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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Back for a bit

Erika is once again producing deep convection that is drawing in on the new center. This pattern may repeat over the next several hours where shear gets the upper hand then the convection fights back.

What an enigma this one is.
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Quoting LUCARIO:
Erika looks amazing, I have a weird feeling she is going to go into the GOMEX. She will hot the western gulf texas or mexico. I don't think this is a florida storm. Florida is protected, God has blessed them. Erika is going to make Ike and Gustav looks like a tropical wave.


Lucario, I understand your trepidation. Texas has taken a beating recently. But its too soon to know where or if Erika will go. Just watch and stay informed. Not bashing you. You got a right to state your opinion like anyone else. And its ok to be worried. But if you start this early that kinda stress will eat ya alive.
Just know that hanging out here you're likely to know if anything is headed your way way before anyone else. And so you'll have plenty of time to deal with it. :)
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Quoting tornadodude:
Computer Models- Millions of Dollars.
Paid NHC Meteorologists- Millions of Dollars.
The Wide Range of Characters on This Blog.......
PRICELESS



You should that on T-shirts, I'll take 2
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Quoting rwdobson:
"I'm just not sure what the null hypothesis is here. Dr. Masters says that we're seeing the effects of small-scale shear, because if it wasn't there, the storm wouldn't be behaving like this. Is there any way to evaluate the veracity of that claim?"

Well, there is upper-air data from the Islands that is showing the small-scale features.

Wind shear is often the most critical factor controlling hurricane formation and destruction. In general, wind shear refers to any change in wind speed or direction along a straight line. In the case of hurricanes, wind shear is important primarily in the vertical direction--from the surface to the top of the troposphere. The troposphere is the region of the atmosphere that our active weather is confined to, and extends up to about 40,000 feet altitude (a pressure of about 200 mb) in the tropics in summer. Hurricanes fill the entire vertical extent of the troposphere, and are steered by the average wind through this layer. When one hears the phrase, "wind shear is 20 knots over the hurricane", this typically refers to the difference in wind speed between 200 mb (the top of the troposphere, 40,000 feet altitude) and a layer where a pressure of 850 mb is found--about 5,000 feet above the surface. This wind shear is computed over a large area--a circle of 700 miles in diameter centered on the hurricane is one technique used. This 200-850 mb wind shear is a crude measure of the actual wind shear a storm experiences, since only changes in wind speed--not wind direction--are considered. Furthermore, the computed shear does not consider any smaller scale changes that may occur within this large volume of the atmosphere. For example, it is common to find a strong jet of wind at about 600 mb blowing along the edge of the Saharan Air Layer (SAL)--that area of dry, dusty air that frequently lies to the north of developing tropical cyclones in the mid-Atlantic. This jet will create significant wind shear that will not show up on the standard 200-850 mb wind shear plots. Since upper-air measurements are very sparse over the open ocean, wind shear that is invisible on 200-850 mb wind shear analysis charts will often unexpectedly kill or weaken a developing tropical cyclone.
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Quoting bluewaterblues:


What is coming real soon?

I am having a hard time deciphering your riddle.


Cool weather....

I think thats what he's saying :0)
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Quoting tornadodude:
Computer Models- Millions of Dollars.
Paid NHC Meteorologists- Millions of Dollars.
The Wide Range of Characters on This Blog.......
PRICELESS
LOL
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I think this storm might not make it.... or is it just me?
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Mission #3 is airborne and on the way.


AOI

AOI

AOI

AOI
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Quoting Floodman:


That's "Citizens of the republic" to you


Love it!
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People will be happy with the rain from erika.
Member Since: May 10, 2007 Posts: 0 Comments: 960
Computer Models- Millions of Dollars.
Paid NHC Meteorologists- Millions of Dollars.
The Wide Range of Characters on This Blog.......
PRICELESS
Member Since: Posts: Comments:
Quoting Floodman:


Welcome to the doc's blog...LOL

Crackpots and tosspots(my personal favorite) run rampant here among the rest of us



Ok I have to ask, tosspots?
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Quoting PanhandleChuck:
WOW.... My ignore list is growing so large. I wish that we could create a list of only individuals that we wanted to see comments from. What's up Patster and Ikester? Think Erica will become a CAT 7 with 330 MPH winds that will affect the entire GOM?

IMHO, This storm is going to do whatever it wants and we will not know if it's going up the coast or into the GOM until Friday sometime.


Erika still holding her cards close to her,..er,chest..so I never dismiss any CV system Se of Me till its gone from the Basin in September.
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Quoting Patrap:


I have the Front door Open and the Far BAck Door and I swear It feels and smells Like October almost


It's great isn't it, we're getting the same weather here in NW Florida! It's hard to belive it's early September, going to be nice doing the yard work this evening without sweating my you know what off!
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Quoting Floodman:


Welcome to the doc's blog...LOL

Crackpots and tosspots(my personal favorite) run rampant here among the rest of us


hahahahaha....
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Quoting PensacolaDoug:
No

Not "actual" people, TEXANS!


That's "Citizens of the republic" to you
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491. jpsb
Quoting alaina1085:


It really does! I was telling my parents I think winter is going to come early...thanks EL NINO! Ill take it tho!

And that video=Creepy for sure.
I've been telling my friends for months, "Watch out for this winter, it is going to be a cold one". A cool front this strong in the middle of summer in Texas! Yikes, been stocking up on firewood, hope we don't get any hard freezes or big snow storms but I am expecting that this winter. I free sorry for the folks up north hope they are prepared.
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490. IKE
12Z GFS takes Erika over PR and then DR/Haiti. If that verifies, that should finish it off. Mountains of DR/Haiti will kill the circulation.
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Quoting Patrap:


Hmm 2 E's in One season.. Id maybe double check yer er,source.


