Hurricane Matthew intensifying in Caribbean

Despite the moderate to strong wind shear, Hurricane Matthew continued to strengthen overnight. Winds were bumped up to 100mph, and it may be a bit stronger than that. Computer models continue to insist on the north turn, but where it turns to the north is huge in the eventual forecast path for the storm. Here is the latest track, and much more will be written on this blog about Matthew later today.matthewmatthew2

Tropical Storm Matthew Gains Strength in the Eastern Caribbean

Matthew continued its westward trek on Thursday away from the Lesser Antilles and into the Caribbean. As of 11am Thursday, the storm had maximum sustained winds of 70mph and a minimum central pressure down to 996mb. Matthew’s forward speed had slowed a bit since its first advisory on Wednesday, but it was still moving at 15mph. Tropical Storm Watches were up for the Netherland Antilles (Aruba, Bonaire, and Curacao).

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The forecasted path of Matthew is rather certain for the next couple of days. Thanks to a large ridge to its north, the storm will continue moving to the west, albeit gradually slowing down at the same time. However, a digging trough across the east coast this weekend will sharply turn the storm to the north. While the models disagree on the timing of this turn, they all feature it at some point. The official forecast from the NHC has Matthew making a turn to the northwest on Saturday, and northward by Sunday. The intensity forecast from NHC has the storm strengthening to a hurricane by Friday, and peaking at Category 2 strength on Monday before landfall on the eastern edge of Cuba Tuesday.

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Matthew is a rather large storm, with tropical storm force winds extending outward up to 205 miles from the center. Tropical rains continued to drench the islands of the Lesser Antilles on Thursday morning despite the storm being several hundred miles west of them. In fact, showers from the storm extended as far north as the northern Lesser Antilles all the way south to the northern coast of South America. However, enhanced satellite imagery still showed a sheared storm. Moderate to at times high wind southwesterly wind shear has continued to push the convection to the east of the center of circulation, exposing the low-level swirl.

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While wind shear is currently high enough to keep Matthew from organizing too much, it is expected to drop in the next couple of days. Models still differ on just how much it will slacken, but even if it drops off marginally, this should allow for Matthew to strengthen this weekend. The maps below depict the GFS wind shear forecast from Thursday morning (top image) to Saturday (bottom image). The lower wind shear will likely stick around through the weekend, allowing for more strengthening of the storm.

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In addition to lower wind shear, Matthew is moving into an area of extremely warm waters. Sea surface temperatures are in the mid 80s and even running a few degrees above the climatological averages.

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While the warm waters and lower wind shear will certainly help Matthew strengthen, one environmental factor working against it is the amount of moisture in the atmosphere. Water vapor imagery shows an area of drier air just to the west of the current location of the storm. It’s not dry enough to choke off Matthew but it may ultimately limit the short-term strengthening of the storm (before this weekend).

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Spaghetti plots show most of the models (statistical, dynamical, and consensus) depict a sharp turn to the north this weekend, though they differ significantly on the timing of that turn and the ultimate intensity of Matthew. It is possible that the storm will have ‘2’ periods of peak intensity – one before landfall or interaction with Cuba/Hispaniola and another after the storm emerges into the Atlantic near the Bahamas.

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Two of the major models we look at for forecasting track and intensity of tropical storms are the GFS and ECMWF (Euro). While both models show a turn northward, the GFS shows it about a day earlier. The ECMWF is also a bit farther east. By the middle of next week, the differences are really highlighted with the GFS showing a storm nearing the East Coast of the US while the Euro is farther south and east with a strengthening storm in the Bahamas. It is interesting to note that the last hurricane to make US landfall north of Florida in October was Hazel in 1954 (Sandy was post-tropical). While it still is more than a week away from any potential US impact, it is worth noting that the forecasted track of Matthew does somewhat mirror that of Hazel.

