Earl is weakening as it moves over cooler Atlantic waters, and enters higher wind shear.  It may become an extra-tropical cyclone as it reaches Nova Scotia this weekend.  This track has been consistent since Earl first neared the U.S.

Computer models haven’t changed much since this storm first developed, and by Friday night/Saturday morning it will skim the NE coast, certainly causing rough surge and rip currents.  Wave heights in parts of coastal Massachusetts are expected to be close to 10 feet.  The worst of this storm will remain offshore, as the center of Earl remains in the Atlantic before heading to Nova Scotia.

Wave heights are still increasing along parts of the NE coast in Earl’s path, with the highest waves near the center.  Wave heights are still high to the south of Earl’s center as the water is still churned up.  South of Cape Cod is experiencing higher seas now, and this will continue into Saturday.  Rip currents will still be a problem over the weekend for the East coast, even after Earl leaves, but will diminish next week.

Hurricane warnings are up mainly for the Cape Cod area, with surrounding tropical storm warnings.  Earl will brush by this area tonight/Saturday morning, then speed up to Nova Scotia.

Tropical storm force winds (40 mph and greater) extend 205 miles from the center of Earl with hurricane force winds (74 mph or greater) extending 70 miles from the center.  Most of the bad weather should remain offshore.

The best chance for tropical storm force winds will be around Nantucket and the Cape Cod area.

Hurricane force winds will most likely be too weak to make much of an impact.

We’re still watching Fiona, which isn’t a threat to the U.S. but Bermuda may experience some tropical storm force winds Friday evening and Saturday morning.  This storm will continue North into the Atlantic before fizzling out over the weekend.  You can even see how unorganized it is below.  It will begin to enter areas of higher wind shear.

There are 2 other tropical waves to keep an eye on in the Atlantic.  The remnants of Gaston are over 1,000 miles West of the Cape Verde Islands.  Gaston is no longer a tropical depression, but it could regenerate next week as it heads West.  Another tropical wave moving off the West coast of Africa, East of the Cape Verde Islands, is showing some potential.  It will be slow to develop as it heads West.

The remnants of Gaston may regenerate next week, as it enters warm waters and lighter wind shear.  Computer models hold on to this system for several days.

The other tropical wave closer to Africa, which we are calling “Invest 99L” will continue Northwest, and any development with this system will be slow to occur. 

A HURRICANE WARNING IS IN EFFECT FOR…
* BOGUE INLET NORTH CAROLINA NORTHEASTWARD TO THE NORTH
CAROLINA/VIRGINIA BORDER INCLUDING THE PAMLICO AND ALBEMARLE
SOUNDS.
* WESTPORT MASSACHUSETTS EASTWARD AROUND CAPE COD TO HULL INCLUDING
MARTHAS VINEYARD AND NANTUCKET ISLAND
A HURRICANE WATCH IS IN EFFECT FOR…
* NORTH OF THE NORTH CAROLINA/VIRGINIA BORDER TO CAPE HENLOPEN
DELAWARE
* NOVA SCOTIA FROM MEDWAY HARBOUR TO DIGBY
A TROPICAL STORM WARNING IS IN EFFECT FOR…
* CAPE FEAR TO WEST OF BOGUE INLET NORTH CAROLINA
* NORTH OF THE NORTH CAROLINA/VIRGINIA BORDER TO SANDY HOOK NEW
JERSEY…INCLUDING DELAWARE BAY SOUTH OF SLAUGHTER BEACH AND THE
CHESAPEAKE BAY SOUTH OF NEW POINT COMFORT
* THE EASTERN PORTION OF LONG ISLAND NEW YORK FROM FIRE ISLAND INLET
TO PORT JEFFERSON HARBOR
* NEW HAVEN CONNECTICUT TO WEST OF WESTPORT MASSACHUSETTS…
INCLUDING BLOCK ISLAND
A TROPICAL STORM WATCH IS IN EFFECT FOR…
* NORTH OF HULL MASSACHUSETTS TO EASTPORT MAINE
* THE COAST OF LONG ISLAND WEST OF FIRE ISLAND INLET AND PORT
JEFFERSON HARBOR
* NOVA SCOTIA FROM ECUM SECUM TO MEDWAY HARBOUR AND FROM DIGBY TO
FORT LAWRENCE
* NEW BRUNSWICK FROM JUST WEST OF FORT LAWRENCE WESTWARD TO THE
U.S./CANADA BORDER

Earl is a very strong hurricane with outer bands extending to the Carolinas, as seen easily on the water vapor imagery.  Strong convection and colder clouds tops exist mostly to the South and Southwest of the center.

