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 chevycanes:


pretty clear there is a break in the ridge and it should turn WNW-NW very soon.
I don't like the location of the weakness.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Must have been old... but this is the closest @00Z:

Member Since: August 14, 2008 Posts: 4 Comments: 5030
Thunderstorms are collapsing around the center. Conditions are still unfavorable for any strengthening before Haiti landfall. Will be interesting to see whats left tomorrow night.
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Quoting tropicfreak:


Lucreto the turn has been supposed to happen for 2 days now, it hasn't occurred because it's a shallow storm.


How about everyone puts Lucreto on IGNORE???? He is posting stuff just to get a rise out of folks. That is not polite behaviour in our WU playground. Just saying.
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Quoting ProgressivePulse:
A little lefty...



Going to be a lot lefty if she does not start a pretty strong NW movement very soon.
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pretty clear there is a break in the ridge and it should turn WNW-NW very soon.
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Thank You FLWeather, I think you answered my question as well.
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Thanks to the repost, I see Lucredo thinks the XTRAP is a model... if that doesn't shout out he's a troll, nothing will.
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One thing for certain the LLC of Emily is the best defined its ever been!
Member Since: April 29, 2007 Posts: 0 Comments: 8023
TS Emily Update with Video
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Quoting ProgressivePulse:
I still find it amazing that this current vortex of 1003 is tied with the lowest pressure in Emily's lifetime.


lol, when it looks its worse appearance wise, we find out it is actually the most well-defined.
Member Since: July 6, 2010 Posts: 113 Comments: 32528
Quoting Twinkster:



how is the BAMM suite so different from dynamics? I definitely trust dynamic models a lot more. The G-IV mission should give models more info to work off of. We could see huge shift in models based on that data
The BAMM models are usually the first to detect changes in steering forecasts. This has proven true year after year.
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Quoting Stormchaser2007:


Highly questionable.
Probably 10 sec peak gust or something
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Quoting lucreto:


He is from the Cayman islands all his bizarre forecasts take this system to the Cayman Islands, seems like textbook wishcasting to me.


He is saying more and more models are on board with it moving west.
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Quoting tropicfreak:


HE IS NOT WISHCASTING LUCRETO. Leave him alone and stop with your theories.


Please...Just:

Member Since: July 6, 2010 Posts: 113 Comments: 32528
VDM would support 50mph/1003mb, correct?
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552. 7544
hwrf 61k se fla landfall will the others follow ?Link
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I think it is important to note that the models that are coming out now are using information received during the morning reconaissance missions, when the storm structure was much better. Remember also, that Emily is a child... not a mature adult storm yet... so until she gets her act together, I see westward for a short time more. I do think that the NHC will adjust the track slightly more to the west, not more than 30 miles though.
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Quoting Levi32:
0z ECMWF ensembles last night actually seemed to favor a westward movement and then a sharp hook straight northward across eastern Cuba.



What do they smoke in Europe these days?
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Quoting Levi32:
12z UKMET has a closed isobar southeast of the keys.



Didn't the ECMWF Ensemble also showed something similar? Looking for it.
Member Since: August 14, 2008 Posts: 4 Comments: 5030
Quoting lucreto:


Come on cloud the turn will happen within the next 18-24 hours


Lucreto the turn has been supposed to happen for 2 days now, it hasn't occurred because it's a shallow storm.
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Im with Angela here, as long as its disorganized, a westward track seems most probable. I doubt this storm will survive the next couple days if nothing changes.

Does anyone know what the 500mb wind sheer forecast is looking like to the west of the storm for the next day or two?

Just for FUN (remember fun?)
If Emily survives ---> Sarasota landfall
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I still find it amazing that this current vortex of 1003 is tied with the lowest pressure in Emily's lifetime.
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Quoting wunderkidcayman:
new models are out not looking nice for me here in Grand Cayman or even the Cayman Islands

new ones are
BAMS 18Z
BAMM 18Z
BAMD 18Z
CLP5 18Z
XTRP 18Z
CMC 18Z
TVCN 18Z

Link



how is the BAMM suite so different from dynamics? I definitely trust dynamic models a lot more. The G-IV mission should give models more info to work off of. We could see huge shift in models based on that data
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Product: Air Force Tropical RECCO Message (URNT11 KNHC)
Transmitted: 3rd day of the month at 18:50Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 306)
Storm Number: 05
Storm Name: Emily (flight in the North Atlantic basin)
Mission Number: 8
Observation Number: 06

Mandatory Data...

Observation Time: Wednesday, 18:43Z
Radar Capability: Yes
Aircraft Altitude: Below 10,000 meters
Coordinates: 15.9N 69.5W
Location: 180 miles (290 km) to the S (172°) from Santo Domingo, Dominican Republic.
Turbulence: None
Conditions Along Flight Route: In the clear
Pressure Altitude: 1,520 meters
Flight Level Wind: From 180° at 31 knots (From the S at ~ 35.6 mph)
- The above is a spot wind.
- Winds were obtained using doppler radar or inertial systems.
Flight Level Temperature: 15°C
Flight Level Dew Point: 9°C
Weather (within 30 nautical miles): Thunderstorm(s)
850 mb Surface Altitude: 1,488 geopotential meters

Remarks Section - Remarks That Were Decoded...

