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 MiamiHurricanes09:
Major shift to the left with the GFDL as well. Since the GFS did kill Emily, I'm quite surprised that it makes Emily a pretty decent system affect the eastern Florida coast.



Looks to be an interesting day for us tomorrow. I was hoping for a little more land interaction. NHC now says SOME weakening instead of we'll see if Emily survives.
Member Since: August 19, 2005 Posts: 5 Comments: 5043
Quoting scooster67:



its crazy not 1 model predicted it south of Haiti.
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Interesting note that Westward movement should continue, with a gradual turn:

AT 800 PM EDT...0000 UTC...THE CENTER OF TROPICAL STORM EMILY WAS
LOCATED BY AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT NEAR
LATITUDE 16.9 NORTH...LONGITUDE 70.6 WEST. EMILY HAS MOVED LITTLE
OVER THE PAST FEW HOURS...BUT IS EXPECTED TO RESUME A WESTWARD
MOTION OF ABOUT 14 MPH...22 KM/H IN THE NEXT FEW HOURS. A GRADUAL
TURN TO THE WEST-NORTHWEST AND NORTHWEST IS EXPECTED DURING THE
NEXT DAY OR SO. ON THIS TRACK...THE CENTER OF EMILY WILL MOVE
ACROSS THE SOUTHWESTERN PENINSULA OF HAITI EARLY THURSDAY AND MOVE
OVER EXTREME EASTERN CUBA THURSDAY NIGHT.
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Quoting cybergrump:
Look at the 18z GFDL.
Link

showing a S. FL landfall.

what are the wind speeds and pressure?
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Quoting Seflhurricane:
94 here in west miami, brush fires over the everglades and Afternoon thunderstorms. by the way has there been a shift on the 18Z models to the west ???


I have not checked but right now the models do not mean a lot.

Gotta run for dinner. Back later.
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Quoting HurricaneDean07:
Nicyclonechaser,
Shes pissed off, cuase the NHC rejected her from being retired after achieving category 5 status, so she has decided to defy all forecasts by the NHC, and is aimed for Miami(where the NHC is).
This storm really hates the NHC...


It's not really the NHC's fault that she wasn't retired, it's the WMO and that Mexico didn't request it.

But I don't think anybody told Emily that... lol
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1814. Levi32
Quoting Seflhurricane:
why does the last vortex message indicate it has moved WSW ???


The pressure/wind centers could be jumping around a little bit, which usually happens in weak systems when new convection suddenly flares up. The center gets pretty excited at the sight of thunderstorms nearby.
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Quoting robj144:


Interesting information. Isn't the location of the center also important because these are highly non-linear systems? For any non-linear system, the initial conditions are extremely important because two model runs with slightly different initial conditions can produce two completely divergent trajectories.


Yes, slightly different initial conditions produce different results. To help account for this Ensemble Models were developed for global models, which start with different initial conditions. They have been working on HWRF Ensembles, they are still in the research phase.
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Quoting stormpetrol:


Your guess is as good as mine, Kman explained it in an earlier post to me , you might want to check it out!
i saw his post but looking at the last 2 Vort Messages the last one indicates a WSW Drift
Member Since: July 14, 2009 Posts: 0 Comments: 2990
Link
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Quoting MiamiHurricanes09:
Major shift to the left with the GFDL as well. Since the GFS did kill Emily, I'm quite surprised that it makes Emily a pretty decent system affect the eastern Florida coast.

what strength and have the rest shifted west , if they have you have been correct all along you did call that Emily would come very close to the Se FLA Coast
Member Since: July 14, 2009 Posts: 0 Comments: 2990
Hi Levi-


So what is your take on Emily? Do you think she has a method to her madness to impact south flo.?
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Quoting Seflhurricane:
moving West with a jog to the south ???? what the hell is this system doing ?????


Your guess is as good as mine, Kman explained it in an earlier post to me , you might want to check it out!
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Edit: NM GFDL already posted^^
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Quoting scooster67:





That was supposed to be animated!
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Nicyclonechaser,
Shes pissed off, cuase the NHC rejected her from being retired after achieving category 5 status, so she has decided to defy all forecasts by the NHC, and is aimed for Miami(where the NHC is).
This storm really hates the NHC...
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Look at the 18z GFDL.
Link
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Major shift to the left with the GFDL as well. Since the GFS did kill Emily, I'm quite surprised that it makes Emily a pretty decent system affecting the eastern Florida coast.

Member Since: September 2, 2009 Posts: 130 Comments: 21091
I wish I had a picture of Christopher Lloyd from Back to the Future scratching his head, looking confused...

Quoting hotrods:
Something intresting, i went to NHC site clicked on the color invared loop, then clicked on the tropical forecast points and just one symbol came up, are they waiting on model runs or they just don't have a clue at the moment?
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Quoting cloudburst2011:


if it keeps moving wsw then its moving away from the weakness...nhc will have to switch the track west at 11pm..

but it's not moving WSW. it's at the same latitude it was at 5PM but is .4 east of where it was.
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Quoting kmanislander:


91 degrees. Just another summer day LOL
94 here in west miami, brush fires over the everglades and Afternoon thunderstorms. by the way has there been a shift on the 18Z models to the west ???
Member Since: July 14, 2009 Posts: 0 Comments: 2990
1798. ackee
LET throw out the MODELS base on what we know so far
where will EMILY TRACK ?

