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 Seflhurricane:
massive explosion of convection with emily


Getting a little ahead of ourselves there...
Member Since: July 6, 2010 Posts: 113 Comments: 32255
Quoting Seflhurricane:
look at the ir image and pt the loop convection is rapidly expanding
Did this 24 hours ago too.
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Sounds about as possible as any other scenario...


Quoting NICycloneChaser:


I'm currently forecasting a sharp 180degree turn to a bearing of 090, and a landfall in the Cape Verde islands in 10 days.
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Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 3rd day of the month at 23:44Z
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: 21
A. Time of Center Fix: 3rd day of the month at 23:00:20Z
B. Center Fix Coordinates: 16°52'N 70°35'W (16.8667N 70.5833W)
B. Center Fix Location: 121 miles (194 km) to the SSW (202°) from Santo Domingo, Dominican Republic.
C. Minimum Height at Standard Level: 1,469m (4,820ft) at 850mb
D. Estimated (by SFMR or visually) Maximum Surface Wind: 38kts (~ 43.7mph)
E. Location of the Estimated Maximum Surface Wind: 5 nautical miles (6 statute miles) to the SSE (165°) of center fix
F. Maximum Flight Level Wind Inbound: From 221° at 26kts (From the SW at ~ 29.9mph)
G. Location of Maximum Flight Level Wind Inbound: 23 nautical miles (26 statute miles) to the S (175°) of center fix
H. Minimum Sea Level Pressure: 1004mb (29.65 inHg)
I. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 18°C (64°F) at a pressure alt. of 1,526m (5,007ft)
J. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 20°C (68°F) at a pressure alt. of 1,524m (5,000ft)
K. Dewpoint Temp (collected at same location as temp inside eye): 9°C (48°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: 2 nautical miles
Remarks Section:
Maximum Flight Level Wind: 43kts (~ 49.5mph) in the southeast quadrant at 21:10:00Z
Maximum Flight Level Wind Outbound: 42kts (~ 48.3mph) in the east quadrant at 23:18:30Z

Fix number 5
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looks like she is moving WSW
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Quoting NICycloneChaser:


I'm currently forecasting a sharp 180degree turn to a bearing of 090, and a landfall in the Cape Verde islands in 10 days.


REALLY ~~~
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Quoting cloudburst2011:


we getting a little dramatic now..
look at the ir image and pt the loop convection is rapidly expanding
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Quoting chevycanes:

or the COC is relocating towards the building convection.

it doesn't just go from moving at 14 mph to stalling normally.


Actually storms do go from motion to a stop in very little time. Remember that each frame of the satellite is not seamless, there is a time lag of 30 minutes to an hour between frames, plenty time to cease forward motion.
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I hate to say this, because it never lasts, but Emily looks a little better organized on the satellite images.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
Quoting hurricaneben:
Wow Emily really wants to surprise us. For all of we know once near The Bahamas she might rapidly intensify and hit Florida as a major hurricane, let's hope not. Or she can just head towards Texas, we never know what's next with this tricky system.


I'm currently forecasting a sharp 180degree turn to a bearing of 090, and a landfall in the Cape Verde islands in 10 days.
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1758. ackee
I notice that some time models do poorly on forecasting how strong or weak trough might be this is key to Emily furture track
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fthb..fthba..fthba...fthb....

I do not know how to type the noise that makes....lol

Quoting tiggeriffic:
apparently it is time to extend your index finger horizontally, place between lips, and shake up and down vigorously...this is the effects Emily is having on everyone in her potential path...
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Quoting kmanislander:


Emily is now caught in a zone where the steering from the East to the WNW is equal to the steering from the West to the WSW. In between is the weakness caused by the trough. One of two things will happen. Either the trough digs down and the steering to the WNW and NW begins or the trough lifts out and the flow recommences to the West.

A wait and see I am afraid to say.
thanks for the explanation, sir!
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Quoting AussieStorm:

Can someone Give Emily a map, oh wait, women have trouble reading maps. Can someone ask the HH to make up a big sign that says " Florida this way" with a big ------>.
Ahem. Women read maps fine. The problem is that men don't read them at all.

