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Post-Tropical Cyclone Rina Forecast Discussion Number 14

2017-11-09 15:48:32| National Hurricane Center (Atlantic)

Issued at 1100 AM AST Thu Nov 09 2017 000 WTNT44 KNHC 091448 TCDAT4 Post-Tropical Cyclone Rina Discussion Number 14 NWS National Hurricane Center Miami FL AL192017 1100 AM AST Thu Nov 09 2017 Satellite images and surface data indicate that Rina has become a post-tropical cyclone. The system is embedded within low stratus clouds, with nippy air temperatures around 45 deg F about a degree to the northwest of the center. Interestingly, despite being over water temperatures around 9 deg C, instability aloft is still producing some elevated deep convection well northeast of the center, though this is not indicative of tropical cyclone status. The initial wind speed will stay at 40 kt, which is the maximum wind value from a pair of recently received scatterometer passes. The cyclone should move rather rapidly to the northeast and east-northeast over the next day before becoming elongated and dissipating west of Ireland. Little change in strength is anticipated, consistent with the global models. This is the last advisory on Rina. Additional information on this system can be found in High Seas Forecasts issued by the National Weather Service, under AWIPS header NFDHSFAT1, WMO header FZNT01 KWBC, and available on the Web at http://ocean.weather.gov/shtml/NFDHSFAT1.shtml Hopefully Rina will be the finale of the extremely active 2017 Atlantic hurricane season. However that might be wishful thinking since, of the top 10 most active hurricane seasons before this year, seven of them still had another tropical storm after today's date. FORECAST POSITIONS AND MAX WINDS INIT 09/1500Z 47.0N 45.5W 40 KT 45 MPH...POST-TROPICAL 12H 10/0000Z 51.0N 39.5W 40 KT 45 MPH...POST-TROP/EXTRATROP 24H 10/1200Z 55.0N 25.0W 40 KT 45 MPH...POST-TROP/EXTRATROP 36H 11/0000Z...DISSIPATED $$ Forecaster Blake

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Tropical Storm Rina Forecast Discussion Number 13

2017-11-09 09:42:34| National Hurricane Center (Atlantic)

Issued at 500 AM AST Thu Nov 09 2017 000 WTNT44 KNHC 090842 TCDAT4 Tropical Storm Rina Discussion Number 13 NWS National Hurricane Center Miami FL AL192017 500 AM AST Thu Nov 09 2017 It is difficult to depict the presence of a tropical cyclone on satellite imagery. The previous convection near the possible center has become completely detached while the circulation is becoming elongated. In fact, my initial position and intensity are primarily based on continuity. Rina is over very cold waters and a frontal system is rapidly approaching the cyclone, so the NHC forecast calls for Rina to become extratropical during the next 12 hours. Visible images later this morning will probably help to determine the structure of Rina if a cyclone exists by then. Rina or the extratropical low should move fast toward the northeast and then to the east-northeast within the mid-latitude westerly flow. Guidance from the NOAA Ocean Prediction Center was use in the NHC forecast. FORECAST POSITIONS AND MAX WINDS INIT 09/0900Z 44.5N 47.0W 40 KT 45 MPH 12H 09/1800Z 49.0N 43.5W 40 KT 45 MPH...POST-TROP/EXTRATROP 24H 10/0600Z 54.0N 32.0W 40 KT 45 MPH...POST-TROP/EXTRATROP 36H 10/1800Z 55.0N 15.0W 40 KT 45 MPH...POST-TROP/EXTRATROP 48H 11/0600Z...DISSIPATED $$ Forecaster Avila

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Tropical Storm Rina Forecast Discussion Number 12

2017-11-09 03:36:56| National Hurricane Center (Atlantic)

Issued at 1100 PM AST Wed Nov 08 2017 000 WTNT44 KNHC 090236 TCDAT4 Tropical Storm Rina Discussion Number 12 NWS National Hurricane Center Miami FL AL192017 1100 PM AST Wed Nov 08 2017 A small area of deep convection persists near the center of Rina, likely supported by very cold temperatures aloft and increasing upper-level divergence overcoming SSTs less than 20C. The initial intensity remains 45 kt based largely on continuity from the ASCAT pass earlier today, as the latest ASCAT passes missed much of Rina's circulation. Given the maintenance of deep convection, Rina remains a tropical cyclone, but should not be one for long as vertical shear is expected to increase above 30 kt and SSTs cool below 15C along the forecast track in the next 12 hours. The cyclone should become post-tropical by 12 hours and merge with a frontal zone by 24 hours. Post-tropical Rina should open up into a trough in 36 to 48 hours in the fast westerly flow over the north Atlantic. No change in strength is forecast prior to dissipation, based on global model guidance. Satellite fixes indicate that Rina moved a little to the west of the previous forecast track in the past few hours, but the cyclone now appears to be moving north-northeastward or 020/20. The cyclone is forecast to accelerate northeastward over the next 24 hours as it becomes embedded in the mid-latitude flow, and an even faster east- northeastward motion is expected on Friday prior to dissipation. The new NHC track forecast has been adjusted to the left and is closer to the ECMWF model in the short range, since that model has best handled the recent motion of Rina. At 24 to 36 hours, the NHC forecast lies to the left of the latest multi-model consensus aids. The track, intensity and structure forecasts of Rina during its post-tropical phase have been coordinated with the NOAA Ocean Prediction Center. FORECAST POSITIONS AND MAX WINDS INIT 09/0300Z 42.5N 48.3W 45 KT 50 MPH 12H 09/1200Z 45.7N 46.5W 45 KT 50 MPH...POST-TROPICAL 24H 10/0000Z 51.0N 40.0W 45 KT 50 MPH...POST-TROP/EXTRATROP 36H 10/1200Z 55.0N 26.5W 45 KT 50 MPH...POST-TROP/EXTRATROP 48H 11/0000Z...DISSIPATED $$ Forecaster Brennan

