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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1420. guygee
Quoting MississippiWx:


That's one hell of a trof in the Central Atlantic and off the Eastern Seaboard.
Agreed, but no longer digging or as meridional as a couple of days ago.
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Quoting catastropheadjuster:
If Emily makes it thru the islands and over cuba alright are you all saying she still want mount to much at all, maybe just a rain maker? It's like she builds herself up and tears herself down. What's out there that's making these storms not mount to much?

sheri


Wind shear, dry air, land interaction(sooner or later), just one too many factors in the negative to go anywhere fast.
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We'll be seeing these as we head later into the month and next month. Lets just hope that none come and impact the United States, although the signs do not look good.

Question: What time does the 18Z HWRF come out?
Member Since: July 6, 2010 Posts: 113 Comments: 32857
Quoting robj144:
I'm most likely wrong, but wouldn't the mountains have very little effect on a broad, non-stacked system as apposed to a compact, stacked system?
Hmm, in this case, mountains could help "stack the system"...I think.
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Not much talk of the storm yet on the NC coast. We don't want our tourists to freak out for no reason and leave!
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CV season should kick up soon anyway.

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Quoting Stormchaser2007:
132 hours

Could be something if the others modes start to pick it up.


That's one hell of a trof in the Central Atlantic and off the Eastern Seaboard.
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1411. wpb
Quoting FLGatorCaneNut:
Per local met 5 mins ago her in South East Florida.... "Weneed to stay aware due to the high uncertainty of Emily's future track
must be watching wsvn.
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SATELLITE AND AIRCRAFT FIXES INDICATE THAT THE EXPECTED TURN TO THE
NORTHWEST HAS NOT MATERIALIZED YET...WITH EMILY STILL MOVING
WESTWARD OR 280 DEGREES AT 12 KNOTS. SO FAR MOST OF THE DYNAMICAL
MODELS...WITH THE EXCEPTION OF THE ECMWF...HAVE HAD A NORTHWARD
BIAS. EVEN THE LATEST RUN OF THE GFS STILL REFORMS THE CYCLONE
NORTH OF THE HIGH TERRAIN OF EASTERN HISPANIOLA. THE OFFICIAL
FORECAST HAS BEEN SHIFTED WESTWARD DURING THE FIRST 12 TO 24
HOURS...BRINGING EMILY OVER THE SOUTHWESTERN PENINSULA OF HAITI AND
THEN EASTERN CUBA. AFTER THAT...THE OFFICIAL FORECAST STILL
ASSUMES THAT THE WESTERN ATLANTIC TROUGH WILL DEEPEN SUFFICIENTLY
TO TURN THE CYCLONE NORTHWESTWARD AND NORTHWARD. HOWEVER...IF THE
NORTHWARD TURN DOES NOT BEGIN SOON...THE THREAT TO THE SOUTHEASTERN
UNITED STATES WILL INCREASE.
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Quoting MississippiWx:


Eh, not so much.

850mb:



500mb:



oopps ! forgot to check the maps just looking at the Sat.
Member Since: April 29, 2007 Posts: 0 Comments: 8134
132 hours

Could be something if the others modes start to pick it up.
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Quoting ElConando:


Looks like someone splashed multicolor paint on a map.
Yup.
*splat*
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Quoting CNYILION:
oh my lol


roflmao, I was wondering if I was the only one who "paused" when reading his comments!!!
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Eugene
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By 138 hours, the system is still south of the Cape Verde Islands.

Member Since: July 6, 2010 Posts: 113 Comments: 32857
Lowest pressure found short time ago:

1002.8 mb
(~ 29.61 inHg)
Member Since: July 20, 2010 Posts: 0 Comments: 225
Per local met 5 mins ago here in South East Florida.... "We need to stay aware due to the high uncertainty of Emily's future track
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If Emily makes it thru the islands and over cuba alright are you all saying she still want mount to much at all, maybe just a rain maker? It's like she builds herself up and tears herself down. What's out there that's making these storms not mount to much?

sheri
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Quoting robj144:
I'm most likely wrong, but wouldn't the mountains have very little effect on a broad, non-stacked system as apposed to a compact, stack system?


