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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1111. centex
It is a virus JS/Exploit-Packed.c.gen low risk trojan type.
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Quoting dwpearson:
Norman Anitvirus.


I love it...medieval French software...not very effective on the modern, non-peasant CPUs
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Quoting louisianaboy444:
Hey all i am reporting from the Weather Research Lab at ULM and we are analyzing Erika...I agree that she appears to be weakening but i think better conditions will ensue once she gets closer to the Bahamas...i also think the 12Z GFDL has the best track for this system as of now...


Would that be ULM, as in the University of Louisiana Monroe? Alias, the Tide Rollers?
;)

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Quoting SQUAWK:

Pay the $10 and become a member and you will never have the problem again. Plus you get a lot more features that the site offers.


It is so worth it. The site works much better.
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Quoting IKE:


Okay...I see the recon fix. NHC was wrong on their coordinates listed.

so it's more northeast than they had it?
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Quoting hurricane23:
12z ECMWF,CMC,UKMET dissipate erika in the not too distant future.


really

Link
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oh boy that is scary. My husband thinks I am nuts but I have tons of hurricane plans should something come our way because I do not want my daughter going through anything more then a cat 1.
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1094. Squak - nope, no ads.

Quote feature doesn't work either. I've run everything. It's only hitting from this site.
Member Since: September 5, 2007 Posts: 0 Comments: 3482


AOI

AOI

AOI

AOI

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Quoting JupiterFL:


If anybody should be able to figure it out its you. Afterall you are MR. Puerto Rico.

Or he could ask Mrs Puerto Rico. You know, behind every good man is a good woman sorta thing :)
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1099. Drakoen
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I see several readings above 45mph, but most of them are 40-45

either way with a 1 mb drop in pressure; I dont see how Erika ibeing downgraded to a TD at 5pm
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Quoting SQUAWK:


Have you ever tried to uninstall Norton or McAfee??


I had to do it the other day...someone installed Norton on a McAfee box here...drop into safe mode as administrator and uninstall it...
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1096. Seastep
Sorry, I'm a little behind folks. Got off to run a quick scan.

I'll stop after this one unless something really strong pops up, but no downgrade yet.

47 knots
(~ 54.0 mph)
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1095. IKE
Quoting Drakoen:


Erika center is just east of the islands. It is not the naked swirl 16.6N 60.8W


Okay...I see the recon fix. NHC was wrong on their coordinates listed.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
1094. SQUAWK
Quoting hurricanehanna:
Squak - I am a paying memmber

Now that is scary. I have not ever had a problem because I don't get the ads. Are you seeing ads??
Member Since: December 9, 2008 Posts: 0 Comments: 2498
BOP,

yep
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Quoting mrpuertorico:
so confusing...so what should i expect for puerto rico rain and some wind or sunshine and breezy conditions...north? south? fizzle or fizazle...my head hurts....DAMN U ERIKA!


If anybody should be able to figure it out its you. Afterall you are MR. Puerto Rico.
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Yeah, a few more now coming up. Still minimal TS readings. Just about hanging on.

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1090. Drakoen
Recon vortex message of the center is 16.6N 60.8W
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thx canehunter! Have a good afternoon everyone.
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Quoting IKE:


I see what you're saying as far as convection. Where the NHC has the center is a naked swirl. And the naked swirl looks headed WSW, looking at it again.
ihave been saying that all morning.
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Quoting mrpuertorico:
so confusing...so what should i expect for puerto rico rain and some wind or sunshine and breezy conditions...north? south? fizzle or fizazle...my head hurts....DAMN U ERIKA!



It all goes back to no one really knows what she will decide to, typical of a woman, but what was Andrews excuse -- didn't he play games for a while, then BAM suprise I'm here.
Quoting bocahurricane:
bocawind I am with you until there are no clouds in the sky or the system is north of me I do not stop watching and monitoring them. I have a 15 month old and 2 dogs so I can't make last minute decisions. I have been through Francis, Jeane and Wilma. 3 too many for me :)


Well, I was dumb enough not to put my shutters up for Wilma! BIG MISTAKE. It was a sheer miracle that my florida room windows didn't brake, considering that the aluminum beams from my pool enclosure were flying around. Just dumb luck. Fortunately my wife and daughter were out of town... Learned a good lesson on that one.
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Quoting centex:
yes WU has virsus issue or something that's being flagged as a virus.


Again, it's not this site but something someone linked to; if this site did have a some kind of virus (it's not really a virus, it's an exploit...two totally different things) then most of us would have it...
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1084. SQUAWK
Quoting Floodman:


The other thing to remember is to never, and I mean under no circumstances ever install two Virus scanners on one machine. It's okay to run Malwarebytes or Adware on a machine with Norton, say, but never Norton AND AVG...bad juju; each AV software install sees the other as a virus and you get bad spooky things going on


Have you ever tried to uninstall Norton or McAfee??
Member Since: December 9, 2008 Posts: 0 Comments: 2498
I am seeing PLENTY of TS force wind readings from recon
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18:21:30Z 15.600N 59.583W 958.7 mb
(~ 28.31 inHg) 434 meters
(~ 1,424 feet) 1008.2 mb
(~ 29.77 inHg) - From 163° at 42 knots
(From the SSE at ~ 48.3 mph)
Member Since: September 5, 2007 Posts: 0 Comments: 3482
1081. Seastep
42 knots
(~ 48.3 mph)
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near 17N 59W ?
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1079. IKE
Quoting btwntx08:

thats the old coc the new one is in the convection


That's the latest coc according to the NHC....

Location: 16.2°N 61.1°W
Member Since: June 9, 2005 Posts: 23 Comments: 37858
1078. Drakoen
Quoting IKE:
Looking at a floater on Erika and the coordinates the NHC lists, I see where they say the COC is at...it's the naked swirl heading, what looks like, south of west from that island.


