Tropical Storm Erika's future highly uncertain

By: Dr. Jeff Masters , 2:21 PM GMT on September 02, 2009

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The tropical wave we were calling Invest 94 finally decided to stop dawdling and become Tropical Storm Erika yesterday. However, Erika seems intent upon keeping us guessing about its intentions, as the storm's future track and intensity remain highly uncertain. After a modest burst of intensification to a 60 mph tropical storm last night, Erika has become quite disorganized this morning. The Hurricane Hunters found multiple swirling centers inside Erika early this morning, and the main center took a jump to the southwest to relocate itself under a batch of intense thunderstorms. The exact location and path of Erika remain uncertain at this point, and it is possible the storm will have another center relocation later today. Wind shear analyses from the University of Wisconsin diagnose a moderate 10 - 15 knots of shear over Erika, a decrease from yesterday. SSTs are warm, 29°C. Why, then, is Erika so disorganized? The trouble with the various wind shear analyses we use is that they take a crude average of winds over a thick layer to arrive at an average shear, and this large-scale average shear does not capture thin layers of shear that can dramatically affect a tropical cyclone. Upper air data from Guadeloupe and Saint Martin from last night show a complicated shear pattern in Erika's region, with 30 knot winds out of the south to southwest at 200 mb height, nearly calm winds between 300 - 500 mb, and northeasterly winds of 10 - 20 knots from the surface to 500 mb. Some extremely dry air with humidities near 10% was present in a thin layer near 600 mb on the Guadeloupe sounding, so dry air from the Saharan Air Layer is probably being injected by a northeasterly jet of wind into the core of Erika. The shear of 30 knots at the top of the storm is ripping away the heat and moisture Erika's thunderstorms are lifting there, and the result of the shear and dry air is a very disorganized tropical storm.

Erika is embedded in a weak steering current pattern, and the future track of the storm will depend greatly upon how strong the storm gets over the next few days. A stronger Erika will extend higher into the atmosphere and be steered more to the northwest by upper-level winds. A weaker Erika will be steered more by the low-level winds, which will keep the storm on a more westerly track. Given the complicated nature of the wind shear pattern in the region, it is difficult to forecast how strong Erika will get. Virtually anything can happen over the next five days, from dissipation (as forecast by the ECMWF model) to intensification to a Category 3 hurricane (as forecast by the HWRF model). Large-scale wind shear is expected to increase to 20 - 25 knots between 3 - 4 days from now, so Erika will have to deal with an increasing amount of adversity. The storm is a long-term threat to the Bahamas and U.S. East Coast, particularly if the storm stays weak over the next three days. Potential landfall solutions from the models range from Florida on Tuesday (GFS model) to North Carolina on Wednesday (Canadian model).


Figure 1. Morning image of Tropical Storm Erika, showing a false center over Guadaloupe--one of several surface swirls the Hurricane Hunters found in the storm.

Elsewhere in the tropics
The tropical wave off the coast of Africa we were watching on NHC's Tropical Weather Outlook as having a low chance of developing into a tropical depression has been done in by the dry air of the Sahara, and is no longer a threat to develop. A large and well-organized tropical wave will emerge from the coast of Africa on Thursday, and several of the models develop this low into a tropical depression by early next week. The remains of an old cold front off the coast of North Carolina could serve as a breeding ground for some tropical development Friday or Saturday, but anything that forms in this region would get swept quickly northeastward into New England by Sunday without enough time to become a tropical depression.

Hurricane Jimena nears Baja
Hurricane Jimena has steadily weakened over the past day, and is now down to a Category 2 hurricane with 105 mph winds. The storm should continue to steadily weaken over the next 24 hours as the waters under the hurricane cool from 28°C to 27°C. Jimena is battering a relatively unpopulated stretch of coast, and largely spared the tourist mecca on the southern tip of Baja. It now appears unlikely that moisture from Jimena will reach the Southwestern U.S., and the hurricane appears poised to stall out over Baja and die five days from now.


Figure 2. Hurricane Jimena on Tuesday, Sep. 1, 2009, as seen by NASA's MODIS instrument. Image credit: NASA Earth Observatory.

Baja's hurricane history
The most powerful hurricane on record to hit the west coast of Baja occurred last year, when Hurricane Norbert made landfall on the central Baja coast with sustained winds of 105 mph (Category 2) . Norbert's central pressure of 956 mb at landfall made it the 3rd strongest hurricane to hit the Pacific coast of Mexico since record keeping began in 1949. Norbert killed eight, knocked out power to 20,000 homes, and damaged or destroyed 40% of the homes on the islands of Margarita and Magdalena. Norbert crossed the Baja Peninsula and made landfall on Mainland Mexico as a Category 1 hurricane with 85 mph winds.

