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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1030. NatureIsle
9:48 PM GMT on September 03, 2009
Well, what an ordeal it must have been for some in the Nature Isle Dominica today and no doubt Guadeloupe/ Antigua. Uninhibited Water from the heavens for hours, However, Knowing the likes of the islands of Dominica and Antigua pretty well, I'd be more concerned for Antigua if the rains keep on coming as they do from what is at least for the moment a downgraded Tropical storm Erika.

Tropical Depression Erika could always gather more symmetry and organisation of convection around its low level center so those in the Virgin Islands and Puerto Rico should not become complacent.

The blog from Dr. Jeff Masters this morning (2:12 PM GMT on September 03, 2009) was pretty much on the mark as regards the overnight onslaught of rains on parts of the Nature Isle Dominica:
...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..

Its a major reminder for us and CDEMA also that no matter the type of weather system we should always BE PREPARED especially as we enter the climatological peak of the hurricane season! Blessings to All!
Member Since: September 1, 2009 Posts: 0 Comments: 13
1029. TropicalGenesis
9:17 PM GMT on September 03, 2009
Quoting serialteg:


Are you for real?

Yes, it was reported in the local news this afternoon.
Member Since: August 16, 2008 Posts: 0 Comments: 103
1028. hydrus
8:54 PM GMT on September 03, 2009
Quoting CaicosRetiredSailor:
meanwhile...

it lurks!
Member Since: September 27, 2007 Posts: 1 Comments: 20328
1027. hydrus
8:52 PM GMT on September 03, 2009
Quoting hydrus:
Storm.W.-I think what has happened is the low level swirl that is almost due south of P.R.,which was one of the original centers of Erika was sheared out from underneath the main area of convection. Meanwhile there was still enough energy and convection in and around the mid level circulation to create a new surface low, the one we are seeing now associated with the convection over the Antilles. Just my harmless hypothesis.
Member Since: September 27, 2007 Posts: 1 Comments: 20328
1026. stormy2008
8:42 PM GMT on September 03, 2009
...ERIKA WEAKENS TO A TROPICAL DEPRESSION...ALL WARNINGS
DISCONTINUED...

AT 5 PM AST...2100 UTC...ALL TROPICAL STORM WARNINGS ASSOCIATED WITH
ERIKA HAVE BEEN DISCONTINUED.

INTERESTS IN NORTHERN CARIBBEAN SEA SHOULD CONTINUE TO MONITOR THE
PROGRESS OF ERIKA.

FOR STORM INFORMATION SPECIFIC TO YOUR AREA IN THE UNITED
STATES...INCLUDING POSSIBLE INLAND WATCHES AND WARNINGS...PLEASE
MONITOR PRODUCTS ISSUED BY YOUR LOCAL NATIONAL WEATHER SERVICE
FORECAST OFFICE. FOR STORM INFORMATION SPECIFIC TO YOUR AREA
OUTSIDE OF THE UNITED STATES...PLEASE MONITOR PRODUCTS ISSUED
BY YOUR NATIONAL METEOROLOGICAL SERVICE.

AT 500 PM AST...2100 UTC...THE CENTER OF TROPICAL DEPRESSION ERIKA
WAS LOCATED NEAR LATITUDE 16.7 NORTH...LONGITUDE 65.3 WEST OR ABOUT
130 MILES...205 KM...SOUTH-SOUTHEAST OF SAN JUAN PUERTO RICO AND
ABOUT 325 MILES...525 KM...EAST-SOUTHEAST OF SANTO DOMINGO IN THE
DOMINICAN REPUBLIC.

THE DEPRESSION IS MOVING TOWARD THE WEST NEAR 12 MPH...19 KM/HR. A
TURN TOWARD THE WEST-NORTHWEST IS EXPECTED TONIGHT...AND THIS
MOTION IS EXPECTED TO CONTINUE UNTIL DISSIPATION. ON THE FORECAST
TRACK...ERIKA OR ITS REMNANTS ARE EXPECTED TO PASS SOUTH OF PUERTO
RICO TONIGHT...AND BE NEAR OR OVER HISPANIOLA ON FRIDAY.

