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Hurricane MATTHEW Forecast Discussion Number 24

2016-10-04 04:58:10| National Hurricane Center (Atlantic)

Issued at 1100 PM EDT MON OCT 03 2016 000 WTNT44 KNHC 040257 TCDAT4 HURRICANE MATTHEW DISCUSSION NUMBER 24 NWS NATIONAL HURRICANE CENTER MIAMI FL AL142016 1100 PM EDT MON OCT 03 2016 An Air Force Reserve Hurricane Hunter aircraft this evening measured two peak SFMR winds of 125 kt in the northeastern eyewall, along with a peak flight-level wind of 129 kt. The lowest pressure measured by a dropsonde has been 934 mb, down 6 mb since the previous flight. Based on these data, the initial intensity has been increased to 125 kt. Matthew continues to move a little east of due north, or 010/07 kt. There is no change to the previous short-term track forecast reasoning. Matthew is expected to move northward around the western periphery of a strong deep-layer ridge for the next 24 hours, followed by a north-northwestward motion at 36 and 48 hours. That portion of the new forecast track is essentially the same as the previous advisory, bringing Matthew over the southwestern peninsula of Haiti tonight and near or over eastern Cuba on Tuesday. Beyond 48 hours, the GFS has again trended westward, and now lies closer to the UKMET model track. This change might be related to the mid-/upper-level trough currently located over the eastern Gulf of Mexico, which is now forecast to split, with the northern portion lifting out to the northeast and dissipating while the southern portion cuts of into a low pressure system that drops southward over the northwestern Caribbean Sea by 36-48 hours. The new track forecast has again been shifted westward closer to Florida, and lies near a blend of the 18Z GFS and 12Z ECMWF model solutions. Only slight weakening is expected during the next couple of days due to Matthew interacting with the land masses of western Haiti and eastern Cuba. After the hurricane emerges over the Atlantic waters between Cuba and the Bahamas, low vertical wind shear and warm SSTs of near 30C should help Matthew to recover some before southwesterly wind shear increases by 96-120 hours and induces a faster rate of weakening. The new NHC intensity forecast is basically identical to the previous advisory, and closely follows the consensus model IVCN. KEY MESSAGES: 1. Matthew is likely to produce devastating impacts from storm surge, extreme winds, heavy rains, flash floods, and/or mudslides in portions of the watch and warning areas in Haiti, Cuba, and the Bahamas. Please consult statements from the meteorological services and other government officials in those countries. 2. Direct hurricane impacts are possible in Florida later this week. Tropical storm and/or hurricane watches are likely tomorrow morning for portions of the Florida peninsula and the Florida Keys. 3. Tropical storm or hurricane conditions could affect portions of Georgia, South Carolina, and North Carolina later this week or this weekend, even if the center of Matthew remains offshore. It is too soon to specify what, if any, direct impacts Matthew might have on the remainder of the U.S. east coast farther north. At a minimum, very dangerous beach and boating conditions are likely along much of the U.S. east coast later this week and weekend. FORECAST POSITIONS AND MAX WINDS INIT 04/0300Z 16.9N 74.6W 125 KT 145 MPH 12H 04/1200Z 18.3N 74.5W 125 KT 145 MPH 24H 05/0000Z 20.0N 74.4W 120 KT 140 MPH 36H 05/1200Z 21.8N 75.2W 115 KT 130 MPH 48H 06/0000Z 23.4N 76.2W 110 KT 125 MPH 72H 07/0000Z 26.6N 78.7W 105 KT 120 MPH 96H 08/0000Z 30.0N 79.6W 100 KT 115 MPH 120H 09/0000Z 33.3N 77.6W 90 KT 105 MPH $$ Forecaster Stewart

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Hurricane MATTHEW Forecast Discussion Number 23

2016-10-03 22:36:26| National Hurricane Center (Atlantic)

