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 NICycloneChaser:


Slightly higher pressure, but more notably....

Due west of the previous fix. I don't see this weakening much over Hispaniola/Cuba, should avoid the highest areas. I still think this is going to come pretty close to Florida.


Actually, ignore that, it's not due west of the last fix at all. Looks like Emily is finally headed NW.
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The HH is now flying due East along the 17 degree lat line , perhaps looking to see if the 1003 mb reading is "circling around"
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1617. ncstorm
959 mb..a category 3
Member Since: August 19, 2006 Posts: 13 Comments: 16215


964 mb. All you people in SC/NC better hope this recurves sharply, although you look safe in this run so far :P
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Quoting IceCoast:
Recon just made another center pass. ~1004.4mb this time.


Slightly higher pressure, but more notably....

Due west of the previous fix. I don't see this weakening much over Hispaniola/Cuba, should avoid the highest areas. I still think this is going to come pretty close to Florida.
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1614. hotrods
18z has it sitting right over my house! Not good!
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Quoting GTcooliebai:
looking more and more like David, also do you think the NHC will shift the cone to the left some because of this?
It's definitely a start. I wanna see what the 00z plots show in about an hour.

Personally, I do expect a shift towards the west at 11p.m, let's see what the models show though before jumping the gun.
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Quoting WatcherCI:
Do not know if this has already been talked about, only read the last 40 posts. Nice little spin at 69 21ish?

maybe that is the MLC dying off up there?
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Quoting Seflhurricane:
i would save that statement for tomorrow morning lets see how it does


tomorrow will take care of itself, so will Emily, tomorrow never really comes :) j/k I understand what you're saying!
Member Since: April 29, 2007 Posts: 0 Comments: 8134
1609. GetReal
....
Member Since: July 4, 2005 Posts: 204 Comments: 8898
Quoting IceCoast:
Recon just made another center pass. ~1004.4mb this time.


Yes, at 17N and 70.56 W. What we need to watch for is IF the 1003 mb reading shows up next and if so where it is found. That will tell us if this system has stalled.
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Quoting IceCoast:
Recon just made another center pass. ~1004.4mb this time.


If that even is the center, hard to figure out what is going on right now.
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102hrs HWRF
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Quoting IceCoast:


Ya i just edited my post. NCEP site confused me for a second. Hasn't shown up there yet, only on raleighwx. We can still use it for comparison to the 18z :)


Hah, np. It does make for good comparison though. Wonder if any more models will follow and go to the west.
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Quoting MiamiHurricanes09:
HWRF wants to have Emily moving at 2-3mph as a hurricane as it drifts up the Florida coast. I don't think I like the upgrade, LOL.

Correct. 18z below (90 hours):

looking more and more like David, also do you think the NHC will shift the cone to the left some because of this?
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Quoting PalmBeachWeatherBoy:
oh hurricane gods please allow me to deal with all the wishcasters and trolls and only find the real analysis, sorry for the outburst.


good luck
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Recon just made another center pass. ~1004.4mb this time.
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1600. wpb
gfs 18z drops e
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Now it's time to see if HWRF recurves Emily sharply or not.
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Quoting Seflhurricane:
i would save that statement for tomorrow morning lets see how it does

Lets just hope that this doesn't turn into one of those:- Houston"We've got a problem," things!
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Expect a weak GFDL since the 18z basically dissipated the system on impact with eastern Cuba.
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1595. Mucinex
Quoting MiamiHurricanes09:
HWRF wants to have Emily moving at 2-3mph as a hurricane as it drifts up the Florida coast. I don't think I like the upgrade, LOL.

Correct. 18z below (90 hours):


Ugh, and that pressure, a solid cat2.
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Quoting scooster67:
Good evening y'all.

I am praying for Emily to keep heading west for another day and leave the Haitians out of this one.

even if it keeps going west Haiti is gonna get lots of rain. just look at how much PR got today.
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Quoting weathermanwannabe:
As many have been observing for the last several days (knowing of the pending brush with Hispanola), we are still in a high degree of uncertainty until the Storm exits Haiti but notice the "smoother" track ride through the MONA passage and NHC keeps Her at TS status crossing Haiti. Not sure if this will pan out (no significant disruption of the very weak circulation) but what do I know. As far as South Florida/Bahamas, not time to put up the shutters yet but definitely a good time to stock up on some supplies and fill up your gas tanks as there will be a very small window to act on Friday if Emily survives the crossing intact and does intensify past TS.
My mom hit the grocery store today, and said the three she went to were all busier than usual on a Wed p.m.... Also the water depot had an excessive crowd for a Wednesday morning. [Just about everybody uses bottled water here.]

