000 WTPZ42 KNHC 260242 TCDEP2 TROPICAL STORM IGNACIO DISCUSSION NUMBER 5 NWS NATIONAL HURRICANE CENTER MIAMI FL EP122015 800 PM PDT TUE AUG 25 2015 Conventional satellite imagery and the latest UW-CIMSS shear analysis indicates that the southeasterly shear has diminished this evening. Subsequently, Ignacio had quickly become better organized this evening with a small Central Dense Overcast forming over the surface circulation. Subjective Dvorak classifications from TAFB and SAB, and a recent objective ADT current intensity estimate yields an initial intensity of 40 kt for this advisory. The shear is forecast to remain relatively light and from the east to southeast during the next 3-4 days. Warm sea surface temperatures and an atmospheric environment conducive for further strengthening should allow the cyclone to intensify during the next 96 hours and become a hurricane in 36 hours. Afterwards, the upper level winds become less favorable as Ignacio approaches an established mid- to upper level trough near the Hawaiian Islands. The NHC intensity forecast is similar to the previous advisory and is based on a compromise of the HWRF hurricane model and the IVCN intensity consensus. Based on Visible imagery and a recent microwave image from the GPM satellite, Ignacio appears to have been moving west-southwestward during the past 12-18 hours, and has recently turned more toward the west or, 260/05 kt. Ignacio should continue moving in this general direction during the next 24 hours or so within the southwestern peripheral flow of the subtropical ridge. After that time, a gradual turn toward the west-northwest is expected as the cyclone rounds the southwestern extent of the ridge. The official forecast track has again been shifted toward the left, primarily due to the previous west-southwestward motion, and agrees with both the GFEX (GFS/ECMWF blend) and the TVCX multi-model consensus. FORECAST POSITIONS AND MAX WINDS INIT 26/0300Z 12.3N 133.4W 40 KT 45 MPH 12H 26/1200Z 12.2N 134.8W 50 KT 60 MPH 24H 27/0000Z 12.3N 136.5W 60 KT 70 MPH 36H 27/1200Z 12.8N 138.3W 65 KT 75 MPH 48H 28/0000Z 13.6N 140.1W 75 KT 85 MPH 72H 29/0000Z 14.9N 143.4W 85 KT 100 MPH 96H 30/0000Z 16.4N 146.9W 75 KT 85 MPH 120H 31/0000Z 17.7N 150.6W 70 KT 80 MPH $$ Forecaster Roberts