000 WTPZ42 KNHC 250842 CCA TCDEP2 TROPICAL STORM OTTO DISCUSSION NUMBER 18...CORRECTED NWS NATIONAL HURRICANE CENTER MIAMI FL EP222016 300 AM CST FRI NOV 25 2016 Corrected for Central Standard Time instead of Central Daylight Time in product header. The cloud pattern of Otto is rather ragged this morning after the circulation moved offshore of Central America. Shortwave infrared imagery suggests that there may now be some tilt to the circulation, with the low-level center possibly located south of the mid-level center. However, this is quite uncertain given the lack of microwave imagery overnight. Based on this apparent decrease in organization, the initial intensity is set to 50 kt, a little below the latest Dvorak estimates of T3.5/55 kt from TAFB and SAB. The intensity forecast is problematic. Most of the guidance suggests that Otto will maintain its current intensity for the next 48 hours or so while the cyclone moves over SSTs of 28-29C but with continued southeasterly shear of 15-20 kt. Through this time the NHC intensity forecast is near or a bit below the IVCN intensity consensus. By day 3, the shear begins to decrease, but the atmosphere dries out as Otto interacts with outflow from a Gulf of Tehuantepec gap wind event. The global models show Otto weakening late in the period, and that trend is reflected in the official forecast, which continues to show Otto becoming a remnant low at day 5. However, given the uncertainty in the current structure of Otto and the interplay between several competing environmental factors during the forecast period, confidence in the intensity forecast is lower than usual. The initial motion estimate is a somewhat uncertain 265/12. I shifted the initial position a little to the south to account for the possible tilt in the circulation mentioned above. This resulted in a southward shift of the track guidance envelope and the NHC forecast even though the synoptic reasoning has not changed. An amplifying mid-level ridge will steer Otto south of due west at around 15 kt for the next 48 hours. Then, as the ridge weakens late in the period, a slowing forward speed and gradual poleward turn are expected. The new NHC track is close to the latest multi-model consensus, but lies north of the latest GFS and ECMWF predictions. FORECAST POSITIONS AND MAX WINDS INIT 25/0900Z 10.5N 86.9W 50 KT 60 MPH 12H 25/1800Z 10.1N 88.8W 50 KT 60 MPH 24H 26/0600Z 9.5N 91.6W 50 KT 60 MPH 36H 26/1800Z 9.2N 94.6W 50 KT 60 MPH 48H 27/0600Z 9.0N 97.5W 45 KT 50 MPH 72H 28/0600Z 9.3N 103.0W 40 KT 45 MPH 96H 29/0600Z 10.5N 106.0W 35 KT 40 MPH 120H 30/0600Z 12.5N 107.0W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Brennan