Home › discussion
 

Keywords :   


Tag: discussion

Tropical Storm IAN Forecast Discussion Number 7

2016-09-14 04:52:57| National Hurricane Center (Atlantic)

Issued at 1100 PM AST TUE SEP 13 2016 000 WTNT45 KNHC 140252 TCDAT5 TROPICAL STORM IAN DISCUSSION NUMBER 7 NWS NATIONAL HURRICANE CENTER MIAMI FL AL102016 1100 PM AST TUE SEP 13 2016 Ian's cloud pattern has changed little in organization since this afternoon. The low-level center remains patrially exposed to the south of a fan-shaped mass of deep convection. This structure is consistent with a deep-layer southwesterly vertical shear of nearly 40 kt associated with a mid- to upper-tropospheric cyclone to the west of the cyclone. A 0018Z ASCAT pass showed reliable surface winds near 45 kt well north of the center, which agrees with a TAFB satellite classifciation of T3.0. On this basis, the initial intensity is increased to 45 kt. The initial motion estimate has been nudged a little more to the right than earlier today and is now 345/11 kt. Ian should continue to move generally northward into a weakness in the subtropical ridge over the central Atlantic during the next 24 hours or so. A significant acceleration toward the northeast should occur in about 36 hours when a shortwave trough moving through Atlantic Canada approaches Ian. The NHC track forecast is adjusted to the right of the previous one, especially after 24 hours, and is in agreement with the the latest track consensus aids. The SHIPS output indicates that the shear should decrease, beginning in about 12 hours, roughly around the time that Ian becomes co-located with the upper low to its west. The shear is forecast to reach a relative minimum 24 hours later while the flow aloft gradually becomes more diffluent. This baroclinic forcing is expected to result in some intensification while Ian remains over warm waters, though the cyclone could possess attributes of both a tropical and an extratropical cyclone. Extratropical transition is indicated in 2 to 3 days, with absorption by a larger extratropical storm system over the North Atlantic likely around 72 hours. The NHC intensity forecast is about the same as the previous one and near the multi-model consensus. FORECAST POSITIONS AND MAX WINDS INIT 14/0300Z 27.6N 52.8W 45 KT 50 MPH 12H 14/1200Z 29.8N 53.2W 45 KT 50 MPH 24H 15/0000Z 32.3N 53.1W 50 KT 60 MPH 36H 15/1200Z 35.2N 51.3W 55 KT 65 MPH 48H 16/0000Z 39.4N 47.0W 55 KT 65 MPH 72H 17/0000Z 49.7N 33.7W 55 KT 65 MPH...POST-TROP/EXTRATROP 96H 18/0000Z...ABSORBED $$ Forecaster Kimberlain

Tags: number discussion storm ian

 

Hurricane ORLENE Forecast Discussion Number 13

2016-09-14 04:49:48| National Hurricane Center (East Pacific)

Issued at 800 PM PDT TUE SEP 13 2016 000 WTPZ41 KNHC 140249 TCDEP1 HURRICANE ORLENE DISCUSSION NUMBER 13 NWS NATIONAL HURRICANE CENTER MIAMI FL EP162016 800 PM PDT TUE SEP 13 2016 Microwave satellite imagery indicates that the inner-core convection of Orlene has steadily degraded during the past 6 hours, with the eyewall no longer closed. The eye briefly appeared in visible and infrared imagery around 0000Z, but is not evident in conventional satellite imagery. The initial remains at 75 kt based on consensus subjective satellite estimates of T4.5/77 kt from TAFB and SAB. The microwave and conventioanl satellite data indicate that Orlene is drifting northward or 360/01 kt. The cyclone is expected to remain nearly stationary overnight, embedded within a narrow break in the subtropical ridge. A slow westward motion is expected to begin by early Wednesday as a shortwave trough lifts out, allowing the ridge to build back in to the north of Orlene in 12-24 hours. After that time, the ridge is forecast to steadily stengthen, forcing the cyclone on a general westward direction at a much faster forward speed. The new forecast track is similar to the previous advisory track, and lies close to the consensus model TVCN and a beldn of the GFS and ECMWF model solutions. Although moderate southwesterly vertical wind shear currently affecting the cyclone is forecast to decrease to around 5 kt throughout the forecast period, the cyclone will also be moving over near 26 deg C SSTs and into a very dry and stable airmass. The result sould be a gradual erosion of the inner-core convection, causing the cyclone to slowly but steadily weaken. The new NHC intensity forecast is similr to the previous intensity forecast, and closley follows the SHIPS and LGEM intensity guidance, which is just a little above the intensity consensus model IVCN. FORECAST POSITIONS AND MAX WINDS INIT 14/0300Z 20.4N 118.6W 75 KT 85 MPH 12H 14/1200Z 20.4N 119.0W 65 KT 75 MPH 24H 15/0000Z 20.4N 120.0W 60 KT 70 MPH 36H 15/1200Z 20.2N 121.7W 50 KT 60 MPH 48H 16/0000Z 20.1N 123.9W 45 KT 50 MPH 72H 17/0000Z 19.9N 128.7W 40 KT 45 MPH 96H 18/0000Z 19.9N 133.4W 35 KT 40 MPH 120H 19/0000Z 20.8N 137.3W 30 KT 35 MPH $$ Forecaster Stewart

