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 TropicalAnalystwx13:


Haha, very similar thinking.


Quoting reedzone:
Here is my thoughts on Emilys future path.. This is my opinion based on observations and trends.


Both of you are wishcasting. The odds of it threading the needle like that just to stay over water are minimal. Cyclones do not have brains. Due to the current west motion I think it's more likely it will pass over eastern cuba, which is also very mountainous. But if it really cannot get it's act together, stays an exposed low like this, I think it could miss the trough and continue WNW even into the gulf, such as a couple models are suggesting.
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Time: 17:36:30Z
Coordinates: 17.9833N 69.1W
Acft. Static Air Press: 587.4 mb (~ 17.35 inHg)
Acft. Geopotential Hgt: 4,583 meters (~ 15,036 feet)
Extrap. Sfc. Press: 1006.8 mb (~ 29.73 inHg)
D-value: -
Flt. Lvl. Wind (30s): From 63° at 28 knots (From the ENE at ~ 32.2 mph)
Air Temp: 2.3°C (~ 36.1°F)
Dew Pt: -2.5°C (~ 27.5°F)
Peak (10s) Flt. Lvl. Wind: 31 knots (~ 35.6 mph)
SFMR Peak (10s) Sfc. Wind: -
SFMR Rain Rate: -
(*) Denotes suspect data
Member Since: April 29, 2007 Posts: 0 Comments: 7935
Quoting TropicalAnalystwx13:


Convection? Thunderstorm activity? Low Level Center?
Thank you... I'm still a rookie at this.
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Quoting
156. presslord 5:42 PM GMT on August 03, 2011 +0
As most of you know, Portlight was very involved for a year in Haiti...and we have maintained our contacts there. As Emily's impact there becomes more clear, please keep me posted as to your thoughts...as we may need to respond. Many thanks!!!

Hey!! Call out you good friend at FEMA!!
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Does anyone think that the tropical wave in the CATL will get mentioned in the TWO?
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http://www.swellinfo.com/tropical/hw3.php?forecas t=plotsystemmodels&storms=®ion=NT&year=&eventnum= 5&hwvstormid=5&usemap=AUTO2&zoom=0&size=&config=tr opsys640x480,tropimap_all&pn=1&ptm=

GFDL model has it a Cat3 right off the Florida East coast. (LINK: Hover over the GFDL model path next to Florida.)
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163. beell
Quoting angelafritz:
Thanks to whoever found the northwest-northeast error. That's important. I tend to get tongue-tied when talking about track forecasts! (Say that 10 times fast.)


It happens to all of us, Angela!

I sent Dr. Rob a very quick note last night with a similar error shortly after his late night update:

Satellite imagery shows a large amount of convection near Emily's center. However, the NHC discussion suggests that Emily is not standing straight up, like an ideal tropical cyclone, but the circulation is tilted westwards with height. This is due to the wind shear present over the storm.

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quoting
reedzone 5:29 PM GMT on August 03, 2011 +3
Here is my thoughts on Emilys future path.. This is my opinion based on observations and trends.

You just forgot the anti-cyclone plus the Norester combine with a cold front giving you the "Perfect storm" .lol
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Quoting SouthDadeFish:
Wow relax, I'm pretty sure she was saying bad news in terms of Emily's perspective. Obviously she doesn't want it to strengthen and cause damage. Chill.


djboca must be a member of the T# Party...
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Quoting Bluestorm5:
Look like clouds (what the correct term for it) is forming around the real center of the storm (again, what the term?).


Convection? Thunderstorm activity? Low Level Center?
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As most of you know, Portlight was very involved for a year in Haiti...and we have maintained our contacts there. As Emily's impact there becomes more clear, please keep me posted as to your thoughts...as we may need to respond. Many thanks!!!
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Quoting lucreto:




I would tell them that, but I would also tell them a Category 2 direct hit is nothing to laugh about, on another note I doubt anywhere expect maybe extreme Southeastern Louisiana (Plaquemines Parish, with Katrina) has actually seen 100+ knot sustained winds since Hurricane Andrew.


This team recorded sustained winds of 147 mph during Charley:

Link

Why would they lie about that?
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If the COC doesn't move NW like right now it is going to miss the mountains of Hispaniola and only cross the thin southern arm of Haiti at best and shoot the gap between Cuba and Haiti. The convection to the east may cross the mountains but not the COC.
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Look like clouds (what the correct term for it) is forming around the real center of the storm (again, what the term?).
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Quoting djboca:
Right now, Emily is tilting to the east. This is bad news, and something that Emily will have to work hard at recovering from.

Bad news? Are you seriously "championing" a storm that may cause death and destruction? Can you PLEASE keep your comments limited to facts and restrict your opinions to weather predictions while avoiding "scare tactics" (ie: worst summer, worst this, worst that) and "cheering" for storms?

This type of blogging by an intelligent and respected scientist is getting to be as bad as our national politicians' behavior.


Whoa, hold on one second. I'm positive she was talking about that from Emily's perspective, not her own.

Lay off Angela.
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151. 7544
didnt don do what emily is doing with the shear and all and came back
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Quoting lucreto:


Poor building codes there is numerous online literature available on the web analyzing Charley's damage most agree that maximum GUSTS were in the 120-130 mph range.


Ok this isn't 1975 lucreto, it was 2004, and building codes were much more mandated then and today.
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Quoting djboca:
Right now, Emily is tilting to the east. This is bad news, and something that Emily will have to work hard at recovering from.