Hurricane force winds (74mph and greater) extend 70 miles out from the center, and tropical storm force winds extend 205 miles out.  Tropical storm  force winds are expected to occur in the outer banks of North Carolina by Thursday night, with hurricane force winds possible at the immediate coast.

Wave heights are close to 15 feet off the coast of the North Carolina, and are expected to continue and grow as Earl moves North.  For the East coast of Florida, Earl has sparked a high surf advisory.

The path takes Earl almost parallel to the East coast, then up near Cape Cod and Maine, as well as Nova Scotia by Saturday.  At this time, Earl will be weakening as it enters cooler waters and higher wind shear.  As it takes a turn to the N/NE, an increase in forward speed should occur.  Storm surge is expected to be anywhere from 3-5 feet along the immediate coast, with rainfall totals as high as 6 inches possible.  Aside from storm surge, large waves may cause some beach erosion.  Maximum sustained winds near the center are 115 mph with higher gusts.

Including Earl, there are now 3 named storms in the Atlantic, followed by a new tropical wave.

We are still watching Tropical Storm Fiona, but this one is unlikely to reach the U.S.  An Atlantic ridge of high pressure in combination with a cold front exiting the East coast will turn and steer Fiona to the North/Northeast, and this system will weaken as it encounters cooler waters and higher wind shear.

Tropical Depression Gaston has yet to become organized.  The enhanced satellite imagery shows no cyclonic circulation and no deep layer moisture.  Dry air is begining to cut off this system as it heads to the West.

Conditions no longer look favorable for Gaston to intensify.  It will slowly weaken as it nears the Lesser Antilles on Tuesday.

The CMC model shows Earl nearing the Lesser Antilles next week, but the model also picks up on a strengthening tropical wave following behind it.  This is something we will have to watch closely.

The other issue unique to the east coast is that as Earl accelerates to the north or northeast on Thursday and Friday, the translational forward speed of the hurricane which is added to the rotational speed will become more of an effect. This means that winds on the east side of the hurricane will be more unevenly distributed and stronger than on the west side where the translational speed will be subtracted from the rotational speed. So, if the hurricane were to move inland in North Carolina or New England the area just to the right of the eye would experience much more damage than the area not too far to the west. If the eye remains offshore, there will be gusty winds, high surf and beach erosion but not catastrophic damage or flooding. Storm surge flooding could be a problem if the storm makes landfall, especially at high tide, but would not be as severe if the hurricane remains offshore. Huge waves will still pound the entire East Coast, however, regardless of whether or not the hurricane makes landfall.

Do not just follow the thin black line of the forecast track. Look at the yellow cone of uncertainty. If you are in the cone you are in danger of a strike.

The gaphics below show the probability of sustained tropical storm force winds and sustained hurricane force winds respectively.

I’ve plotted the Air Force Flight 306 on Skytower OMNI shown below. The vortex message on Wednesday, August 2 at 11:27 AM EDT, showed a maximum sustained surface wind of 101.3 MPH and a maximum flight level sustained wind of 126.6 MPH at an elevation of 8572 ft. The flight meteorologists reported a closed circular eye.

The high resolution McIDAS GOES E satellite image shown below clearly shows the circular eye as seen from 22,500 miles above the earth’s surface.  

The image below is a magnification of the McIDAS image below. Even though there are some low ragged clouds in the eye which prevent the observer from seeing the ocean surface, the eye seems to have a “stadium” effect with the edges sloping out with height. Transverse banding can be in chaotic eyewall indicating significant turbulence. An outer cloud top maximum rings the inner eyewall. Earl has been undergoing eyewall replacements over the last 2 days. It is possible that the outer ring could contract and form a new inner eyewall over the next 12 to 24 hours.

The high resolution GOES image of Fiona shown below confirms a circular appearance to the low level cumulus clouds. The IR images do not show the circulation, as well. Sometimes, the visible images can show features that are not as defined in the IR images. Radar data from the Leeward Islands also showed a circular appearance to the center which was not evident in some of the infra-red images.