MAXIMUM SUSTAINED WINDS ARE NEAR 35 MPH...55 KM/HR...WITH HIGHER
GUSTS. SOME WEAKENING IS FORECAST IN THE NEXT 24 HOURS...AND ERIKA
IS EXPECTED TO BECOME A REMNANT LOW ON FRIDAY. ERIKA COULD ALSO
DEGENERATE INTO A TROPICAL WAVE AT ANY TIME.

THE LATEST MINIMUM CENTRAL PRESSURE REPORTED BY AN AIR FORCE RESERVE
HURRICANE HUNTER AIRCRAFT IF 1007 MB...29.74 INCHES.

ERIKA IS EXPECTED TO PRODUCE TOTAL RAINFALL ACCUMULATIONS OF 2 TO 4
INCHES OVER THE CENTRAL AND NORTHERN LESSER ANTILLES...PUERTO
RICO...AND THE U.S. AND BRITISH VIRGIN ISLANDS...WITH ISOLATED
MAXIMUM AMOUNTS OF 6 INCHES POSSIBLE.

...SUMMARY OF 500 PM AST INFORMATION...
LOCATION...16.7N 65.3W
MAXIMUM SUSTAINED WINDS...35 MPH
PRESENT MOVEMENT...WEST OR 275 DEGREES AT 12 MPH
MINIMUM CENTRAL PRESSURE...1007 MB
Member Since: August 18, 2008 Posts: 4 Comments: 215
1025. lurkn4yrs
8:41 PM GMT on September 03, 2009
Hi everyone back from picking up my children of the corn... So what's new what have i missed since 3..
Member Since: August 15, 2009 Posts: 0 Comments: 90
1024. StormChaser81
8:32 PM GMT on September 03, 2009


New pops of convection near the new coc.
Member Since: August 11, 2008 Posts: 0 Comments: 2315
1023. WXHam
8:31 PM GMT on September 03, 2009
<>img src="9-3-09 @ 1945 utc" alt="" />

Strengthening maybe?
Member Since: July 1, 2008 Posts: 0 Comments: 33
1022. StormChaser81
8:30 PM GMT on September 03, 2009


Starting to really spin on radar
Member Since: August 11, 2008 Posts: 0 Comments: 2315
1021. gordydunnot
8:19 PM GMT on September 03, 2009
Captain Ahab believes he sees something out at sea coming from Africa.
Member Since: August 18, 2008 Posts: 0 Comments: 3112
1020. CaicosRetiredSailor
8:11 PM GMT on September 03, 2009
meanwhile...

Member Since: July 12, 2007 Posts: 0 Comments: 5995
1019. BioWeather
8:02 PM GMT on September 03, 2009
Quoting ShesACaneiac:
I've been lurking for 3 days and I'm more confused now than I was 3 days ago.
You're not alone!
Member Since: September 3, 2007 Posts: 0 Comments: 368
1017. hydrus
8:01 PM GMT on September 03, 2009
Quoting StormW:


Explain which?
Storm.W.-I think what has happened is the low level swirl that is almost due south of P.R.,which was one of the original centers of Erika was sheared out from underneath the main area of convection. Meanwhile there was still enough energy and convection in and around the mid level circulation to create a new surface low, the one we are seeing now associated with the convection over the Antilles. Just my harmless hypothesis.
Member Since: September 27, 2007 Posts: 1 Comments: 20328
1016. LMCid
8:01 PM GMT on September 03, 2009
Quoting serialteg:


Are you for real?


Yes:

www.endi.com
1015. serialteg
8:00 PM GMT on September 03, 2009
Quoting Seflhurricane:
i will bet this has been the most fustrating storm to forecast and deal with


I remember one, I have been trying to find it for a long time now, it was around 1995 and it was going far south from PR (around 400mi) into the Caribbean, pure west. Then it stopped, went full north, and hit us. By full I mean 360 - 1 deg. N. It was weak, a lot like Erika. But still... I remember tracking that one as a kid and going 'whoa...'
Member Since: August 22, 2006 Posts: 2 Comments: 1975
1014. masonsnana
8:00 PM GMT on September 03, 2009
Quoting btwntx08:
once again new blog guys/gals

What do you mean exactly???
Member Since: February 14, 2004 Posts: 2 Comments: 663
1013. WatchingThisOne
7:59 PM GMT on September 03, 2009
Loop current forecast for next 6 days. Could have a small eddy pinching off in GOM, but there are other areas to note.