Bad news? Are you seriously "championing" a storm that may cause death and destruction? Can you PLEASE keep your comments limited to facts and restrict your opinions to weather predictions while avoiding "scare tactics" (ie: worst summer, worst this, worst that) and "cheering" for storms?

This type of blogging by an intelligent and respected scientist is getting to be as bad as our national politicians' behavior.
Wow relax, I'm pretty sure she was saying bad news in terms of Emily's perspective. Obviously she doesn't want it to strengthen and cause damage. Chill.
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#130: Sorry not sure what you're referring to. Please point out which "old" model run.
Member Since: August 14, 2008 Posts: 4 Comments: 4977
Quoting angelafritz:
Thanks to whoever found the northwest-northeast error. That's important. I tend to get tongue-tied when talking about track forecasts! (Say that 10 times fast.)
thatthatthatthatthatthatthatthatthatthat

edit: good catch Gro and thanks Angela
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I'm done feeding the troll. Don't want to get trouble on my 3rd day here.
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Quoting TropicalAnalystwx13:


Haha, very similar thinking.

yeah.. pretty much my thoughts too, but perhaps a more westward component.
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Quoting patrikdude2:
hmm, but maybe the north part of the COC getting more convection wrapping around? Thanks for the reply :)
I don't think that new convection will stick around long. Shear isn't stopping any time soon.
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I don't get why people are debating Charley when you can just read the NHC Tropical cyclone report.

Link

An excerpt from:

Charley deepened extremely rapidly as it approached the southwest coast of Florida. Based on dropsonde measurements on 13 August from the AFRES, the central pressure fell from 964 mb at 1522 UTC to 941 mb at 1957 UTC, around the time of landfall, a deepening rate of about 5.02 mb h-1. The hurricane’s peak intensity is estimated to be 130 kt, which occurred at landfall in Cayo Costa, FL. This estimate is based on maximum 700 mb flight-level winds of 148 kt measured in the southeastern quadrant of the hurricane’s eyewall at 1955 UTC 13 August. As usual, there were no official surface anemometer measurements of wind speeds even approaching the intensity estimate near the landfall location. The wind sensor at the Punta Gorda ASOS site, which experienced the eyewall of Charley, stopped reporting after measuring a sustained wind of 78 kt at 2034 UTC with a gust to 97 kt at 2036 UTC. Ten minutes later, that site reported its lowest pressure, 964.5 mb. Since it is presumed that the center was closest to the Punta Gorda site at the time of lowest pressure, and since Charley’s maximum winds covered an extremely small area, it is highly likely that much stronger winds would have been observed at the site, had the wind instrument not failed. Instrument failures remain a chronic problem in landfalling hurricanes. Based on the few wind sensors that did not fail, Charley carried strong winds well inland along its path across the Florida peninsula. For example, Orlando International Airport measured sustained winds of hurricane force (69 kt), with a gust to 91 kt.
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Emily will NOT be downgraded to a TD anytime soon, winds are 45-50 mph.. Satellite presentation shows a classic sheared TS.
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sure is nice to add to 'Ignore' someone other than... for once.

i'm thinking Emily will be on a continued western track with low intensity for the next day or two.. between the dry air and shear, doesn't seem to get the stacking and strength to pull north any sooner... Cuba may tear her apart.
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Quoting lucreto:


Give me some official sustained wind measurements on land of those winds??? There are none... those storms had that wind speed over water.
How about State of Flordia's report on Hurricane Wilma? I'm seeing few cities reporting 115+ winds. Florida also maked Wilma's landfall winds at 115 MPH. Can't agrue with state's government. Link
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WXlogic why bother looking at old model runs the new ones will be out soon enough. If you want to use old against new to study the model changes run by run great do it. But the models run every six hours I believe, do some comparison shopping and you can learn something from the models. I usually compare three sets of consecutive runs then read the NHC discussion and form my own opinion. I thought the NHC made a bold statement last night at 5 saying it would not hit the con US. today they backtracked that statement. Just get some darts and a tracking map for this one might be just as good. IMO
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And why are we feeding the evil troll lucreto? If he is not fed, he will wither... Momma always said "Consider the source..." he is not worth sustaining... let him wander in the uncommented wilderness... and ignore him... he (and his feeders) are just eating up bandwidth...

:-)
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127. angelafritz (Admin)
Thanks to whoever found the northwest-northeast error. That's important. I tend to get tongue-tied when talking about track forecasts! (Say that 10 times fast.)
Quoting TropicalAnalystwx13:


Haha, very similar thinking.



Bright minds think alike :P
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Quoting stormpetrol:
Though void of deep convection , though some is nearing the LLC from the SE now also, the center has become better defined imo.
come on that thing looks very sick and may never recover.
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the center is goin back undertheclouds i belive
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Quoting FLWeatherFreak91:
Of course it will unwind some as it loses the support from its thunderstorms.
hmm, but maybe the north part of the COC getting more convection wrapping around? Thanks for the reply :)
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Quoting PcolaDan:


Think I'll make a new name - MrGullible - and start responding solely to those that come here just to pull peoples chains and make up numerous names acting like a bad version of someone else. ;>)
LOL...cmon I have seen your chains pulled before...When friends were lost in storms your reaction would be the same. Trust me!
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Please ppl. Charley is past, and we all know how devastating it was. Let's move on to the current situation don't feed the Troll.
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Quoting MiamiHurricanes09:
Emily's circulation appears to be opening up on the western semicircle.


I noticed that too however, it could be shading from the new convection at the center, the sun just past overhead and to the west now.
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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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