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Tropical Storm Matthew Forms East of the Windward Islands

It’s official. Hurricane hunters confirm Matthew, the 13th named storm of the 2016 season, forms near the Lesser Antilles Wednesday. Reconnaissance aircraft found a peak flight level wind over 70 mph and a surface wind  (SFMR) of 60 mph which, along with a weak closed center of circulation, triggered the upgrade to tropical storm status. The deepest convection and strongest winds are displaced east of the center due to moderate westerly wind shear. As of 11 AM, maximum sustained winds are at 60 mph and it races west towards the Windward Islands at 21 mph. A Tropical Storm Warning is in effect for Guadeloupe and Martinique, St. Lucia, Dominica, Barbados, St. Vincent, and the Grenadine Islands. Tropical storm conditions are expected through early Thursday.

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Here is the first official track from the NHC. In the short-term a westerly track into the central Caribbean is expected along with gradual strengthening. Matthew will gradually slow down a bit too during this time. The forecast is pretty clear cut until the weekend. Under the influence of an east coast trough Matthew will lift northward towards Jamaica and mountainous east Cuba as a strengthening hurricane late in the weekend and Monday.

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12Z computer models are in the line with the official forecast through Friday. By the weekend there is a spread in how quick future hurricane Matthew gets picked up by the trough. The longer it stays in the Caribbean the further west it may head late next week and possibly threaten the U.S..

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Commonly as is the case with newly formed tropical systems there is a big  difference in timing and strength between the GFS and European model. Data from hurricane hunters will help models have a better grasp on Matthew in the days ahead. The GFS shows Matthew lifting north much quicker. As a result the model shows a hurricane by Wednesday morning exiting the Bahamas and east of Florida. At this pace if Matthew makes landfall in the U.S. it won’t be until late next week.

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Meanwhile the European has Matthew much slower to make its northward turn. Below is the forecast for next Wednesday morning. At a slower pace the hurricane is still in the Caribbean with hurricane conditions affecting Cuba at this time. This track with put Hurricane Matthew in the Bahamas late next week. The official NHC forecast is a blend of the timing of the quicker GFS and slower European.

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NHC forecasts a category 2 hurricane by Monday but other intensity models are more aggressive. There are a couple of potential issues for the intensity forecast of Matthew over the coming days. The first will be wind shear, which is rather high over the Southeast Caribbean at this time. This will likely limit how much Matthew can strengthen before the weekend. Another problem will be how close to the South American coastline Matthew tracks. Historically, storms that track too close pull in dry air from the continent, thus affecting the structure of the storm. The third problem will be the mountainous terrain in Cuba and Hispaniola. While they won’t affect the near-term strengthening, they certainly can disrupt the storm later this weekend or early next week if it passes over them. This could ultimately impact what type of storm will be left in the Bahamas for early to mid-next week (timing dependent on the model). One factor aiding Matthew’s development will be extremely warm waters in its path. Sea surface temperatures in some areas are as much as 3°C above average and pushing 90° – certainly warm enough to push Matthew’s intensity up.

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Invest 97L Likely to Become Matthew in Caribbean; Complicated Long-Range Forecast

Hurricane hunters did not find a low level circulation in their mission Tuesday afternoon but they did find winds near tropical storm strengthen. Invest 97L is still likely to become Tropical Storm Matthew when it enters the Caribbean mid-week. The vigorous open wave has organized over the past 24 hours with improving outflow and deep convection on its eastern side. Southwesterly wind shear will stay elevated in the days ahead so intensification will be a gradual process. Interest in the Windward Islands need to keep a close eye on Invest 97L as squalls and tropical storm conditions are possible Wednesday and Thursday. Data from Tuesday’s hurricane hunter mission will be imputed into late Tuesday computer model runs.

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Model consensus is decent that future Matthew tracks westward into the central Caribbean through at least Friday. The question remains how long will it head west before it lifts northward under the influence of a trough over the eastern U.S. Below is the 12Z suite of models through Saturday afternoon. If future Matthew can overcome wind shear hurricane strength is possible by Saturday.

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By late Saturday or Sunday 12Z models suggest a northerly track towards Cuba, Jamaica, or Hispaniola and onto the Bahamas or Turks and Caicos Monday. If future Matthew passes over mountainous east Cuba or Hispaniola this may cause temporary weakening. The time stamp on the graphic below is 7 days away. If Matthew heads for the U.S. it won’t be for another 7-10+ days so there is plenty of time to watch. Models have trended a bit closer to the U.S. Tuesday.

