Erika steadily weakening

By: Dr. Jeff Masters , 7:43 PM GMT on September 03, 2009

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Tropical Storm Erika has weakened steadily this afternoon, and has not generated any sustained winds of tropical storm force (39 mph) at any weather stations in the Lesser Antilles Islands today, according to our wundermap for the region. Erika has dumped some heavy rain on the islands, with 8.03" of rain measured on Dominica over the past two days. The Hurricane Hunters are in the storm now, and have thus far found top winds of 36 mph at the surface and at their flight level of 1000 feet. Radar animations out of Martinique show that the areal coverage and intensity of rain echoes has diminished greatly since this morning, and IR satellite loops also show a major decrease in heavy thunderstorm activity. Visible satellite images (Figure 1) show that the low-level center has become exposed to view, and there is very little heavy thunderstorm activity near Erika's center. Erika is probably just a tropical depression now.


Figure 1. Visible satellite image of Erika showing the exposed swirl of its low-level center southeast of Puerto Rico.

The forecast for Erika
Erika is headed west, in defiance of most of the computer models that predicted a northwest or west-northwest track. Regardless, Erika's track will take the storm into a band of significantly higher wind shear of 25 - 35 knots, Friday through Saturday. Considering that Erika is steadily weakening and is barely alive now, the storm should dissipate by Saturday, and perhaps much sooner. Erika's remains will still be capable of dumping very heavy rains of 3 - 5 inches over the Dominican Republic, Puerto Rico, and the northern Lesser Antilles Islands, and 1 - 3 inches over Haiti and the Southeast Bahamas over the next few days. However, the recent decrease of Erika's heavy thunderstorms makes lower rainfall totals more probable. By Monday, when the remains of Erika should have penetrated through the band of high wind shear over the Greater Antilles, shear may fall low enough to allow redevelopment. This is a scenario offered by the NOGAPS and GFS models. The other models predict quite a bit more shear in the region, and I believe any redevelopment of Erika early next week is unlikely. The GFDL and HWRF models continue to insist that Erika will head northwest, brush off the high shear, and intensify into a Category 2 hurricane five days from now.

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 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 continues to predict development of this wave into a tropical depression early next week.

I'll have an update Friday.

Jeff Masters

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Im sitting in a Box Suite at the Superdome ..as the Saints Miami Game starts at 7 CDT.

Just looping the GOM and views.

Beers damn Cold here too..LOL
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IS that flare up of Erika right now a sighn of a comeback?
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I will post a video here tonight that I just made. The question "What is DMAX and DMIN?" has been asked too many times here. The explains how diurnal phases work.
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Quoting Hurricane009:

!!!!!!!!!!!!!!!!!!! This picture shows Fred, Grace, Henri, and Ida. Fred near South Carolina and North Carolina, Grace in the central atlan -
tic, Henri almost halfway between the Islands and Ida coming off the coast of africa in


No... it shows what was SUPPOSED to be Erika next to the east coast... then the possible Fred and Grace behind that.
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i see a 1014mb low and a 1012mb low on this map

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Quoting Weather456:
Erika provided us more than enough info but it can all be summarize below

"Computer models should only be used as guidance"
Is that flare up of covection going on right now on the sat, around Erikas center?
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Quoting ackee:
looks like 2009 seasons may be best seasons in recent time even when we do have system develop the centre is no where near convection hope this trend will continue


Umm, Bill and Claudette!
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Quoting Hurricane009:

!!!!!!!!!!!!!!!!!!!


