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Tropical Storm Karina Forecast Discussion Number 2
2020-09-13 11:02:00| National Hurricane Center (East Pacific)
Issued at 300 AM MDT Sun Sep 13 2020 ZCZC MIATCDEP1 ALL TTAA00 KNHC DDHHMM Tropical Storm Karina Discussion Number 2 NWS National Hurricane Center Miami FL EP162020 300 AM MDT Sun Sep 13 2020 Recent scatterometer data showed an area of 30-35 kt winds within about 80 n mi of the center of Tropical Depression Sixteen-E in the southwestern quadrant. Based on this data, along with 35-40 kt intensity estimates from TAFB and the CIMSS satellite consensus, the depression is upgraded to Tropical Storm Karina with an initial intensity of 35 kt. Satellite imagery show that the system is still being affected by northeasterly vertical shear, with the low-level center exposed to the northeast of the main convective mass. The initial motion is now 310/10. The global models forecast a mid-level ridge to build westward to the north of Karina in a day or two, causing the cyclone to move west- northwestward. A more westward motion is expected near the end of the forecast period as a weakening Karin is steered more by the low-level trade winds. The track guidance is in fair agreement with this scenario, although there is some spread in the forward speed, possibly due differences in how Karina interacts with the larger ITCZ/monsoon trough circulation, including the remnants of Invest 91E. The new forecast track will follow the forward speed of the consensus models and has only minor adjustments from the previous track. The forecast track takes the center of Karin over cooler water, with the system crossing the 25-26C isotherms in 48-72 h. Present indications are that the shear will decrease a little before the 72 h point, so the intensity forecast calls for gradual strengthening during that time. After 72 h, the cooler water and dry air entrainment should cause weakening. The new intensity forecast has some minor adjustments from the previous forecast, and it is in best agreement with the HCCA corrected consensus model and the Florida State Superensemble. FORECAST POSITIONS AND MAX WINDS INIT 13/0900Z 17.4N 113.8W 35 KT 40 MPH 12H 13/1800Z 18.1N 114.8W 40 KT 45 MPH 24H 14/0600Z 18.8N 116.4W 45 KT 50 MPH 36H 14/1800Z 19.4N 118.0W 50 KT 60 MPH 48H 15/0600Z 19.9N 119.4W 55 KT 65 MPH 60H 15/1800Z 20.5N 120.7W 55 KT 65 MPH 72H 16/0600Z 21.2N 122.0W 55 KT 65 MPH 96H 17/0600Z 22.0N 124.5W 45 KT 50 MPH 120H 18/0600Z 22.0N 127.0W 30 KT 35 MPH $$ Forecaster Beven NNNN
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