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The upper level pattern over the U.S. is quite complex over the next week. Water vapor imagery Tuesday afternoon shows a deepening trough slipping through the Southeast. The stronger the trough stays the more likely future Hurricane Matthew will lift north out of the Caribbean. If future Matthew stays further south in the Caribbean closer to South America it will be slower to feel the influence of this trough and stay in the Caribbean longer. This could mean a more westward track in the long run and a stronger tropical system due to very warm Caribbean waters.

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As is often the case in an extended tropical forecast it’s the battle between the GFS and European model. Models will likely change quite a bit in the days ahead so don’t focus on just one model run. The 12Z GFS model shows future Matthew moving westward into the Caribbean and becoming a hurricane early Saturday south of Haiti. After a brief hiccup with Haiti late in the weekend the GFS shows a future Hurricane Matthew strengthening over the southeast Bahamas Monday. It brings a hurricane dangerously close to the Northeast U.S.  late next week.

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The 12Z Euro shows a slight westward shift too. As it has shown for a few day now the Euro is slower to organize future Matthew in the extreme southern Caribbean closer to South America. It eventually shows a northerly track but this is much slower than other models and not until late Sunday. The European model suggests Jamaica could see more impacts than Hispaniola followed by eastern Cuba as a hurricane Tuesday and Wednesday. With a further south and more westerly track in the short-term this model suggests Florida impacts and brings a strong hurricane near southeast Florida late next week.  Again, stay tuned as a lot will continue to change in the days ahead.

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Invest 97L Likely to Become Matthew; Headed for the Caribbean Mid-Week

Karl and Lisa lost tropical characteristics over the weekend in the north Atlantic. All eyes are on Invest 97L a vigorous broad area of low pressure headed for the Caribbean. The odds are high that it becomes Matthew in the days ahead. As of Monday afternoon the disturbance is pretty close to the equator but it is getting more organized. It moves quickly west-northwest to a slightly higher latitude by Tuesday. This is when more spin may develop and a tropical depression or tropical storm will likely form. Hurricane reconnaissance aircraft will investigate Invest 97L Tuesday afternoon. As is always the case with a developing tropical cyclone model data is essential in assessing the future track and strength.

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12Z computer models are in pretty good agreement future Matthew heads for the Windward Islands late Wednesday. During this time models are on board with tropical storm conditions. A few forecast weak hurricane strength but that would mean rapid strengthening pretty soon. Beyond mid-week future Matthew enters the Caribbean. The question remains if it will track more southerly near South America and stay a bit weaker or blossom into a strong hurricane over the central Caribbean. Many models suggest a northerly track towards mountainous Hispaniola Monday. It’s still way too early to say with confidence if future Matthew stays out the sea, heads for the Gulf, or threatens the U.S.. We will be monitoring this feature for the next 7-10+ days easily.

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It’s the time of year when cold fronts swing across the eastern U.S. and bring cooler air and lower humidity to some. The strength in a cold front/trough will play a big role is where future Matthew heads late next week. The GFS is pretty aggressive in deepening a trough over the weekend displacing the Atlantic ridge to the east. This setup would favor a stronger Hurricane Matthew lifting north out of the Caribbean and into the west Atlantic. The stronger the trough stays into early next week could mean a track out to sea (which would be good news). All of the 12Z GFS ensemble models hint at this possibility with a track east of Florida. The 12Z GFS shows Matthew weakening as it passes over Hispaniola and then recharging near the Southeast Bahamas as it lifts northward. It’s still way too early to have confidence in this outcome.

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Meanwhile the reliable European model suggests Matthew will be slower to organize in the Caribbean but also slower to exit too. The 12Z Euro hints at a track further south over the southern Windward Islands and just north of South America late week.  The Euro is also on board that future possible Hurricane Matthew will lift northward towards Hispaniola but not until early next week. This model banks on a weaker East coast trough hence the delay to exit the Caribbean. We’ll continue to monitor the model trends.

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One thing for sure is despite wind shear or interaction with land water temperature favor rapid organizing in the Gulf, Caribbean and western Atlantic. Water temperatures are 1-2°C above average in the eastern Caribbean and up to 1-3°C above average in the western and northern Gulf and western Atlantic.

