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Tropical Storm Erika a Potential Threat to the Bahamas and U.S. East Coast

By: Jeff Masters 3:33 PM GMT on August 26, 2015

Tropical storm warnings are flying for Puerto Rico, the Virgin Islands, and much of the northern Lesser Antilles Islands as Tropical Storm Erika speeds westwards at 17 mph. An Air Force hurricane hunter aircraft was in the storm Wednesday morning, and found Erika's winds had increased slightly, with top surface winds up to 45 mph from their previous 40 mph. Erika's tropical storm-force winds were all on the east and northeast sides of the storm. Satellite loops on Wednesday morning showed that Erika continued to be disorganized in the face of dry air and wind shear. The low-level center was partially exposed to view on the north side, the location of plenty of dry air from the Saharan Air Layer. Erika had only a modest area of heavy thunderstorms on its east side, and these thunderstorms did not change much in intensity or areal coverage on Wednesday morning. Wind shear due to upper-level winds out of the west was a moderate 10 - 20 knots, and this shear was driving dry air on the northwest side of Erika into its core, disrupting the storm. Sea surface temperatures (SSTs) were favorable for development, though—near 28°C (82°F).


Figure 1. Latest satellite image of Tropical Storm Erika.


Figure 2. NOAA Hurricane Hunter aircraft N43RF flew into Tropical Storm Erika on Tuesday evening, and the crew captured this rainbow SE of the center. Image credit: @NOAA_HurrHunter.

Erika's impact on the Caribbean islands
Erika's expected rainfall amounts of 3 -5" in the islands may cause some isolated flash flooding and mudslides, but should help alleviate severe to extreme drought conditions some of the islands are experiencing. Puerto Rico, for example, desperately needs the rain--the remnants of Danny brought 0.48" of rain to the capital of San Juan on Tuesday, but the city is still 10" below the normal 33" of rain it should have received by this point in the year. Water restrictions are in place in the city, whereby hundreds of thousands of residents receive water only two days per week.

Erika's potential impact on the Bahamas and U.S. East Coast
The 8 am EDT Wednesday run of the SHIPS model predicted that wind shear would remain in the moderate range through Thursday, then increase to a high 25 - 30 knots Thursday night though Friday afternoon, due to an upper-level low that is expected to remain near eastern Cuba through Friday. At that time, Erika will be passing just north of Puerto Rico and the Dominican Republic, and it is quite possible that the increasing shear and interaction with the high terrain of Hispaniola and Puerto Rico will cause Erika to dissipate, as predicted by the Wednesday morning runs of the GFS model. If Erika survives into Friday afternoon, the potential for a dangerous storm that will affect the Bahamas and U.S. East Coast increases substantially. Sea surface temperatures (SSTs) warm to near 29°C (84°F) in the Southeast Bahamas, and 30°C (86°F) in the Northwest Bahamas. This will provide plenty of extra fuel for intensification. The upper low over Cuba is forecast to weaken on Saturday, which should cause wind shear to drop to the moderate range, 10 - 15 knots, as Erika traverses the Bahamas, allowing the storm to take advantage of the warmer ocean temperatures are grow more organized. A weak trough of low pressure capable of turning Erika to the north will set up shop along the U.S. East Coast late this week, and it is possible that Erika will be strong enough to get picked up by this trough and turn to the north just before reaching the Florida coast on Sunday evening or Monday morning, as suggested by the Wednesday morning runs of two of our top models for predicting hurricane tracks, the UKMET and HWRF models. If Erika stays weak, the storm is more likely to plow into Florida, as predicted by the Wednesday morning run of the European model. I give a 20% chance that Erika will end up being a landfalling hurricane for the U.S. East Coast, a 40% chance storm will dissipate by Saturday, and a 30% chance the storm will be too weak and disorganized to have time to organize into a hurricane before hitting the U.S. East Coast. There is also a small chance (10%) that Erika could miss the U.S. East Coast--a situation that would most likely arise if Erika quickly organizes into a hurricane by Saturday, and thus "feels" the steering influence of winds higher up in the atmosphere, forcing the storm to recurve out to sea.