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Tropical Storm Rina Forecast Discussion Number 11

2017-11-08 21:32:21| National Hurricane Center (Atlantic)

Issued at 500 PM AST Wed Nov 08 2017 000 WTNT44 KNHC 082032 TCDAT4 Tropical Storm Rina Discussion Number 11 NWS National Hurricane Center Miami FL AL192017 500 PM AST Wed Nov 08 2017 The only significant change to Rina in the past several hours is the redevelopment of a small area of deep convection near the center. Otherwise, the large cyclone continues to have a somewhat subtropical appearance in satellite imagery, although available microwave data still indicate Rina is best classified as tropical. The initial wind speed is set to 45 kt based on ASCAT data from earlier today. Rina should lose all deep convection overnight as it moves over very cold waters and is forecast to become a frontal cyclone within 24 hours. Little change in strength is forecast throughout the period, consistent with the global model guidance. The extratropical cyclone is forecast to dissipate near or west of Ireland by day 3, although some of the guidance isn't clear on exactly when that will occur. Rina continues to accelerate northward, now at about 20 kt. The storm has been interacting with an upper-level low, as seen on water vapor images, which has kept the cyclone a bit west of the previous forecast. However, Rina is forecast to turn north-northeastward overnight and accelerate northeastward by Thursday night due to the cyclone leaving the influence of the upper low and entering stronger mid-latitude flow. The models are again west of the previous forecast in the short term, so the new NHC forecast is adjusted to the west, similar to a blend of the latest consensus and corrected consensus guidance. FORECAST POSITIONS AND MAX WINDS INIT 08/2100Z 40.9N 48.6W 45 KT 50 MPH 12H 09/0600Z 44.0N 47.5W 45 KT 50 MPH...POST-TROPICAL 24H 09/1800Z 49.5N 42.0W 45 KT 50 MPH...POST-TROP/EXTRATROP 36H 10/0600Z 53.5N 31.0W 45 KT 50 MPH...POST-TROP/EXTRATROP 48H 10/1800Z 55.5N 19.0W 40 KT 45 MPH...POST-TROP/EXTRATROP 72H 11/1800Z...DISSIPATED $$ Forecaster Blake

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Tropical Storm Rina Forecast Discussion Number 10

2017-11-08 15:43:53| National Hurricane Center (Atlantic)

Issued at 1100 AM AST Wed Nov 08 2017 000 WTNT44 KNHC 081443 TCDAT4 Tropical Storm Rina Discussion Number 10 NWS National Hurricane Center Miami FL AL192017 1100 AM AST Wed Nov 08 2017 Rina continues to have some subtropical characteristics with satellite images showing an asymmetric, comma-cloud structure. Still, AMSU and model analyses are showing the system as moderately warm core, and there are no signs of fronts near the core. Thus, Rina will stay as a tropical cyclone, and 50 kt is kept as the initial wind speed based on the latest satellite estimates. Little change in strength is expected before Rina loses all deep convection within the next 24 hours over chilly waters. The system should become embedded within a frontal zone over the far north Atlantic in a day or two, and dissipate west of Ireland. No changes were made to the previous intensity forecast. The storm is moving northward a bit faster at 18 kt. A continued acceleration and a turn to the north-northeast is expected overnight as Rina moves ahead of a shortwave over the Canadian Maritimes. The cyclone should move quite rapidly to the northeast by late Thursday and east-northeast on Friday due to strong mid-latitude flow. The westward guidance trend in the short-term part of the forecast is still present, and the new NHC prediction is moved in that direction in the first 24 hours, with little change thereafter. FORECAST POSITIONS AND MAX WINDS INIT 08/1500Z 39.4N 48.7W 50 KT 60 MPH 12H 09/0000Z 42.2N 47.8W 50 KT 60 MPH 24H 09/1200Z 47.1N 44.3W 50 KT 60 MPH...POST-TROPICAL 36H 10/0000Z 52.5N 36.0W 50 KT 60 MPH...POST-TROP/EXTRATROP 48H 10/1200Z 55.5N 22.5W 45 KT 50 MPH...POST-TROP/EXTRATROP 72H 11/1200Z...DISSIPATED $$ Forecaster Blake

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