A NW
B WNW
C WEST
D WSW
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Quoting Seflhurricane:
thanks kman , how has the weather been treating you down there


91 degrees. Just another summer day LOL
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1796. hotrods
Something intresting, i went to NHC site clicked on the color invared loop, then clicked on the tropical forecast points and just one symbol came up, are they waiting on model runs or they just don't have a clue at the moment?
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Quoting Levi32:
Good evening. It appears that a very slow north of west movement has begun with Emily. The slow movement indicates that the weakness in the ridge to the north has been found, and I expect that the track will continue to be north of west from here on out. Emily looks to be shooting for the southwest peninsula of Haiti.
why does the last vortex message indicate it has moved WSW ???
Member Since: July 14, 2009 Posts: 0 Comments: 2990
With no forward motion this effectively reduces the shear over the system significantly. Look for the deep convection to cover over the center.This may give the storm enough vertical depth to feel the trough and head off to the WNW
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Quoting FLdewey:
Stall? Push forward on the controls... TOGA thrust!

(any aviation people in the house?)

*crickets


Word.
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Its like she knows!

Tropical systems sure like making everyone who tries to analyze them look silly...

I think DestinJeff's Sarcastaholism is taking hold...

Quoting BoroDad17:
So lets get this straight, for almost two days NHC has been predicting a WNW-NW turn, and it hasn't happened. FINALLY they change the short term track to reflect the non-turn, and Emily almost immediately STOPS.
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Quoting BoroDad17:
So lets get this straight, for almost two days NHC has been predicting a WNW-NW turn, and it hasn't happened. FINALLY they change the short term track to reflect the non-turn, and Emily almost immediately STOPS.


She's just got sick of the NHC after all these years.... Haha
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Just waiting till the real bad boy storm forms this year, this place is gonna go absolutely nuts :)
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Quoting kmanislander:


Completely stalled and drifting very little
thanks kman , how has the weather been treating you down there
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Quoting PRZEDCASTER:


REALLY ~~~
it could happen remember wrong way Lenny? Although heading back to the Cape Verde Islands would only happen if it went around the Azores High.
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1786. Levi32
Good evening. It appears that a very slow north of west movement has begun with Emily. The slow movement indicates that the weakness in the ridge to the north has been found, and I expect that the track will continue to be north of west from here on out. Emily looks to be shooting for the southwest peninsula of Haiti.
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1784. ackee
Quoting BoroDad17:
So lets get this straight, for almost two days NHC has been predicting a WNW-NW turn, and it hasn't happened. FINALLY they change the short term track to reflect the non-turn, and Emily almost immediately STOPS.
GOOD POINT cant predict mother nature
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I wouldn't go as far to say that the blow-up of convection is "Massive", but it is definitely building some more deeper convection...Not a good thing for Haiti/Dominican Republic.



BB in 30-45 minutes everyone.
Member Since: July 6, 2010 Posts: 113 Comments: 31537
Quoting Seflhurricane:
moving West with a jog to the south ???? what the hell is this system doing ?????


Completely stalled and drifting very little
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Quoting TropicalAnalystwx13:


Getting a little ahead of ourselves there...
not quite tropical looks impressive
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1780. robj144
Quoting nrtiwlnvragn:


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.


Interesting information. Isn't the location of the center also important because these are highly non-linear systems? For any non-linear system, the initial conditions are extremely important because two model runs with slightly different initial conditions can produce two completely divergent trajectories.
Member Since: August 19, 2008 Posts: 0 Comments: 825
Quoting NICycloneChaser:


This thing is now stationary, I'm afraid. Models have been all over the place with Emily, and with the whole season so far, it must be said.


Been a long day at the office missed the last 4 hours, I now see what is happening. Stalled out or at least slowed to a crawl. GFS shows the trough picking it up, most models support this, CMC the outlier as always to the west. Guess we need to see how high Emily gets her clouds at this point. The trough just does not impress me as much as the GFS is showing.
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So lets get this straight, for almost two days NHC has been predicting a WNW-NW turn, and it hasn't happened. FINALLY they change the short term track to reflect the non-turn, and Emily almost immediately STOPS.
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Well hello everybody. I see that Miss Emily is headed in the exact direction I have been saying she would since a few days ago. I am still not entirely convinced that she isn't going to end up in the GOM. If she continues to move westward than we might have to start looking for that. I also see that she has stalled again and so I bet she is giving people plenty of headaches.
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Quoting stormpetrol:
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
moving West with a jog to the south ???? what the hell is this system doing ?????
Member Since: July 14, 2009 Posts: 0 Comments: 2990
1775. jonelu
Quoting BahaHurican:
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

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 ------>.

I enjoyed both of these comments! Nice break in the monotony.
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Quoting aislinnpaps:
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.

Typical woman storm. How many of us here know of a woman that sticks to what she wants and never changes her mind once? Emily is doing just that, keeping us all guessing on what she is going to do. At least she's decided to put her clothes back on and not swirl around naked for all to see.
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Quoting PRZEDCASTER:


REALLY ~~~


Well, you never know... Lol
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ok...bouncin out to take the munchkin on a short walk before it gets dark...thank goodness my hair is in a pony tail or i would have begun pulling it out strand by strand
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Quoting NICycloneChaser:


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.

the couple of times it seems to have stopped is when the convection was building to it's east. it then has resumed moving at a good clip in the past.

we'll just have to wait and see what it does in the next few hours to really tell what its doing.

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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: 31537

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About

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