Even though the early run of the GFS model did not pick up on the development of T.D. #9, we have been watching the tropical wave since it emerged off of Africa. T.D. #9 was upgraded to Tropical Storm Gaston at 5PM Wednesday. Yet, another strong wave is about to emerge, as well. The next name on the list is Hermine.

The eye of Hurricane Earl passed directly over buoy 41046 early Wednesday morning. The graphic below shows that 1:10 PM EST even though the eye of Earl was much farther NW, the winds were still 40 MPH with gusts to 49 MPH.

The time graph below wind speed and barometric pressure. The green line is pressure, which shows a classic “V” pattern. Winds increased as the eyewall approached and then dropped precipitously as the eye passed over (approximately 15 knots at the minimum). Winds increased rapidly but were not as high as the southeast eyewall passed over.

Winds reported for hurricane purposes are given in 1-minute time averages for sustained winds and 3 seconds for gusts. The standard observation height is 10 meters. In order to accurately compare measurements, the time average and the height must be standardized. Buoy data is generally reported in 6 minute increments and the anemometer on this buoy was at a height of 5 meters. Thus, standardized winds were higher than the graph below indicates.

The following graphics show expected wind fields. Keep in mind, however, that if the track of Earl shifts east or west, the wind field will obviously shift, as well. The graphics do give an idea of the extent and width of expected winds. The forecast below indicates sustained gale force winds by 8PM Thursday over much of coastal North Carolina.

By Noon Friday, gale force winds could extend from southern Delaware to the central coast of North Carolina (See below).

By Friday at midnight (shown below) winds could be at storm force or above over Cape Cod and gale force from coastal New Hampshire to central Long Island.

By Noon Saturday, storm to hurricane force winds could affect Maine and Nova Scotia with gale force winds further east and west.

Buoy 41047 was NNE of the eye of Earl at 1:23 PM, as shown below. Earl will probably not pass directly over this buoy but winds were 40 MPH gusting to 60 MPH at 1:23 PM with amazingly high 28′ seas.

The water vapor image below shows that dry air has wrapped around the periphery of Hurricane Earl. There will be a balancing act in intensity over the next 24 hours as drier air may try to weaken the storm at the same time as near record warm water temperatures and low shear keep the intensity high.

The enhanced satellite image below shows that there is more than adequate cirrus outflow from Earl. In order to intensify, moist air must be drawn in at lower level and drier air expelled at higher levels.

If Earl and Fiona were not enough, Gaston could threaten the Leeward Islands for a third time. Yet, another wave is moving off of Africa. Could that eventually become Hermine? We”ll see.

On Tuesday afternoon, Earl has pulled away from the Leeward Islands, the Virgin Islands and Puerto Rico. Conditions have improved rapidly over the northern Leeward Islands and the Virgin Islands but it is still a windy day in Puerto Rico. There are lots of trees and power lines down in St. Thomas and air travel is being impacted. St. Croix fared better since it is further south away from the center of the hurricane.

Unfortunately, just as Earl is pulling away from the Leeward Islands, Tropical Storm Fiona is approaching them. As a result, as of 1PM on Tuesday, August 31, 2010, Tropical storm warnings are in effect once again for St. Martin and St. Barthélemy and tropical storm watches are in effect for Antigua, Barbuda, Monterrat, St. Kitts, Nevis, Anguilla, St. Marteen, Saba and St. Eustatius. Anguilla is just recovering from hurricane force gusts experienced Monday due to Hurricane Earl. It is amazing in just a few days apart, the northern Leewward could be affected by two seperate storms.

Hurricane Earl could impact travel during the upcoming Labor Day weekend. Many people will begin their travel on Friday, when Earl will be near or  just off the eastern seaboard. Anyone who lives from North Carolina to the Nova Scotia or has any plans to travel to those areas, should very closely monitor the path of Earl. You should not focus on the thin line that shows the forecast track of Earl!  Look at the cone of uncertainty. If you are in the cone of uncertainty, there is a chance of Earl passing directly over you. The forecasting problem with Earl is that he will be in the process of recurving just at the point in time where he is passing close to large population centers along the Eastern Seaboard. Any deviation to the left(west) or right (east) of the forecast path will have huge implications to many people. If Earl stays at sea, the area from coastal North Carolina to Nova Scotia will have a 12 to 24 hour period of gusty northeast gale force winds or maybe even lighter winds. If Earl makes landfall in the Outer Banks they will be directly affected with hurricane force winds. The same reasoning exists for New England and Nova Scotia, if the eye passes directly over Cape Cod or near Halifax hurricane force winds will hit. Since forecast errors at 4 and 5 days are significant, it is just too early to say exactly where Earl will be in that time frame. Since the path of Earl will generally be paralleling the U.S. East coast, any deviation left or right will have a huge difference in where Earl makes landfall. The best advice is to be prepared and follow Earl closely until it passes your latitude.

