ZCZC MIATCDEP2 ALL TTAA00 KNHC DDHHMM Hurricane Fernanda Discussion Number 10 NWS National Hurricane Center Miami FL EP072023 500 PM HST Mon Aug 14 2023 This evening, Fernanda's inner-core structure is beginning to show signs of decay, with its well-defined eye becoming cloud filled on both visible and infrared satellite images. Earlier, a 2144 UTC AMSR2 microwave pass suggested the hurricane might be undergoing an eyewall replacement cycle, which could be partially responsible for its recent structural degradation. 0000 UTC subjective Dvorak intensity estimates from TAFB and SAB were 115 kt and 102 kt, respectively. Objective intensity estimates from UW-CIMSS have either leveled off or have begun to decline, with the most recent D-MINT estimate at 107 kt associated with the aforementioned AMSR2 pass above. The initial intensity has been lowered to 105 kt this advisory given the continued decline since that time. Fernanda has been moving a bit more poleward over the last 6 to 12 hours, with the latest estimated motion at 290/8 kt. The mid-level ridging has been taking its time building back in to the north over the past 24 hours, but is still forecast to do so over the next few days, leading to Fernanda gradually accelerating to the west-northwest. Beyond 48 hours, a weakening Fernanda should quickly become more vertically shallow, resulting in the cyclone turning more westward as it comes under the influence of the more extensive North Pacific low-level subtropical ridge. The official forecast continues to be very close to the prior forecast, other than a short-term nudge further north given the initial motion. This track remains close to both the simple and corrected consensus model guidance. In addition to a possible eyewall replacement cycle, Fernanda might also be feeling the effects of some higher (15-20 kt) mid-level vertical wind shear out of the south. Very dry mid-level environmental air could also be attempting to wrap around the southwest quadrant of the cyclone. Given these factors, it now seems more likely Fernanda will continue weakening in the short-term, with the rate of weakening increasing after it crosses the 26-C isotherm in about 24-36 hours. Both the global and regional-hurricane models now show Fernanda losing its organized convection in about 3 days, with the latest NHC intensity forecast showing the system becoming a post-tropical remnant low at that time. FORECAST POSITIONS AND MAX WINDS INIT 15/0300Z 16.5N 119.8W 105 KT 120 MPH 12H 15/1200Z 17.0N 121.2W 100 KT 115 MPH 24H 16/0000Z 17.4N 123.5W 90 KT 105 MPH 36H 16/1200Z 17.6N 126.0W 70 KT 80 MPH 48H 17/0000Z 17.8N 128.7W 50 KT 60 MPH 60H 17/1200Z 18.0N 131.5W 40 KT 45 MPH 72H 18/0000Z 18.1N 134.6W 30 KT 35 MPH...POST-TROP/REMNT LOW 96H 19/0000Z 18.2N 141.0W 30 KT 35 MPH...POST-TROP/REMNT LOW 120H 20/0000Z 18.0N 147.0W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Papin NNNN