Figure 3. The 00Z Wednesday (8 pm EDT Tuesday) runs of the European and GFS models had two very different predictions of the intensity of Erika for 5 pm Sunday August 30, 2015. The European model showed Erika as a strong tropical storm just off the coast of Florida (purple colors = winds of at least 58 mph), while the GFS model showed Erika merely as a strong tropical wave with no closed circulation. Image taken from our wundermap with the “Model Data” layer turned on.


Figure 4. Forecasts of the track of Tropical Storm Erika from the 00Z Wednesday (8 pm EDT Tuesday) run of the GFS model from the twenty members of the GFS Ensemble model. The GFS Ensemble takes the operational version of the GFS model and makes twenty different runs of it at lower resolution with slightly different initial conditions to generate an ensemble of possible forecasts. As we can see, there are a wide variety of possible solutions. The operational high-res version of the GFS (white line) shows Erika moving over South Florida. Most of the GFS ensemble members keep Erika weak, resulting in a more southwards track for the storm than our other top models are showing.

Tropical Storm Ignacio a threat to Hawaii
Hawaii needs to closely watch Tropical Storm Ignacio, which is gathering strength in the waters about 1400 miles east-southeast of the islands. Satellite loops on Wednesday morning showed that Ignacio had an impressive area of heavy thunderstorms that were growing in intensity and areal extent, and Ignacio is over warm waters with moderate wind shear, conditions that favor possible rapid intensification. Our two top models for forecasting hurricane tracks, the European and GFS models, both showed Ignacio passing within 200 miles of Hawaii on Tuesday. Hawaii should also watch Invest 96E, which is close to tropical depression status over 1500 miles east-southeast of the islands. 96E will track towards the Hawaiian Islands over the next seven days, and could be a long-range threat late next week.

Bob Henson will have another Erika post later today. Hope you caught his retrospective look back at Hurricane Katrina on #WUTV last night!

Jeff Masters

Hurricane

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Reader Comments



Yes I know lol don't need to remind me ;)
Quoting 1486. Hurricanes101:

1481. HurricaneAndre

You seriously need to stop this pattern. You get like this and later on apologize and say it won't happen again. Are you interested in meteorology? It sounds like you are, but you need to realize that you have to be very patient with most storms as they will not develop at the drop of a hat. Just some advice.


He just wants attention, just ignore him.
Quoting 1495. WDEmobmet:



How do we watch is it on the internet? Could someone from say Cali watch it now?
for those who are in florida im sure have seen the same live news feed from channel 13 in orlando and you actually can watch it from the internet
1504. Michfan
Quoting 1419. floridabuckeyes:

Just like a Michigan Fan....always at least a point behind!!


Hahahaha. Gators first for me......then Michigan.....but still screw Urban Meyer on both fronts. :P
Quoting 1466. Geoboy645:

uhh irene came in august late august in fact
http://www.nhc.noaa.gov/archive/1999/dis/NAL1399. 007.html
depends on which Irene you are talking about....Broward got hammered by THIS Irene.
1506. MahFL
The Global Hawk is still over Erika :

AV6


Shows center at a slightly lower latitude
Quoting 1484. Crazman:



Are you trying to get banned? Whats with all the trolls on this blog lately.


He's a good member, no troll. He just fluctuates between dead season, active season, dead storm, and major storm sometimes. An emotional endeavor this can be sometimes. Very confusing. :)
Here's something that hasn't been talked about yet. I understand the NHC has a new storm surge model that they will be breaking out this year if necessary that takes into account shore line, how the storm approaches, how big it is, how strong it is and how fast it is moving. I understand evacuations, if necessary, would be based on this new model and that just because you live in a flood zone, that doesn't mean you will be asked to leave. It just depends on the many variables. I foresee lots of confusion with using this model for evacuations as many will want to leave anyway and others won't believe it thinking that conditions and tracks can and will change. Any thoughts? One thing to mention when it comes to floods (and I think most on this blog are aware of it) is that a slow moving tropical storm or cat 1 hurricane can inflict some serious damage via flooding. What many people in SE Florida don't realize is that much flooding is caused not just by storm surge but by canals being clogged with debris as well as overflowing with copious amounts of rain.
Quoting 1505. floridabuckeyes:

http://www.nhc.noaa.gov/archive/1999/dis/NAL1399. 007.html
depends on which Irene you are talking about....Broward got hammered by THIS Irene.


but they were talking about and posted the forecast track for the one in 2011
,
Quoting 1499. HurricaneAndre:

it's just that I told people it might come and if it don't come, I'm in trouble and I can't have a life anymore.


