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Hurricane JOAQUIN Forecast Discussion Number 29

2015-10-04 23:04:48| National Hurricane Center (Atlantic)

Issued at 500 PM AST SUN OCT 04 2015 000 WTNT41 KNHC 042104 TCDAT1 HURRICANE JOAQUIN DISCUSSION NUMBER 29 NWS NATIONAL HURRICANE CENTER MIAMI FL AL112015 500 PM AST SUN OCT 04 2015 The satellite cloud pattern of Joaquin, especially the inner-core convection, has continued to erode during the past several hours. The Bermuda radar also indicates a very ragged-looking banded eye pattern. The initial intensity has been decreased to 85 kt for this advisory based on some dropsonde data from a WB-57 research aircraft that is part of the NASA Tropical Cyclone Intensity Experiment. Joaquin is moving to the north-northeast at 015/12 kt. There is no significant change to the previous forecast track or reasoning. Joaquin is expected to move toward the north-northeast tonight and and turn toward the northeast on Monday as the cyclone moves around the western periphery of a ridge located to its east. By days 2-5, the hurricane should accelerate to the east-northeast as the cyclone moves into the strong mid-latitude westerlies. The new NHC track forecast is essentially just an update of the previous advisory track, and lies down the middle of the tightly packed track model guidance envelope. Joaquin should continue to steadily weaken during the next 48 hours or so, followed by transition to an extratropical cyclone on days 3-5 as the cyclone moves over the cold waters of the far north Atlantic where the vertical shear is forecast to be 45-50 kt. The intensity forecast is similar to the previous advisory and the consensus model IVCN through 48 hours, and is based on guidance from the Ocean Prediction Center for days 3-5 when the cyclone is forecast to be an extratropical low. FORECAST POSITIONS AND MAX WINDS INIT 04/2100Z 32.2N 66.4W 85 KT 100 MPH 12H 05/0600Z 33.8N 65.8W 80 KT 90 MPH 24H 05/1800Z 35.6N 64.5W 75 KT 85 MPH 36H 06/0600Z 37.3N 61.9W 70 KT 80 MPH 48H 06/1800Z 39.2N 56.9W 65 KT 75 MPH 72H 07/1800Z 42.5N 42.3W 60 KT 70 MPH...POST-TROP/EXTRATROP 96H 08/1800Z 46.1N 27.0W 55 KT 65 MPH...POST-TROP/EXTRATROP 120H 09/1800Z 49.7N 18.0W 55 KT 65 MPH...POST-TROP/EXTRATROP $$ Forecaster Stewart

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Hurricane JOAQUIN Forecast Discussion Number 28

2015-10-04 16:52:49| National Hurricane Center (Atlantic)

Issued at 1100 AM AST SUN OCT 04 2015 000 WTNT41 KNHC 041452 TCDAT1 HURRICANE JOAQUIN DISCUSSION NUMBER 28 NWS NATIONAL HURRICANE CENTER MIAMI FL AL112015 1100 AM AST SUN OCT 04 2015 The overall cloud pattern of Joaquin has changed little since the previous advisory. An Air Force Reserve Unit reconnaissance aircraft has reported peak 700-mb flight-level winds of 107 kt and SFMR surface wind values of 90 kt during its mission so far this morning, so the initial intensity has been decreased to 95 kt for this advisory. A ragged eye feature is just becoming apparent on the Bermuda radar, with strong inner-core rain bands currently located less than 50 nmi southwest of the island. Recon center fixes indicate that Joaquin has made the expected turn toward the north-northeast, and is now moving 030/15 kt. Joaquin is forecast to move around the western portion of a modest mid-level ridge to its east and ahead of an eastward-moving deep-layer low located over the southeastern United States. This is expected to result in the hurricane moving toward the north-northeast today and tonight, followed by a turn toward the northeast on Monday. On the short term forecast track, the center of Joaquin is expected to pass about 60 nmi west and northwest of Bermuda during the next 12-24 hours. By days 2-5, Joaquin is forecast to accelerate to the east-northeast as the cyclone gets caught up in the fast mid-latitude westerlies. The new NHC track forecast is essentially just an update of the previous advisory track, albeit slightly slower, and lies down the middle of the tightly packed track model guidance. Excluding a slight respite this afternoon, the vertical wind shear is forecast to increase during the next two days, with the mid-level environment expected to dry out with humidity values decreasing to around 50 percent. These less favorable conditions should result in gradual weakening for the next 48 hours or so, followed by more significant weakening on days 3-5 when Joaquin is expected to become an extratropical cyclone over the north Atlantic where SSTs are 20C-24C and vertical shear is forecast to be 45-50 kt. Extratropical transition is forecast to occur by 96 hours, but it is possible that it could sooner by around 72 hours as per guidance from the SHIPS and LGEM statistical-dynamical models, and the EMCWF model. The intensity forecast is similar to the previous advisory and the consensus model IVCN through 72 hours, and is based on guidance from the Ocean Prediction Center at 96 h and 120 h when the cyclone is expected to be an extratropical low. FORECAST POSITIONS AND MAX WINDS INIT 04/1500Z 31.0N 66.8W 95 KT 110 MPH 12H 05/0000Z 32.8N 65.9W 85 KT 100 MPH 24H 05/1200Z 34.8N 64.8W 80 KT 90 MPH 36H 06/0000Z 36.6N 62.7W 80 KT 90 MPH 48H 06/1200Z 38.4N 58.5W 75 KT 85 MPH 72H 07/1200Z 42.3N 45.5W 60 KT 70 MPH 96H 08/1200Z 46.4N 29.9W 55 KT 65 MPH...POST-TROP/EXTRATROP 120H 09/1200Z 51.4N 19.7W 55 KT 65 MPH...POST-TROP/EXTRATROP $$ Forecaster Stewart

