High wind shear disrupts Emily as it approaches Hispaniola

By: Dr. Jeff Masters , 5:06 PM GMT on August 03, 2011

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In defiance to its forecast, Tropical Storm Emily continues to move due west this morning, and we wonder just how far west it will get before turning toward Hispaniola. Recent Hurricane Hunter missions have shown that Emily is still very poorly organized, and although the center of circulation is plainly obvious on satellite imagery, it's only because it is so displaced from the thunderstorm activity. Wind shear around the storm is just high enough, around 20 knots out of the west, to push the upper levels of circulation and thunderstorm activity to the east, exposing the surface low. 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. Right now, Emily is tilting to the east. This is bad news for the organization of the storm, and something that Emily will have to work hard at recovering from. In addition to the wind shear, dry air continues to wrap around the north and west of the storm. This isn't as critical as unfavorable wind shear, but it's not helping to create new thunderstorm activity. The strongest winds of 50 mph were found to the north and east of the center this morning, and Emily is not expected to intensify before making landfall in Hispaniola, which is forecast for tonight. The HWRF is forecasting the strongest precipitation to fall on the northeast side of the storm as is passes over Hispaniola. This is relatively good news for Haiti, but the country could still receive up to 5 inches of rain, and since the models have been trending the track west over the past couple of runs, it's something to watch closely. No matter the scenario, Emily is expected to produce heavy rains, flash flooding, and mudslides in Haiti and the Dominican Republic, which are all to common on the mountainous island.


Figure 1. Forecast precipitation accumulation from the HWRF high resolution model's 6Z (2am EDT) run. The color contour scale is in inches. The coastlines are a thin, red line. The Dominican Republic is expected to get the most rain out of Emily. You can view the HWRF model runs on Wundermap.

Forecast for Tropical Storm Emily
The future of Emily remains uncertain, and even the National Hurricane Center is using the "if" word when forecasting Emily's track after crossing Hispaniola. "If" it makes it north of Hispaniola. Over the past couple of runs, the models have been trending their forecast tracks back to the west, most likely because Emily has remained on a westward track longer than expected. This is expected—the longer Emily remains shallow and unorganized, the longer it will track west. It will need to build up taller in the atmosphere to be influenced by the steering winds that can push it north. Given its westward track, today's models are likely closer to reality than what we've seen in the past couple of days. This morning, the CMC, UKMET, and HWRF models send Emily on a northwest track to Florida. This is a change from the past couple of days for the HWRF, but the CMC and UKMET have consistently been the western boundary of model consensus. THE GFDL has also taken a huge swing to the west, and now suggests it will come very close to a southeast Florida landfall. The ECMWF and GFS continue to forecast that Emily will take a harder turn north through the Bahamas, not reaching the Florida coast.


Figure 2. Satellite image of Tropical Storm Emily at 11:15am EDT. The surface circulation is visible to the west of the strongest thunderstorm activity.

Consensus of the models falls between the HWRF/GFDL solution and the ECMWF/GFS solution, and the National Hurricane Center continues to use the consensus for the official track forecast, which calls for Emily to take a turn to the northwest and make landfall in Hispaniola this afternoon, after which continuing northwest until Saturday morning when it's between the island of Grand Bahama and West Palm Beach, Florida. At this point, they expect the storm to jog north and then northeast.

Emily's intensity forecast continues highly dependent on the track it takes. Assuming it can survive the wrath of Hispaniola, Emily will enter slightly more favorable environmental conditions to the north of the islands. This is what the Hurricane Center is forecasting, although they remain cautious. There is a very good chance that, if Emily does turn northwest today, it will not be able to reorganize after crossing Hispaniola. If it does maintain organization, Emily could reach hurricane strength as it moves northeast out to the open Atlantic. The other scenario at this point is that the storm keeps moving west, which will be detrimental to its orgnization. The models that track Emily into the far eastern Gulf of Mexico don't suggest any reintensification—the CMC fizzles the system below tropical storm strength quickly, probably because of the long track over Cuba it would have to take. In any case, Emily remains a threat most certainly to Hispaniola, and potentially to Florida.

I'm planning a quick update later this afternoon/evening for an update on new model runs, and potential Hispaniola landfall.

Angela

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Quoting BahaHurican:
Am I wrong to associate clockwise meanders with a change in direction? [Thinking Jeanne here, not to mention Betsy...]
I don't think the storm really moved NE. The actual center has fairly calm winds (as we see from recon data) and small vortices can rotate around inside of the center.
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looking at recon data i dont see a reason to up the winds or pressure , correct me if i am wrong i am still reading
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Skirting along the coast slowly. 6 hours later...78:

Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting MiamiHurricanes09:
Goes through some last minute (rapid?) intensification over the Gulf Stream. 72 hours:

looks like a strong TS
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Am I wrong to associate clockwise meanders with a change in direction? [Thinking Jeanne here, not to mention Betsy...]
Member Since: October 25, 2005 Posts: 19 Comments: 22728
winds in S. FL today and tonight are out of the SSW.

when running a sat. loop from NHC site you can click on HDW-low showing the lower level winds and from the Bahamas out to the middle of the Atlantic the winds are out of the SW.

the winds coming out of the N are in the upper levels and shouldn't affect the steering of Emily since it isn't a deep system.
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Quoting Levi32:


The folks in the western Caribbean who don't want an angry lady. No matter where this goes, someone gets affected.
this could be a great rainmaker for florida
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Lots of allies tonight then!
West it is, at least for some?
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Goes through some last minute (rapid?) intensification over the Gulf Stream. 72 hours:

Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting stormpetrol:
Emily looks as though she's finally getting her act together, she could be a tricky one, already is!
yes she is i think she will come out just fine but my fear is if she approaches Se fl as a strong TS
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HHs heading for another pass through the center.
Member Since: April 29, 2007 Posts: 0 Comments: 8134
66Hrs HWRF
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Quoting FLWeatherFreak91:
16°57'N 70°29'W
so its a slight NE relocation and not by much and it appears she is meandering which coincides with what the current steering maps indicate
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1555. ackee
I think EMILY is either not moving or is moving a bit WEST
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Emily looks as though she's finally getting her act together, she could be a tricky one, already is!
Member Since: April 29, 2007 Posts: 0 Comments: 8134
1553. jonelu
Quoting HurricaneHunterJoe:
why do we want a turn? Poll? How many want a turn?....lol
Honestly Im "wishcasting" it north towards FL now. We could use the rain...badly. As long as she is a TS...BRING IT!
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Out until the night shift. Later guys.
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Quoting HurricaneHunterJoe:
thats what I thought,it's why I picked lower SW Florida coast for land fall. Who knows, Emily may change her mind and ignore all atmospheric dynamics and head for Costa Rica.......lol
or head back east, like one Blogger said with Don.
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Well...as an observer and gatherer of thoughts from those that know more....I have to say that the forecast for this cyclone is as uncertain as they come. We don't know a lot more than we do know, apparently. The timing of the turn, the land interaction, the present condition even of the storm. A meandering possibly organizing TS just south of the DR? The only forecast one can give is a definitive "I don't know". Any forecast that turns out right is a very very educated guess. There is one forecaster here on the blog that's had the track/intensity right from the start. We'll see if the end of the forecast verifies.
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Quoting Seflhurricane:
from the new vortex message what are the new coordinates
16°57'N 70°29'W
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18z HWRF has southern Florida in its sights. Let's see if it recurves it. 60 hours:

Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting Bretts9112:

they got the time right at 2pm wed
Did you notice they haven't really changed the projected track very much at all? The models have flopped all over the place, but after they looked at the models, the storm, and all the data they've been getting, they've pretty much brought this storm to the NW Bahamas by Friday night.... I think this suggests a strong confidence that Emily is going into that gap. And all along they expected it to happen tonight.... passage over Hispaniola sometime between 2 p.m. Wed and 2 p.m. Thursday.

Tomorrow morning, if Emily is still zipping along towards JA, I'd be somewhat concerned about the NHC forecast. Until then, lets just say I have my shutters standing by.... and so do many Bahamians.
Member Since: October 25, 2005 Posts: 19 Comments: 22728
18Z HWRF 48Hrs
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High resolution CMC regional domain 48 h position along the South-central Cuban coast. The graphic windows barely make it that far south so I made a pic to better illustrate the position forecast. Can't quite make out SLP but 1009 maybe..

Link
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1542. WxLogic
Won't be surprised if the VDM for this next pass ends up in the same place or close to it where it originally got the first/second VDMs. Appears to be performing a clockwise loop.
Member Since: August 14, 2008 Posts: 4 Comments: 5038
Quoting Beachshell:

How many other profiles do you have out there besides CalebDancemastah?
just the 2, I'm using this one since most people know me by this handle.
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from the new vortex message what are the new coordinates
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1538. ackee
WHAT DIRECTION is EMILY MOVING NOW ?
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Quoting kmanislander:


A stall followed by meandering ??


Your previous statement might be correct!
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Quoting Seflhurricane:
so looks like Emily may be on track with the NHC but is she still moving west
She's moving wnw
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COC is trying to reform.
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Psss...Hey! Where's your Emily post?
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Quoting GetReal:
The trof over the Bahamas that was to start Emily NW and north, has flattened out, and is being replaced by CONUS high pressure currently centered over N. Alabama. The flow around this high is now northerly from VA south into the Bahamas. I haven't seen many tropical systems turn into a flow from the opposite direction.

See for yourself... Link

What ever is left of Emily over the next 48 hours should head in the direction of the Florida Straits, or extreme S. Florida in a WNW direction. IMO
thats what I thought,it's why I picked lower SW Florida coast for land fall. Who knows, Emily may change her mind and ignore all atmospheric dynamics and head for Costa Rica.......lol
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Quoting FLWeatherFreak91:
Yes, the latest vortex message was NE of the previous one.
so looks like Emily may be on track with the NHC but is she still moving west
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1530. ncstorm
Quoting nrtiwlnvragn:


Like this?

that looks like the length..I was looking for the width..or maybe I am reading it wrong?
Member Since: August 19, 2006 Posts: 13 Comments: 16226
Quoting Seflhurricane:
what is this that i am reading that Emily relocated to the NE , can someone confirm ????? and have the 18Z models been released yet
Yes, the latest vortex message was NE of the previous one.
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what is this that i am reading that Emily relocated to the NE , can someone confirm ????? and have the 18Z models been released yet
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1526. wxhatt
Now that the convection is firing back on the center of Emily we should see the influence from the break in the ridge to the north. I believe the NHC has a good handle on the forcasted track now.

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Quoting MississippiWx:
Lol...WTH?



A stall followed by meandering ??
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Quoting wayne0224:
16.57 FROM 16.9 IS SOUTH


Raw data from the HH is in Degrees/Minutes format and needs to be converted to Lat

16.57 = 16.95N
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Quoting MississippiWx:
Lol...WTH?

LOL
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Quoting cloudburst2011:
still moving due west levi...no wnw turn..
Last vortfix that just updated on my GoogleEarth was NE of the one before that... u sure we're still going W?
Member Since: October 25, 2005 Posts: 19 Comments: 22728
Quoting ncstorm:
does anyone know where I can find out how wide is Emily?


Well, the NHC advisories contain the wind radii, if that helps.
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Gfs 18z shows Tropical waves(2) forming in 10 days
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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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