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Erika dumping heavy rain on the Lesser Antilles

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

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

Hurricane

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Reader Comments

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...
Who thinks ERIKA may actually strengthen?? Also, who thinks that the wave off the coast of Africa will be something big??
1003. Lizpr
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!!
Sadly one death has been reported in Puerto Rico from Erika - person preparing for the storm.
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:)
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!
Quoting TampaSpin:
img src="Image and video hosting by TinyPic" width="650" height="450" alt="" />


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

;)
Is there any circulation that could develop into anything on the southern side of Erika?
doppler radar out of martinique indicates a Center developing could we have a new LLC ????????
Quoting TropicalGenesis:
Sadly one death has been reported in Puerto Rico from Erika - person preparing for the storm.


Are you for real?
once again new blog guys/gals
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
Quoting btwntx08:
once again new blog guys/gals

What do you mean exactly???
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...'
1016. LMCid
Quoting serialteg:


Are you for real?


Yes:

www.endi.com
1017. hydrus
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.
dr masters has put up a new blog up please go to it
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!
meanwhile...

Captain Ahab believes he sees something out at sea coming from Africa.


Starting to really spin on radar
1023. WXHam
<>img src="9-3-09 @ 1945 utc" alt="" />

Strengthening maybe?


New pops of convection near the new coc.
Hi everyone back from picking up my children of the corn... So what's new what have i missed since 3..
...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
1027. hydrus
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.
1028. hydrus
Quoting CaicosRetiredSailor:
meanwhile...

it lurks!
Quoting serialteg:


Are you for real?

Yes, it was reported in the local news this afternoon.
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!