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 rwdobson:
Right now "downcasting" is what's supported by all the available data. Nothing's over till it's over, but there is no real reason to predict any strengthening any time soon.


The majority of the forecast models still call for strengthening close to hurricane force
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Quoting stormsurge39:
Could this high pressure protect Erika some from wind sheer?


The NOGAPS and CMC show shear lowering in the Bahamas favoring strengthening. The GFS has marginal conditions.
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Quoting Drakoen:
HWRF 12Z:



Garbage...serious issues intensity wise.
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758. Relix
I am expecting heavy rains for PR though =P
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757. JRRP
Quoting BurnedAfterPosting:
let the downcasting begin lol


oh well

lol
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Right now "downcasting" is what's supported by all the available data. Nothing's over till it's over, but there is no real reason to predict any strengthening any time soon.
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Does anyone want to speculate on the chances that Erika might dissipate, but this naked swirl from the decoupled old LLC might generate into something in the western Caribbean ?

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Quoting bluewaterblues:


A convention is a gathering of friends or associattes.


This is too funny, plus you hit post #666... I almost fell out of my chair.
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Quoting Orcasystems:


ROFLMAO... I tried something different
Maybe I should try something a little more mellow?


OMG Orca what is that!! An asteroid hitting the west of the lesser antilles? Gosh let us brace for the tsunami... LOL
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Front in Gomex is forecast to move slowly North as a warm front later this week. Oh well, it was nice while it lasted. (low humidity) wonder what happens to front along E
coast?
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HWRF 12Z:

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Erika is not done yet.
It has a lot of convention.
Member Since: May 10, 2007 Posts: 0 Comments: 960
Quoting Drakoen:
What a difference a day makes. The models now show a stronger ridge of high pressure north of Erika which would prevent the system from recurving out to sea.
Could this high pressure protect Erika some from wind sheer?
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Quoting PanhandleChuck:


I was playing basketball that afternoon. I didn't have much to worry about, just graduated from Ursuline. I told my friend that there was going to be some bad weather later on in the day. He laughed and said you're crazy, it's 85 and sunny. I said mark my word. He called after seeing the evening news that night and he asked how'd I know that. I said I could smell it in the air.


There was a set of railroad tracks that ran about a half mile behind the house I grew up in. My mom always said she could tell when it was going to storm because the train whistles were loud and clear. She was *always* right, and all we had was a black and white tv we only watched after my dad came home from work, i.e. no weather news...

I think the 5 senses are better at predicting (short term) bad weather than any high tech model...
Quoting RyanFSU:
The HyperCane WRF model (HWRF) for 12Z has erupted with a ridiculous intensity forecast for Erika. I am starting to question why this model is even run at this point.

A 60-hour forecast of a near Category 5 hurricane at 930 mb...come on.

maybe the run was based on the previous convective dev and posit and possible forward movement but atlast now things have change and the stationary affect with the disorganized convection has not been taken into account yet next runs should show this
Member Since: July 15, 2006 Posts: 178 Comments: 56141
Ok...

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let the downcasting begin lol


oh well
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743. Relix
Seems like Erika is done for. Looking so bad in satellite. I am very sure it will be downgraded to a TD at 5PM and will probably pass south of PR.
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Quoting WeatherLoverinMiami:
Quoting eddye:
look at all convention growing

sorry dude this guys are making fun of you it's spelled convection


I think he meant convention as in everyone's here and now Hurricane23 is too. I could be wrong tho. wouldnt be the first time. :)
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What a difference a day makes. The models now show a stronger ridge of high pressure north of Erika which would prevent the system from recurving out to sea.
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Good afternoon ladies, gents, lurkers and pita's. Greetings from Winter Haven in central Fl where it's quite cloudy and we are seeing sporadic, extremely light showers. It's a bit after 1 PM and it's 77 degrees. That's right, 77 degrees. The AC is off and the windows are open.