There should be some time in the NW Bahamas to do stuff tomorrow, but Friday morning with an approaching hurricane would not be good. Not liking our chances on the slow intensification, either. :o/

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1592. hahaguy
Quoting MiamiHurricanes09:
Goes through some last minute (rapid?) intensification over the Gulf Stream. 72 hours:



With how hot those waters are it would not surprise me.
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Do not know if this has already been talked about, only read the last 40 posts. Nice little spin at 69 21ish?
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Quoting HurricaneSwirl:


That's 12Z. 18Z (coming out now) is further west.


Ya i just edited my post. NCEP site confused me for a second. Hasn't shown up there yet, only on raleighwx. We can still use it for comparison to the 18z :)
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Quoting msgambler:
Thank You emguy


If I recall correctly,BAM Did well with "The Don" also.
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Good evening y'all.

I am praying for Emily to keep heading west for another day and leave the Haitians out of this one.
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thats not a fish
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Quoting MiamiHurricanes09:
HWRF wants to have Emily moving at 2-3mph as a hurricane as it drifts up the Florida coast. I don't think I like the upgrade, LOL.


It just got an upgrade? Wow.
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HWRF wants to have Emily moving at 2-3mph as a hurricane as it drifts up the Florida coast. I don't think I like the upgrade, LOL.

Quoting HurricaneSwirl:


That's 12Z. 18Z (coming out now) is further west.
Correct. 18z below (90 hours):

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Quoting IceCoast:
HWRF 90Hrs
Loop Link





That's 12Z. 18Z (coming out now) is further west.
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oh hurricane gods please allow me to deal with all the wishcasters and trolls and only find the real analysis, sorry for the outburst.
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Quoting IceCoast:
HWRF 90Hrs
Loop Link




that's the 12Z run. 18Z isn't out on that site yet.
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Quoting stormpetrol:
Emily imo has now become a well defined TS.
i would save that statement for tomorrow morning lets see how it does
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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...]


It could mean several things but primarily it would mean that the steering has collapsed and it will go where the dominant flow next comes from. That could either be from the trough to the N or the high to the NW if it bridges enough with the Atl high to close off the weakness.

All a guessing game right now.
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1579. jonelu
Quoting MiamiHurricanes09:
Skirting along the coast. 6 hours later...78:


Thats doesnt make me happy...if she stalls over PB county as a Cat1 and then slowly lifts out...that will suck for us..
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Emily imo has now become a well defined TS.
Member Since: April 29, 2007 Posts: 0 Comments: 8134
HWRF 90Hrs
Edit- my bad, think this is last run, but use it for comparison.
Loop Link



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1576. ncstorm
whoa..973mb 18Z HWRF off of florida..
Member Since: August 19, 2006 Posts: 13 Comments: 16215
Time: 22:58:30Z
Coordinates: 16.7667N 70.5667W
Acft. Static Air Press: 842.5 mb (~ 24.88 inHg)
Acft. Geopotential Hgt: 1,544 meters (~ 5,066 feet)
Extrap. Sfc. Press: 1007.0 mb (~ 29.74 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 233° at 17 knots (From the SW at ~ 19.5 mph)
Air Temp: 16.5°C (~ 61.7°F)
Dew Pt: 9.2°C (~ 48.6°F)
Peak (10s) Flt. Lvl. Wind: 18 knots (~ 20.7 mph)
SFMR Peak (10s) Sfc. Wind: 39 knots (~ 44.8 mph)
SFMR Rain Rate: 13 mm/hr (~ 0.51 in/hr)
(*) Denotes suspect data
Member Since: April 29, 2007 Posts: 0 Comments: 8134
Quoting BahaHurican:
Just as a point of comparison, here's the first advisory map NHC posted for Emily:



Here is the current map, for advisory 9:



What do you notice?

Also I thought I heard somebody mention a slowing of Emily's motion. The three vortfixes I thought I saw on the GoogleEarth seem to suggest the 3rd was NW of the first.... could just be meandering, though.



I see the 2pm Saturday point's a very close to each other. Other than the detour through the Caribean it may just follow the orginal track.
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Complete Update

TS BUSTED FORECAST ALIBI






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Quoting Seflhurricane:
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


Still not quite at the center yet.
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Still moving west. Will be moving west for a while, Why is the cone not moved. ego?
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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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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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