Emily knows exactly where she's going.... it's the rest of us who are lost.... lol
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Afternoon/Evening all. Wow, Emily really can't make up her mind as to what to do. This is one of the strangest storms I remember following the last few years.
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massive explosion of convection with emily
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Quoting tiggeriffic:
apparently it is time to extend your index finger horizontally, place between lips, and shake up and down vigorously...this is the effects Emily is having on everyone in her potential path...

boing!
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Quoting snow2fire:
I have a question.

How important is the location of the storm in the hurricane models? It seems to me that the close tracking of starting and ending positions of a storm in a particular time period is important in evaluating which models are accurately predicting the weather factors that steer the storm.

But, if a storm gets torn apart and then assembles a hundred miles away, does that significantly affect the predicted location a few days out?

Sorry if this is a dumb question.


For the hurricane models (GFDL, HWRF) tracking of the storm center is important. These models use a multi-nest approach, where the nest around the storm center has a finer resolution so it can more accurately determine the strength of the storm. When storms get torn apart or dissipate, this inner nest "loses" the storm center and the model can no longer accurately predict reintensification. An example below, the "outer nest" on the left and the "inner nest" on the right.





Hope this helps and not confuses you.

Global models are different.
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Quoting chevycanes:

or the COC is relocating towards the building convection.

it doesn't just go from moving at 14 mph to stalling normally.


Not the first time she's just stopped. Been a very difficult and unusual storm, since it was designated as 91L it's cause endless headaches and confusion.
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apparently it is time to extend your index finger horizontally, place between lips, and shake up and down vigorously...this is the effects Emily is having on everyone in her potential path...
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Quoting GTcooliebai:
Ahahaha is that a challenge, does she dare challenge the High of Death?
She will have a little time to buffer up though before hitting it! Those waters off Cuba's west coast and little to no shear there.
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i have a bad feeling South Florida is going to get a direct hit from emily , and for those in jamaica and central cuba need to watch carefully , i just have a bad feeling . IMO
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1745. aquak9
Quoting weatherxtreme:


Hello Aqua, we sure could use the addtional rain for sure. my grass is very dry. Just don't want the destruction, small tropical storm would be fine though LOL!

hey I'd be totally pleased with another Faye event in this area.
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Wow Emily really wants to surprise us. For all of we know once near The Bahamas she might rapidly intensify and hit Florida as a major hurricane, let's hope not. Or she can just head towards Texas, we never know what's next with this tricky system.
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Quoting AussieStorm:

Can someone Give Emily a map, oh wait, women have trouble reading maps. Can someone ask the HH to make up a big sign that says " Florida this way" with a big ------>.


Haha, I think a few on this blog might have something to say about that... Lol.
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Quoting kmanislander:


Emily is now caught in a zone where the steering from the East to the WNW is equal to the steering from the West to the WSW. In between is the weakness caused by the trough. One of two things will happen. Either the trough digs down and the steering to the WNW and NW begins or the trough lifts out and the flow recommences to the West.

A wait and see I am afraid to say.

or the COC is relocating towards the building convection.

it doesn't just go from moving at 14 mph to stalling normally.
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Quoting doabarrelroll:

into to high sheer and death
Ahahaha is that a challenge, does she dare challenge the High of Death?
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1740. Torgen
Quoting FLdewey:
Stall? Push forward on the controls... TOGA thrust!

(any aviation people in the house?)

*crickets


This thing is going to need JATO and hard right foot on the rudder to conform with what the forecast is.
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Quoting kmanislander:


See post 1732


Thanks, Kman.
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Quoting kmanislander:


Emily is now caught in a zone where the steering from the East to the WNW is equal to the steering from the West to the WSW. In between is the weakness caused by the trough. One of two things will happen. Either the trough digs down and the steering to the WNW and NW begins or the trough lifts out and the flow recommences to the West.

A wait and see I am afraid to say.


Thanks, now I understand!
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Quoting NICycloneChaser:


You think Emily will begin trucking westward again?