Hurricane force winds may only extend 25 miles in the southwest quadrant of Earl as he passes near the East Coast as opposed to 60 miles in the northeast quadrant. So, the width of hurricane force winds is narrow and the consequences great. If Earl is 100 miles offshore, the affects will obviously be much more minimal than if he is 10 miles offshore.

The satellite picture below shows the circulation Earl in the center and Fiona approaching on the right. Winds at 12:45 PM EDT, August 31, 2010 were SW sustained at 20 MPH with gusts to 24 MPH on the western shore of Puerto Rico. The water temperature is still warm at 83 even with all of the recent wave action.

 A bouy east of Earl (shown by the arrow in the image below) was reporting a sustained wind of 34 MPH with gusts to 45 MPH at 12:45 PM EDT. Wave heights were 23 feet.

The image below shows the flight path of Air Force flight 309. The vortex message taken at 9:42 AM EDT, August 31, showed an incredibly strong storm with a maximim flight level wind of 140.4 MPH. Maximum surface winds were reported at the surface were 125.4 MPH. Note that the Air Force also reported a circular but that it was open in the SW quadrant,which is usually the weakest quadrant. If Earl remains offshore of the east coast of the U.S. the weaker southwest quadrant would be on the landward side of the hurricane.

Another buoy northwest of Earl (and in the path of Earl) was reporting sustained winds of 31 MPH with gusts to 38 MPH with waves of 17 feet and a water temperature of 85°.

The radar presentation from San Juan today was not as impressive since the eye has now moved closer t0 the outer range of the radar due to the curvature of the earth. There are still squalls that are affecting Puerto Rico and the Dominican Republic. It looks like the worst weather will lift north of Haiti with only moderate convection tonight and Wednesday.

 Even though Earl remains at Category 4 strength the eye is not clearly seen in high resolution satellite imagery shown below from our McIDAS system. This is partly due to eyewall replacement cycles which will be occurring over the next few days leading to fluctations in intensity.

The enhanced satellite image below is able to pick out an eye even through the cirrus overcast.

 Wave heights will be increasing from Florida to Maine to Nova Scotia over the next 2 to 5 days as large swells emanate from Earl. The graphic below shows buoy heights on Tuesday afternoon.

The Turks and Caicos Islands should be spared a direct hit by Earl but they are under tropical storm warnings. The Turks and Caicos Islands are not volanic like most of the Leeward Islands so the land is mostly flat.

I took the picture below in 2008 at the cruise ship entrance to Grand Turk.

The picture I took below shows how the island is mostly flat with lagoons and does not have the elevations that the Caribbean Islands have.

As of Tuesday afternoon (as shown below), the NOGAP model shows the track of Earl further to the west and the Canadian model (CMC) is the easternmost outlier.

Fiona will be right behind Earl but the tracks shown below are still expecting Fiona to be weaker in the shadow of Earl and she should remain further east.

Use caution in the gaphics below. These are forecasts made 4 to 5 days in advance and there could be changes. Keep up to date with the latest information. The graphic shows the NHC forecast for Noon, Friday. The yellow shaded area is the cone of uncertainty. The orange area is the expected area of gale force winds and the red area is storm force winds. Remember, though, that any change to the left or right could make a big difference in wind speed.

The image below is the forecast wind field for Friday night with the same color scheme as in the graphic above.

If Earl and Fiona were not enough, we are also following Invest 98L and a new tropical wave emerging off of Africa.