I don't know how old you are, but you're acting very immature. If you get like this over weather, you have A LOT of learning to do.
also the tidbit video also explains that there is a nice channel between the trough in the north conus and the high for erika to channel ots...
Tropical Storm Erika Strengthens, Where Is It Headed?
Tropical storm watches are in effect for Puerto Rico and the Virgin Islands. The storm strenghtens and has a track of uncertainty.

Tropical Storm Erika is currently about 155 miles east of Antigua.
The northern Leeward Islands may feel tropical storm-force winds later tonight.
Tropical storm warnings have been issued as far west as Puerto Rico, including the Virgin Islands and most of the northern Leeward Islands.
Erika is expected to remain a tropical storm with little change in strength the next few days as it moves quickly to the west-northwest.
Erika will then bring more rain to drought-suffering Puerto Rico and the Virgin Islands and tropical storm-force winds Thursday and Thursday night.
Erika's future track and intensity beyond Puerto Rico and the Virgin Islands remains uncertain, and may involve a track near the Bahamas this weekend and possibly parts of the Florida peninsula and the Southeast coast early next week.
Quoting 1468. ProgressivePulse:

Convection still chasing the center tonight


Is that a new center on radar as that doesn't appear to be the one depicted by the NHC. Might be a mid level and low level swirl separated from each other. Another strange thing is the radar that Gearst is showing isn't showing that much rain under those dense cloud tops. Sure sign Erika is really lacking in organization. In terms of track i give up on that. Seems to be another tricky forecast the next 2 days.
JeffMasters has created a new entry.
Quoting 1507. stormpetrol:



Shows center at a slightly lower latitude


Interesting

Quoting 1499. HurricaneAndre:

it's just that I told people it might come and if it don't come, I'm in trouble and I can't have a life anymore.


That may be catastrophizing just a bit mate. :)
1519. MahFL
CDO continues to expand, been doing that for hours now :



Just what the need in South FL any rain producing storm, would be interesting if Erika does show up in this area considering the flooding in certain areas from an afternoon storm.
http://miami.cbslocal.com/2015/08/26/heavy-rains- leave-flooding-in-opa-locka-warehouse-district/
Quoting 1413. Michfan:



Yeah yeah......you get my point. Nitpick. :P
Took me a while to learn the difference .... doesn't matter so much until the end of EDT.... when suddenly everything changes .... lol
Quoting 1499. HurricaneAndre:

it's just that I told people it might come and if it don't come, I'm in trouble and I can't have a life anymore.
your not in trouble its weather never works out as forecasted not till 72 hrs out then u can state with certain claim that it will happen
What is the benefit of data from a radar versus satellite data?
Evening everyone. .if she stays weak..she will go more west I believe. .but not fizzle like Danny did though. .all going to depend on that high and how low the 'lol' goes south..could be an Erin type of storm here in the panhandle. ..just my 2 cents worth
but ya need to chillax and sit back learn to observe
Camerooski
Perhaps you missed this question earlier, regarding your response to StormJunkie. I'd still like to see your answer:
1217. Camerooski:
I wouldn't quite say that but maybe from Pensacola to Cape Hatteras
...
1258. Barefootontherocks
I'm curious. IF Erika remains an entity and works into the Gulf of Mexico... What would make you rule out east TX to Pensacola?
Quoting 1467. thefalsereport1:

i just watched our local live chanel 13 weather met from orlando. he just said that erika is struglling and may in fact fizzle out like danny. but if erika hangs in there for 2 more days it could strengthen but will most likely go out to sea .... go watch for your selves
My local said something similar. That if it survives until Friday, that's going to be key. Showing at at 45mph through entire day Thursday and the start of Friday and after that is where we would know more. If it remains weak at that point , more westward. If it gets very strong more north/northeast and the middle path as shown now would be if it was I guess a cat 1 strength
I am a self admitting "wish caster"... It is what it is.. With that being said, and as much as I wish she would get her act together.......... Its not going to happen.