Loop current
Member Since: July 15, 2005 Posts: 3 Comments: 1262
1011. serialteg
7:57 PM GMT on September 03, 2009
Quoting TropicalGenesis:
Sadly one death has been reported in Puerto Rico from Erika - person preparing for the storm.


Are you for real?
Member Since: August 22, 2006 Posts: 2 Comments: 1975
1010. Seflhurricane
7:57 PM GMT on September 03, 2009
doppler radar out of martinique indicates a Center developing could we have a new LLC ????????
Member Since: July 14, 2009 Posts: 0 Comments: 2990
1009. thegoldenstrand
7:57 PM GMT on September 03, 2009
Is there any circulation that could develop into anything on the southern side of Erika?
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1008. serialteg
7:56 PM GMT on September 03, 2009
Quoting TampaSpin:
img src="Image and video hosting by TinyPic" width="650" height="450" alt="" />


Your Paint skills are other-worldly. Sistine Chapel rival.

;)
Member Since: August 22, 2006 Posts: 2 Comments: 1975
1007. serialteg
7:55 PM GMT on September 03, 2009
Quoting atmoaggie:

Even better, it moves! (I found the server without finding the front page the first time)



From here: http://twister.sbs.ohio-state.edu/
go to satellite, tropical, Caribbean in the drop downs at the top.


Nice! Thanks!
Member Since: August 22, 2006 Posts: 2 Comments: 1975
1006. TampaSpin
7:55 PM GMT on September 03, 2009
Image and video hosting by TinyPic
Member Since: September 2, 2007 Posts: 178 Comments: 20439
1005. watchingnva
7:55 PM GMT on September 03, 2009
Quoting atmoaggie:

Even better, it moves! (I found the server without finding the front page the first time)



From here: http://twister.sbs.ohio-state.edu/
go to satellite, tropical, Caribbean in the drop downs at the top.


thank you again:)
Member Since: September 7, 2005 Posts: 7 Comments: 1494
1004. TropicalGenesis
7:54 PM GMT on September 03, 2009
Sadly one death has been reported in Puerto Rico from Erika - person preparing for the storm.
Member Since: August 16, 2008 Posts: 0 Comments: 103
1003. Lizpr
7:53 PM GMT on September 03, 2009
Quoting serialteg:


Right! :D

Is it a paid free day tho?

And a friday! You get to do the long weekend dance!


Yeah it's paid!!
Member Since: August 14, 2009 Posts: 0 Comments: 53
1001. OSUWXGUY
7:53 PM GMT on September 03, 2009
Quoting atmoaggie:
Ah, found a good one.
Of course there is Unisys (had no buoy data).

And there is the one from OSU (shocked and dismayed that OSUWXGUY hasn't been blessing us with these):

(From 30 minutes ago)


Ok Ok... Glad you found those. One of the guys I was in Grad School with runs that site. I honestly rarely have gone to it, but yeah it has some good tropical info...
1000. Seflhurricane
7:53 PM GMT on September 03, 2009
i will bet this has been the most fustrating storm to forecast and deal with
Member Since: July 14, 2009 Posts: 0 Comments: 2990
998. atmoaggie
7:52 PM GMT on September 03, 2009
Quoting atmoaggie:

Go here: http://twister.sbs.ohio-state.edu/surface/
and pick caribbean.gif

Even better, it moves! (I found the server without finding the front page the first time)



From here: http://twister.sbs.ohio-state.edu/
go to satellite, tropical, Caribbean in the drop downs at the top.