Monday morning the center of the eyewall passed just north of the the Leeward Islands. The northernmost Leeward Island is Anguilla and Earl passed  just to the north of Anguilla at 9 AM EDT. Saint Martin/St.Maarten is the next island just south of Anguilla made up of a French and a Dutch side. The Princess Juliana International Airport in the Dutch part of the island of Sint Maarten. The Dutch side of the island is on the south side which was further away from the center of Earl than the northern French side of the island. The population of the island is about 75,000. Winds gusts were recorded at 68 MPH at 8AM EDT at the Princess Juliana Airport more than an hour before the point of closest approach. It is possible that winds gusted to hurricane force in Anguilla since Anguilla was closer to the center of the eye. Winds may have gusted to hurricane force also on the French side of the island (Saint-Martin) since it was closer to Earl than the Dutch side.

At 1:57 PM EDT on Monday, the southern eyewall was passing near Anegada, which is the northernmost British Virgin Island. Unlike most of the other Leeward and Virgin Island, Anegada is a fairly flat atoll. The other islands have higher elevations since they are volcanic. The population of Anegada is only about 200 so the worst part of Earl is affecting the island with the least population in the region.

In the Skytower OMNI image below, the outer bands of Earl are reaching St. Croix, where winds have gusted to 39 MPH but the central core of hurricane force winds are in the eyewall around the circular center clearly visible in the radar image.

The enhance satellite image below shows magenta colored areas representing the strongest convection mostly wrapped in the northern semicircle. This means that the strongest winds are likely to the north of the islands. At 12:48 PM EDT Monday there was a large feeder band with very heavy convection (magenta) that was headed for the north coast of  Puerto Rico.

The St. Croix harbor cam picture we are carrying on our website is located in Christiansted located on the north central coast of St. Croix. St. Croix is protected by barrier reefs which cuts down on wave action somewhat. Tides are running above normal but there is not a lot of wave action in the protected harbor due to the reef. The camera is facing north.

The warning map as of 5PM EDT Monday is shown below. All warnings for Antigua, Barbuda, Montserrat, St. Kitts and Nevis were dropped and these islands did not have as much effect from Earl since they were further south. For Monday afternoon and evening the greatest threat will be to the northern U.S. and British Virgin Islands, Puerto, Culebra and Vieques, especially the northern facing coasts of these islands. A tropical storm warning is in effect for Puerto Rico.  A tropical storm warning is in effect for the Puerto Rican islands of Culebra and Vieques, which are the islands west of St. Thomas. Also, Turks and Caicos Islands have been added to the tropical storm warnings.

The warnings have changed from where they were at 1PM EDT Monday (shown below) as the hurricane has tracked farther to the west. All hurricane warnings were dropped at 5PM Monday.

The Puerto Rican web camera image we are carrying on our web site shown below at about 2:00 PM EDT is in Luquillo, Puerto Rico. Luquillo is on the northeast coast. Large waves can be seen breaking on the beach there. Compare the Luquillo beach area to the protected harbor at Christiansted, St. Croix. 

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 The vortex message from the Air Force reconnaissance flight into Earl is shown below along with the entire flight path. At 11:27 AM EDT on Monday, they reported surface winds of 124.3 MPH with flight level winds of 133.5 MPH. The eye was circular but open in the southwest quadrant.

The McIDAS image shown below was taken at 8:0o AM EDT Monday shortly before the closest point of approach to Anguilla. The northern eyewall appears stronger in this image than the southern edge which was closer to Anguilla. Fortunately, then Anguilla did not receive the strongest part of the storm . The population of Anguilla is about 13,500.

The basin-wide satellite image below shows that Danielle has moved well into the mid-latitudes and does not have the same shape and structure of a tropical system such as Earl (shown near the center of the image). Danielle should become extratropical over the next 24 hours.

Invest 97L quickly developed into tropical storm Fiona Monday  afternoon at 5PM. Fiona is moving west at 20 MPH. Earl is moving WNW at a slower speed of 15 MPH. Fiona is “gaining” on Earl and since Earl will be the stronger of the two systems, Earl will likely inhibit any rapid strengthening of Fiona especially as she gets closer to Earl. It is too early to say what there final interaction will be.  There is still yet another tropical wave with a potential to become a depression that is near the Cape Verde Island. It emerged off of Africa south of where Danielle, Earl and Fiona did.

