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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Well on another note....its HOT!!! Millen, GA 102F feels like 110F Dewpoint 70F
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Eugene! How beautiful...
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Emily should have been going over Hispaniola now, but she just keeps trucking west, look for storms watches in Jamaica soon.
Member Since: April 29, 2007 Posts: 0 Comments: 7506
Quoting DestinJeff:


Your actions are waranted. Nothing to be worried about so long as you did indeed wave your arms in the air and scream hystreically.

DOOM:CON formerly advised waving your hands in the air like you don't care during DOOM:CON 2, but that was so, like, eighties.


I'd like to apologize for leaving the colon out of DOOM:CON.



Yes, I'm intentially teeing up some colon jokes for you. Swing away.


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Quoting ncstorm:


thats a strong storm right there..



Sure is... of course we know that won't happen.
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462. GoWVU
Quoting Stormchaser2007:
12z GFDL takes Emily up to a Cat 3 just off of EFL.


Not good, where does she go from the coast of Florida?
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461. 7544
Quoting reedzone:
Expect a slight adjustment to the left on the next NHC track.


agree and maybe a bit south ?
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Hi Chaser, Logic...

Took a looooooooong break.
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Quoting cloudburst2011:



i think a little to late for that the trof has started to lift out and emily is much to far south to feel any tug or pull to the north...


They've been forecasting the move for a while. So far the ridge has been blocking all attempts. When she finally slides by that blocking hand and feels the pull, that is when you will see a shift and it'll squirt on through that gap.....whatever happens after that is up to the Atlantic.
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Quoting nash28:
Hey guys. Long time no see:-) How goes it in the blogosphere?


Hey Nash!

Good to see you.
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Expect a slight adjustment to the left on the next NHC track.
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12z GFDL takes Emily up to a Cat 3 just off of EFL.
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Hi Nash...
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Time: 18:21:00Z
Coordinates: 16.7667N 70.4W
Acft. Static Air Press: 843.7 mb (~ 24.91 inHg)
Acft. Geopotential Hgt: 1,526 meters (~ 5,007 feet)
Extrap. Sfc. Press: 1003.2 mb (~ 29.62 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 256° at 7 knots (From the WSW at ~ 8.0 mph)
Air Temp: 21.8°C (~ 71.2°F)
Dew Pt: 10.3°C (~ 50.5°F)
Peak (10s) Flt. Lvl. Wind: 9 knots (~ 10.3 mph)
SFMR Peak (10s) Sfc. Wind: 24 knots (~ 27.6 mph)
SFMR Rain Rate: 0 mm/hr (~ 0 in/hr)

This is probably the center imo.
Member Since: April 29, 2007 Posts: 0 Comments: 7506
Key word there is should...just like Emily should have already been going the NW route.
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Quoting DVG:


Am I wrong in seeing that this should have already turned north on this model?


Per NHC 11 am discussion,

ASSUMING EMILY CAN MAINTAIN A VERTICALLY DEEP
CIRCULATION...THE CYCLONE SHOULD SOON TURN MORE TO THE NORTHWEST AND EVENTUALLY TOWARD THE NORTH AROUND THE PERIPHERY OF THE SUBTROPICAL RIDGE.

The models continue to assume a deeper circulation that what currently exists.
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Quoting WxLogic:
12Z GFDL To be expected from a strong 12Z GFS run.


thats a strong storm right there..

Member Since: August 19, 2006 Posts: 13 Comments: 13460
Hey guys. Long time no see:-) How goes it in the blogosphere?
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Yes, this run is too far north and slighty off to the east IMO

Quoting DVG:


Am I wrong in seeing that this should have already turned north on this model?
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444. Kearn
florida needs rain

lets hope emily keeps going west
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Daytime heating might help moisten up the air to the NW of Emily, allowing a slightly more favorable environment.
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12Z GFDL To be expected from a strong 12Z GFS run.
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emily looks like she might be getting her act together ATM.
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Quoting OUSHAWN:


Emily has been doing this same thing day in and day out. She pulses up...and then loses it all. The same thing has happened with her pressure...she drops...and then rises again. She needs to show that she can maintain the convection, get the llc and mlc back aligned, and can sustain her lower pressure before I buy into her. Looks to be more shear awaiting her straight ahead as well.