Why are people still reacting to the 12z models? Obviously they were way off target for the umpteenth time. *rolls eyes*
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537. ackee
looks like 2009 seasons may be best seasons in recent time even when we do have system develop the centre is no where near convection hope this trend will continue
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473
fxus64 klix 032029
afdlix


Area forecast discussion
National Weather Service New Orleans la
329 PM CDT Thursday Sep 3 2009


Synopsis...
inverted surface trough remains over the area today. Yesterdays 700
mb low has dropped southward into the Gulf and appears to be
centered south of Pensacola. An impulse moving out of the Texas
Panhandle is producing rain over Oklahoma into extreme northeast
Texas...but this area is dropping almost due south and will remain
west of the area. A few showers over southern Plaquemines
Parish...but remainder of the area is dry. Temperatures generally
in the middle to upper 80s with dew points in the middle to upper 60s
with light northerly winds.
&&


Short term...
impulse over Texas...along with another one over the Dakotas will
move southward and effectively drag the axis of the longwave trough
back to our west over the next 48 hours or so. This will place the
area in the moist half of the trough. As moisture increases over the
next two days...probability of precipitation will increase. Any land based precipitation
tonight should be limited to current area of occurrence...southern
Plaquemines Parish. Probability of precipitation increase to chance northwest...slight
chance southeast tomorrow...and to likely all areas by Saturday.
Saturday and Sunday will both see likely probability of precipitation during the day...and
chance probability of precipitation at night. Clouds and precipitation will hold
temperatures in the 80s during the day through the weekend. 35
&&


Long term...
trough axis remains to the west on Monday...with still a pretty good
chance of precipitation during the day Monday. Trough then shifts to
the east for midweek...allowing slightly drier air to move into
the area...with probability of precipitation falling back down into the chance category.
Temperatures generally fairly close to normal. 35
&&
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largest threat to the US will be middle of September on through October

a pretty strong upward motion in the MJO is forecasted for October for the GOM and Caribbean

wouldnt be surprised if there was an upswing at that point
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534. Relix
OMG I had an old floater link opened LOL! I am seeing the new floaters and circulation seems stronger than ever at this point. Comeback time?
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Quoting violetprofusion:
I'm sorry if this has been asked before - Why are the GFDL and HWRF models acting so loony? Do they not deal well with weak/ill-defined storms?


Okay, last post...the answer is that none of them do, really..the weaker the system, the less well defined the effects of the variables: shear, water temp, moisture, etc...
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Erika provided us more than enough info but it can all be summarize below

"Computer models should only be used as guidance"
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527. Relix
Seems like PR won't even get wet from Erika. Hot as heck in here. In fact I am gonna go watch a movie or something at the cinema. Not expecting much from Erika at all here in PR. Also, regeneration right now would be pretty hard. Don't count on it at all. Right now, if it stays where it is... it's a dead system.
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526. IKE
Quoting violetprofusion:
I'm sorry if this has been asked before - Why are the GFDL and HWRF models acting so loony? Do they not deal well with weak/ill-defined storms?


HWRF blows every system up w-a-y too much. It's been terrible.

Here's the 6 hour frame on Erika from the 12Z run, which shows where it should be at right about now. Fifty-six knot winds....wrong!

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525. JLPR
that's one good MLC =P maybe it will light up tonight and bring some rain to PR tomorrow
IR Link
Member Since: September 4, 2007 Posts: 36 Comments: 5223
Quoting TheDawnAwakening:
Thanks Weather456, for the explanation that makes sense. What do you think about the conditions now for the MLC and convection which seems to be organizing somewhat and is quite stationary?


dont see much with it since it has no upper support.
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NexSat African Vis to Night IR,exiting waves
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Erika is beginning her evening fit, right at DMIN! "The fat lady got up on the stage, she had nails in hand, she was about to sing and Erika gave her a look! She got off the stage, dropped the nails and RAN"! LMAO!! For fun, lets see if she does it AGAIN!!
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Quoting CaneHunter031472:
Well, finally Erika is RIP... Now to start looking at Africa again. Is there anything of interest comming out of there. How bout that wave off the coast of Africa will it develop?


Lets wait for the offical word from the NHC (whenever that may come) before saying that.
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Quoting lizrod43:
when is the last year Florida was NOT hit with a tropical system?? One this year...and of course it hit Florida.
Can't wait to move...


2007 the most it got was a TD, in Barry.

