Tropical Storm Emily stalls, remains a threat to Hispaniola

By: Dr. Jeff Masters , 12:37 AM GMT on August 04, 2011

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All afternoon, Tropical Storm Emily has remained on a westward track with maximum sustained winds of 50 mph. In the 8pm EDT update from the National Hurricane Center, the storm was nearly stationary, with no forward movement. The storm gained some thunderstorm activity over its center of circulation throughout the day, but remains sheared to the east. In order for tropical cyclones to intensify (or, continue to exist at all), they need to be vertically stacked and standing straight up in the atmosphere. Emily continues to be tilted east due to 20 knots of westerly wind shear, which is apparent on satellite and also in recent satellite analysis of upper-level circulation.

Emily's tropical storm-force winds extend 115 miles to the north and east of the center, and tropical storm conditions are probably already being felt in Hispaniola. Isolated rainfall amounts of up to 20 inches are expected on the eastern side of the storm. The longer Emily tracks west before making a turn to the northwest, the more likely it is that Haiti will see the heavier rainfall amounts. In any case, Emily is a serious threat for flash flooding and mudslides on the island of Hispaniola and eastern Cuba.


Figure 1. MODIS satellite imagery from earlier today, plotted using NASA's new Rapid Response Web Mapping Service.

Forecast for Tropical Storm Emily
The forecast for Emily remains similar to this morning's update, with a slight shift to the east in track. The National Hurricane Center forecasts that the storm will make landfall in Haiti overnight tonight or early tomorrow as a tropical storm. After that, it will continue on a track to the northwest until Saturday, when it will turn to the northeast and out to sea. This is all assuming Emily makes the turn to the northwest over the next 12 hours.

This afternoon the HWRF and GFDL shifted their forecast track slightly to the east away from the Florida coast. Consensus shifted this way as well, and that change is also present in the official forecast track. As the storm moves north of Hispaniola and Cuba, environmental conditions will become more favorable, and the storm could gain some organization. But this is very hard to predict since Emily hasn't actually made a turn to the northwest, yet. Furthermore, the longer Emily tracks to the west, the more of a threat it becomes to the Florida coast.

Typhoon Muifa a landfall threat for China coast

Typhoon Muifa has sustained winds of 109 mph, with gusts up to 132 mph, and is a category 2 on the Saffir-Simpson Hurricane Scale. Muifa's concentric eyewalls are plainly visible on both infrared satellite imagery as well as radar, which is indicative of a mature, intense cyclone undergoing eyewall replacement cycles. Typhoon Muifa is expected to remain a category 2 with winds of at least 104 mph through mid-day Saturday, at which point it is forecast to intensify slightly to a category 3 as it approaches the China coast. As of this afternoon, Muifa is expected to make landfall south of Shanghai, near Zhoushan, Saturday afternoon or evening (local time). In addition to being a serious threat to all of the involved coastal cities, this is a particularly dangerous track for Shanghai and Hangzhou, since near-hurricane-strength winds will be out of the east, pushing water into the surrounding inlets. The forecast landfall location has been trending south along the coast, so it doesn't appear that China will be able to escape a Muifa landfall.


Figure 2. Infrared satellite imagery of Typhoon Muifa from August 3rd.

Dr. Carver will have an update later tonight should there be any interesting changes to Emily or the forecast. I'll be back tomorrow with another post.

Angela

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is emily still moving west according to recon's new center fix?
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1359. Drakoen
Based on the center fix Emily continues to move towards the west.
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Quoting MississippiWx:


Would make no sense at all. I'm ready for her to be dead.


Haha, yeah.. It's a confusing system.
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Id say they can keep her at 45kts on the next advisory because of the SFMR, but its hard to ignore that the the flight level winds have consistently supported a slightly weaker system. Increasing pressure isn't good either.
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I still hold strong on my initial forecast, which I made this morning.

Tropical Storm Emily moves WNW as the weakness pulls it north. The a ridge will build back in for about 12-24 hours and steer Ems to South Florida, then either scraping or making landfall on the South Florida coastline. A shortwave trough diving south pulls Ems and recurves her around Melbourne or east of Melbourne, depending if she makes landfall, sharply recurves out to sea. As for the strength, I'm looking at least a strong TS near or landfall in Florida. Adrians forecast is also a very good possibility, but right now, until Ems makes her move WNW, I'm not buying a straight NW to NE movement right now. If she recurves, it will be dangerously close to Florida, enough to get watches and warnings.
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1354. JRRP
Quoting BahaHurican:
Ten cuidao, u 2.....

yes...esto me recuerda a Noel 2007
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Vortex message is pretty unimpressive.
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1352. Seawall
Not to be redundant, but if anyone wants to learn all they can, go to this site and take the training videos thanks to the blogger this AM. They are incredible.
Link
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Quoting MiamiHurricanes09:
Looks like Emily has weakened after we expected her to have strengthened. Surprise surprise?