Issued at 500 PM EDT MON OCT 03 2016 000 WTNT44 KNHC 032035 TCDAT4 HURRICANE MATTHEW DISCUSSION NUMBER 23 NWS NATIONAL HURRICANE CENTER MIAMI FL AL142016 500 PM EDT MON OCT 03 2016 Matthew's structure has not changed much today. The most recent Air Force Hurricane Hunter aircraft mission found peak SFMR winds of 124 kt on their last pass through the northeastern eyewall, and a peak flight-level wind of 118 kt. Based on a blend of these data, the initial intensity is held at 120 kt for this advisory. The central pressure has been steady around 940 mb for much of the day. Matthew's satellite presentation remains impressive, with a 15 n mi wide eye surrounded by convective tops of -80C or colder and excellent outflow, especially poleward. Little change in intensity is expected during the next couple of days, with the exception of some possible weakening due to land interaction with Haiti and eastern Cuba. However, there could be fluctuations in intensity due to eyewall cycles that are difficult to predict. While Matthew is expected to be a little weaker once it moves into the Bahamas as the shear increases somewhat and the ocean heat content decreases a little, it is expected to remain a dangerous hurricane through the next 5 days, as shown by the global models. The new NHC intensity forecast is close to or a little above the latest intensity consensus through 4 days and is closest to the GFDL model at day 5. Matthew is now moving a little to the east of due north, or 010/06. The short term track forecast reasoning remains unchanged, as the hurricane will move generally northward for the next 24 to 36 hours around the western periphery of the Atlantic subtropical ridge. The new NHC track forecast during this time has been nudged eastward toward the latest multi-model consensus aids, and continues to show the core of the dangerous hurricane moving near or over the southwestern peninsula of Haiti tonight and near or over eastern Cuba on Tuesday. At 48 hours and beyond, the GFS has trended sharply westward, and now is in agreement with the UKMET and ECMWF in showing the western extent of the Atlantic subtropical ridge nosing north of Matthew across the Carolinas in 3-4 days. This results in Matthew taking a more northwesterly track across the Bahamas, and closer to the Florida peninsula during this time. The UKMET is farthest west, with a track over the east coast of Florida and into South Carolina in 4-5 days. The GFS, ECMWF, and the GFDL model are a little farther east and remain close to but offshore of Florida. The GFDL and GFS are close to southeastern North Carolina by day 5, while the ECMWF is slower. The new NHC track forecast has been adjusted significantly westward at days 3-5, and now lies near the middle of the guidance envelope and close to the ECMWF/GFS blend. While there remains significant uncertainty in the track of Matthew in the long range, the threat to Florida and the southeastern U.S. coast has increased. KEY MESSAGES: 1. Matthew is likely to produce devastating impacts from storm surge, extreme winds, heavy rains, flash floods, and/or mudslides in portions of the watch and warning areas in Haiti, Cuba, and the Bahamas. Please consult statements from the meteorological services and other government officials in those countries. 2. Direct hurricane impacts are possible in Florida later this week. Tropical storm and/or hurricane watches could be issued sometime tonight or early tomorrow for portions of the Florida peninsula and the Florida Keys. 3. Tropical storm or hurricane conditions could affect portions of Georgia, South Carolina, and North Carolina later this week or this weekend, even if the center of Matthew remains offshore. It is too soon to specify what, if any, direct impacts Matthew might have on the remainder of the U.S. east coast. At a minimum, very dangerous beach and boating conditions are likely along much of the U.S. east coast later this week and weekend. FORECAST POSITIONS AND MAX WINDS INIT 03/2100Z 16.3N 74.7W 120 KT 140 MPH 12H 04/0600Z 17.4N 74.6W 120 KT 140 MPH 24H 04/1800Z 19.2N 74.4W 120 KT 140 MPH 36H 05/0600Z 21.0N 74.7W 115 KT 130 MPH 48H 05/1800Z 22.8N 75.5W 110 KT 125 MPH 72H 06/1800Z 26.0N 78.0W 105 KT 120 MPH 96H 07/1800Z 29.5N 79.0W 100 KT 115 MPH 120H 08/1800Z 33.0N 78.0W 90 KT 105 MPH $$ Forecaster Brennan

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Hurricane MATTHEW Forecast Discussion Number 21

2016-10-03 10:52:01| National Hurricane Center (Atlantic)