This morning the center of the eyewall has been passing just north of the the Leeward Islands. The northernmost Leeward Island is Anguilla and Earl passed  just to the north of Anguilla at 9 AM EDT. Saint Martin/St.Maarten is the next island just south of Anguilla made up of a French and a Dutch side. The Princess Juliana International Airport in the Dutch part of the island of Sint Maarten. The Dutch side of the island is on the south side which was further away from the center of Earl than the northern French side of the island. The population of the island is about 75,000. Winds gusts were recorded at 68 MPH at 8AM EDT at the Princess Juliana Airport more than an hour before the point of closest approach. It is possible that winds gusted to hurricane force in Anguilla since Anguilla was closer to the center of the eye. Winds may have gusted to hurricane force also on the French side of the island (Saint-Martin) since it was closer to Earl than the Dutch side.

At 1:57 PM EDT on Monday, the southern eyewall was passing near Anegada, which is the northernmost British Virgin Island. Unlike most of the other Leeward and Virgin Island, Anegada is a fairly flat atoll. The other islands have higher elevations since they are volcanic. The population of Anegada is only about 200 so the worst part of Earl is affecting the island with the least population in the region.

In the Skytower OMNI image below, the outer bands of Earl are reaching St. Croix, where winds have gusted to 39 MPH but the central core of hurricane force winds are in the eyewall around the circular center clearly visible in the radar image.

The enhance satellite image below shows magenta colored areas representing the strongest convection mostly wrapped in the northern semicircle. This means that the strongest winds are likely to the north of the islands. At 12:48 PM EDT Monday there was a large feeder band with very heavy convection (magenta) that was headed for the north coast of  Puerto Rico.

The St. Croix harbor cam picture we are carrying on our website is located in Christiansted located on the north central coast of St. Croix. St. Croix is protected by barrier reefs which cuts down on wave action somewhat. Tides are running above normal but there is not a lot of wave action in the protected harbor due to the reef. The camera is facing north.

The warning map as of 1PM EDT Monday is shown below. All warnings forAntigua, Barbuda, Montserrat, St. Kitts and Nevis were dropped and these islands did not have as much effect from Earl since they were further south. For Monday afternoon and evening the greatest threat will be to the northern U.S. and British Virgin Islands, Puerto, Culebra and Vieques, especially the northern facing coasts of these islands. A tropical storm warning and hurricane watch is in effect for Puerto Rico but may be upgraded to a warning later today. A hurricane warning is effect for Puerto Rican islands of Culebra and Vieques, which are the islands west of St. Thomas.

The Puerto Rican web camera image we are carrying on our web site shown below at about 2:00 PM EDT is in Luquillo, Puerto Rico. Luquillo is on the northeast coast. Large waves can be seen breaking on the beach there. Compare the Luquillo beach area to the protected harbor at Christiansted, St. Croix. 

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 The vortex message from the Air Force reconnaissance flight into Earl is shown below along with the entire flight path. At 11:27 AM EDT on Monday, they reported surface winds of 124.3 MPH with flight level winds of 133.5 MPH. The eye was circular but open in the southwest quadrant.

The McIDAS image shown below was taken at 8:0o AM EDT Monday shortly before the closest point of approach to Anguilla. The northern eyewall appears stronger in this image than the southern edge which was closer to Anguilla. Fortunately, then Anguilla did not receive the strongest part of the storm . The population of Anguilla is about 13,500.

The basin-wide satellite image below shows that Danielle has moved well into the mid-latitudes and does not have the same shape and structure of a tropical system such as Earl (shown near the center of the image). Danielle should become extratropical over the next 24 hours.

Invest 97L could still become a depression or tropical storm over the next few days. Invest 97L is moving west at 20 MPH. Earl is moving WNW at a slower speed of 15 MPH. Invest 97L is “gaining” on Earl and since Earl will be the stronger of the two systems, Earl will likely inhibit any rapid strengthening of Invest 97L especially as 97L gets closer to Earl. It is too early to say what there final interaction will be.  There is still yet another tropical wave with a potential to become a depression that is near the Cape Verde Island. It emerged off of Africa south of where Danielle, Earl and Invest 97L did.

Of all the tropical systems currently in the Atlantic, Earl has the potential to cause the most problems. The most immediated areas that are being affected are the Leeward Islands. There is the possibility that Earl could directly or indirectly affect the U.S. eastern seabord from Wednesday through Friday of the upcoming week.

