000 WTPZ45 KNHC 220246 TCDEP5 TROPICAL STORM PATRICIA DISCUSSION NUMBER 7 NWS NATIONAL HURRICANE CENTER MIAMI FL EP202015 1000 PM CDT WED OCT 21 2015 The convective cloud pattern of Patricia has improved significantly since the previous advisory. A large CDO feature and a pronounced curved convective band in the western semicircle has developed, and a primitive eye feature has been noted in recent passive microwave imagery. The last report from a NOAA Hurricane Hunter aircraft indicated a SFMR surface wind value of 56 kt, which arrived after the previous advisory had been issued. That data, along with a 2056Z UW-CIMSS AMSU intensity estimate of 59 kt and the improved satellite appearance, is the justification for increasing the intensity to a conservative 55 kt. The initial motion estimate is 290/12 kt. The new forecast track is similar to the previous advisory track except to widen the turn toward the northwest slightly in 24-36 hours. The new 18Z GFS model shifted slightly westward and is now very close to the ECMWF solution. As a result, the official forecast track has been nudged slightly westward at the 24-, 36-, and 48-hours, which delays landfall by another 6 hours or so. Otherwise, the track forecast reasoning remains unchanged. Patricia is expected to move west-northwestward along the south side of a deep-layer ridge over the Gulf of Mexico for the next 24 hours, followed by a gradual turn toward the northwest, and a turn toward the north at 36-48 hours. The model guidance remains in excellent agreement on this track scenario, and the official forecast lies between the GFS-ECMWF (GFEX) and TVCE consensus model tracks. The improved organization of Patricia along with favorable environmental and oceanic conditions consisting of low vertical wind shear of less than 5 kt, a very moist mid-level environment, SSTs in excess of 30 deg C, and high upper-ocean heat content values in excess of 60 units support rapid intensification of the tropical cyclone. The NHC intensity forecast closely follows the IVCN consensus model through 24 hours and then is above the consensus after that, following a blend of the SHIPS and LGEM models. The justification for going above the IVCN consensus is due to the low bias caused by the HWRF model, which moves Patricia inland sooner, resulting in a much lower intensity at 48 hours. As a result, rapid intensification is explicitly forecast for the next 36 hours, making Patricia a major hurricane by the end of that period. The intensity is then leveled off at 48 hours due to the possibility of modest southerly wind shear and some land interaction affecting the cyclone as Patricia nears the coast of southwestern Mexico. FORECAST POSITIONS AND MAX WINDS INIT 22/0300Z 13.5N 100.5W 55 KT 65 MPH 12H 22/1200Z 14.2N 102.1W 70 KT 80 MPH 24H 23/0000Z 15.5N 103.8W 85 KT 100 MPH 36H 23/1200Z 17.0N 104.9W 100 KT 115 MPH 48H 24/0000Z 19.0N 105.0W 100 KT 115 MPH 72H 25/0000Z 24.1N 103.2W 30 KT 35 MPH...INLAND 96H 26/0000Z...DISSIPATED $$ Forecaster Stewart