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Tropical Storm Kristy Forecast Discussion Number 13
2018-08-10 04:49:58| National Hurricane Center (East Pacific)
Issued at 800 PM PDT Thu Aug 09 2018 319 WTPZ43 KNHC 100249 TCDEP3 Tropical Storm Kristy Discussion Number 13 NWS National Hurricane Center Miami FL EP132018 800 PM PDT Thu Aug 09 2018 Recent 37-GHz microwave images show that Kristy's low-level structure has improved markedly with a solid cyan ring and multiple low-cloud spiral bands. Inner-core convection has increased too, and recent infrared satellite imagery is suggesting the possible development of a ragged eye. Although 00Z Dvorak estimates were a consensus T3.5 from TAFB and SAB, the continued improvement in structure supports an initial intensity of 60 kt. Given the cyclone's well-defined structure, Kristy could become a hurricane overnight or early Friday while it remains over sufficiently warm water and in a low-shear environment. After that time, cooler waters and gradually increasing shear will cause the winds in the circulation to slowly diminish, with deep convection likely dissipating, and Kristy becoming post-tropical, by 72 hours. The updated NHC intensity forecast is a little higher than the guidance in the first 12 hours but then is similar to the previous forecast and close to the HCCA guidance and the ICON intensity consensus thereafter. Kristy is moving slightly east of due north, or 010/6 kt. There has been little change in the tune of the various track models. The GFS and HWRF continue to show Kristy being pulled north- northeastward by Tropical Storm John, while the ECMWF and UKMET models show less interaction and have Kristy turning west- northwestward by 36-48 hours with more ridging to the north. This might be a classic case of why the consensus approach can work so well. So far, with 72 hours of forecasts for Kristy under our belt, the GFS and the ECMWF have been the two worst-performing track models, each having a significant eastward and westward bias, respectively. The various consensus aids, on the other hand, have proven to be the most skillful so far. For that reason, the NHC track forecast continues to be down the middle of the guidance envelope, close to a blend of the HCCA and TVCX aids. FORECAST POSITIONS AND MAX WINDS INIT 10/0300Z 17.4N 129.9W 60 KT 70 MPH 12H 10/1200Z 18.4N 129.5W 65 KT 75 MPH 24H 11/0000Z 19.7N 129.1W 60 KT 70 MPH 36H 11/1200Z 20.7N 129.0W 55 KT 65 MPH 48H 12/0000Z 21.4N 129.1W 45 KT 50 MPH 72H 13/0000Z 23.2N 129.5W 35 KT 40 MPH...POST-TROPICAL 96H 14/0000Z 25.5N 130.5W 25 KT 30 MPH...POST-TROP/REMNT LOW 120H 15/0000Z 27.0N 131.0W 20 KT 25 MPH...POST-TROP/REMNT LOW $$ Forecaster Berg
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