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Tropical Storm Kristy Forecast Discussion Number 5
2018-08-08 04:32:10| National Hurricane Center (East Pacific)
Issued at 800 PM PDT Tue Aug 07 2018 165 WTPZ43 KNHC 080232 TCDEP3 Tropical Storm Kristy Discussion Number 5 NWS National Hurricane Center Miami FL EP132018 800 PM PDT Tue Aug 07 2018 Kristy has become a little less organized this evening. An upper tropospheric low situated to the northeast of Kristy is producing moderate northwesterly shear which has degraded the cyclone's cloud pattern. A 2035 UTC AMSR2 overpass revealed that the surface center was partially exposed to the north of the convective banding features. The subjective Dvorak intensity estimates from TAFB and SAB have decreased as well, so the initial intensity for this advisory is lowered to 40 kt. Statistical and global models all show the upper low to the northeast of Kristy weakening and lifting out in 24 hours or so, which should provide a more conducive upper wind environment for intensification, at least through mid-period. Afterwards, a weakening trend should commence due to an intruding drier/stable air mass and cooler oceanic sea surface temperatures. The HWRF and HCCA show Kristy becoming a hurricane in 48 hours, which still seems quite reasonable and is reflected in the forecast. All of the other guidance reaches just below 65 kt. The NHC intensity forecast is based primarily on these two models, and indicates a peak intensity of 65 kt in 48 hours. The initial motion is estimated to be 285/7 kt, and Kristy is being steered by a narrow mid-level ridge to the northeast. A complex synoptic steering pattern comprised of an approaching deep-layer low pressure system to the northwest of the tropical storm, and John to the northeast, is forecast by most of the global and regional models to weaken what's left of the ridge currently steering Kristy. The increasing weakness in the subtropical ridge should cause Kristy to turn northwestward and northward through day 4. At the end of the period, a gradual turn toward the northwest around the periphery of larger John's circulation. The ECMWF deterministic and ensemble models continue to be outliers in the aforementioned scenario due to less influence from the growing weakness to the north and significantly less binary interaction with John. The official forecast is similar to the previous one, with a slight adjustment to the right and is basically in the middle of the HCCA and TVCE consensus models. FORECAST POSITIONS AND MAX WINDS INIT 08/0300Z 14.2N 127.8W 45 KT 50 MPH 12H 08/1200Z 14.6N 128.7W 45 KT 50 MPH 24H 09/0000Z 15.4N 129.6W 50 KT 60 MPH 36H 09/1200Z 16.4N 130.0W 60 KT 70 MPH 48H 10/0000Z 17.2N 130.1W 65 KT 75 MPH 72H 11/0000Z 19.5N 129.9W 60 KT 70 MPH 96H 12/0000Z 22.0N 130.6W 50 KT 60 MPH 120H 13/0000Z 24.3N 133.0W 30 KT 35 MPH...POST-TROP/REMNT LOW $$ Forecaster Roberts
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