I've been here for 58 years. I'm sure it's happened but I do not recall ever having a 77 degree temp at 1 PM on Sept. 2nd here before. This is a bit strange. Pleasant but strange. It makes me wonder when the hammer will fall.
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A new burst of convention on the SW of Erika.
Member Since: May 10, 2007 Posts: 0 Comments: 960
here comes 23 on here again, disrespecting people as usual

show respect for others please
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Quoting PcolaDan:


Holy Sunburst Batman!!! Looks like a bad movie.


ROFLMAO... I tried something different
Maybe I should try something a little more mellow?
Member Since: October 1, 2007 Posts: 81 Comments: 26516
I dont know why most of the models are still going father N than the obvious steering of due W to just barely N of W? Somebody please explain.
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Quoting RyanFSU:
The HyperCane WRF model (HWRF) for 12Z has erupted with a ridiculous intensity forecast for Erika. I am starting to question why this model is even run at this point.

A 60-hour forecast of a near Category 5 hurricane at 930 mb...come on.



It's better for track. Same as GFDL. They like to blow things up, so just adjust based on your experience with the model.

I like SHIPS for intensity.
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Quoting WeatherLoverinMiami:
Quoting eddye:
look at all convention growing

sorry dude this guys are making fun of you it's spelled convection


Impressive convention.
Member Since: May 10, 2007 Posts: 0 Comments: 960
Quoting leftovers:
if that but historically between where she is now and prico has been a developmental area


?? Development area for what.

One has to look through the various layers to really see where the strongest vertical wind shear really is taking place.As tpc mentioned on there 11am package at the 300-200mb continues to under cut the 200mb flow. Iam really not sure this thing will be around much longer recon might have a difficult time finding a closed low level circulation.

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Quoting rxse7en:
Back on the laptop. Here's the link for the NEXRAD loop of Jax. See anything trying to spin up offshore?

http://tinyurl.com/5ql4om
there is its forming will just be low pressure move up along and off the east coast
Member Since: July 15, 2006 Posts: 178 Comments: 56141
730. JRRP
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Quoting Orcasystems:


OMG Orca what is that!! An asteroid hitting the west of the lesser antilles? Gosh let us brace for the tsunami... LOL
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Quoting apocalyps:
now that ERIKA is entering the Carribbean all hell could break loose.
All hope is over.
The end is near.
Luckely i am positive.



VERTICAL WIND SHEAR HAS INCREASED EARLIER THAN EXPECTED...WITH CIMSS
DIAGNOSING ABOUT 15-20 KT OF SHEAR. AT FIRST GLANCE...THE SHEAR DOES
NOT APPEAR TO BE TOO STRONG OVER THE SYSTEM WITH SOUTH OR
SOUTHEASTERLY WINDS REPORTED AT 200 MB OVER THE NORTHERN LEEWARD
ISLANDS. HOWEVER...UPPER-AIR DATA FROM GUADELOUPE AND ST. MAARTEN
SUGGEST THAT THE SHEAR IS PRIMARILY COMING FROM SOUTHWESTERLY WINDS
BETWEEN 300 MB-250 MB...AND THIS IS APPARENTLY UNDERCUTTING THE
OUTFLOW LAYERS AT 200 MB AND ABOVE. MOST OF THE GLOBAL MODELS DO
NOT SHOW MUCH RELAXATION OF THIS SHEAR...AND ACTUALLY SHOW IT
INCREASING SIGNIFICANTLY IN A COUPLE OF DAYS. DESPITE ALL THIS
SHEAR...ALL RELIABLE GUIDANCE RESTRENGTHENS THIS SYSTEM TO NEAR
HURRICANE STRENGTH IN A FEW DAYS. THIS REINTENSIFICATION
DOES NOT SEEM VERY LIKELY AND THE NHC FORECAST IS MUCH LOWER THAN
THE GUIDANCE. GIVEN THE POSSIBLE SHEAR DURING THE FORECAST
PERIOD...IT WOULD NOT BE SURPRISING IF ERIKA DISSIPATED.


