ZCZC MIATCDEP3 ALL TTAA00 KNHC DDHHMM Tropical Storm Hernan Discussion Number 4 NWS National Hurricane Center Miami FL EP132020 1000 PM CDT Wed Aug 26 2020 Hernan remains a sheared tropical cyclone with a new burst of deep convection, characterized by cloud tops of -75C to -85C, having developed near and southwest of the well-defined low-level circulation center. The initial intensity remains 35 kt based on a TAFB Dvorak satellite classification of T2.5/35 kt using a shear pattern. Up until a few hours ago, Hernan had been moving slowly north-northeastward, but the motion is now estimated to be northward or 360/05 kt. Hernan is forecast to remain trapped within and move around the northeastern periphery of a large-scale, eastern North Pacific monsoon gyre during the next few days. This is expected to result in a slow northward motion tonight, followed by a turn toward the northwest on Thursday, and a west-northwestward motion on Friday. By Saturday, Hernan is forecast to degenerate into a remnant low pressure system and be steered generally westward by the low-level easterly flow on the north side of the gyre. On the forecast track, Hernan and most of its significant winds and convection should remain just offshore the southwestern coast of Mexico tonight and Thursday, and pass near or just south of the southern tip of Baja California Sur on Friday and Saturday. The new NHC track is a very similar to the previous advisory track, and lies close to the simple track consensus models TVCE and GFEX, and lies to the left of the NOAA-HCCA corrected-consensus model. Hernan is expected to remain a sheared tropical cyclone throughout its lifetime due to moderate to strong east to northeasterly vertical wind shear. However, the cyclone will also be over warm waters and within a moist mid-level environment for the next 48 hours or so. Although the official intensity forecast calls for no change in strength, some slight intensification to 40 kt can't be ruled out, especially tonight during the approaching convective maximum period. By 60 hours and beyond, Hernan is forecast to move over marginal sea-surface temperatures and be affected by strong easterly shear of at least 20 kt, which should cause the cyclone to weaken into a remnant low. The NHC intensity forecast follows the IVCN intensity consensus model. FORECAST POSITIONS AND MAX WINDS INIT 27/0300Z 18.3N 105.8W 35 KT 40 MPH 12H 27/1200Z 19.0N 105.9W 35 KT 40 MPH 24H 28/0000Z 20.2N 106.6W 35 KT 40 MPH 36H 28/1200Z 21.4N 108.1W 35 KT 40 MPH 48H 29/0000Z 22.0N 109.9W 30 KT 35 MPH 60H 29/1200Z 22.5N 112.3W 30 KT 35 MPH...POST-TROP/REMNT LOW 72H 30/0000Z 22.5N 113.8W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 31/0000Z 22.4N 115.7W 20 KT 25 MPH...POST-TROP/REMNT LOW 120H 01/0000Z...DISSIPATED $$ Forecaster Stewart NNNN