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Karl and Lisa to Become Post-Tropical; Watching the Caribbean Next Week

Karl passed east of Bermuda early Saturday morning as a strong tropical storm. However, the good news for the island nation was that it was on the weaker side of the system, and therefore didn’t see much in the way of wind. However, it did see heavy rain from time to time. As of Saturday evening, Karl was about 450 miles NE of Bermuda and continuing to move to the NE at 29mph. Maximum sustained winds were 65mph and minimum pressure was 992mb. Enhanced satellite imagery shows a large area of deep convection – however that convection is somewhat removed from the low level center.

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Karl will continue accelerating to the northeast during the day on Sunday. The storm is expected to strengthen some by Sunday night before undergoing extratropical transition and being absorbed by a large upper level low. Before the transition, Karl may become the season’s 5th named hurricane. Nonetheless, it will remain out to sea and won’t affect land.

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Farther east, Lisa was devoid of convection for several hours on Saturday and therefore was designated post-tropical. The remnants of the storm will continue moving northward over the next 24-48 hours before completely dissipating.

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While Karl and Lisa are winding down, another area in the Atlantic is just heating up. Several hundred miles southwest of the Cabo Verde Islands is a disorganized tropical wave. The wave is too close to the equator right now (<10°N) to develop any spin of its own at this point.

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The wave is moving very quickly (20-25mph) to the west and should gain more latitude in the coming days. As it does so, there’s a decent chance it becomes the next tropical depression or storm. In fact, many of the models and their ensemble members develop this wave into a tropical storm in the Caribbean later next week once it moves beyond the Lesser Antilles. The National Hurricane Center is giving the wave only a 10% chance of development by Monday evening, but a 70% chance of development by Thursday night.

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Since the potential movement into the Caribbean is still 5-7 days out, there remains plenty of uncertainty for this wave’s future, including how close it gets to certain islands or even South America. However, if it does emerge unscathed in the Caribbean, this is a dangerous spot for it to be. Sea surface temperatures are running 1°-2°C above average and there shouldn’t be much dry air around. We’ll continue to monitor this potential in the coming days.

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Karl Now a Depression; Lisa Still Disorganized

Karl became more disorganized early Wednesday morning, officially downgraded to a tropical depression for the 5am advisory. As of 5pm, the storm was located about 800 miles SSE of Bermuda, with maximum sustained winds of 35mph and minimum central pressure of 1007mb. It was moving to the NW at 12mph, but it is expected to turn more to the north and eventually the northeast over the coming days. The official track from the NHC has it sliding just SE of Bermuda over the weekend. However, it will be close enough that interests in the area should pay attention to future forecast updates.

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It has been struggling for days with wind shear associated with an upper level low. That wind shear will slacken a bit over the coming days but will still remain somewhat hostile for strengthening. Nonetheless, with water temperatures above average the storm is still expected to intensify and is forecasted to become the season’s 5th hurricane just east of Bermuda this weekend.

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Meanwhile, to the east of Karl is weak Tropical Storm Lisa. Lisa is about 600 miles WNW of the Cabo Verde Islands and is moving to the NW at 7mph. As of 5pm Wednesday, maximum sustained winds were 45mph and minimum central pressure was 1004mb. The storm has also been struggling with strong upper level winds and vertical wind shear of 15-20kts. That shear is expected to increase in the next day or so, and therefore the forecast is not promising for Lisa’s prospects. The track turns Lisa quickly to the north and the forecasted intensity never climbs above where it’s at right now. It’s no threat to land and should become a remnant low over the open Atlantic waters later this weekend.

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Tropical Depression 13 Forms Near Africa; Karl May Pass Close to Bermuda This Weekend

Tropical Depression 13 forms Monday just west of the Cabo Verde Islands. It is likely to become the 13th named storm of the 2016 Atlantic season by Tuesday. While future Tropical Storm Lisa will gradually strengthen through mid-week it should stay shy of hurricane strength. It will weaken late week and over the weekend due to a batch of dry African air, increased upper level winds, and slightly cooler waters. It is no threat to land and will stay over the open Atlantic.

