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 7544:


anyone else have a strong felling we might see this same cone again as it was on monday ? but maybe without the h this time


You got it.
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668. emguy
This whole setup has a similar feel to Tropical Storm Ernesto in 2006 and Fay in 2008. Will be interesting if this passes between Jamaica and Cuba.
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Quoting Ameister12:
Emily looks a bit like a swan.


I see it!

lol.
Member Since: July 6, 2010 Posts: 113 Comments: 32562
Quoting PcolaDan:


not reported, re ported, two different things ;)


reading way to fast...roflmbo...jumped the gun...ooops on me
Member Since: September 16, 2007 Posts: 0 Comments: 3650
Quoting tiggeriffic:


reported for what? coc=center of convection...tucking it under is pulling it together to get stacked...


Thanks for clearing that up...I was worried

un re ported.
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663. 7544
Quoting MiamiHurricanes09:
First track in contrast with the 2p.m position. Pretty good with timing.



anyone else have a strong felling we might see this same cone again as it was on monday ? but maybe without the h this time
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Quoting Levi32:


It means that Emily's SW quad remains weak, and that her appearance on a surface analysis is that of a closed low hanging onto the northern end of a tropical wave or trough. In short, Emily's surface circulation remains ill-defined. ASCAT gives a good picture:



See my post 648
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Quoting lottotexas:
Still in the cone


But she will take the cone with it.
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Quoting PrivateIdaho:


re ported!

How come? He meant center of circulation, not what you think it is. Lol.
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Hey LiLi !!
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Quoting tiggeriffic:


reported for what? coc=center of convection...tucking it under is pulling it together to get stacked...


not reported, re ported, two different things ;)
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Quoting zoomiami:
Levi: post 624 -- translate to English for those of who don't speak met please -- this means what?


It means that Emily's SW quad remains weak, and that her appearance on a surface analysis is that of a closed low hanging onto the northern end of a tropical wave or trough. In short, Emily's surface circulation remains ill-defined. ASCAT gives a good picture:

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Levi, do you expect Emily to be a Florida coast event, or a Bahamian event?
Member Since: June 21, 2010 Posts: 0 Comments: 528
Quoting MiamiHurricanes09:
First track in contrast with the 2p.m position. Pretty good with timing.

Still in the cone
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The HWRF, GFDL, and ECMWF 12z runs look to have a good track with a system that crosses over the narrow strip of Haiti and through the Windward Passage on a track in the general direction of South Florida.
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651. 7544
Quoting MeterologyStudent56:


No the BAMM models are Highly Unreilabile and should never be used as he was abusing them...

The real Dynamic "Trustworthy" models is the GFS,NOGAPS,UKMET,HWRF,GFDL,EURO... Etc


and the hwrf should not be taaken lightly have u seen the new run yet peeps
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Quoting weatherman566:
Link

These model runs are so confusing. Looks like half of them wants it to emerge in the Gulf, and the other half into the Atlantic. Middle ground? Florida.


The difference is that the gulf models are based entirely on steering winds in the initial frame only, while the others are dynamical forecasts.
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Levi, the ASCAT pass this morning shows the elongated low pressure to the SW quite well. Almost a typical convergence line
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Emily better hook a quick right if she is going to pass over Cabo Beata, as the NHC expects!
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Quoting PrivateIdaho:


re ported!


reported for what? coc=center of convection...tucking it under is pulling it together to get stacked...
Member Since: September 16, 2007 Posts: 0 Comments: 3650
Quoting MiamiHurricanes09:
First track in contrast with the 2p.m position. Pretty good with timing.


I give the NHC a thumb up for that pretty amazing to get the time right.
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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


No the BAMM models are Highly Unreilabile and should never be used as he was abusing them...

The real Dynamic "Trustworthy" models is the GFS,NOGAPS,UKMET,HWRF,GFDL,EURO... Etc
Member Since: July 21, 2011 Posts: 1 Comments: 332
Quoting Ameister12:
Emily looks a bit like a swan.


OK, I'll bite.... how in gods name do you see a swan?
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If anything..this is giving everyone a blogging "dry run" in the event a Cat 3+ comes around..
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Quoting stormwatcherCI:
I see it but she is still trying to organize imo.


