000 WTPZ44 KNHC 300839 TCDEP4 TROPICAL STORM GUILLERMO DISCUSSION NUMBER 2 NWS NATIONAL HURRICANE CENTER MIAMI FL EP092015 200 AM PDT THU JUL 30 2015 GOES satellite imagery show that the cloud pattern has become better organized with numerous cyclonically curved convective bands around the center of circulation. The upper-level outflow has improved during the past several hours. Dvorak T-numbers are now 3.0 and 2.5 from TAFB and SAB, respectively. Thus, the depression has been upgraded to Tropical Storm Guillermo with an initial intensity of 35 kt. Guillermo is the seventh tropical storm of the 2015 eastern north Pacific hurricane season. The environment of low shear and warm SSTs is quite favorable for strengthening, and Guillermo will likely become a hurricane in about 36 hours. The probability of rapid intensification included in the SHIPS guidance is 32 percent. After 72 hours, both cooler ocean and increasing shear will likely induce gradual weakening. The NHC forecast follows very closely the intensity consensus. The best estimate of the initial motion is toward the west- northwest or 285 degrees at 13 kt. Guillermo is well embedded within the deep easterly flow south of a moderate subtropical ridge. There is high confidence that this pattern should keep the cyclone on this general track for the next 2 to 3 days, given that the guidance is tightly clustered during that period. After that time, Guillermo will reach the western edge of the ridge and will turn more to the northwest toward a mid-latitude trough. The NHC track forecast is similar to the previous one and is basically on top of the consensus of the ECMWF and the GFS global models. FORECAST POSITIONS AND MAX WINDS INIT 30/0900Z 8.5N 126.3W 35 KT 40 MPH 12H 30/1800Z 8.9N 128.2W 45 KT 50 MPH 24H 31/0600Z 10.1N 131.1W 55 KT 65 MPH 36H 31/1800Z 11.2N 134.2W 65 KT 75 MPH 48H 01/0600Z 12.2N 137.4W 75 KT 85 MPH 72H 02/0600Z 14.5N 141.6W 70 KT 80 MPH 96H 03/0600Z 16.3N 144.3W 65 KT 75 MPH 120H 04/0600Z 18.0N 146.5W 55 KT 65 MPH $$ Forecaster Avila