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Tropical Storm Emilia Forecast Discussion Number 4
2018-06-28 16:37:01| National Hurricane Center (East Pacific)
Issued at 900 AM MDT Thu Jun 28 2018 000 WTPZ41 KNHC 281436 TCDEP1 Tropical Storm Emilia Discussion Number 4 NWS National Hurricane Center Miami FL EP062018 900 AM MDT Thu Jun 28 2018 Deep convection continues in the western semicircle of the cyclone, although a fair portion of the eastern side of the low-level circulation is exposed due to shear. Satellite classifications are essentially the same as 6 hours ago, so the initial wind speed will stay 35 kt. Global models are in good agreement that the wind shear will decrease over the next 24 hours, which should promote strengthening. In a couple of days, Emilia is predicted to move over cool SSTs and through a drier environment, causing its inevitable weakening to begin. The official forecast is essentially an update of the previous one, showing a gradual increase in strength until late Friday, then weakening on Sunday. Emilia should become a remnant low by 96 hours as it moves over SSTs of about 23C. Emilia has been a challenging storm to track because of limited microwave passes and an elongated low-level structure. Even with 1-min GOES-16 visible data, it is difficult to tell how embedded the center of Emilia is within the deep convection. The available data suggest the storm has slowed a little bit and turned to the right, so my motion estimate is 290/12 kt. A mid-level ridge over Mexico and the adjacent eastern Pacific should gradually weaken during the next few days, resulting in a reduction of Emilia's forward speed. The biggest change from the last forecast cycle is that there could be a more substantial break in the subtropical ridge in the medium-range period, allowing the storm to continue a more west-northwestward motion, rather than taking a climatological westward turn. This track is dependent on how strong the cyclone is at that time and, since Emilia is forecast to be rather weak at long range, the official forecast is on the southern side of the guidance envelope, albeit with a northward adjustment since the last advisory. FORECAST POSITIONS AND MAX WINDS INIT 28/1500Z 14.4N 112.4W 35 KT 40 MPH 12H 29/0000Z 15.1N 114.1W 40 KT 45 MPH 24H 29/1200Z 15.9N 116.2W 45 KT 50 MPH 36H 30/0000Z 16.6N 118.0W 50 KT 60 MPH 48H 30/1200Z 17.2N 119.7W 50 KT 60 MPH 72H 01/1200Z 18.6N 123.0W 40 KT 45 MPH 96H 02/1200Z 20.5N 126.5W 30 KT 35 MPH...POST-TROP/REMNT LOW 120H 03/1200Z 21.5N 131.0W 20 KT 25 MPH...POST-TROP/REMNT LOW $$ Forecaster Blake
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