Invest 97L located east of Earl has shown a decrease in convection today. None of the models intesify invest 97L anywhere nearly as strong as Earl is forecast to become. Earl is forecast to be a Category 4 hurricane east of the Bahamas. For the same reason that Danielle inhibited Earl, Earl may also inhibit the development of Invest 97L. As Earl strengthens a large upper level high will develop over Earl. The ouflow and subsidence will likely prevent Invest 97L from any rapid intensification.

There is yet another wave moving off of Africa which bears watching. The latest wave located east of Invest 97L is exiting Africa even farther south than Earl or Invest 97L did. Earl is destined to track further west than Danielle did. Without Earl, Invest 97L would likely also track further west. However, the interaction between a strong Earl and a weaker 97L in 3 to 5 days could cause a Fujiwhara affect (where two cyclones rotate around each other) or more likely recurve Invest 97L out to sea further east than Earl.

The tropical wave in the western continues to produce large areas of clouds and convection but without any circulation. The low in the northern Gulf appears to have moved inland over Louisiana and is weakening.

The enhanced satellite image of Earl shown below indicates the circular central core in magenta where the strongest winds are, as well as a strong feeder band to the east. There is also a strong line of convection which preceeds the hurricane which spread over most of the Leeward Islands Sunday afternoon.

Even though Danielle, passed almost 300 miles east of Bermuda and much further away from Florida, large swells that were formed when Danielle was a Category 4 hurricane are impinging on the east coast of Florida causing dangerous rip currents. Seas of 8.5′ were reported at the buoy near Cape Canaveral on Sunday afternoon. Here in the Bay area we do not have to worry about rip currents since the swells will break on the east coast and our flow will continue to be east to northeast (offshore flow).

the graphic below shows wave height in the western Atlantic. They increase closer to the center of Danielle. Just about time the waves will start to settle down from Danielle, Hurricane Earl will produce more swell from the southeast. Thus, much of the east coast of the U.S. from Florida to Maine will experience large waves and dangerous rip currents this week.

The Martinique radar from METEO France shown below clearly identifies the eye of Earl located east of the Leeward Islands on Sunday evening. The improving structure can be seen between 23 UTC 8/28/10 (second image below) and 0215 UTC 8/29/10 (first image below). Notice the eye getting more circular and defined.

The warning map below shows the status of warnings as of 11PM Sunday night. Since Anguilla, St. Martin and St. Barthelemy are located the furthest northeast in the Leeward Islands they will experience the brunt of Earl first.

A NOAA P3 aircraft found flight level winds of 77 MPH on Sunday afternoon at 6:03 PM. However, Earl has continued to rapidly intensify since the image. The graphic below shows the flight path of the aircraft.

The storm surge is expected to be 2 to 4 feet above ground level near the coast in areas of onshore winds in the Leeward Island. The smaller islands are not as susceptible to high storm surge as are large coastlines with shallow continental shelves. I had the opportunity to visit St. Barthélemy earlier this year. I am standing in the capital city of Gustavia, St. Barthémely in the picture below.  Notice that many homes are built close to to sea level in the protected harbor city, which is is on the south side of the island. If Earl passes to the north of St. Bart’s, Gustavia should fare well regarding storm surge. Many of the the Leeward Islands are volcanic, so many homes are also able to built high on the hillsides above any potential storm surge.  

In the picture below, the downtown shops are on the right. Notice that the main street is only about 4 feet or so above sea level.

The map below shows the protected port area of Gustavia.

The picture I took below was from a ship off the coast looking northeast towards Gustavia. The downtown area is where the red roofed building are located.

As of 11PM, the British Virgin Islands were under a hurricane warning and the U.S. Virgin Islands such as St. Thomas shown below were under a hurricane watch. The warning may be extended westward on Monday. I took the picture below from a hillside above the capital city of Charlotte Amalie looking south-southwest towards the harbor and downtown area. Charlotte Amalie is also on the more protected south shore of St. Thomas, U.S. Virgin Islands.

In addition, as can be seen in the picture I took below looking southwest other islands are evident which serve to break up wave action.

We are still watching Hurricane Danielle, Hurricane Earl, and Invest 97L, all located in the Atlantic.

Hurricane Danielle will continue to stay away from the United States as it moves on a N/NE path.  Cooler waters and higher wind shear ahead will destroy this system over the next several days.

