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Post-Tropical Cyclone MATTHEW Forecast Discussion Number 45
2016-10-09 10:55:11| National Hurricane Center (Atlantic)
Issued at 500 AM EDT SUN OCT 09 2016 000 WTNT44 KNHC 090855 TCDAT4 POST-TROPICAL CYCLONE MATTHEW DISCUSSION NUMBER 45 NWS NATIONAL HURRICANE CENTER MIAMI FL AL142016 500 AM EDT SUN OCT 09 2016 Satellite and radar imagery indicate that Matthew has become a post-tropical cyclone, with the closest deep convection now located more than 150 nmi north and northeast of the exposed low-level center. Despite this change in structure, surface observations across eastern North Carolina and an earlier ASCAT pass indicate that strong winds persist northwest through southwest of the center. An Air Force Reserve reconnaissance mission completed earlier this morning also indicated that hurricane-force winds were occuring southwest of the center, so the initial intensity is being maintained at 65 kt for this advisory. Surface observations indicate that a cold front should overtake Matthew's center shortly, resulting in extratropical transition. The global and regional models forecast Matthew to slowly weaken over the next 48 hours, and that trend has been followed in the official intensity forecast. In the 48-72 hour time period, Matthew's circulation is expected to dissipate within the frontal system. A combination of satellite and radar imagery, aircraft data, and coastal surface observations indicate that Matthew is moving 065/12 kt. Matthew is now fully embedded within the mid-latitude westerly flow, and this deep-layer steering pattern is expected to move the cyclone east-northeastward and away from the coast of North Carolina today. An eastward motion is expected by tonight and should continue until Matthew dissipates in 48 hours or so. The new NHC track forecast is a little north of the previous track and lies close to a blend of the ECMWF, UKMET, and GFS solutions. Recent observations and the forecast strength of the band of winds over the eastern North Carolina coastal area requires maintaining the Hurricane Watch. Strong winds in the Tidewater Region of Virginia are being handled by non-tropical wind warnings. KEY MESSAGES: 1. As Matthew's structure changes, the system's strongest winds continue to shift to the west side of the circulation. The winds are expected to increase significantly over the coastal areas of eastern North Carolina during the next several hours, and during the next 6 to 12 hours there is the possibility of near-hurricane force winds over the North Carolina Outer Banks, as well as the Pamlico and Albemarle Sounds. There is also an increased threat of storm surge in these areas. Please see the Prototype Storm Surge Watch/Warning Graphic for a depiction of the areas at risk. 2. Although Matthew has become a post-tropical cyclone, NHC will continue to issue its full suite of advisory and warning products as long as the system remains a significant threat to land areas. FORECAST POSITIONS AND MAX WINDS INIT 09/0900Z 34.9N 75.1W 65 KT 75 MPH...POST-TROPICAL 12H 09/1800Z 35.2N 73.0W 60 KT 70 MPH...POST-TROP/EXTRATROP 24H 10/0600Z 35.4N 70.0W 50 KT 60 MPH...POST-TROP/EXTRATROP 36H 10/1800Z 35.9N 66.5W 40 KT 45 MPH...POST-TROP/EXTRATROP 48H 11/0600Z 36.5N 62.5W 35 KT 40 MPH...POST-TROP/EXTRATROP 72H 12/0600Z...DISSIPATED $$ Forecaster Stewart
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Hurricane MATTHEW Forecast Discussion Number 44
2016-10-09 04:49:11| National Hurricane Center (Atlantic)
Issued at 1100 PM EDT SAT OCT 08 2016 000 WTNT44 KNHC 090249 TCDAT4 HURRICANE MATTHEW DISCUSSION NUMBER 44 NWS NATIONAL HURRICANE CENTER MIAMI FL AL142016 1100 PM EDT SAT OCT 08 2016 A combination of satellite imagery, aircraft data, and coastal surface and radar observations indicate that Matthew is undergoing extratropical transition, and there is barely enough convection near the center to keep the system classified as a hurricane. However, SFMR data from an Air Force show hurricane-force winds to the southwest of the center, and based on this and the marginal convection Matthew remains a hurricane for this advisory. The cyclone is likely to become post-tropical in 12 hours or less and become an extratropical frontal low by 24 hours. As this happens though, a band of strong winds forming in the western semicircle near eastern North Carolina and the adjacent waters should keep the intensity near 65 kt for the next 12 hours or so. After that, Matthew