That shear ahead should move out in the next day or so..
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As illustrated above, IMO the CONUS high and Azores high are bridgeing together wiping out the escape route NW into the Bahamas. The only way open to Emily will be WNW towards the Florida Straits, or south Florida.
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Emily's low level structure has never looked this good. Lowest pressure yet, and stronger inflow coming in from the SW with 20 knot winds being reported there. If she can shake off the dry air and shear, she might wrap up enough to survive Hispaniola. What a storm.
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ATCF says the pressure is at its lowest ever:

AL, 05, 2011080318, , BEST, 0, 168N, 703W, 45, 1005, TS, 34, NEQ, 100, 75, 0, 20, 1010, 150, 40, 0, 0, L, 0, , 0, 0, EMILY, M,
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Time: 18:22:00Z
Coordinates: 16.7167N 70.3667W
Acft. Static Air Press: 843.6 mb (~ 24.91 inHg)
Acft. Geopotential Hgt: 1,528 meters (~ 5,013 feet)
Extrap. Sfc. Press: 1003.7 mb (~ 29.64 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 260° at 8 knots (From the W at ~ 9.2 mph)
Air Temp: 21.3°C (~ 70.3°F)
Dew Pt: 10.4°C (~ 50.7°F)
Peak (10s) Flt. Lvl. Wind: 8 knots (~ 9.2 mph)
SFMR Peak (10s) Sfc. Wind: 25 knots (~ 28.7 mph)
SFMR Rain Rate: 0 mm/hr (~ 0 in/hr)
(*) Denotes suspect data
Member Since: April 29, 2007 Posts: 0 Comments: 7506
Quoting unf97:
Convection really beginning to fir around the LLC. It looks remarkably improved since late this morning. Shear may be letting up a bit in that area now and in fact, Emily may be trying to start to really organize right now. Time will tell.


Emily has been doing this same thing day in and day out. She pulses up...and then loses it all. The same thing has happened with her pressure...she drops...and then rises again. She needs to show that she can maintain the convection, get the llc and mlc back aligned, and can sustain her lower pressure before I buy into her. Looks to be more shear awaiting her straight ahead as well.
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Recon has found a pressure back down to 1003mb, interestingly lower than before, likely due to some small thunderstorms that keep trying to develop near Emily's center, which is looking more defined all the time. However, the system remains heavily asymmetric.
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Time: 18:23:00Z
Coordinates: 16.6667N 70.3333W
Acft. Static Air Press: 843.6 mb (~ 24.91 inHg)
Acft. Geopotential Hgt: 1,530 meters (~ 5,020 feet)
Extrap. Sfc. Press: 1003.8 mb (~ 29.64 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 240° at 15 knots (From the WSW at ~ 17.2 mph)
Air Temp: 21.3°C (~ 70.3°F)
Dew Pt: 10.3°C (~ 50.5°F)
Peak (10s) Flt. Lvl. Wind: 15 knots (~ 17.2 mph)
SFMR Peak (10s) Sfc. Wind: 28 knots (~ 32.2 mph)
SFMR Rain Rate: 0 mm/hr (~ 0 in/hr)
(*) Denotes suspect data

These are strongest winds recorded out of west since the HHs been flying Emily as far I can remember
Member Since: April 29, 2007 Posts: 0 Comments: 7506
Clear path to the NW anytime Emily decides to get going:

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Quoting BrandiQ:
How reliable are these intensity models? Does anyone really believe she could become a cat one Saturday near fl? Or a cat four for that matter in a few days?


Cat 1 or 2 if it can maintain a well defined circulation is not out of the question. HWRF and GFDL are hellbent on this scenario at the moment.
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Quoting lucreto:
With the track record so far I think we should throw all recon findings out as erroneous.


No we shouldn't lucreto, first your ridiculous theory that Hugo really came ashore as a cat 2/3, now this????
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18Z Models come out at 7-8Pm Right?
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just got back and see that DOOMCON has been raised/lowered/whatever to DOOMCON 2!?!?!

At what DOOMCON level am I supposed to start running around in circles, waving my arms in the air and screaming hysterically? I hope it's DOOMCON 2 or I'm gonna feel pretty stupid about the display I just put on in the office.



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423. DVG
Quoting bayoubrotha:
NOGAPS 12z

Link


Am I wrong in seeing that this should have already turned north on this model?
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Wow, Emily is a fighter. :)
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Post 390.

the weakness or path to the north looks to have moved closer to the west..
Member Since: August 19, 2006 Posts: 13 Comments: 13460
How reliable are these intensity models? Does anyone really believe she could become a cat one Saturday near fl? Or a cat four for that matter in a few days?
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About JeffMasters

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