As of the 11am advisory from the National Hurricane Center, Earl has been upgraded to a category 1 hurricane.  It’s gained organization and wind speed over the past 24 hours.  Through the end of next week, atmospheric conditions are looking favorable for strengthening of Earl.  At that time, it may be a major hurricane (category 3+).  The good news right now for the Southeast is an area high pressure in the forecast at the time Earl will be closest.  This will help block it from the Southeast U.S., and another area of high pressure in the Atlantic will help steer it to the North.  Hopefully this will follow closely to Danielle’s path, but a forecast this far out can always change.

As for Invest 97L, a tropical depression is not far in the future. . .  We could see one form in the next 24 to 48 hours.  As of  now, computer models are agreeing on another path, similar to Danielle’s, several days from now.

Wind shear ahead of Earl and Invest 97L is fairly light.  Conditions as of now look more favorable for Earl to develop into a strong storm system, whereas Invest 97L may run into some moderate shear at times.

The HWRF model suggests Earl becoming a major hurricane, skimming the East coast, with Invest 97L following behind, weaker.  This is an extended computer model forecast for September 3rd, which we cannot rely heavily on at this time, but it does seem somewhat likely.

The main concern will now be Earl. Earl could be a dangerous category 3 hurricane off of the eastern seaboard during the upcoming week. Danielle is moving through a weakness in the Bermuda-Azores high. Ironically, as Danielle becomes a monster extratropical storm in the far north Atlantic, she will indirectly cause relative pressures to rise off the east coast of the U.S. This effect will allow Earl to come much farther west than Danielle did and could allow Earl to threaten the east coat of the  U.S. by mid-week. In addition, eventually the remains of Danielle will move back to the west south of Greenland which could induce a blocking pattern north of Earl mid-week. This may allow Earl to sit for a long time off of the east coast. Usually storms accelerate northward off of the middle Atlantic but this may not be the case with Earl.

In addition, another system (Invest 97L) will likely become a depression and possible Tropical Storm Fiona over the next days. Due to the rapid movement of Invest 97L and the outflow from Earl as he strengthens, Invest 97L will not likely achieve the same strength as Earl will achieve. There is the possibility of a Fujiwhara effect where two storms rotate around each other or Earl could eventually absorb 97 L (future Fiona?).

Another strong tropical wave just coming off of Africa is also a candidate for becoming a tropical cyclone this week The distubance in the Caribbean remains unorganized. The low in the Gulf is non-tropical and will be moving northward onshore by Sunday and Monday.

The enhanced satellite view below shows that although Danielle is the largest current system, cloud tops are cooling. The coldest cloud tops (magenta colors) are now associated with Earl as he strengthens in purely tropical waters.

Wave height are already picking up. Waves near Danielle are more than 25′ high. The buoy west of Bermuda is reported 9.2′ swells on Sunday afternoon.

The Bermuda radar shown below indicates that the outer bands of rain with Danielle are affecting Bermuda as they rotate from the north-northeast to the south-southwest.

The long range GFS model below is valid for Friday at 9:00 AM. Remember that there are large errors this far in advance. However, the general trend is that the remains of Danielle will be a mega-storm in the north Atlantic, Earl will be very strong off or near the east coast of the U.S. and Fiona? may be overshadowed by Earl.

Hurricane Danielle has weakened to a category 2 hurricane, and continued weakening is expected as it moves into higher wind shear and cooler waters.  An old frontal boundary moving off the Northeast will push Danielle back out to sea, keeping it away from the United States.

Tropical Storm Earl will continue behind Danielle, possibly traveling in a similar path.  This storm is expected to near Puerto Rico as a hurricane, then head up the Atlantic.  A large ridge of high pressure over much of the Eastern seaboard should keep Earl in the Atlantic for most of the time, but it’s still too far out to be certain.

Invest 97L may be on a similar path as Earl, since computer  models are currently agreeing on a Northwest turn once near the United States.  This system may become a tropical depression soon, then possibly the next named storm which would be “Fiona”.

Through the extended period, the GFS doesn’t significantly develop Invest 97L, but it does keep Earl at a strong hurricane.  This is also something we’ll have to keep an eye on as the forecast becomes more uncertain with time.

There are pockets of light wind shear throughout the Atlantic where conditions are favorable for further strengthening of both Earl and Invest 97L.  As for Danielle, weakening will occur on a continued path to the NE.