Tags: number discussion forecast hurricane

 
 

Tropical Storm JULIA Forecast Discussion Number 1

2016-09-14 04:27:40| National Hurricane Center (Atlantic)

Issued at 1100 PM EDT TUE SEP 13 2016 000 WTNT41 KNHC 140226 TCDAT1 TROPICAL STORM JULIA DISCUSSION NUMBER 1 NWS NATIONAL HURRICANE CENTER MIAMI FL AL112016 1100 PM EDT TUE SEP 13 2016 The area of low pressure that has been moving along the Florida east coast has managed to maintain persistent deep convection, accompanied by a small area of tropical-storm-force winds, close to the area of lowest pressure for well over 12 hours now. And while the winds to the west and south of the center are not more than about 10 kt, they have defined a closed center for much of the afternoon and evening. Given this persistent organization, the system is classifiable as a tropical cyclone and advisories are being initiated on Tropical Storm Julia, the tenth named storm of the 2016 Atlantic hurricane season. The motion of the system has been north-northwestward today, with the convective asymmetry likely contributing to a track to the right of much of the objective track guidance. That trend is forecast to continue for the next day or so, and the official forecast lies to the right of the model consensus - leaning in the direction of the HWRF. With the center expected to remain over land, and westerly shear of about 20 kt expected over the next day or so, little change in strength is expected until the system pushes farther inland and begins to weaken. Nevertheless, a small area of tropical-storm-force winds should continue to push northward along the coast within the warning area tonight and early Wednesday. The slow forward speed of Julia is expected to result in locally heavy rainfall of 3 to 6 inches with isolated maximum amounts near 10 inches along and east of where the center moves. These rains could result in flash flooding. Also, Doppler weather radar data during the past few hours indicate a significant improvement in the curved banding features to the north and east of the center. As a result, an isolated tornado or two will be possible overnight and on Wednesday when some of the stronger rainbands move onshore across northeastern Florida and southeastern Georgia. FORECAST POSITIONS AND MAX WINDS INIT 14/0300Z 30.3N 81.6W 35 KT 40 MPH...INLAND 12H 14/1200Z 31.2N 81.9W 35 KT 40 MPH...INLAND 24H 15/0000Z 31.8N 82.2W 30 KT 35 MPH...INLAND 36H 15/1200Z 32.1N 82.3W 25 KT 30 MPH...INLAND 48H 16/0000Z 32.3N 82.3W 20 KT 25 MPH...POST-TROP/REMNT LOW 72H 17/0000Z...DISSIPATED INLAND $$ Forecaster Stewart/Franklin

Tags: number discussion storm tropical

 

Tropical Storm IAN Forecast Discussion Number 6

2016-09-13 23:11:04| National Hurricane Center (Atlantic)