She's a fighter for sure but most systems that battle 20 knots of shear persist like this. 20 knots is just enough to expose the center but not quite enough to destroy a tenacious circulation. The shear eases off near the Western tip of the Tiburon peninsula so if the track continues to the West and she can hold on it could get very interesting to the South of Cuba.
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Levi: post 624 -- translate to English for those of who don't speak met please -- this means what?
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will be back later, its addicting being on the computer and iphone for the majority of the day
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Quoting stormwatcherCI:
Looks like she tucked her coc back under the convection.


re ported!
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These model runs are so confusing. Looks like half of them wants it to emerge in the Gulf, and the other half into the Atlantic. Middle ground? Florida.
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Quoting Levi32:
Recon is encountering lowering pressures as they travel westward into the SW quad of Emily, indicating that even after all this time, a pronounced low pressure trough still hangs to the southwest of Emily's center.



000
URNT15 KNHC 031920
AF306 0805A EMILY HDOB 18 20110803
191030 1549N 07049W 8437 01547 0075 +185 +074 285010 010 016 000 00
191100 1549N 07051W 8436 01548 0076 +181 +074 293009 009 016 000 00
191130 1549N 07053W 8436 01547 0076 +184 +074 297008 008 017 000 00
191200 1549N 07054W 8436 01548 0076 +183 +074 298006 006 018 001 00
191230 1549N 07056W 8434 01549 0075 +185 +074 305007 007 017 000 00
191300 1549N 07058W 8440 01543 0074 +185 +074 296007 007 019 000 00
191330 1549N 07059W 8434 01548 0074 +185 +075 303007 007 016 000 00
191400 1549N 07101W 8436 01548 0076 +183 +075 310008 009 017 000 00
191430 1549N 07103W 8429 01555 0078 +183 +074 317008 008 017 000 00
191500 1549N 07104W 8428 01558 0078 +184 +074 311008 008 019 000 00
191530 1549N 07106W 8434 01553 0079 +183 +074 317006 007 017 000 00
191600 1549N 07108W 8429 01557 0078 +183 +074 325006 006 016 000 00
191630 1549N 07109W 8430 01556 0081 +180 +074 331007 007 016 000 00
191700 1549N 07111W 8428 01559 0082 +180 +073 342006 006 018 000 00
191730 1549N 07113W 8432 01554 0083 +180 +073 345006 007 017 000 03
191800 1549N 07114W 8428 01561 0083 +180 +073 339007 007 017 000 00
191830 1549N 07116W 8431 01557 0081 +181 +072 339009 009 017 000 00
191900 1549N 07118W 8430 01557 0081 +185 +072 343009 009 017 000 00
191930 1549N 07119W 8429 01560 0081 +185 +072 342009 009 017 000 00
192000 1549N 07121W 8430 01558 0081 +185 +072 350009 009 018 000 00
i would imagine that that is a bad thing in a sense thats its still disorganized
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First track in contrast with the 2p.m position. Pretty good with timing.

Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting nash28:
Hey guys. Long time no see:-) How goes it in the blogosphere?
Hey, nash! I see Emily dragged you out.... lol.... pull up a keyboard and give us ur take on our tropical storm...
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Quoting zoomiami:


Best post of the day!


:) you know me Zoo...i call em like i see em snicker snicker snort snort
Member Since: September 16, 2007 Posts: 0 Comments: 3650
Emily looks a bit like a swan.
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I find highly unlikely that Emily will dissipate over the mountains of Haiti. The circulation is well-defined, as we saw when it was exposed. What it needs to do though is get stacked with its MLC, which it probably wont do until after it crosses the island and enters the Bahamas.

May briefly become a tropical depression as it crosses, but the intensity should pick right back up under very favorable conditions.
Member Since: July 6, 2010 Posts: 113 Comments: 32562
Quoting FLdewey:


Yeah they can't seem to figure that out. Maybe I can post it in Braille.


. . .. . . . . . .. . . . . . .. .. . . . . . .. ..
. . . .. . . . . . . . .. . . . .. . .. . .
. . . . . . . .. . .. . . . . .

well, that sure didn't work
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Long live XTRP!!
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Quoting FLdewey:


Yeah God forbid we actually see a major this year... blog will come unglued.

So far so good... been getting a little rain here and there. Sprinklers still working overtime though.

How ya been? Waiting for big Emily? ;-)
been good so far , hoping for some good rain to help replenish lake O , but NOTHING more
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Quoting DestinJeff:


you ca poke 'em with the XTRP.