Erika center is just east of the islands. It is not the naked swirl. Center is at 16.6N 60.8W
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Quoting bocahurricane:
bocawind I am with you until there are no clouds in the sky or the system is north of me I do not stop watching and monitoring them. I have a 15 month old and 2 dogs so I can't make last minute decisions. I have been through Francis, Jeane and Wilma. 3 too many for me :)


You are doing the responsible thing. That is how a smart person should take this.
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Squak - I am a paying memmber
Member Since: September 5, 2007 Posts: 0 Comments: 3482
1075. IKE
Quoting Drakoen:
Erika is centered a bit to the north and east of the NHC coordinates


I see what you're saying as far as convection. Where the NHC has the center is a naked swirl. And the naked swirl looks headed WSW, looking at it again.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
1074. Seastep
Quote

966. jeffs713 2:04 PM EDT on September 02, 2009 Hide this comment.

Quoting leftovers:
are the bad guys targeting google ads or are they aiming at dr masters blog?


Its google ads. I've never had an issue on here, but I also have a paid subscription with no ads. (and NoScript on my home computer)

-- End Quote ---

Sorry, quote's not working. Not ads because I am paid member. Virus scanner caught it, though.

Tip: Keep your virus defs updated DAILY, not weekly. Used to be ok, but not anymore.
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12z ECMWF,CMC,UKMET dissipate erika in the not too distant future.
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Quoting jeffs713:

McAfee = McCrappy. Its almost as much of bloatware as Norton, but it is just as ineffective. But as flood mentioned, if you are on a corporate network, your choices are limited, and you are best off following common sense.


The other thing to remember is to never, and I mean under no circumstances ever install two Virus scanners on one machine. It's okay to run Malwarebytes or Adware on a machine with Norton, say, but never Norton AND AVG...bad juju; each AV software install sees the other as a virus and you get bad spooky things going on
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1071. Grothar
Quoting jeffs713:

For 925Mb to the surface, its generally good to take 20-25% off.


Thanks Jeff!!
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1070. centex
yes WU has virsus issue or something that's being flagged as a virus.
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Quoting Drakoen:
Erika is centered a bit to the north and east of the NHC coordinates


A have this feeling too
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1067. SQUAWK
Quoting hurricanehanna:
So again I'll ask about the virus cause I'm not a computer tech - I'm getting the virus message only when I pull up this site or refresh it. Can I or do I need to do anything (note: sarcastic answers will be ignored) :) Thanks

Pay the $10 and become a member and you will never have the problem again. Plus you get a lot more features that the site offers.
Member Since: December 9, 2008 Posts: 0 Comments: 2498
Quoting keys33070:



I haven't read any updates lately. How much rain do they expect you guys to get?


If the forward speed remains this low I'm guessing anywhere upwards of 6" especially where I am 1500ft up in the centre of the island. We often can get 4" plus from the normal waves that pass through. We are talking about an area with 200" + annually.
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so confusing...so what should i expect for puerto rico rain and some wind or sunshine and breezy conditions...north? south? fizzle or fizazle...my head hurts....DAMN U ERIKA!
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Guys I'm login out, Erika is killing me and I have decided to stay away from the blog for the next twelve hours and hopefully by then we should have a better idea of where this baby is going. I have 6 cold ones in the fridge, and I now for sure where those are going.
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000
WHXX01 KWBC 021826
CHGHUR
TROPICAL CYCLONE GUIDANCE MESSAGE
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1826 UTC WED SEP 2 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) 20090902 1800 UTC

...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...
090902 1800 090903 0600 090903 1800 090904 0600

LAT LON LAT LON LAT LON LAT LON
BAMS 16.4N 61.3W 16.9N 63.2W 17.6N 65.2W 18.2N 67.3W
BAMD 16.4N 61.3W 16.9N 62.7W 17.4N 64.2W 17.9N 65.4W
BAMM 16.4N 61.3W 16.7N 62.9W 17.2N 64.5W 17.6N 65.9W
LBAR 16.4N 61.3W 16.9N 63.0W 17.6N 64.9W 18.2N 66.7W
SHIP 35KTS 32KTS 36KTS 40KTS
DSHP 35KTS 32KTS 36KTS 40KTS

...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...
090904 1800 090905 1800 090906 1800 090907 1800

LAT LON LAT LON LAT LON LAT LON
BAMS 18.9N 69.3W 19.7N 73.4W 20.3N 77.6W 20.6N 81.3W
BAMD 18.2N 66.6W 18.5N 69.0W 19.1N 71.8W 20.0N 74.7W
BAMM 18.0N 67.4W 18.6N 70.7W 19.3N 74.2W 20.0N 77.5W
LBAR 18.8N 68.4W 19.4N 71.7W 19.4N 74.6W 19.2N 77.2W
SHIP 44KTS 48KTS 51KTS 55KTS
DSHP 41KTS 46KTS 49KTS 52KTS

...INITIAL CONDITIONS...
LATCUR = 16.4N LONCUR = 61.3W DIRCUR = 275DEG SPDCUR = 10KT
LATM12 = 16.5N LONM12 = 58.8W DIRM12 = 253DEG SPDM12 = 10KT
LATM24 = 16.7N LONM24 = 57.3W
WNDCUR = 35KT RMAXWD = 75NM WNDM12 = 45KT
CENPRS = 1008MB OUTPRS = 1011MB OUTRAD = 120NM SDEPTH = M
RD34NE = 90NM RD34SE = 75NM RD34SW = 0NM RD34NW = 0NM

$$
NNNN

That SHIPs intensity has come down a fair jump this time round.
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I wonder if a new center could form near the new burst of convection around 17N 59W.... What do you think? ... Vis Loop
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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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