Damn I hate this system.


Would make no sense at all. I'm ready for her to be dead.
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1350. JRRP
Quoting MiamiHurricanes09:
Looks like Emily has weakened after we expected her to have strengthened. Surprise surprise?

Damn I hate this system.

lol
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Quoting JRRP:

amigo... aqui el viento esta pitaando...
Ten cuidao, u 2.....
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1348. Drakoen
hmmm didn't think the circulation was that far south still....
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1346. JRRP
voy apagar mi pc ..las rafagas de viento soplan con bastante fuerza..
see you tomorrow
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Looks like Emily has weakened after we expected her to have strengthened. Surprise surprise?

Damn I hate this system.

H. EXTRAP 1007 mb
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Quoting sarepa:
I live in Santo Domingo. What I don't get is, if there is so much cloud coverage on the Satellite over us, why isen't it raining? It's just cloudy over here.

Because that cloudiness over us isn't convective yet, as most of rainy clouds are south of Santo Domingo, where I live too.
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Quoting extreme236:
UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 8.1.3
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 04 AUG 2011 Time : 051500 UTC
Lat : 17:15:19 N Lon : 71:23:44 W


CI# /Pressure/ Vmax
3.0 /1001.0mb/ 45.0kt


Final T# Adj T# Raw T#
3.0 3.2 3.8


Probably went down because the overall cloud structure is a little less organized than earlier. However, Emily has instantly fired up convection again over the center. This is something she hasn't been doing.
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Quoting robj144:


Yes, but in the different hemispheres, low pressure systems rotate in opposite directions. So low and high pressure systems rotate opposite of one another in each hemisphere and thus produce opposite angular momentum vectors.


Indeed, this is true if the storms were diametrically opposed on the Earth. When you consider storms at the same longitude the angular momentum vectors will not completely cancel, and result in a vector that points into the Earth.

So I guess I need to think bigger -- the whole atmosphere. Presumably, the angular momentum vector, integrated over the entire surface of the Earth, cancels out nearly completely. But my question dealt with the rapid spin up of a hurricane. Exactly where does this angular momentum come from, and what is its fate? If it comes from another part of the atmosphere, there has to be some physical mechanism belying the transfer process, like some fluid flow. Or, since it's the Coriolis force that exerts the torque, the storm picks up its angular momentum from the immense angular momentum of the Earth.

Seriously now, though, last post for me tonight. I'm zombifying out now. Maybe I'll wake up tomorrow and realize this made no sense whatsoever :P
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Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 4th day of the month at 06:06Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 309)
Storm Number & Year: 05L in 2011
Storm Name: Emily (flight in the North Atlantic basin)
Mission Number: 10
Observation Number: 04
A. Time of Center Fix: 4th day of the month at 5:41:50Z
B. Center Fix Coordinates: 16°59'N 71°13'W (16.9833N 71.2167W)
B. Center Fix Location: 130 miles (210 km) between the SE and SSE (146°) from Port-au-Prince, Haiti.
C. Minimum Height at Standard Level: 1,470m (4,823ft) at 850mb
D. Estimated (by SFMR or visually) Maximum Surface Wind: 43kts (~ 49.5mph)
E. Location of the Estimated Maximum Surface Wind: 76 nautical miles (87 statute miles) to the E (81°) of center fix
F. Maximum Flight Level Wind Inbound: From 130° at 43kts (From the SE at ~ 49.5mph)
G. Location of Maximum Flight Level Wind Inbound: 97 nautical miles (112 statute miles) to the E (83°) of center fix
H. Minimum Sea Level Pressure: 1007mb (29.74 inHg) - Extrapolated
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 15°C (59°F) at a pressure alt. of 1,525m (5,003ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 15°C (59°F) at a pressure alt. of 1,538m (5,046ft)
K. Dewpoint Temp (collected at same location as temp inside eye): 15°C (59°F)
K. Sea Surface Temp (collected at same location as temp inside eye): Not Available
L. Eye Character: Not Available
M. Eye Shape: Not Available
N. Fix Determined By: Penetration, Wind, Pressure and Temperature
N. Fix Level: 850mb
O. Navigation Fix Accuracy: 0.02 nautical miles
O. Meteorological Accuracy: 1 nautical mile
Remarks Section:
Maximum Flight Level Wind: 43kts (~ 49.5mph) in the east quadrant at 5:13:30Z
Sea Level Pressure Extrapolation From: 850mb
Maximum Flight Level Temp: 17°C (63°F) which was observed 43 nautical miles (49 statute miles) to the ENE (73°) from the flight level center
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04/0545 UTC 17.1N 71.6W T3.0/3.0 EMILY -- Atlantic
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Good night, night shift. See you on the flip side.
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UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 8.1.3
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 04 AUG 2011 Time : 051500 UTC
Lat : 17:15:19 N Lon : 71:23:44 W