See post 1732
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1736. ackee
I think the longer Emily stalls the more likely track west think track might be between cuba and jamaica it should have started to move NW or even WNW by now according to the models that clearly has not happen
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Quoting NICycloneChaser:
Emily doesn't have a clue where she wants her centre to be. Could well be (pretty much) stationary. Longer she sits there, the more time for the high pressure to build in before she's clear of the CONUS East Coast.

Can someone Give Emily a map, oh wait, women have trouble reading maps. Can someone ask the HH to make up a big sign that says " Florida this way" with a big ------>.
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Quoting IceCoast:
18z HWRF
'

Would be pretty impressive if it can pull that off.
Member Since: August 2, 2007 Posts: 19 Comments: 19234
so it's .4 east of the 5PM position. convection increasing a lot right in that area.
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Quoting stormpetrol:


Hi Kman,

Great to see you back! What do you think this means? NHC says an initial westward track with a turn to WNW/NW, they are very hung up on this NW turn that has not materialized , just saying


Emily is now caught in a zone where the steering from the East to the WNW is equal to the steering from the West to the WSW. In between is the weakness caused by the trough. One of two things will happen. Either the trough digs down and the steering to the WNW and NW begins or the trough lifts out and the flow recommences to the West.

A wait and see I am afraid to say.
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Quoting aquak9:


Can't hardly tell till it gets north (west?) of Hispaniola.

Jax native here, watching impatiently as well.


Hello Aqua, we sure could use the addtional rain for sure. my grass is very dry. Just don't want the destruction, small tropical storm would be fine though LOL!
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Quoting TropicalAnalystwx13:
Atlantic ACE:

Arlene (TS): 1.63
Bret (TS): 2.95
Cindy (TS): 1.84
Don (TS): 1.50
Emily (TS): 1.38 (Ongoing)
-------
Total: 9.29 (Up to 8/3/2011)

Eastern Pacific ACE:

Adrian (C4): 11.9
Beatriz (C1): 3.00
Calvin (C1): 2.43
Dora (C4): 14.7
Eugene (C4): 8.66 (Ongoing)
--------
Total: 40.6 (Up to 8/3/11)


Emily should be top of the chart by the time she's done, assuming she doesn't die before she's reaches the low shear. Can't see her dissipating just yet.
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Quoting kmanislander:


Yes, the stall was to be expected based upon the collapsed steering regime. The next move will likely be either to the W or the WNW.
I have a feeling we're all waiting on the next move...... lol
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1728. guygee
Did somebody mention "Emily Stalled"?
How do we know it is not moving in tiny circles?
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Quoting hotrods:
So what could be next if she has stalled?
that's like asking how many licks does it take to get to the center of a tootsie roll pop... the world may never know ...
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18z HWRF
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Quoting FLdewey:
Stall? Push forward on the controls... TOGA thrust!

(any aviation people in the house?)

*crickets


GPWS "Don't Sink!...Don't Sink!"
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1724. aquak9
Quoting weatherxtreme:
Question, I just logged back in from being away all day at work. What is emily doing now and should I worry if in Jax, NE Florida? Back to lurking...


Can't hardly tell till it gets north (west?) of Hispaniola.

Jax native here, watching impatiently as well.
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Quoting kmanislander:


Yes, the stall was to be expected based upon the collapsed steering regime. The next move will likely be either to the W or the WNW.


You think Emily will begin trucking westward again?
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Quoting FLdewey:
Stall? Push forward on the controls... TOGA thrust!

(any aviation people in the house?)

*crickets

Stall recovery procedure

Full thrust
Nose Down
Monitor speed
Nose up
Resume flight
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...EMILY STALLS...STILL PRODUCING HEAVY RAIN OVER HISPANIOLA...
------------------------------------------------- -------------------------------

8:00 PM EDT Wed Aug 3
Location: 16.9°N 70.6°W
Max sustained: 50 mph
Moving: Stationary
Min pressure: 1004 mb

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So if Emily stalled, that could mean that the predicted turn to the NW is about to start. If that's not the case then I wonder if it will get pull NW at all.
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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.