I have seen countless storms go through what Erika is going through. Large storm having issues consolidating and ends up running out of real estate. This storm has such a broad circulation that it just cant get its act together. Im not saying the storm will "poof" completely, but Id be willing to bet that it has already peaked.

She is too big for her own good. We keep seeing flare ups, and then..... nada.. Back to stage 1. Re-fire... then nada.. Back to stage 1.

She will soon run out of space and before we know it, she will be riding off into the sunset off the east coast as a remnant low.
It was a sunny and rainy day here in Central Florida.

Quoting 1475. ExumaMET:

I just had the irene epiphany myself... not a pleasant thought.


That's two unhappy tracks I have "noticed" .... though hopefully Erika has no chance of being another 1928 cane ....
What I'm not liking is the flipflopping with the models.... I'd sure like more certainty, especially if that means I will have to do extensive preps ....
Quite unimpressive.......(Barbados NEXRAD is down)...

Quoting 1504. Michfan:



Hahahaha. Gators first for me......then Michigan.....but still screw Urban Meyer on both fronts. :P
Love the Banter. He got UF 2 NC's....not bad. Great Coach. Probably need to get back to Erika.
Quoting 1510. Hurricanes101:



but they were talking about and posted the forecast track for the one in 2011
Didnt notice the date....only the name.... I stand corrected.
1537. JRRP
Quoting 1527. Barefootontherocks:

Camerooski
Perhaps you missed this question earlier, regarding your response to StormJunkie. I'd still like to see your answer:
1217. Camerooski:
I wouldn't quite say that but maybe from Pensacola to Cape Hatteras
...
1258. Barefootontherocks
I'm curious. IF Erika remains an entity and works into the Gulf of Mexico... What would make you rule out east TX to Pensacola?
Hi, sorry I missed your question earlier but with the major ridge that would force Erika through South Florida and into the Gulf almost Katrina like, there would need to be no dip in the trough covering Texas, however the Euro model shows a dip which would force Erika out and into the FL panhandle at the furthest West...
The blog is in Dmin or Dmax?
Quoting 1523. Sharkicane:

What is the benefit of data from a radar versus satellite data?
if ya have a good eye you can see the cyclonic structure of the rain bands and how they wrap within the storm
New Blog!!!

Quoting 1516. WunderAlertBot:

JeffMasters has created a new entry.
Quoting 1539. Camerooski:

Hi, sorry I missed your question earlier but with the major ridge that would force Erika through South Florida and into the Gulf almost Katrina like, there would need to be no dip in the trough covering Texas, however the Euro model shows a dip which would force Erika out and into the FL panhandle at the furthest West...
I'm not sure I get the "trough covering TX" part. Most troughs are dips. Thanks for the answer just the same.

Quoting 1458. StormTrackerScott:



1.09" here in Longwood. Over 11" now for August.
2.75 " here in NE palm bay area at my house on my pws. 2.6" in my acu rite rain gauge. Came down very hard between 4 and 6pm.
Quoting 1421. NativeSun:

Hi false, I think I will go the other way, and say a cat 3 or 4 hitting S. Florida and going into the Gulf, and eventually the Florida Panhandle. The high is building in as this weak trough backs to the West and will be stronger come this weekend. It will cross the Gulfstream like so many other storms in the past and intensify up until landfall.


I've started prepping today for just that scenario. Garage at home has been cleared. Generator has been pulled out and started/load tested. Batteries, weather radio, and flashlights checked. Food and water supplies are always on-hand.

If the storm maintains it's current course I will start backing up all of the systems at work on Friday. As it stands now, I have 7,000 thousand gallons of diesel, give or take a few hundred, available for the back-up generators. A 1.2 Meg and a 750K. We are prioritized at my office for refueling, both diesel, and unleaded for our vehicles. I hope it is not needed, but we will be prepared if S. Florida takes a hit.

While there is still a lot of uncertainty in the forecast, it never hurts to be prepared for the worst.
Quoting 1427. Camerooski:

Very interesting to hear your side, and I have to say that i am a bit surprised as to the recent shift in models, if that ridge is still in place me in Fort Laud. are going to see some nasty effects,...
They will keep shifting back and forth until get a better idea how strong the high will be and how far West the trough retrogrades as it splits.