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Tropical Storm Kirk Forecast Discussion Number 10
2018-09-26 10:44:52| National Hurricane Center (Atlantic)
Issued at 500 AM AST Wed Sep 26 2018 961 WTNT42 KNHC 260844 TCDAT2 Tropical Storm Kirk Discussion Number 10 NWS National Hurricane Center Miami FL AL122018 500 AM AST Wed Sep 26 2018 Infrared satellite imagery during the past several hours indicates that deep convection has increased and become better organized near the center of the remnants of Kirk. In addition, two earlier ASCAT scatterometer passes between 0000-0100Z indicated that the low-level center had become a little better defined, and that the inner-core wind field had contracted, now with a radius of maximum winds (RMW) of about 40 nmi. Given the continued increase in the amount and organization of the deep convection, advisories have be re-initiated on Tropical Storm Kirk. The two ASCAT passes showed peak winds of 38 and 44 kt, so the initial intensity will be a blend of these two values or 40 kt. An Air Force Reserve reconnaissance aircraft will be investigating Kirk later this morning to provide more detailed information on the location and intensity of the tropical storm. The initial motion estimates is an uncertain 280/16 kt, due to the lack of a well-defined center to track for the past two days. The global and regional models, excluding the HWRF model, are in very good agreement on Kirk moving between west and west-northwest for the next 72 hours along the south side of a strong Bermuda-Azores high pressure system anchored across most of the subtropical Atlantic. After that time, strong shear is forecast to weaken Kirk into a remnant low, resulting in a more westward motion as the shallow cyclone will be steered by the low-level easterly trade wind flow. The official forecast track closely follows the HCCA corrected-consensus model, and is a little south of the simple consensus model TVCA due to an apparent northward bias in the HWRF member. The current modest west to southwesterly vertical wind shear is forecast to decrease to less than 10 kt during the next 24 hours, which should allow for some slight strengthening to occur. After 48 hours when Kirk is forecast to emerge over the eastern Caribbean Sea, the shear is expected to increase to more then 30 kt, which should act to displace the deep convection to the east of the low-level center, resulting in rapid weakening. Kirk is forecast to degenerate into a remnant low pressure system after 72 hours, but this could occur a little sooner than indicated in the official forecast if Kirk moves farther north and into even stronger shear conditions. The NHC intensity forecast closely follows a blend of the HCCA, FSSE, and IVCN consensus models. FORECAST POSITIONS AND MAX WINDS INIT 26/0900Z 11.8N 52.7W 40 KT 45 MPH 12H 26/1800Z 12.4N 55.0W 45 KT 50 MPH 24H 27/0600Z 13.2N 57.6W 45 KT 50 MPH 36H 27/1800Z 14.1N 60.0W 45 KT 50 MPH 48H 28/0600Z 14.8N 62.3W 40 KT 45 MPH 72H 29/0600Z 15.7N 67.0W 30 KT 35 MPH 96H 30/0600Z 15.9N 71.6W 25 KT 30 MPH...POST-TROP/REMNT LOW 120H 01/0600Z 16.0N 76.0W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Stewart
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