Then.. probably 1997 for nothing making landfall, though Danny was really close with landfall in Louisiana.*

* and Alabama, I should say.
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519. JRRP
well... i am out... go to the uni
Link
PR radar
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Quoting BurnedAfterPosting:
um no miami2009 you were dead wrong

you said Ana and Bill were fish storms, WPB posted advisories showing you that both impacted land

how does that rest your case?
I know, that is why i rest my case, i lost, that is it, you all defeated me.
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.
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516. JLPR
Quoting Lizpr:


oops I mean 10 haha


lol
but 10 yrs is very lucky =]
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515. Relix
http://moe.met.fsu.edu/cgi-bin/cmctc2.cgi?time=2009090312&field=Sea+Level+Pressure&hour=Animation
CMC Moves the wave WSW at a point

http://moe.met.fsu.edu/cgi-bin/gfstc2.cgi?time=2009090312&field=Sea+Level+Pressure&hour=Animation
GFS shows a west movement then up


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513. JRRP
Quoting Relix:
Any models for the African Wave?

yes
Link
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512. Lizpr
Quoting JLPR:


20yrs? xD what about Georges in 98? =P


oops I mean 10 haha
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IF Erika's MLC becomes the COC....it would look better and would be much more symmetrical.
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Well, finally Erika is RIP... Now to start looking at Africa again. Is there anything of interest comming out of there. How bout that wave off the coast of Africa will it develop?
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um no miami2009 you were dead wrong

you said Ana and Bill were fish storms, WPB posted advisories showing you that both impacted land

how does that rest your case?
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507. JLPR
Quoting Lizpr:
I wonder if she pulls something over night like she's been doing lol. We are very lucky it's been 20 years since a major hurricane hit us.


20yrs? xD what about Georges in 98? =P
Member Since: September 4, 2007 Posts: 36 Comments: 5223
506. Relix
Any models for the African Wave?
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Did the system we had back in May,in the N GOM, ever make it to a TD?
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Quoting clwstmchasr:
Weather456 - How much do you believe El Nino played into the demise of Erika?



the increase low level easterlies may have allowed the wind shear difference to be large since the upper winds weren't all that destructive. The same principle applies to Hurricane Wilma which was moving the same direction as the upper winds and thus restrengthen into a cat 3 in a barolcinic environment. El Nino may have effectively killed 1 bird with 2 stones.
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AOI

AOI

AOI

AOI

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Quoting WPBHurricane05:


Are you crazy? LOL

HURRICANE BILL INTERMEDIATE ADVISORY NUMBER 35A
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL032009
200 AM AST MON AUG 24 2009


...BILL MOVING ACROSS SOUTHEASTERN NEWFOUNDLAND...HURRICANE FORCE
WIND GUSTS REPORTED AT CAPE RACE...

BILL IS MOVING TOWARD THE EAST-NORTHEAST NEAR 40 MPH...65 KM/HR.
THIS GENERAL MOTION IS EXPECTED TO CONTINUE TONIGHT AND MONDAY. ON
THE FORECAST TRACK THE CENTER OF BILL WILL EXIT THE EAST COAST OF
SOUTHEASTERN NEWFOUNDLAND DURING THE NEXT COUPLE OF HOURS.


TROPICAL DEPRESSION ANA ADVISORY NUMBER 20
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL022009
1100 PM AST SUN AUG 16 2009

...ANA MOVING ACROSS THE LEEWARD ISLANDS...

I rest my case.
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Thanks Weather456, for the explanation that makes sense. What do you think about the conditions now for the MLC and convection which seems to be organizing somewhat and is quite stationary?
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when is the last year Florida was NOT hit with a tropical system?? One this year...and of course it hit Florida.
Can't wait to move...
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498. Lizpr
I wonder if she pulls something over night like she's been doing lol. We are very lucky it's been 20 years since a major hurricane hit us.
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All named storms hit land (Danny as an Extratropical storm):

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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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