Issued at 500 PM AST TUE SEP 13 2016 000 WTNT45 KNHC 132110 TCDAT5 TROPICAL STORM IAN DISCUSSION NUMBER 6 NWS NATIONAL HURRICANE CENTER MIAMI FL AL102016 500 PM AST TUE SEP 13 2016 Ian continues to be sheared, and the low-level center is estimated to be near the southern edge of a ragged-looking area of deep convection. Since there has been no appreciable increase in the organization of the tropical cyclone, the advisory intensity is held at 40 kt, which is the mean of Dvorak intensity estimates from TAFB and SAB. Given that the shear is forecast to remain strong enough to inhibit strengthening for the next 24 hours or so, with some relaxation thereafter, the official intensity forecast shows some slow strengthening beginning tomorrow night. The official forecast is in good agreement with the latest LGEM guidance. In 72 hours, the global models predict the cyclone to have a frontal structure over the north Atlantic, so the official forecast shows Ian as extratropical by that time. The storm has sped up a bit, and the initial motion is now near 340/14 kt. Over the next day or so, Ian will continue to move through a weakness in the mid-level subtropical ridge. Later, when the cyclone moves into the mid-latitude westerlies, a shortwave trough approaching from the west should cause Ian to accelerate north-northeastward to northeastward. The official track forecast is faster than the previous one, but not quite as fast as the latest ECMWF and GFS solutions. This is close to the multi-model consensus and the FSU Superensemble. FORECAST POSITIONS AND MAX WINDS INIT 13/2100Z 27.0N 52.7W 40 KT 45 MPH 12H 14/0600Z 29.1N 53.3W 40 KT 45 MPH 24H 14/1800Z 31.8N 53.6W 40 KT 45 MPH 36H 15/0600Z 34.5N 53.0W 45 KT 50 MPH 48H 15/1800Z 37.5N 50.5W 50 KT 60 MPH 72H 16/1800Z 48.5N 37.0W 50 KT 60 MPH...POST-TROP/EXTRATROP 96H 17/1800Z 58.0N 22.0W 50 KT 60 MPH...POST-TROP/EXTRATROP 120H 18/1800Z 64.5N 8.0W 45 KT 50 MPH...POST-TROP/EXTRATROP $$ Forecaster Pasch

Tags: number discussion storm ian

 

Tropical Storm IAN Forecast Discussion Number 5

2016-09-13 16:44:15| National Hurricane Center (Atlantic)

Issued at 1100 AM AST TUE SEP 13 2016 000 WTNT45 KNHC 131444 TCDAT5 TROPICAL STORM IAN DISCUSSION NUMBER 5 NWS NATIONAL HURRICANE CENTER MIAMI FL AL102016 1100 AM AST TUE SEP 13 2016 Ian remains a sheared tropical storm, with the low-cloud center exposed to the south of the main area of deep convection. The current intensity estimate remains 40 kt, since the system has not become better organized since the time of the last scatterometer pass. The strong shear over Ian is being produced by an upper-level low a couple of hundred miles to the west-northwest. The global models predict this low to open up into a negatively-tilted trough, with some slight relaxation of the shear over the storm, in 24-36 hours. Therefore slight strengthening is shown by the official forecast after 24 hours, in line with the latest model consensus. The global model guidance depicts the cyclone to become frontal over the north Atlantic by 96 hours, and this is also reflected in the official forecast. The tropical cyclone is moving north-northwestward at a slightly faster forward speed, or around 330/11 kt. Ian is expected to continue to move through a weakness in the mid-level subtropical ridge over the next day or so. Then, an approaching trough in the westerlies should cause the cyclone to turn north-northeastward and accelerate. The official track forecast is a little faster than the previous one, but not as fast as the latest GFS and ECMWF model predictions. FORECAST POSITIONS AND MAX WINDS INIT 13/1500Z 25.4N 52.3W 40 KT 45 MPH 12H 14/0000Z 27.3N 53.0W 40 KT 45 MPH 24H 14/1200Z 29.9N 53.7W 40 KT 45 MPH 36H 15/0000Z 32.6N 53.8W 45 KT 50 MPH 48H 15/1200Z 35.5N 52.5W 50 KT 60 MPH 72H 16/1200Z 44.0N 42.4W 50 KT 60 MPH 96H 17/1200Z 54.0N 28.0W 50 KT 60 MPH...POST-TROP/EXTRATROP 120H 18/1200Z 62.0N 13.0W 45 KT 50 MPH...POST-TROP/EXTRATROP $$ Forecaster Pasch

Tags: number discussion storm ian

 

Sites : [819] [820] [821] [822] [823] [824] [825] [826] [827] [828] [829] [830] [831] [832] [833] [834] [835] [836] [837] [838] next »