ZCZC MIATCDEP5 ALL TTAA00 KNHC DDHHMM Tropical Depression Fifteen-E Discussion Number 1 NWS National Hurricane Center Miami FL EP152017 300 PM MDT Mon Sep 11 2017 The remnants of Atlantic Hurricane Katia have redeveloped after reaching the Pacific Ocean a couple of days ago. The system maintained a mid-level circulation while transiting the high terrain of Mexico, but had lost its surface center. Yesterday, deep convection began in association with the mid-level circulation and today a well-defined surface center formed. While it was originally thought that the convection would be sporadic because of the moderate vertical shear, the deep convection has instead persisted close to the system's center during the last several hours. Since the system now meets the definition of a tropical cyclone, advisories are initiated as Tropical Depression Fifteen. The depression is moving toward the west at 13 kt, steered primarily by the deep-layer ridge to its north. The official track forecast is a westward or west-southwestward motion at a slower rate of forward speed during the next two days, then a turn back toward the west or west-northwest at days 3 and 4. This forecast is based upon a blend of the GFS and ECMWF global models, as the remaining guidance either doesn't know about the depression or unrealistically intensifies it and takes it toward the north. The system likely will not become very substantial. The moderate shear should continue, while the depression heads toward cool SSTs and dry air. The official intensity forecast shows just modest strengthening to a low-end tropical storm in about a day, before weakening begins. Deep convection may cease in about three days, marking the system's transition to a remnant low. The intensity forecast is based upon the LGEM/DSHIP statistical guidance as the mesoscale dynamical models spin the depression up to near hurricane strength, which is not plausible. If the system does reach tropical storm intensity - by no means assured, then it would be named "Max", not "Katia". FORECAST POSITIONS AND MAX WINDS INIT 11/2100Z 16.4N 112.3W 25 KT 30 MPH 12H 12/0600Z 16.2N 114.1W 30 KT 35 MPH 24H 12/1800Z 15.8N 116.2W 35 KT 40 MPH 36H 13/0600Z 15.4N 118.0W 30 KT 35 MPH 48H 13/1800Z 15.3N 119.6W 25 KT 30 MPH 72H 14/1800Z 15.7N 121.7W 25 KT 30 MPH...POST-TROP/REMNT LOW 96H 15/1800Z 16.0N 123.5W 20 KT 25 MPH...POST-TROP/REMNT LOW 120H 16/1800Z...DISSIPATED $$ Forecaster Landsea NNNN