Only two major hurricanes have made landfall on Baja since record keeping began in 1949. Both hurricanes hit the east (Gulf of California) side of Baja. The first was Hurricane Olivia of 1967. Olivia made landfall on October 13, 1967 as a Category 3 hurricane with 125 mph winds. Due to its small size and the unpopulated region of coast it hit, damage was minimal. The second major hurricane was Hurricane Kiko, which made landfall on August 27, 1989, as a Category 3 hurricane with winds of 115 mph (minimal Category 3). Kiko was a small hurricane and hit a relatively unpopulated area, resulting in no loss of life and only scattered reports of damage.


Figure 3. A plot of all the major hurricanes to pass within 200 miles of Mexico's Baja Peninsula since 1949. Image credit: NOAA Coastal Services Center.

California fire webcams
As I discussed in yesterday morning's post, you can use our wundermap for Los Angeles with the fire layer turned on to see where the fire and smoke are located, and track the temperatures and winds during today's air pollution event. We also have two webcams with views of the fire: Altadena and Tujunga.

I'll have an update by 4pm this afternoon, when the data from the next hurricane hunter flight into Erika will be available.

Jeff Masters

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Quoting JLPR:
nope im not a paid member

but I got all the ads blocked with AdBlock
so I dont know what happened


Adblock isn't 100% effective, especially if the script in question was written to exploit a security weakness...
Member Since: August 2, 2006 Posts: 10 Comments: 9922
1210. Relix
Quoting JLPR:
nope im not a paid member

but I got all the ads blocked with AdBlock
so I dont know what happened


Well that's interesting XD!!!
Member Since: August 3, 2006 Posts: 0 Comments: 2725
1209. RJT185
Quoting cybergrump:

114-117 Knots right when it reaches the bahamas


Thanks for the 411!
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Quoting OSUWXGUY:


Assuming you're right and that it is an average of positions...

That's the first time I'ver EVER seen them do that with a Vortex message.

Now with their discussions, or in their public advisory I've seen them hedge their direction of motion or CoC coordinates. Weird.


FROM THE NHC

THERE ARE
MULTIPLE SWIRLS APPARENT ON THE SATELLITE IMAGERY ROTATING IN THE
LARGER CIRCULATION ENVELOPE WITH A MEAN CENTER TO THE WEST OF THE
DEEP CONVECTION.
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Quoting RJT185:


How much?
Quoting RJT185:


How much?


Cat 3....

Thus the extreme uncertainty in the entire forecast for Erika.......
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Quoting Weather456:
Someone asked me about the future of develop based on the highest winds not the center but cannot find the question but the answer is that it does not signify a developing system.


Ok thanks! I forgot I asked that lol
1203. amd
recon is now looking for the center of Erika near the 850 mb threshold.

I'll be interested to see the distance between the 850 mb center and the surface center
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1202. JLPR
nope im not a paid member

but I got all the ads blocked with AdBlock
so I dont know what happened
Member Since: Posts: Comments:
Quoting RJT185:


How much?

114-117 Knots right when it reaches the bahamas
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1200. Relix
For those getting viruses...

Firefox + AdBlockPlus works perfect. No warning here at all.
Member Since: August 3, 2006 Posts: 0 Comments: 2725
Quoting Seastep:
Floodman - I didn't click and it came up as detected.

And, I'm with you. I like McAfee enterprise and run our IT. Fairly lightweight and unobtrusive. Also, complete control over settings on all workstations. No issues at all.

Might be folks with personal versions.


Odd...well, I suggest using a secondary program like Malwarebytes to double check the primary VS software...it catches registry errors as well

You;d be surprised how many IT folks are in here...glad to meetcha, by the way!
Member Since: August 2, 2006 Posts: 10 Comments: 9922
1198. NARCHER
recon finding strong winds east of center. think a new center could form in the ts east of current location?
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Quoting Floodman:


Amazing...they just let this guy create handle after handle, all the same as the last...


Well at least he keeps the same name so we know who he is. Better than the one that changes her name and posts the same stupid questions over and over and over and over.
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1196. Relix
Now she could miss Puerto Rico by going to the south? well that's something entirely different than 2 days ago with it passing 250 miles to the north lol.
Member Since: August 3, 2006 Posts: 0 Comments: 2725
Someone asked me about the future of develop based on the highest winds not the center but cannot find the question but the answer is that it does not signify a developing system.
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1194. Patrap
Member Since: July 3, 2005 Posts: 426 Comments: 128874
1193. IKE
Quoting Floodman:


Amazing...they just let this guy create handle after handle, all the same as the last...


True. I've had multiple handles of his on ignore. I'll add the new one.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
What is the next trick Erika will pull out of the bag?
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1191. RJT185
Quoting cybergrump:
The HWRF is scary. It intensifies it.