Surface Wind Speed (likely by SFMR): 43 knots (~ 49.5mph)

Remarks Section - Additional Remarks...
Member Since: April 29, 2007 Posts: 0 Comments: 8023
Quoting lucreto:


Stop wishcasting when you are using the BAMMS/Clipper/XTRAP as support you know you are wishcasting (albeit they have performed somewhat decently so far due to poor organization)


HE IS NOT WISHCASTING LUCRETO. Leave him alone and stop with your theories.
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JMA 168 Hours
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Quoting stormpetrol:


oh gee thanks...that one track has it popping charleston right on her nose...and the worst part is that at this moment, it is pretty much smack dab in the middle of the tracks...glad i have been cleanin up the toys from the yard already...could make for an interesting weekend...and birthday...YAY ME
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Levi, what is the BAM suite? I have noticed for the last few days that it has been almost spot on with EM. I don't remember BAM being that reliable last year.
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000
URNT12 KNHC 031850
VORTEX DATA MESSAGE AL052011
A. 03/18:20:40Z
B. 16 deg 47 min N
070 deg 24 min W
C. 850 mb 1465 m
D. 44 kt
E. 050 deg 48 nm
F. 138 deg 41 kt
G. 048 deg 77 nm
H. 1003 mb
I. 17 C / 1517 m
J. 21 C / 1520 m
K. 10 C / NA
L. NA
M. NA
N. 1345 / 08
O. 0.02 / 1 nm
P. AF306 0805A EMILY OB 04
MAX FL WIND 41 KT NE QUAD 17:51:20Z
MAX FL TEMP 21 C 325 / 6 NM FROM FL CNTR
;
Member Since: November 24, 2005 Posts: 635 Comments: 26684
Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 3rd day of the month at 18:50Z
Aircraft: Air Force Aircraft (Last 3 digits of the tail number are 306)
Storm Number & Year: 05L in 2011
Storm Name: Emily (flight in the North Atlantic basin)
Mission Number: 8
Observation Number: 04
A. Time of Center Fix: 3rd day of the month at 18:20:40Z
B. Center Fix Coordinates: 16°47'N 70°24'W (16.7833N 70.4W)
B. Center Fix Location: 122 miles (196 km) to the SSW (196°) from Santo Domingo, Dominican Republic.
C. Minimum Height at Standard Level: 1,465m (4,806ft) at 850mb
D. Estimated (by SFMR or visually) Maximum Surface Wind: 44kts (~ 50.6mph)
E. Location of the Estimated Maximum Surface Wind: 48 nautical miles (55 statute miles) to the NE (50°) of center fix
F. Maximum Flight Level Wind Inbound: From 138° at 41kts (From the SE at ~ 47.2mph)
G. Location of Maximum Flight Level Wind Inbound: 77 nautical miles (89 statute miles) to the NE (48°) of center fix
H. Minimum Sea Level Pressure: 1003mb (29.62 inHg)
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 17°C (63°F) at a pressure alt. of 1,517m (4,977ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 21°C (70°F) at a pressure alt. of 1,520m (4,987ft)
K. Dewpoint Temp (collected at same location as temp inside eye): 10°C (50°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 Levels (sfc and flt lvl centers are within 5nm of each other): Surface and 850mb
O. Navigation Fix Accuracy: 0.02 nautical miles
O. Meteorological Accuracy: 1 nautical mile
Remarks Section:
Maximum Flight Level Wind: 41kts (~ 47.2mph) in the northeast quadrant at 17:51:20Z
Maximum Flight Level Temp: 21°C (70°F) which was observed 6 nautical miles to the NW (325°) from the flight level center
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0z ECMWF ensembles last night actually seemed to favor a westward movement and then a sharp hook straight northward across eastern Cuba.

Member Since: November 24, 2005 Posts: 635 Comments: 26684
Emily...heartbreaker or homewrecker?
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Quoting wunderkidcayman:
new models are out not looking nice for me here in Grand Cayman or even the Cayman Islands

new ones are
BAMS 18Z
BAMM 18Z
BAMD 18Z
CLP5 18Z
XTRP 18Z
CMC 18Z
TVCN 18Z

Link
looks like they has shifted even further west but Again i doubt that will materialize
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Quoting hurricanejunky:
Cone about the same for 2pm. Looks like some convection trying to re-fire around COC. She's tenacious...


The cone doesn't change in the 2pm advisory, they only change at 11 and 5 morning and evening.
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Time to get the boards waxed, Florida will get some surf out of this...
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G-IV has taken off from Nassau.
Member Since: June 9, 2007 Posts: 4 Comments: 15946
new models are out not looking nice for me here in Grand Cayman or even the Cayman Islands

new ones are
BAMS 18Z
BAMM 18Z
BAMD 18Z
CLP5 18Z
XTRP 18Z
CMC 18Z
TVCN 18Z

Link
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A little lefty...

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523. Hugo7
anyone else giving the blob in the gulf a point of interest for developement?
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Dropsonde Location: Dropped in eye.

Splash Location: 16.77N 70.4W
Splash Time: 18:22Z

1003mb (Surface) 27.8°C (82.0°F) 26.4°C (79.5°F)

Emily just got a haircut over the COC from southerly shear.
Member Since: September 23, 2005 Posts: 14 Comments: 11274
12z UKMET has a closed isobar southeast of the keys.

Member Since: November 24, 2005 Posts: 635 Comments: 26684
Member Since: April 29, 2007 Posts: 0 Comments: 8023

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About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.