CI# /Pressure/ Vmax
3.0 /1001.0mb/ 45.0kt


Final T# Adj T# Raw T#
3.0 3.2 3.8
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1337. emguy
Folks...I wanted to take a moment to touch on the "synoptic" end of Emily. The focus on these storms always seems to be in the models and the model trends. Okay, good, but maybe it's a good time to break things down another way:

1.) If the storm follows the current path through Haiti, the passage, then East Cuba, then that is not necessarily good if it does so at a decent clip. First Haiti and a brief path over mountains yes...then into an opening between Cuba. In the passage, the geography of the mountains over Cuba, and haiti will allow for an area of angular momentum. Add to it that Emily typically has a SW oriented trough as a tail that would focus completely over water. In 1998 Hurricane George did this and got back together. I wanna say Dennis was somewhat similar in 2005. In other words, she'd strengthen there then pass over Cuba and spend what is now what we could consider a limited amount of lime over land and a maximum amount of time over water before approaching FL. Not good.
2.) Other Option, continue west and shoot the gap between Cuba and Jamaica. Not good either. Emily would hit what is typically known as the warmest water of the basin, then cross a short path of low elevation Cuba and enter the Keys area and extreme SE Gulf where water is extremely warm.
3.) Both those options are not good since the atmospheric support is improving...so lets go with considering option 3...reflective of Enresto in 2006 and Fay in 2008. Increased interaction with land and mountains, limited time over water to reassemble. The land intereaction is major with subtle track shifts, but leads to severe differences in intensities, landfall solutions and impacts.
4.) I personally hate storms that approach from this angle for one simple reason...with all the variables, one simple and very minor change/nudge/factor is the difference between a weak TS to a CAT 4 anywhere in SW or SE Florida. The impact is significantly different even if the path correction is not and that makes planning for a "potential something" a challange.
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Quoting SouthDadeFish:
Seems like the models now have a very tight consensus of coming through the Bahamas and missing Florida to the east. Depending on the strength of the storm at that time, we might only feel very limited effects. I have confidence in these model runs as they have the Gulfstream data in them and all seem to be pointing towards the same solution.


Breezy squally weather at best. Most of the heavy should stay over water. Assuming that Emily survives the interaction with the high mountainous terrain, the subtropical high should build back in, but only temporarily and weakly. This will allow a WNW to NW movement from the 48-96 hour period. However, if Emily gets significantly stronger than expected, a more northerly track is likely as the ridge is not very strong in between the two subtropical highs. Combined with a strengthening subtropical high to the east of Emily should start to steer the tropical cyclone away from land/florida.
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Guy over at Storm2k is making some great pictures of recon obs over satellite photos. Here is one and it seems that recon found the center at some point with this windshift:

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Quoting Twinkster:
This entire model watching is getting stupid. I do not think the models will get a good handle on this until after it passes hispanola. For this reason anyone in the 3 day cone should remain vigilant despite latest models moving east


Looks like Models don't seem to work well with Invests, trop. waves and weak storms.... They are more accurate once it achieves Hurricane status... (That was the data that was feed into them)
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Quoting Twinkster:
This entire model watching is getting stupid. I do not think the models will get a good handle on this until after it passes hispanola. For this reason anyone in the 3 day cone should remain vigilant despite latest models moving east


Very good post right here folks! You're right, we should have a much clearer picture on what Emily is gonna do after it crosses the gap between Haiti and Cuba. It's best we just be patient and watch the storm. However I must say, people in Volusia County, FL are already preparing for Emily just in case she heads off track, according to the news.
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Quoting TomTaylor:
yea makes sense.

idk why they don't put the little asterisks next to it though, if that is the case.
I agree. The flagging seems random at times.
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Quoting MississippiWx:


Emily's center is very close to land. I'm really not sure how close recon is allowed to get to Hispaniola before they have to change directions. I hope that doesn't limit our information.
Oh very interesting point! that makes a lot of sense after looking at the geography of DR and where the center is located. Thanks for bringing this up.
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This entire model watching is getting stupid. I do not think the models will get a good handle on this until after it passes hispanola. For this reason anyone in the 3 day cone should remain vigilant despite latest models moving east

Edit:HWRF and CMC have been most consistent over the last couple of model cycles
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Quoting SouthDadeFish:
Look at the rain rates and you'll know why ;~)
yea makes sense.

idk why they don't put the little asterisks next to it though, if that is the case.
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Quoting SouthDadeFish:
yeah lowest pressure reading was in 20 knots of SW winds... I'm pretty sure they went too far south... Doh. Oh well. I doubt it has strengthened much since the last fix a few hours ago. Still getting sheared pretty strongly.