should weaken and become absorbed within the frontal system between 48-72 hours. The new intensity forecast is mostly an update of the previous forecast. The initial motion is now 070/12. Matthew is embedded in the mid-latitude westerly flow and this steering pattern is forecast to move the system east-northeastward and then eastward until dissipation. The new forecast track is a little south of the previous track for the first 12 hours and a little north of it after that time. The forecast strength of the band of winds over the eastern North Carolina coastal area requires a northward extension of the hurricane watch. Strong winds in the Tidewater Region of Virginia are being handled by non-tropical wind warnings. KEY MESSAGES: 1. As Matthew's structure changes, the system's strongest winds are shifting to the west side of the circulation. The winds are expected to increase significantly over the coastal areas of eastern North Carolina during the next several hours, and during the next 12 hours there is the possibility of near-hurricane force winds over the North Carolina Outer Banks, as well as the Pamlico and Albemarle Sounds. There is also an increased threat of storm surge in these areas. Please see the Prototype Storm Surge Watch/Warning Graphic for a depiction of the areas at risk. FORECAST POSITIONS AND MAX WINDS INIT 09/0300Z 34.1N 76.5W 65 KT 75 MPH 12H 09/1200Z 34.6N 74.7W 65 KT 75 MPH...POST-TROPICAL 24H 10/0000Z 34.4N 72.0W 55 KT 65 MPH...POST-TROP/EXTRATROP 36H 10/1200Z 33.8N 70.0W 45 KT 50 MPH...POST-TROP/EXTRATROP 48H 11/0000Z 33.0N 69.0W 35 KT 40 MPH...POST-TROP/EXTRATROP 72H 12/0000Z...DISSIPATED $$ Forecaster Beven
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Tropical Storm NICOLE Forecast Discussion Number 20
2016-10-09 04:40:08| National Hurricane Center (Atlantic)
Issued at 1100 PM AST SAT OCT 08 2016 000 WTNT45 KNHC 090240 TCDAT5 TROPICAL STORM NICOLE DISCUSSION NUMBER 20 NWS NATIONAL HURRICANE CENTER MIAMI FL AL152016 1100 PM AST SAT OCT 08 2016 Strong convection continues to fire near the center of Nicole, although microwave data still suggest the center is on the northern edge of the convection. Dvorak estimates range from 37 to 55 kt for this advisory, so the initial wind speed is held at 45 kt. Northerly wind shear is forecast to continue for the next couple of days, perhaps at a slightly weaker value than the current 35 kt. By about Tuesday, almost all of the global models drop the shear significantly, which will probably allow Nicole to restrengthen since it will be moving over very warm waters. The guidance is more insistent on this cycle that Nicole will become a hurricane again by day 4, and the official forecast goes with this scenario. The initial motion is 180/4, a little to the left of earlier. Nicole should meander for a day or so before a ridge to the east builds, causing the tropical cyclone to move slowly northward until about day 2. Some interaction with the remnants of Matthew are likely to steer Nicole to the northwest for about a day until Nicole turns back to the north and northeast in increasing southwesterly flow. Models are in good agreement on this unusual Atlantic track scenario, so very little change was made to the previous NHC forecast. FORECAST POSITIONS AND MAX WINDS INIT 09/0300Z 24.4N 65.7W 45 KT 50 MPH 12H 09/1200Z 24.0N 65.7W 50 KT 60 MPH 24H 10/0000Z 24.4N 65.7W 50 KT 60 MPH 36H 10/1200Z 25.2N 65.7W 50 KT 60 MPH 48H 11/0000Z 26.3N 65.7W 50 KT 60 MPH 72H 12/0000Z 28.0N 66.5W 55 KT 65 MPH 96H 13/0000Z 30.5N 66.0W 65 KT 75 MPH 120H 14/0000Z 34.0N 62.0W 65 KT 75 MPH $$ Forecaster Blake
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Hurricane MATTHEW Forecast Discussion Number 43
2016-10-08 22:55:06| National Hurricane Center (Atlantic)
Issued at 500 PM EDT SAT OCT 08 2016 000 WTNT44 KNHC 082055 TCDAT4 HURRICANE MATTHEW DISCUSSION NUMBER 43 NWS NATIONAL HURRICANE CENTER MIAMI FL AL142016 500 PM EDT SAT OCT 08 2016 Satellite images indicate that the cloud pattern associated with Hurricane Matthew is gradually losing tropical characteristics while it becomes embedded within a mid-latitude trough. The hurricane is accompanied by a very extensive area of intense rains mostly located north of the center. Recent data from an Air Force reconnaissance aircraft indicate that the winds are still 65 kt, and these winds are limited to a small area over water east of the center. The low-level circulation is becoming separated from the mid-level circulation due to strong