Honestly think that whether a storm survives crossing a mountainous region is more based on the structure of the individual storm. It's really hard to say exactly what impact it will have on Emily, and thus the uncertain wording from the NHC about intensity with regards to landfall.
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Quoting robj144:
I'm most likely wrong, but wouldn't the mountains have very little effect on a broad, non-stacked system as apposed to a compact, stacked system?


Correct. In general, mountainous terrain will have a far less effect on weak systems, large or small, because they lack the inner cores that mature hurricanes possess.
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Quoting Grothar:


I will WU mail you the instructions. You DO know how to access that, don't you?
what's ironic here is that Grothar can successfully instantly "mail" someone with no stamp needed...

Grothar was prolly expecting email to be this at some point.
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Local West Palm Met (Steve Weagle) said don't be surprised if T.S. Watches/Warnings are issued for Palm Beach County tonight or tomorrow morning.
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1396. jonelu
Local Mets here in WPB are being pretty mellow. Saying gusty winds and rain on Saturday. Equated it with the conditions we had under Ernesto in 2006 which basically passed over Lake Okeechobee to our west. I hope we get that much rain! We need it!
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Time: 22:02:30Z
Coordinates: 16.8667N 70.5W
Acft. Static Air Press: 842.7 mb (~ 24.88 inHg)
Acft. Geopotential Hgt: 1,533 meters (~ 5,030 feet)
Extrap. Sfc. Press: 1002.8 mb (~ 29.61 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 211° at 14 knots (From the SSW at ~ 16.1 mph)
Air Temp: 21.8°C (~ 71.2°F)
Dew Pt: 8.4°C (~ 47.1°F)
Peak (10s) Flt. Lvl. Wind: 14 knots (~ 16.1 mph)
SFMR Peak (10s) Sfc. Wind: 34 knots* (~ 39.1 mph*)
SFMR Rain Rate: 1 mm/hr* (~ 0.04 in/hr*)
(*) Denotes suspect data

Probably this slightly due E of the last fix? Weird Emily!
Member Since: April 29, 2007 Posts: 0 Comments: 8134
Quoting Hurricanes12:
MH09, where do you think Emily is headed?
I'm in fair agreement with the NHC track through about 12 hours, lol.

I just don't think Emily will turn northwest as soon as they indicate. A gradual turn towards the west-northwest seems more plausible. And then by around the time it reaches 23˚N, it could turn more towards the west as ridging develops to the northeast of the system. The Bahamas will probably be receiving the worst of this system, but the eastern Florida coast really needs to watch this system because by no means are they out of the woods. Tropical Storm watches are probably going to be warranted tonight, or early tomorrow morning IMHO.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Hey Pulse,

Do you think the next model runs will shfit west? and when do the next ones come out?
Member Since: July 21, 2011 Posts: 1 Comments: 332
1392. robj144
I'm most likely wrong, but wouldn't the mountains have very little effect on a broad, non-stacked system as apposed to a compact, stacked system?
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1391. guygee
A Emily continues chasing the setting sun, every successive model run showing an immediate NW turn becomes garbage...garbage in, garbage out.
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Quoting Stormchaser2007:


Thanks lol
----

18z GFS has a rather interesting storm just south of the CV islands by 120.

Trough might send it OTS though.