Emily's center is very close to land. I'm really not sure how close recon is allowed to get to Hispaniola before they have to change directions. I hope that doesn't limit our information.
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1326. GetReal
my best guess right now is 17.1n and 71.5w on the center of emily.
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Quoting sarepa:
I live in Santo Domingo. What I don't get is, if there is so much cloud coverage on the Satellite over us, why isen't it raining? It's just cloudy over here.


Depends if you're in an area where you are receiving high top clouds or if you are inside the Storms core...
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Quoting MississippiWx:


Looks like they missed the center.
yeah lowest pressure reading was in 20 knots of SW winds... I'm pretty sure they went too far south... Doh. Oh well. I doubt it has strengthened much since the last fix a few hours ago. Still getting sheared pretty strongly.
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TS Emily should just be dismantled. It's giving me a headache.
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Quoting ChrisDcat5Storm:
when do the latest modles come out


Link

Try this.
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Quoting JRRP:

exactamente en Santo Domingo
ha calmado un poco la brisa



Well, you're in the South.... in the capital...

Bueno, pues estas al Sur... Hace tiempo q. no voy para alla... a la capital... Una vez estuve tambien en San Pedro de Macoris...


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Quoting hurricane23:


00Z gfdl shifts futher eastward...
Seems like the models now have a very tight consensus of coming through the Bahamas and missing Florida to the east. Depending on the strength of the storm at that time, we might only feel very limited effects. I have confidence in these model runs as they have the Gulfstream data in them and all seem to be pointing towards the same solution.
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Quoting SouthDadeFish:
Wind shifts I'm seeing would suggest either this is messy again or recon missed the center...
The lightest west winds were located in an area of a 1009mb pressure reading then it was lower as they moved towards the southwest.

Weak circulation with surface trough extending towards the southwest?

Like you said, they could of missed the circulation but the wind shift sorta suggests otherwise.
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when do the latest modles come out
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1315. GetReal
Recon has found west winds due south of the southern tip of Hispaniola. It appears that Emily is almost due west of the previous position.
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Quoting SouthDadeFish:
Wind shifts I'm seeing would suggest either this is messy again or recon missed the center...


00Z gfdl shifts futher eastward...
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1313. robj144
Quoting QPhysFTW:


Yes, but the rotation about a storm is all counterclockwise (NH). So I guess I'm saying that the Earth needn't rotate at a different rate if there's a high pressure that suffers an increase of clockwise swirling air that might counterbalances the net magnitude increase of L pointing into the Earth's surface by the storm. But that's only one stab at a mechanism.

But again, there's a whole host of simplifications I guess I'm making too. Like applying rigid body mechanics to fluids. Still, angular momentum is always conserved, and I'm curious as to how that exactly comes about. But I feel safe in saying that it CANNOT cancel out within the storm itself.

I, too, find it amusing that they chopped the 'N' off of 'NMRI'. But then it makes me a little sad, because then I consider the state of science literacy in this country...


Yes, but in the different hemispheres, low pressure systems rotate in opposite directions. So low and high pressure systems rotate opposite of one another in each hemisphere and thus produce opposite angular momentum vectors.
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Quoting Seawall:


It's pretty clear that he doesn't have Aspergers; it looks like a manic depressive disorder to me, and without his meds, it gets worse. Talking won't help him; he's also obsessed with this blog, and he's also obsessed with posting something as quickly as he can, for recognition. It's sad, but it's not ours or mine to cure. Just the way it is. It's for Jason's family to help him; we simply can't. All we will do is enable him.


Look, if you have a burden for Jason then start a "Jason" blog. Stop distracting people who come here to talk tropics with off-topic posts.
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Quoting SouthDadeFish:
Wind shifts I'm seeing would suggest either this is messy again or recon missed the center...


Looks like they missed the center.
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2:00 AM EDT Thu Aug 4
Location: 17.1°N 71.3°W
Max sustained: 50 mph
Moving: W at 5 mph
Min pressure: 1006 mb
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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.