Why you holding out on the good stuff OSUWXGUY?
Member Since: August 16, 2007 Posts: 6 Comments: 12461
997. palmasdelrio
7:51 PM GMT on September 03, 2009
Quoting Floodman:


It's where to lows are in close enough proximity to start orbiting one another...typically one becomes dominant or stronger and consumes the other, typically resulting in a much weaker low, despite the stronger ingesting the weaker

thanks
Member Since: May 22, 2008 Posts: 0 Comments: 178
994. OSUWXGUY
7:51 PM GMT on September 03, 2009
Quoting Elena85Vet:


If that's the case wouldn't shear finish her off?


I honestly feel that shear is not the big problem at the moment. I think it's actually quite manageable - in the 10-15 knot range if not less.

Now down the road, the westerly flow at 200mb is supposed to pick up as well as the speed of motion into the shear, increasing its effect.
993. palmasdelrio
7:52 PM GMT on September 03, 2009
Quoting Floodman:


It's where to lows are in close enough proximity to start orbiting one another...typically one becomes dominant or stronger and consumes the other, typically resulting in a much weaker low, despite the stronger ingesting the weaker
Member Since: May 22, 2008 Posts: 0 Comments: 178
992. serialteg
7:51 PM GMT on September 03, 2009
Quoting Lizpr:
I think nothing it's going to happen in PR since I see that thing going south but at least I got out of work 2 hours early and no work tomorrow lol.


Right! :D

Is it a paid free day tho?

And a friday! You get to do the long weekend dance!
Member Since: August 22, 2006 Posts: 2 Comments: 1975
990. watchingnva
7:48 PM GMT on September 03, 2009
Quoting atmoaggie:

Go here: http://twister.sbs.ohio-state.edu/surface/
and pick caribbean.gif


thank you:)
Member Since: September 7, 2005 Posts: 7 Comments: 1494
989. serialteg
7:48 PM GMT on September 03, 2009
Quoting JLPR:


I have no idea what to say anymore


yet you just did!

just enjoy the free leave from work afternoon / no class status :D
Member Since: August 22, 2006 Posts: 2 Comments: 1975
988. hurricane23
7:48 PM GMT on September 03, 2009
westerly flow right now all the way down to south FL this afternoon... so there is a "protective wall" for the time being near the SEUS coast.

Member Since: May 14, 2006 Posts: 8 Comments: 13621
987. KarenRei
7:48 PM GMT on September 03, 2009
I take that back.. there's a 34.5mph surface extrap also.
Member Since: September 7, 2007 Posts: 1 Comments: 937
986. Seflhurricane
7:47 PM GMT on September 03, 2009
Quoting StormW:


I think it has alot of us baffled. Right now, the only thing I'm doing at the moment, as far as track, is based on what I've been looking at in shallow and mid layer steering, is if she keeps new centers popping west or NW, the forecast track I feel, of what I posted in my sysnopsis this late morning, will most likely be the same direction...exception being that if a real center develops west, then the track will be further left. If it develops north, same type of track, more to the right. I'm not even going to try and pinpoint a center...looks like a pinball table. The only way I can see her coming back and strengthening, is if the shear frecast is totally off base.
storm is that a new center developing Se of puerto rico ?????
Member Since: July 14, 2009 Posts: 0 Comments: 2990
985. serialteg
7:47 PM GMT on September 03, 2009
Quoting atmoaggie:

Thanks, but wanted to see them all together on one plot.


Get back to me on that one, looks like an interesting thing to have!
Member Since: August 22, 2006 Posts: 2 Comments: 1975
982. JLPR
7:46 PM GMT on September 03, 2009
Quoting btwntx08:

meant east lol


right lol xD

to me it looks like what is rotating is a MLC that is starting to dig down to the surface

I have no idea what to say anymore
Member Since: September 4, 2007 Posts: 36 Comments: 5223
981. Lizpr
7:46 PM GMT on September 03, 2009
I think nothing it's going to happen in PR since I see that thing going south but at least I got out of work 2 hours early and no work tomorrow lol.
Member Since: August 14, 2009 Posts: 0 Comments: 53
980. atmoaggie
7:45 PM GMT on September 03, 2009
Quoting watchingnva:



can i have a link to that, pretty please...:)

Go here: http://twister.sbs.ohio-state.edu/surface/
and pick caribbean.gif
Member Since: August 16, 2007 Posts: 6 Comments: 12461

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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.