Member Since: July 6, 2010 Posts: 113 Comments: 32857
Time: 22:03:00Z
Coordinates: 16.85N 70.5167W
Acft. Static Air Press: 843.0 mb (~ 24.89 inHg)
Acft. Geopotential Hgt: 1,530 meters (~ 5,020 feet)
Extrap. Sfc. Press: 1002.9 mb (~ 29.62 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 210° at 11 knots (From the SSW at ~ 12.6 mph)
Air Temp: 21.5°C (~ 70.7°F)
Dew Pt: 8.4°C (~ 47.1°F)
Peak (10s) Flt. Lvl. Wind: 13 knots (~ 14.9 mph)
SFMR Peak (10s) Sfc. Wind: 34 knots (~ 39.1 mph)
SFMR Rain Rate: 0 mm/hr (~ 0 in/hr)
(*) Denotes suspect data

Is the new center Fix slightly south of the last one?
Member Since: April 29, 2007 Posts: 0 Comments: 8134
I think the 18z gfs needs to be thrown out. Went from developing strong system for several runs to no system at 18z also it doesn't have G-IV data I would wait for 00z and beyond for a better grasp on this system
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1387. BrandiQ
Quoting stormpetrol:


Looks is deceiving :)


It seems that way... lol
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Quoting cat5hurricane:

Agreed. And maybe my projection is a bit biased, cuz somehow I'm hoping she does skip south of Haiti and then have time to stay alive and give FL a nice soaking.

Let's just not hope she doesn't get too out of hand. I wouldn't want FL to have a hurricane landfall either.


Agreed, a weak TS up the West Coast of Florida wold bring the whole State the heaviest rainfall without doing damage, that's what my hope would be, but this thing is very unpredictable, so lets just watch and wait.
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Quoting stormpetrol:
Looks like LLC and MLC are just about aligned!


Eh, not so much.

850mb:



500mb:

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Quoting cat5hurricane:

You got the best avatar man.


Thanks lol
----

18z GFS has a rather interesting storm just south of the CV islands by 120.

Trough might send it OTS though.
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Quoting BrandiQ:


But she doesn't look good right now...


Looks is deceiving :)
Member Since: April 29, 2007 Posts: 0 Comments: 8134
I can see the possibility of this making contact with land somewhere in SE FL if it survives landfall in Cuba, and if it doesn't strengthen too much. A lot of if's tho.. That's about as far West as I see it going though unless the ridge over the central gulf retrogrades some.
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1381. GetReal


The weakness that was supposedly going to turn Emily is pulling out towrds the NE, and is currently at 30N and 70W. There is a northerly flow coming off the Carolina coast into the N. Bahamas from the CONUS high over the Se U.S.

It will be interesting to see a weak Emily turn NW into that northerly flow... IMO

Link
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MH09, where do you think Emily is headed?
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What time does the 18Z HWRF run?
Member Since: July 6, 2010 Posts: 113 Comments: 32857
if GFS is consistent with this solution with a wave developing just off Africa, we could see an invest by Saturday.
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Looks like LLC and MLC are just about aligned!
Member Since: April 29, 2007 Posts: 0 Comments: 8134
Quoting Jedkins01:


Well based on whats currently happening in the atmosphere, the weakness is shifting towards Florida before Emily can take that right curve, in other words, based on what I'm seeing, the path of least resistance is beginning to shift westward anyway, so if Emily does start to turn more WNW, it probably won't take a sharp turn, rather a more gradual one towards the FL straights.

Just my current view.
sounds like a Fay, remember she was Fickle too!
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Quoting MiamiHurricanes09:
Down to 1002.8mb. Not bad.

220200 1653N 07029W 8422 01536 0028 +217 +083 214013 015 030 001 03


Yeah, just when she seems to be getting her act together a little more, visible starts fading. :-(
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Quoting MiamiHurricanes09:
Down to 1002.8mb. Not bad.

220200 1653N 07029W 8422 01536 0028 +217 +083 214013 015 030 001 03


Its definitely trying.
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ok...like i said before, i am no met...but thought i had a pretty good understanding of how storms move. Emily is a TS...meaning she isn't stacked vertically based on intensification. High pressure systems are in the upper atmosphere...if these 2 facts are true, then how is the high going to affect where Emily goes if she isnt stacked high enuf to feel the pull?
Member Since: September 16, 2007 Posts: 0 Comments: 3666
1002.8 mb
(~ 29.61 inHg)


LOWEST PRESSURE FOUND!?
Member Since: July 20, 2010 Posts: 0 Comments: 225

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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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