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Hurricane JOAQUIN Forecast Discussion Number 27

2015-10-04 10:43:45| National Hurricane Center (Atlantic)

Issued at 500 AM AST SUN OCT 04 2015 000 WTNT41 KNHC 040843 TCDAT1 HURRICANE JOAQUIN DISCUSSION NUMBER 27 NWS NATIONAL HURRICANE CENTER MIAMI FL AL112015 500 AM AST SUN OCT 04 2015 The cloud pattern of Joaquin has continued to gradually deteriorate overnight with most of the deep convection now located over the eastern and southeastern portions of the circulation. The earlier reconnaissance aircraft mission reported peak 700-mb flight-level winds of 125 kt, and SFMR surface winds of 94 kt during its last pass through the southeastern portion of eyewall just before 0500 UTC. Dropsonde and SFMR data suggest that the flight-level winds are not mixing down as efficiently as before, and the initial intensity is lowered to 105 kt, which is a blend of the various reconnaissance wind data. Another Air Force Reserve Hurricane Hunter aircraft is currently en route to the storm and should provide a better assessment of Joaquin's intensity this morning. Recent center fixes indicate that the motion of Joaquin has started to bend toward the north-northeast, but the longer term motion is still northeastward or 040/17 kt. The hurricane should turn north-northeastward this morning, and pass near Bermuda this afternoon as it moves between a large mid- to upper-level low to its west and a mid-level ridge over the central Atlantic. After passing the Bermuda Joaquin is expected to turn northeastward, then east-northeastward after 48 hours when it reaches the mid-latitude westerlies. The updated NHC track is similar to the previous advisory and it remains near the center of the tightly cluster guidance models. Moderate to strong southwesterly shear is expected to cause some weakening during the next 12 to 24 hours, but Joaquin is forecast to remain a strong hurricane while it passes near or over Bermuda later today. Gradual weakening should continue after 24 hours, as the hurricane encounters cooler waters and remains within an environment of moderate shear. Joaquin is expected to become an extratropical cyclone over the North Atlantic in a little more than 72 hours. The official intensity forecast is close to the model consensus through 72 hours, and is based on guidance from the Ocean Prediction Center at 96 and 120 h when the cyclone will be post-tropical. FORECAST POSITIONS AND MAX WINDS INIT 04/0900Z 29.7N 67.7W 105 KT 120 MPH 12H 04/1800Z 31.6N 66.4W 90 KT 105 MPH 24H 05/0600Z 33.7N 65.5W 85 KT 100 MPH 36H 05/1800Z 35.5N 64.1W 80 KT 90 MPH 48H 06/0600Z 37.6N 61.0W 75 KT 85 MPH 72H 07/0600Z 41.8N 49.0W 65 KT 75 MPH 96H 08/0600Z 45.0N 33.0W 60 KT 70 MPH...POST-TROP/EXTRATROP 120H 09/0600Z 50.0N 21.0W 55 KT 65 MPH...POST-TROP/EXTRATROP $$ Forecaster Brown

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Hurricane JOAQUIN Forecast Discussion Number 26

2015-10-04 04:52:42| National Hurricane Center (Atlantic)

