000 WTPZ41 KNHC 192041 TCDEP1 TROPICAL STORM RICK DISCUSSION NUMBER 6 NWS NATIONAL HURRICANE CENTER MIAMI FL EP212015 200 PM MST THU NOV 19 2015 Rick is exhibiting a shear pattern, with the low-level center of the cyclone estimated to be near the southeastern edge of a curved convective band over the northwestern semicircle of the circulation. A 1616 UTC ASCAT-A overpass indicated peak uncontaminated winds of 36 kt, so the initial intensity is held at 35 kt. Some further reduction in southeasterly shear over the cyclone should occur tonight or early Friday while other large- scale factors remain generally favorable, which could allow for some additional intensification over the next 24 hours or so. However, the broad nature of the cyclone's circulation shown by the scatterometer data is most likely to result in only slow strengthening before a substantial increase in west-southwesterly shear occurs in about 36 to 48 hours. Even higher shear is expected over Rick by 72 hours once the storm gains more latitude and a trough in the eastern Pacific subtropics nears the cyclone from the west. A rapid decoupling of the cyclone should occur not long after that time, and remnant low status is indicated in 96 hours, though this could occur sooner. The new intensity forecast is is a bit lower than the previous one and slightly lower than the multi-model consensus through 48 hours. ASCAT passes were quite helpful in determining that the location of Rick's low-level center was farther south and west than previously estimated. Those fixes indicate that Rick has turned northwestward with an initial motion estimate of 320/07. A mid-level ridge over mainland Mexico should build north of Rick tonight and tomorrow, resulting in a west-northwestward turn with an increase in forward speed. Once Rick reaches the western periphery of this ridge in about 3 days, a more poleward track is forecast until dissipation. The new track forecast is adjusted back to the left, primarily due the center re-location. FORECAST POSITIONS AND MAX WINDS INIT 19/2100Z 14.8N 107.0W 35 KT 40 MPH 12H 20/0600Z 15.5N 108.3W 40 KT 45 MPH 24H 20/1800Z 16.2N 109.9W 45 KT 50 MPH 36H 21/0600Z 16.9N 111.6W 45 KT 50 MPH 48H 21/1800Z 17.5N 112.8W 40 KT 45 MPH 72H 22/1800Z 19.0N 114.4W 30 KT 35 MPH 96H 23/1800Z 21.2N 115.1W 20 KT 25 MPH...POST-TROP/REMNT LOW 120H 24/1800Z...DISSIPATED $$ Forecaster Kimberlain