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As mentioned above future Tropical Storm Lisa will encounter some dry Saharan air later this week. That is indicated by the yellow and orange on the graphic below. This is courtesy the University of Wisconsin and NOAA.

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Also in the Atlantic is a sub par Tropical Storm Karl. Karl has battled strong wind shear for days but wind shear is dropping and all signs point to a strengthening tropical storm this work week. Karl is likely to become the 5th hurricane of the 2016 Atlantic season by Friday. The question remains how close will it pass to Bermuda Friday or Saturday under the influence of an approaching trough. The official forecast from the NHC is just east of the island but it will be a close call.

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Julia lost tropical characteristics Sunday night but the remnant low and a frontal boundary drench parts of the Carolinas and Mid Atlantic Monday. This is welcomed soaking rain as parts of this region are in a big rain deficit.

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Not Much Change with Julia and Karl

Julia remained a tropical depression on Sunday evening about 110 miles SSE of Myrtle Beach, with maximum sustained winds of 30mph. The storm continues to lack convection near the center and buoy reports have been unimpressive. However, the storm does have a decent low level swirl evident on satellite. In addition, wind shear, which has been hostile for the storm, is expected to drop Sunday night into Monday. This, combined with the proximity of the extremely warm Gulf Stream waters, may allow for a brief re-strengthening of Julia on Monday. By Monday night, conditions are expected to once again become unfavorable for Julia and should allow for it to weaken. The track forecast brings Julia (or its remnants) inland by Tuesday.

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Meanwhile, Tropical Storm Karl continues to churn in the central Atlantic. Environmental conditions are expected to become slightly more conducive to strengthening over the coming days, and so the official intensity forecast is fairly conservative for the storm. By the middle of the week, it is expected to become the 5th hurricane of the season as it passes well north of the Greater Antilles islands. A trough approaching the East Coast around this time should allow for the storm to curve to the north and head toward Bermuda. Interests in this area should pay close attention.

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The European model in particular brings a strong tropical storm or hurricane near Bermuda by next weekend.

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East of Karl is Invest 96L. The NHC is giving this cluster of showers and storms a 50% chance of development by Tuesday evening, but a high (80%) chance for development by late week. Either way, the models have consistently been immediately curving whatever system may form to the north of where Karl is currently located and therefore no long term threat to land.

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Busy Weekend in the Atlantic; Watching Pesky Julia, Karl & Invest 96L Near Africa

It’s been a busy week in the Atlantic Basin with the formation of Julia and Karl. On Saturday we’ve added an African disturbance to an area we are watching. Pesky stationary Julia hangs on to tropical depression status at 11 AM  southeast of the Carolinas. Despite high northwest wind shear there is enough convection east of its center to maintain tropical characteristics. Julia is likely to become a remnant low by Saturday evening but the area of low pressure will meander for a few more days. Besides an increased risk of rip currents and a spotty sprinkle near the coast it has little impact to South and North Carolina.

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Further east in the Atlantic is Tropical Storm Karl. It maintains intensity as a weak tropical storm Saturday. At 11 AM max sustained winds are at 45 mph. Until Karl pulls away from a nearby upper-level low hostile upper level winds keep the named storm from gaining much strength. By early and especially mid work week conditions favor gradual strengthening over warmer Atlantic waters. Most models are on board with a category 1 hurricane by mid-week and so is the NHC. Karl is likely to become the 5th hurricane of the 2016 Atlantic season. Karl will pass north of the eastern Caribbean Wednesday and Thursday.

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Karl may threaten Bermuda in about a week but models keep the future hurricane well east of the U.S.. Karl could enhance the risk for rip currents and bring swells to east coast beaches next weekend.

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A broad area of low pressure churns between the Cabo Verde Islands and Africa Saturday. While there is dry air west of Invest 96L  it is not extensive. Gradual organization is expected with light to moderate wind shear overhead. There is a high chance it becomes our next named Atlantic storm, Lisa, over the next 5 days. While Invest 96L will bring squalls to the Cabo Verde Islands beyond that models are on board with a west/northwest track over the open Atlantic.

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