shear. Most of the global models, primarily the GFS and the UKMET, forecast that Matthew will become entangled with a cold front, and the NHC forecast calls for Matthew to weaken and become absorbed within this frontal system within the next couple of days. Fixes from a reconnaissance plane indicate that Matthew is moving toward the east-northeast or 060 degrees at 10 kt while hugging the coast of South Carolina. During the next 12 hours or so, while the Matthew is hugging the US coast and taking on a more extratropical structure, the tropical-storm-force winds are expected to expand and strengthen in the western semicircle and continue to affect portions of the coast within the warning area. Since Matthew is already embedded in the mid-latitude westerly flow and the steering pattern is forecast to persist for the next day or two, the NHC forecast moves the cyclone eastward or east- southeastward until it becomes absorbed. KEY MESSAGES: 1. As Matthew's structure changes, the system's strongest winds will shift to the back side of the circulation. These winds will persist over land even after the center begins to move away from the coastline, and have also increased the threat of storm surge in portions of the North Carolina Outer Banks. Please see the Prototype Storm Surge Watch/Warning Graphic for a depiction of the areas at risk. FORECAST POSITIONS AND MAX WINDS INIT 08/2100Z 33.8N 78.2W 65 KT 75 MPH 12H 09/0600Z 34.5N 76.5W 60 KT 70 MPH 24H 09/1800Z 34.5N 74.0W 55 KT 65 MPH 36H 10/0600Z 34.0N 71.8W 45 KT 50 MPH...POST-TROP/EXTRATROP 48H 10/1800Z 33.0N 70.5W 35 KT 40 MPH...POST-TROP/EXTRATROP 72H 11/1800Z...ABSORBED $$ Forecaster Avila
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Tropical Storm NICOLE Forecast Discussion Number 19
2016-10-08 22:38:40| National Hurricane Center (Atlantic)
Issued at 500 PM AST SAT OCT 08 2016 000 WTNT45 KNHC 082038 TCDAT5 TROPICAL STORM NICOLE DISCUSSION NUMBER 19 NWS NATIONAL HURRICANE CENTER MIAMI FL AL152016 500 PM AST SAT OCT 08 2016 A tremendous burst of deep convection has developed this afternoon, partially covering and southeast of Nicole's low-level center. A late-morning ASCAT pass indicated 41-kt uncontaminated wind vectors east of the center, and given the recent burst of convection, the initial intensity estimate is increased to 45 kt. This is in agreement with latest Dvorak intensity estimate from TAFB. The initial motion estimate is 195/05. A blocking ridge north of Nicole should keep Nicole moving on this general course for another 12 hours or so, though its forward speed should begin to decrease. As the ridge shifts to the northeast of Nicole by late tomorrow, the cyclone should reverse its motion 180 degrees and begin moving north-northwestward. The global models continue to show a binary interaction between Matthew or its remnants in 2 to 3 days, but the ECMWF no longer is drawing Nicole as far west as it was previously. A turn toward the north and then northeast is expected by days 4 and 5. The track guidance has come into much better agreement and has resulted in a more confident track forecast this cycle. The new forecast track is slower than the previous one and shifted a bit to the east but not as far east as the model consensus aids. As high as the vertical shear has been over Nicole, it is puzzling that no additional weakening has taken place. At a minimum, the strong northerly shear should preclude significant intensification in the short term. A nominal decrease in the shear over the next couple of days could allow Nicole to re-intensify, perhaps more than indicated in this forecast. A more substantial reduction of the shear is forecast by 72 hours, and a re-intensification of the cyclone seems more likely than it did earlier on days 3 and 4, similar to what the global models have been showing. By the end of the forecast period, increasing shear could cause the intensity to level off. The new intensity forecast is higher than the previous one and is generally near the multi-model consensus. It continues to be of low confidence after 48 hours. FORECAST POSITIONS AND MAX WINDS INIT 08/2100Z 24.8N 65.8W 45 KT 50 MPH 12H 09/0600Z 24.2N 65.9W 50 KT 60 MPH 24H 09/1800Z 24.2N 65.9W 50 KT 60 MPH 36H 10/0600Z 24.7N 65.9W 50 KT 60 MPH 48H 10/1800Z 25.7N 65.9W 50 KT 60 MPH 72H 11/1800Z 27.5N 66.1W 55 KT 65 MPH 96H 12/1800Z 30.4N 65.9W 55 KT 65 MPH 120H 13/1800Z 33.9N 62.5W 55 KT 65 MPH $$ Forecaster Kimberlain
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