Issued at 500 AM EDT MON OCT 03 2016 000 WTNT44 KNHC 030851 TCDAT4 HURRICANE MATTHEW DISCUSSION NUMBER 21 NWS NATIONAL HURRICANE CENTER MIAMI FL AL142016 500 AM EDT MON OCT 03 2016 The Air Force Reserve reconnaissance mission that ended shortly before 0600 UTC did not find flight-level or surface winds as high as reported during the previous flight yesterday afternoon. It is not clear from microwave imagery if the reduction in winds is the result of an eyewall replacement. There was no evidence of a double wind maximum in the aircraft data, but the crew reported that the eyewall was open to the southwest. Using a blend of the aircraft data and recent satellite intensity estimates, the initial intensity has been reduced to 115 kt for this advisory. The center of Matthew has recently passed over NOAA buoy 42058 in the central Caribbean Sea, which reported a minimum pressure of 943 mb and light winds around 0650 UTC. Satellite and aircraft fixes show that Matthew is moving northward or 360/5 kt. The hurricane is expected to move generally northward around the western periphery of a subtropical ridge over the west-central Atlantic during the next couple of days, and little change was needed to the NHC forecast through 48 hours. Once Matthew moves near the southeastern Bahamas on Wednesday, it is forecast to turn northwestward or north-northwestward in southeasterly flow between the ridge and a mid- to upper-level low/trough over the southeastern Gulf of Mexico and northwestern Caribbean Sea. The model guidance is in relatively good agreement through 72 hours, but begin to diverge by days 4 and 5. The UKMET which was previously the western outlier, has shifted eastward this cycle, and is now close to the GFS. The 0000 UTC ECMWF trended westward and that model is now along the western edge of the guidance envelope. The NHC track has been nudged westward at days 4 and 5, and lies close to the GFS and UKMET solutions. This is a bit west of the model consensus since the higher quality models are on that side of the guidance envelope. Matthew is forecast to remain in low shear and over warm water while it moves northward toward the Greater Antilles. Some restrengthening is possible, but fluctuations in intensity are likely due to eyewall cycles that are difficult to predict. Some weakening is forecast when the hurricane interacts with land in a couple of days, however Matthew is expected to remain a powerful hurricane throughout much of the forecast period. Although the official forecast continues to show a track east of Florida, it is still too soon to rule out possible hurricane impacts there. It is also too soon to know whether, or how, Matthew might affect the remainder of the United States east coast. FORECAST POSITIONS AND MAX WINDS INIT 03/0900Z 15.2N 74.9W 115 KT 130 MPH 12H 03/1800Z 16.2N 74.9W 115 KT 130 MPH 24H 04/0600Z 17.9N 74.7W 115 KT 130 MPH 36H 04/1800Z 19.7N 74.6W 115 KT 130 MPH 48H 05/0600Z 21.4N 74.8W 105 KT 120 MPH 72H 06/0600Z 24.6N 75.9W 105 KT 120 MPH 96H 07/0600Z 27.6N 76.9W 95 KT 110 MPH 120H 08/0600Z 30.8N 77.0W 90 KT 105 MPH $$ Forecaster Brown

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Hurricane MATTHEW Forecast Discussion Number 20

2016-10-03 04:58:05| National Hurricane Center (Atlantic)

Issued at 1100 PM EDT SUN OCT 02 2016 000 WTNT44 KNHC 030257 TCDAT4 HURRICANE MATTHEW DISCUSSION NUMBER 20 NWS NATIONAL HURRICANE CENTER MIAMI FL AL142016 1100 PM EDT SUN OCT 02 2016 Although an Air Force Reserve reconnaissance aircraft investigating Matthew this evening has yet to report flight-level or surface winds anywhere close to the 130-kt winds measured in the previous flight, recent aircraft data have indicated that the surface pressure and 700-mb height have both decreased since the previous flight. The eye has cleared out in infrared satellite imagery and cloud tops have cooled around the 8-12 nmi diameter eye. Given the lower central pressure of 943 mb, which corresponds to about 120 kt on the Dvorak pressure-wind relationship, the small eye, and recent NHC objective T-numbers of T6.3/123 kt to T6.5/127 kt, the initial intensity will remain at 125 kt for this advisory. Matthew has continued to meander and wobble over the past several hours, but the best estimate of the forward motion based on recent recon fixes is 360/04 kt. Although some erratic motion could still occur due to Matthew interacting with a large convective complex and mid-/upper-level vortex located about 150 nmi east of Matthew, the cyclone is expected to move in a general northward direction for the next 48 hours or so. After clearing the northeastern coast of Cuba, Matthew is expected to turn toward the north-northwest within southeasterly flow between the western periphery of a strong ridge located over the southwestern Atlantic and a weak mid- to upper-level trough currently located over the eastern Gulf of Mexico. The 12Z UKMET and 18Z GFS and GFS-ensemble mean models now show a weaker trough over the Gulf of Mexico on days 3-5 as a larger storm system currently located over the northwestern U.S. is forecast to not be as strong or as far south as previously expected. This has resulted in more downstream ridging in those models over the southeastern United States, and the model tracks of Matthew have responded by shifting westward. The new NHC track forecast has been shifted slightly to the west or left of the previous advisory track, mainly to account for the more westward initial position. However, the forecast track remains to the east of the UKMET, GFS, and GFS-ensemble mean models, and lies near the TVCX consensus model. Matthew is forecast to remain in a low vertical wind shear environment for the next 36-48 hours, with the shear reaching near zero values by 24 hours. This condition, along with the very favorable upper-level outflow pattern noted in water vapor imagery, should allow for the cyclone to at least maintain its current intensity, barring the eye making any direct interactions with Jamaica or Haiti. By 48 hours, however, land interaction with eastern Cuba should induce more significant weakening. The official intensity forecast remains near or above the latest model consensus. Although the official forecast continues to show a track east of Florida, it is still too soon to rule out possible hurricane impacts there. It is also too soon to know whether, or how, Matthew might affect the remainder of the United States east coast. FORECAST POSITIONS AND MAX WINDS INIT 03/0300Z 14.7N 75.0W 125 KT 145 MPH 12H 03/1200Z 15.7N 75.1W 125 KT 145 MPH 24H 04/0000Z 17.1N 75.0W 125 KT 145 MPH 36H 04/1200Z 18.8N 74.8W 120 KT 140 MPH 48H 05/0000Z 20.6N 74.9W 105 KT 120 MPH...INLAND 72H 06/0000Z 24.0N 75.6W 105 KT 120 MPH...OVER WATER 96H 07/0000Z 27.1N 76.6W 95 KT 110 MPH 120H 08/0000Z 30.1N 76.7W 90 KT 105 MPH $$ Forecaster Stewart