How much?
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Quoting masonsnana:

Amen to that!!

guess that may put us here in florida a little more on alert.. or at least make people pay attention.. any thoughts on steering patterns? they seem to be pretty weak still...
thanks,
dennis
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Quoting OSUWXGUY:


Assuming you're right and that it is an average of positions...

That's the first time I'ver EVER seen them do that with a Vortex message.

Now with their discussions, or in their public advisory I've seen them hedge their direction of motion or CoC coordinates. Weird.


I have to admit..after watching hundreds of Vortex runs on Google earth.. this one was just not right... I don't think they actually hit it right on. They never even got down to a low wind.. or multiple directional airs.

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The HWRF is scary. It intensifies it.
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JLPR, are you a paid member?
Member Since: August 2, 2006 Posts: 10 Comments: 9922
1185. Seastep
Floodman - I didn't click and it came up as detected.

And, I'm with you. I like McAfee enterprise and run our IT. Fairly lightweight and unobtrusive. Also, complete control over settings on all workstations. No issues at all.

Might be folks with personal versions.
Member Since: Posts: Comments:
Quoting IKE:


In case nobody else responds, I'm not knowledgeable enough to answer your question.


Thanks Ike. Maybe no one knows but the NHC.
the naked swirl is like a pointer we can see direction she is taking, this is starting to worry me, what troublesome wench.....!
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Quoting AllStar17:


HOWEVER, THE FUTURE OF ERIKA IS CONSIDERABLY UNCERTAIN IN BOTH INTENSITY AND TRACK.


Isn't that pretty much a given?
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Quoting apocalyps2:
Could erika be a problem for the egyptian pyramides?


Amazing...they just let this guy create handle after handle, all the same as the last...
Member Since: August 2, 2006 Posts: 10 Comments: 9922
The blog is heating up and getting interesting now.
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Quoting BurnedAfterPosting:


the naked swirl is NOT the true center

the NHC positions is the average between the two circulations, but to me it appears the one inside the convection is winning out.


Assuming you're right and that it is an average of positions...

That's the first time I'ver EVER seen them do that with a Vortex message.

Now with their discussions, or in their public advisory I've seen them hedge their direction of motion or CoC coordinates. Weird.
Looks like Erika might have a date with the DR. The mountains would be the final act in her death.
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Erika is extremely stubborn....not following her forecasts at all, even when she was 94L she did not.
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Quoting Drakoen:
Erika has dual closed low level circulations according to the surface observations and recon data. The naked one that has raced out will likely not be able to maintain itself.


Drak. Thanks you for all of your great observations. Are you going to college to study this full time when you graduate from HS?
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1175. JLPR
yep loks liek WU has a bug
my antivirus just blocked a trojan

and I only entered the blogs page
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Quoting JupiterFL:


You might want to remove that post. Pretty sure the government can arrest you for posting things like that.


LOL. What do you have against Anew?
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Quoting louisianaboy444:


Tide Rollers? lol but yeah its ULM i work in the WRC


Well, yall did "Roll the Tide" year before last. I cherish that memory. ;)

My husband is from the Monroe area. Great school.
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Quoting apocalyps2:
Could erika be a problem for the egyptian pyramides?




a tutcast?
Quoting Elena85Vet:
McAfee just blocked a Trojan from this site.


Did you click on a link? I don't get anything by way of a warning and this machine is clean...on the other hnd, I haven;t clicked on any links that take me away fronm this site...I use my bookmarks to take me out
Member Since: August 2, 2006 Posts: 10 Comments: 9922
Erika appears to be following the naked swirl towards the WSW. It may not be good if Erika gets into the Caribbean if conditions become favorable.

HOWEVER, THE FUTURE OF ERIKA IS CONSIDERABLY UNCERTAIN IN BOTH INTENSITY AND TRACK.
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Quoting apocalyps2:
Could erika be a problem for the egyptian pyramides?


Don't know, but I heard she will cause a blizzard on the moon, no really check it out. It is noted in the 7-14 day outlook....
Quoting IKE:
What a reversal on the 12Z CMC. Here's the last frame before hitting DR/Haiti....at 36 hours....

And note the low pressure off the NE coast.
Member Since: August 3, 2008 Posts: 16 Comments: 5886
depends on the land interaction.
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1161. IKE
Quoting OSUWXGUY:
Here's what I don't get...

From the RGB image at 1745 or 4 minutes before the vortex fix was taken (1749), the center of the naked swirl is over one degree west of their coordinates and a little over a half of a degree south of their coordinates.

Their coordinates: 16.6333N 60.8333W

Center of Naked Swirl at 1745: 16.0N 62.0W


They mention a 10 mile tilt to the north which would explain the half degree south bias, but does NOT explain the west by over a degree bias...

What am I missing? Is there something wrong with the SSD projection?
RGB Loop


In case nobody else responds, I'm not knowledgeable enough to answer your question.
Member Since: June 9, 2005 Posts: 23 Comments: 37858

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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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