LUCAR said two years not one
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.....and all my EX's...
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Quoting LUCARIO:


yes, or die like chris

two years straight texas been getting storms

gustav and fay were the only ones not to hit the big state

erin
humb
dolly
edward
ike


Hmm 2 E's in One season.. Id maybe double check yer er,source.
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WOW.... My ignore list is growing so large. I wish that we could create a list of only individuals that we wanted to see comments from. What's up Patster and Ikester? Think Erica will become a CAT 7 with 330 MPH winds that will affect the entire GOM?

IMHO, This storm is going to do whatever it wants and we will not know if it's going up the coast or into the GOM until Friday sometime.
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Quoting Patrap:
Get ready,,,wait for it..itsa coming real soon..!


What is coming real soon?

I am having a hard time deciphering your riddle.
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Quoting EarthMuffin:


So you are essentially saying every reputable meteorologist, every scientific model as well as 99% of the posters on this blog are wrong and TS Erika is going to hit...Texas.


Welcome to the doc's blog...LOL

Crackpots and tosspots(my personal favorite) run rampant here among the rest of us
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483. slavp
Ahh yes this time last year I was sweating my tush off with no AC and waiting in 4 hour lines for groceries! Dont want that again..ever.
I Agree!!! But last year a week later I had to do it all over again because of IKE...Hope we get a few years reprieve...lol
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She brought home some of that pumpkin pie coffee creamer. Between that, the cool temps, and the crape myrtle blooms falling... I'm ready for some football!!!!
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Quoting EarthMuffin:


So you are essentially saying every reputable meteorologist, every scientific model as well as 99% of the posters on this blog are wrong and TS Erika is going to hit...Texas.


yes, or die like chris

two years straight texas been getting storms

gustav and fay were the only ones not to hit the big state

erin
humb
dolly
edward
ike
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Quoting atmoaggie:

I very much agree.
Question: Do you find it odd that we are running GFDL, HWRF, etc. looking for a five-day solution without running any balloons up at 06Z and 18Z? One would think that upper air obs in FL, Bahamas, even Georgia and Bama would be useful info.


I know they do launch those balloons for a storm that is closer. Not sure if someone did a cost/benefit analysis and decided that the improvement in forecasts wasn't worth the cost?

Having ships release ballons during hurricane season might not be a bad thing either...
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Quoting stormpetrol:

Erika catchin up to the old LLC moving slightly south of due west at a liitle faster clip, new center just about fully formed and becoming the dominant one at 16N/60W, taking a comma like shape, getting in gear one might say just my opinion, I guess I'll get blasted as usual :)
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Quoting alaina1085:


It really does! I was telling my parents I think winter is going to come early...thanks EL NINO! Ill take it tho!

And that video=Creepy for sure.


cant wait till feb of 2010 to get that kind of weather in SFLA, for now, afternoon thunderstorms, mosquitoes and humidity.
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No
Quoting apocalyps:
Are there actually living people in texas?


Not "actual" people, TEXANS!
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"I'm just not sure what the null hypothesis is here. Dr. Masters says that we're seeing the effects of small-scale shear, because if it wasn't there, the storm wouldn't be behaving like this. Is there any way to evaluate the veracity of that claim?"

Well, there is upper-air data from the Islands that is showing the small-scale features.
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Quoting alaina1085:
Pat,

Are you enjoying this wonderful weather? Im sitting on my back porch with my laptop. The breeze is blowing, the humidity is low now alls I need is a margarita!


the baby and i were out there for about an hour enjoying the weather and my happy flowers. but of course, she had to start eating the ashes underneath the weber grill!
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Quoting NRAamy:
458. apocalyps 9:20 AM PDT on September 02, 2009
Are there actually living people in texas?


and I get banned?!


Are there people in texas?
Or are they banned?
just curious.
Member Since: May 10, 2007 Posts: 0 Comments: 960
Quoting Seastep:
For the ignore function, maybe you have to be a paying member to use it? I'm a subscriber, so can't test it.

oh, maybe that's it.
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Quoting LUCARIO:
http://en.wikipedia.org/wiki/Tropical_Storm_Chris_(2006)


Erika Aka Chris part 2


So you are essentially saying every reputable meteorologist, every scientific model as well as 99% of the posters on this blog are wrong and TS Erika is going to hit...Texas.
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Quoting alaina1085:


Ahh yes this time last year I was sweating my tush off with no AC and waiting in 4 hour lines for groceries! Dont want that again..ever.

AMEN to that....
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Quoting Patrap:


I have the Front door Open and the Far BAck Door and I swear It feels and smells Like October almost


It really does! I was telling my parents I think winter is going to come early...thanks EL NINO! Ill take it tho!

And that video=Creepy for sure.
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458. apocalyps 9:20 AM PDT on September 02, 2009
Are there actually living people in texas?


and I get banned?!
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For the ignore function, maybe you have to be a paying member to use it? I'm a subscriber, so can't test it.
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Erika? reminds me of Andrew in 1992. unorganized and unpredictable and almost impossible to predict/forecast......
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Quoting belizeweatherfan:
The conversations have been so enlightening today. I have heard Erika will potentially threaten the Lesser Antillies, Bahamas,The Carolinas Florida to Texas and everything in between...is the Yucatan safe? Back to lurking...thanks!


maybe Denver
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http://en.wikipedia.org/wiki/Tropical_Storm_Chris_(2006)


Erika Aka Chris part 2
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Quoting belizeweatherfan:
The conversations have been so enlightening today. I have heard Erika will potentially threaten the Lesser Antillies, Bahamas,The Carolinas Florida to Texas and everything in between...is the Yucatan safe? Back to lurking...thanks!


You should be fine.
Member Since: September 2, 2006 Posts: 110 Comments: 6874

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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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