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Hurricane MATTHEW Forecast Discussion Number 19

2016-10-02 22:39:24| National Hurricane Center (Atlantic)

Issued at 500 PM EDT SUN OCT 02 2016 000 WTNT44 KNHC 022038 TCDAT4 HURRICANE MATTHEW DISCUSSION NUMBER 19 NWS NATIONAL HURRICANE CENTER MIAMI FL AL142016 500 PM EDT SUN OCT 02 2016 After temporarily losing some of its organization this morning, Matthew has become a little more impressive in its appearance. The eye, while not quite cleared out on visible imagery, has become more distinct during the day and the overall cloud pattern has become a bit more symmetric. Consistent with these changes, observations from the Air Force Hurricane Hunters indicated that some strengthening has taken place. The advisory intensity is set to 125 kt based on a blend of flight-level winds, SFMR-observed surface winds, and eyewall dropsonde data from the aircraft. Dynamical guidance indicates that the vertical shear over Matthew should remain low or at most moderate at least until the cyclone moves near the Bahamas, which would imply little decrease in intensity. However, interactions with land should cause some weakening during the next couple of days. Aside from that, some fluctuations in strength could occur due to eyewall replacements. The official intensity forecast is near or above the latest model consensus. Earlier today, the hurricane meandered westward for several hours, but recent aircraft and satellite fixes indicate that the motion is northwestward, albeit slowly, at around 4 kt. The track forecast reasoning is about the same as in the previous advisory package. Matthew is expected to turn northward and move along the western side of a mid-level high pressure area for the next several days. Later in the forecast period, a ridge building slightly to the north of the tropical cyclone could induce a turn to the left. In general, the track models have not shifted closer to the coast with the exception of the U.K. Met. Office global model, which is an outlier. The official track forecast is along essentially the same trajectory as the previous one, but is a little slower than before. This is slightly west of the latest multi-model consensus. Although the official forecast continues to show a track east of Florida, it is still too soon to rule out possible possible hurricane impacts there. It is also too soon to know whether, or how, Matthew might affect the remainder of the United States east coast. FORECAST POSITIONS AND MAX WINDS INIT 02/2100Z 14.6N 74.8W 125 KT 145 MPH 12H 03/0600Z 15.4N 74.9W 125 KT 145 MPH 24H 03/1800Z 16.7N 74.9W 125 KT 145 MPH 36H 04/0600Z 18.3N 74.7W 115 KT 130 MPH 48H 04/1800Z 20.1N 74.5W 110 KT 125 MPH...INLAND 72H 05/1800Z 23.6N 75.1W 100 KT 115 MPH 96H 06/1800Z 26.8N 76.1W 95 KT 110 MPH 120H 07/1800Z 30.0N 76.5W 90 KT 105 MPH $$ Forecaster Pasch

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