Issued at 1100 PM AST SAT OCT 03 2015 000 WTNT41 KNHC 040252 TCDAT1 HURRICANE JOAQUIN DISCUSSION NUMBER 26 NWS NATIONAL HURRICANE CENTER MIAMI FL AL112015 1100 PM AST SAT OCT 03 2015 While the cloud pattern has deteriorated a little this evening, reports from an Air Force Reserve Hurricane Hunter aircraft indicate that Joaquin is still a Category 4 hurricane. The aircraft reported 700-mb flight-level winds of 131 kt southeast of the center along with a central pressure near 944 mb. Surface wind estimates from the Stepped Frequency Microwave Radiometer were as high as 126 kt, but it is uncertain how reliable these are. Based mainly on the flight-level winds, the initial intensity is decreased to 115 kt. The aircraft also reports that the size of the 50 kt and 64 kt wind radii have expanded in the southeastern quadrant. Joaquin has moved a little to the right for the past several hours and the initial motion is now 050/17. Water vapor imagery shows a mid- to upper-level low near 34N 71W and a mid- to upper-level ridge east of 60W between 25N and 40N. Joaquin is expected to turn north-northeastward between these features during the next 12 hours, with this motion continuing through about 48 hours. After that time, the tropical cyclone is expected to recurve northeastward into the westerlies and accelerate. The forecast track, which has been shifted about 30 n mi eastward from the previous track, lies near the center of the tightly clustered track guidance models. The intensity guidance is in good agreement that Joaquin should weaken during the forecast period as it encounters episodes of moderate to strong vertical wind shear. However, it is likely to be a Category 2 hurricane in 24-36 hours at the time of closest approach to Bermuda. Extratropical transition should begin around 72 hours and be complete by 96 hours, with the winds decreasing below hurricane force during the transition. The new intensity forecast is an update of the previous forecast and lies near the upper edge of the intensity guidance. The combination of the shift in the forecast track and the expansion of the hurricane-force winds requires a hurricane warning for Bermuda at this time. FORECAST POSITIONS AND MAX WINDS INIT 04/0300Z 28.0N 68.9W 115 KT 130 MPH 12H 04/1200Z 29.9N 67.3W 105 KT 120 MPH 24H 05/0000Z 32.3N 66.2W 95 KT 110 MPH 36H 05/1200Z 34.3N 65.0W 85 KT 100 MPH 48H 06/0000Z 36.4N 62.7W 80 KT 90 MPH 72H 07/0000Z 41.0N 52.5W 70 KT 80 MPH 96H 08/0000Z 45.5N 36.5W 60 KT 70 MPH...POST-TROP/EXTRATROP 120H 09/0000Z 50.5N 22.0W 55 KT 65 MPH...POST-TROP/EXTRATROP $$ Forecaster Beven

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Hurricane JOAQUIN Forecast Discussion Number 25

2015-10-03 22:32:10| National Hurricane Center (Atlantic)

Issued at 500 PM EDT SAT OCT 03 2015 000 WTNT41 KNHC 032032 TCDAT1 HURRICANE JOAQUIN DISCUSSION NUMBER 25 NWS NATIONAL HURRICANE CENTER MIAMI FL AL112015 500 PM EDT SAT OCT 03 2015 The cloud pattern is not as impressive as it was earlier today, but the eye continues to be distinct. Both objective and subjective T-numbers are decreasing slightly, and on this basis, the initial intensity has been set at 130 kt. Another plane will investigate Joaquin in a few hours. Despite the observed intensification this morning, the NHC forecast still calls for gradual weakening due to increasing shear and cooler waters. Joaquin is forecast to become a strong extratropical cyclone by the end of the forecast period. Earlier reconnaissance data and current satellite fixes indicate that Joaquin is moving toward the northeast or 045 degrees at 15 kt. The hurricane continues to be steered by the flow between an eastward-moving trough over southeastern United States and a weakening subtropical ridge over the western Atlantic. Joaquin is forecast to turn more to the north-northeast as the trough swings eastward. Then, in about 3 days, the hurricane will be fully embedded in the mid-latitude flow and will turn to the northeast with an increase in forward speed. The NHC forecast is very similar to the previous one, primarily during the first 24 to 36 hours, and is on top of the multi-model consensus and the consensus of the ECMWF and the GFS models. Although the confidence in the track forecast is quite high due to the good model agreement, a small deviation to the east of the forecast track would bring the core of the hurricane with stronger winds to Bermuda. FORECAST POSITIONS AND MAX WINDS INIT 03/2100Z 27.0N 70.5W 130 KT 150 MPH 12H 04/0600Z 29.0N 68.7W 125 KT 145 MPH 24H 04/1800Z 31.5N 67.0W 110 KT 125 MPH 36H 05/0600Z 33.7N 66.0W 95 KT 110 MPH 48H 05/1800Z 36.0N 64.0W 80 KT 90 MPH 72H 06/1800Z 40.0N 56.0W 70 KT 80 MPH 96H 07/1800Z 45.0N 40.0W 60 KT 70 MPH...POST-TROP/EXTRATROP 120H 08/1800Z 50.0N 25.0W 60 KT 70 MPH...POST-TROP/EXTRATROP $$ Forecaster Avila

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