ROFLMBO!!!!!!
Member Since: September 16, 2007 Posts: 0 Comments: 3650
Quoting GetReal:


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.
Wherever Emily turns between 70W and 80W, she's got to go through / into the Bahamas i.e. Bahamian waters. [I'm including TCI because geographically we are one archipelago.] This is especially true given the shape/location of the AB high at this time.
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Recon is encountering lowering pressures as they travel westward into the SW quad of Emily, indicating that even after all this time, a pronounced low pressure trough still hangs to the southwest of Emily's center.



000
URNT15 KNHC 031910
AF306 0805A EMILY HDOB 17 20110803
190030 1549N 07017W 8436 01552 0086 171 076 227015 015 022 000 00
190100 1549N 07018W 8433 01553 0085 174 075 220013 015 021 000 00
190130 1549N 07020W 8440 01547 0085 174 075 217013 014 022 000 00
190200 1549N 07021W 8436 01553 0085 175 075 220013 014 024 000 00
190230 1549N 07023W 8436 01550 0086 172 075 220013 013 026 000 00
190300 1549N 07025W 8434 01553 0086 170 074 214012 013 028 004 00
190330 1549N 07026W 8446 01541 0092 164 073 216013 014 031 011 00
190400 1549N 07028W 8442 01542 0099 150 071 223013 015 040 012 00
190430 1549N 07030W 8435 01551 0090 166 066 217011 012 029 004 00
190500 1549N 07031W 8440 01545 0099 150 064 248009 011 036 011 00
190530 1549N 07033W 8432 01556 0085 176 063 259011 011 022 000 00
190600 1549N 07035W 8436 01551 0085 175 064 247010 011 021 000 00
190630 1549N 07036W 8433 01555 0084 176 067 239009 010 021 001 00
190700 1549N 07038W 8442 01545 0082 182 070 244007 007 020 000 00
190730 1549N 07040W 8435 01551 0079 184 073 241010 011 017 000 00
190800 1549N 07041W 8436 01548 0076 185 074 241010 011 017 000 00
190830 1549N 07043W 8434 01550 0074 186 074 234008 010 017 001 03
190900 1549N 07044W 8435 01551 0074 190 074 236007 007 016 000 00
190930 1549N 07046W 8432 01553 0072 191 075 248008 010 017 000 00
191000 1549N 07048W 8432 01553 0073 188 075 267009 009 017 000 00
$$
;
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roduct: NOAA Temp Drop (Dropsonde) Message (UZNT13 KWBC)
Transmitted: 3rd day of the month at 18:57Z
Aircraft: Gulfstream IV-SP (G-IV) (Reg. Num. N49RF)
Storm Number: 05
Storm Name: Emily (flight in the North Atlantic basin)
Mission Number: 9
Observation Number: 02

Part A...

Date: Near the closest hour of 19Z on the 3rd day of the month
Highest Mandatory Level For Which Wind Was Reported: 200mb
Coordinates: 25.0N 75.9W
Location: 90 miles (145 km) to the E (93°) from Nassau, Bahamas.
Marsden Square: 080 (About)
Significant Wind Levels...
Level Wind Direction Wind Speed
1013mb (Surface) 180° (from the S) 10 knots (12 mph)
1003mb 180° (from the S) 5 knots (6 mph)
850mb 190° (from the S) 4 knots (5 mph)
412mb 25° (from the NNE) 3 knots (3 mph)
392mb 90° (from the E) 10 knots (12 mph)
368mb 65° (from the ENE) 19 knots (22 mph)
345mb 75° (from the ENE) 24 knots (28 mph)
326mb 40° (from the NE) 27 knots (31 mph)
291mb 60° (from the ENE) 32 knots (37 mph)
262mb 45° (from the NE) 27 knots (31 mph)
229mb 65° (from the ENE) 15 knots (17 mph)
223mb 75° (from the ENE) 16 knots (18 mph)
218mb 50° (from the NE) 18 knots (21 mph)
199mb 15° (from the NNE) 31 knots (36 mph)
187mb 10° (from the N) 23 knots (26 mph)
179mb 20° (from the NNE) 25 knots (29 mph)
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Quoting tiggeriffic:


personally wish there was such a thing as a cyber rubberband shooter to ward off the trolls and pop em between the eyes at the same time...


Best post of the day!
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Quoting kmanislander:


Actually, shear is blowing the convection away as fast as the storm tries to pull it over the top of the center. Take a look at the visible loop and you will see that only a wisp remians of the latest blow up that was trying to cover the center
I see it but she is still trying to organize imo.
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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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