a TD. In 24 hours it will be a remnant low. Going by all the obs we have under and around the storm higest winds hitting the ground are 25kts.
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Quoting GeauxGirl:


Ouch! You're in the bullseye...one of them at least. ;)

Your telling me, it has been raining for 10 hrs steady which is ok but now it is pouring down, no wind though. Our valley is definitely going to flood.
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663. Relix
Quoting Orcasystems:
Quick straw vote... do I post the HH track once per page as I update it about every 10 minutes (it auto updates the image thats already there).. or should I just post it on my blog and let who ever wants to see it go and look?


\

Post it here please =P
Member Since: August 3, 2006 Posts: 0 Comments: 2648
Ok all, i'm out...see u all tonight, if not tomorrow...laterz
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Quoting toasterbell:
animalrsq, THANK YOU! I had no clue.


They're not the most interesting classes but teach you to "work within the system". Red Cross also offers many classes on disaster response.
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The thunderstorms on the southwest side of the newly develop coc are rotating into the rotation center now indicating surface convergence and thunderstorms in this region are really firing up in the last image.
Member Since: October 21, 2008 Posts: 243 Comments: 3673
good to see you on iceman55 what do you think this storm is going to do next? imo i think its going to gain some strength over water as it don't seem to be following the track once again. do you think it will have more time than expected over water or do you think it will ride pr. until it dies? your knowledge is appreciated.
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Quoting StonedCrab:


In a tavern!


Ahh, now it makes sense...tabernus, tavern...
Member Since: August 2, 2006 Posts: 10 Comments: 9922
655. IKE
Quoting btwntx08:
new center forming ike look at my link of the radar


I see a spin. I don't see recon flying over there though.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting JamesSA:
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?


As a long-time resident of Florida (both SE and NE), I find that it is these "messy" storms that do the crazy things and cause the most damage. Erika looks like a storm that will wander around and then just sit over an area of land and dump a bunch of rain for days and days. Sometimes the lower level disturbances can cause worse flooding than a cat1 hurricane that blows through rather quickly. We HAVE to watch these storms whether they make it to hurricane strength or not.
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Quick straw vote... do I post the HH track once per page as I update it about every 10 minutes (it auto updates the image thats already there).. or should I just post it on my blog and let who ever wants to see it go and look?


Member Since: October 1, 2007 Posts: 81 Comments: 26511
Quoting DellOperator:



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


Between the westerly shear at 200 forecast to build in, and the dry air. One thing is for sure, she's going be fighting an uphill battle the whole way. Forgetting the shear for a second, I just don't see a way you can moisten an environment this dry. Downdraft will continually disrupt the circulation and prevent organization.

All that said, the low/area of strong 850 vorticity will probably stick around for quite a while unless it goes directly over Puerto Rico or Hispaniola.

She's could be a thorn in our side for another week...
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650. IKE
Quoting Cotillion:
DATE/TIME LAT LON CLASSIFICATION STORM
03/1745 UTC 16.6N 64.8W TOO WEAK ERIKA

You said it.



Unless recon heads to 16N and 62W...and then finds something....fat-lady is clearing her throat.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting Beachfoxx:
The Paul Hebert Box?????
LOL


Nope, "taberna", cabinet or box...unless my mind is failing me again...not unlikely at this point

How are you, kiddo?
Member Since: August 2, 2006 Posts: 10 Comments: 9922
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.


What out DR. They make a lot of shoes there!
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2 pm NHC advisory has conceded she is moving west and will continue to do so for several days..

Have also indicated they found center "farther southwest", though they didn't fix it as far SW as it seems to be currently.
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DATE/TIME LAT LON CLASSIFICATION STORM
03/1745 UTC 16.6N 64.8W TOO WEAK ERIKA

You said it.

Member Since: August 23, 2008 Posts: 7 Comments: 5300
Quoting Floodman:


Wait, wait...you want to die in a box? Funny and morbid...


In a tavern!
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If patrap is in here, there is always talk of the hebert box and you past a pic of Bobby Hebert. If it is possible the next time you do could you maybe use a pic of Bobby's son T-Bob in honor of him being named the starter for the Tigahs. If you make this happen you will be my new hero. TIA.
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animalrsq, THANK YOU! I had no clue.
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Quoting Beachfoxx:
Something sparkly!
that is a neat way of putting it.
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Ya'll are cracking me up!
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Quoting tbrett:

Montserrat 16.74N, 62.19W and the rain has started pouring down.


Ouch! You're in the bullseye...one of them at least. ;)
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636. IKE
Naked swirl sure generating a lot of rain on the long-range PR radar. I guess the speck on the SE portion of the radar image is Erika....

Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting thegoldenstrand:
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?
The Tropical Prediction Center was saying that there were several areas of lower pressure within the broad circulation which is the Cape Verde wave itself. Each of these vortexes tend to compete with each other for dominance. Usually the one that orchestrates the largest volume of atmosphere wins out.But with the highly complex shear anomalies continuing ,it is almost impossible to determine where the next vortex may form or which direction it is moving.It is difficult to track a vortex in a vortex! Especially when they keep disappearing. The wind fields you speak of can also hard to keep tabs on in a system like Erika.
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Quoting toasterbell:
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).


If you want to involved in disaster response in any way, one of the first things you can do is go to the FEMA website. They offer online courses that are required by most states and certainly for Federally-declared disasters for any responders, even volunteers. The most necessary are ICS-100, ICS-200 and ICS-700. Good luck.
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Thank you!

Watching Erika, hoping she does not visit the GOM....
Quoting Orcasystems:


I'm just going to leave it alone.. good to see you up and around again...
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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.
Member Since: October 21, 2008 Posts: 243 Comments: 3673

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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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