I believe we could see the end of Erika, very soon
The HyperCane WRF model (HWRF) for 12Z has erupted with a ridiculous intensity forecast for Erika. I am starting to question why this model is even run at this point.

A 60-hour forecast of a near Category 5 hurricane at 930 mb...come on.

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Could be an interesting extra-tropical (or subtropical) low forming north of the Bahamas over the next 24-48 hours...which could possibly impact the Outer Banks.

Anticyclone, check (look east of Miami over the Bahamas):

Shear


Improving 850 vorticity, check:

Link

Low sea level pressures, check:




Finally, there is a whole BUNCH of moisture pooling in this area shown by the precipitable water loop below.

<
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Quoting eddye:
look at all convention growing

sorry dude this guys are making fun of you it's spelled convection
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Quoting Orcasystems:


Holy Sunburst Batman!!! Looks like a bad movie.
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Quoting Seastep:


They're almost there.

Thanks I wasn't sure.
Member Since: April 29, 2007 Posts: 0 Comments: 8134
Back on the laptop. Here's the link for the NEXRAD loop of Jax. See anything trying to spin up offshore?

http://tinyurl.com/5ql4om
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Sadly, if you go to Pancho's (bad Mexican chain restaurant), that's the flag you raise for a waiter. I figure if they can't get their flag right, I surely won't eat there.

Out of curiosity, let's say it heads west and gets torn up by DR and Haiti. As a remnant low, would it be able to pick itself back up again later, or is getting torn up the end, period?
Member Since: August 21, 2008 Posts: 0 Comments: 8
FYI...

Any non-tropical related musings or discussions are being reported to the Admin...
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Member Since: October 1, 2007 Posts: 81 Comments: 26516
Quoting BurnedAfterPosting:


That isnt the real center of the system, as Dr M posted above


Chances are very Slim <10%... For it to make it to the GOMEX...
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now that ERIKA is entering the Carribbean all hell could break loose.
All hope is over.
The end is near.
Luckely i am positive.
Member Since: May 10, 2007 Posts: 0 Comments: 960
BBL
Member Since: May 13, 2008 Posts: 0 Comments: 1414
Quoting stormpetrol:
Are the HHs going out at 2pm again today?


They're almost there.
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Apparently, it's a little more than just ITCZ activity, NHC Discussion mentiont this feature..

Something to watch as far I am concernd!

"TROPICAL WAVE EXTENDS FROM 16N40W TO 8N37W MOVING W 10-15 KT. THIS WAVE REMAINS ILL-DEFINED AS IT HAS DRY AIR INTRODUCED AS
INDICATED BY TOTAL PRECIPITABLE WATER IMAGERY. WAVE IS ALSO EMBEDDED WITHIN SAHARAN DUST THUS LIMITING ANY SHOWERS OR CONVECTION."
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Are the HHs going out at 2pm again today?
Member Since: April 29, 2007 Posts: 0 Comments: 8134
Quoting Patrap:
Welcome EarthMuffin....

By the way, I am "socially handicapped", so if I appear rude, I dont intend to, I just have very poor social skills. Seriously...and sorry


I as well..so you'll fit right in.

I'll steer ya clear of the Bad uns here.


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Quoting cchsweatherman:


Just because convection may be increasing, it doesn't mean its strengthening. Its got such a poor low-level structure that it doesn't matter how much convection it has. You need to have a defined low-level structure in order to have a strengthening system and its really lacking that at this time. Wouldn't surprise me to see this be downgraded to a tropical depression at 5pm unless it can start developing a nice low-level circulation structure.

That's exactly what happened last night. Erika started blowing off massive amounts of convection, but because the structural organization just wasn't there, Erika couldn't sustain herself, which leads her to her current state: blatantly unhealthy.
Member Since: August 2, 2006 Posts: 47 Comments: 11709

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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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