ZCZC MIATCDEP4 ALL TTAA00 KNHC DDHHMM Tropical Storm Madeline Discussion Number 11 NWS National Hurricane Center Miami FL EP142022 300 AM MDT Tue Sep 20 2022 Since the last advisory, Madeline's structure has gone downhill in a hurry. The convection that existed earlier today has largely sheared away to the west and dissipated, revealing a well-defined low-level swirl that is easy to find on nighttime proxy-vis GOES-17 satellite imagery. It appears the increase in easterly shear, in combination with the tropical cyclone crossing the 26 C sea-surface temperature (SST) isotherm, has led to this structural collapse. Subjective Dvorak T-numbers were falling as fast as the constraints would allow, but based on the rapid deterioration in the structure, in addition to some west edge scatterometer wind data indicating only 29-31 kt winds just 50 n mi west-southwest of the center, the initial intensity is being reduced to 35 kt this advisory. Madeline has nearly completed its turn to the west, with the motion now estimated at 280/7 kt. This motion should continue with an additional gentle bend leftward as the storm becomes increasingly shallow and steered by the low-level flow. The NHC track forecast is a touch south of the prior one, in good agreement with the multi-model consensus aids. Madeline's track overnight has put it over anomalously cold SSTs that are a leftover from Hurricane Kay that traversed this area more than a week ago. With the overnight evaporation of deep organized convection, the clock is now ticking on Madeline's remaining lifespan as a tropical cyclone. The latest NHC forecast now shows the cyclone becoming a post-tropical remnant low in just 24 hours. There is one caveat to this forecast. Along Madeline's track, SSTs do start to increase again in 36 hours, and simulated satellite imagery from both the GFS and ECMWF suggest some brief puffs of deep convection could occur in the day 2-3 period. However, this forecast will assume that these convective bursts will not be organized enough to allow the system to regenerate. The latest NHC intensity forecast is lower than the previous one, but largely follows the HCCA and IVCN consensus aids. FORECAST POSITIONS AND MAX WINDS INIT 20/0900Z 21.2N 111.3W 35 KT 40 MPH 12H 20/1800Z 21.3N 112.4W 30 KT 35 MPH 24H 21/0600Z 21.5N 113.7W 25 KT 30 MPH...POST-TROP/REMNT LOW 36H 21/1800Z 21.6N 115.1W 25 KT 30 MPH...POST-TROP/REMNT LOW 48H 22/0600Z 21.5N 116.6W 25 KT 30 MPH...POST-TROP/REMNT LOW 60H 22/1800Z 21.4N 118.1W 25 KT 30 MPH...POST-TROP/REMNT LOW 72H 23/0600Z 21.3N 119.7W 20 KT 25 MPH...POST-TROP/REMNT LOW 96H 24/0600Z 21.0N 123.5W 20 KT 25 MPH...POST-TROP/REMNT LOW 120H 25/0600Z 20.8N 126.6W 20 KT 25 MPH...POST-TROP/REMNT LOW $$ Forecaster Papin NNNN