ZCZC MIATCDEP3 ALL TTAA00 KNHC DDHHMM TROPICAL STORM JIMENA DISCUSSION NUMBER 4 NWS NATIONAL HURRICANE CENTER MIAMI FL EP132015 800 AM PDT THU AUG 27 2015 Jimena is steadily becoming better organized with deep convection persisting near the center and more pronounced banding developing around the circulation. The initial intensity is 40 kt based on Dvorak estimates of T2.5/35 kt from TAFB and T3.0/45 kt from SAB. Embedded in an environment of low shear, high moisture, and very warm ocean water, Jimena should have no problems continuing to intensify. In fact, rapid intensification (RI) is a distinct possibility during the next 24 hours. A low-level inner core ring was noted in the 37-GHz channel of a 0946 UTC GPM microwave pass, and the SHIPS RI index is showing a 1 in 3 chance of a 30-kt intensity change during the next 24 hours. Therefore, the NHC intensity forecast shows Jimena becoming a hurricane on Friday. After 24 hours, the overall environment should remain favorable for strengthening, and Jimena is forecast to be a major hurricane from day 3 through day 5. The updated NHC intensity forecast is a little higher than the IVCN intensity consensus and shows a bit more strengthening than the previous forecast through 96 hours. The storm has been moving quickly west-northwestward with a 12-hour motion of 285/15 kt. A strong deep-layer ridge extends from northwestern Mexico to just east of the Hawaiian Islands, and this feature should steer Jimena generally westward during the next 48 hours. A weakness is expected to develop in the ridge by 72 hours, which should turn the cyclone west-northwestward through day 5. The track guidance has shifted slightly southward during the first 48 hours, and the updated NHC track forecast follows suit but still lies a little north of the model consensus. The updated forecast is largely unchanged from the previous one after 48 hours. FORECAST POSITIONS AND MAX WINDS INIT 27/1500Z 12.4N 117.7W 40 KT 45 MPH 12H 28/0000Z 12.7N 119.7W 50 KT 60 MPH 24H 28/1200Z 13.0N 122.1W 65 KT 75 MPH 36H 29/0000Z 13.1N 124.2W 80 KT 90 MPH 48H 29/1200Z 13.1N 126.1W 90 KT 105 MPH 72H 30/1200Z 13.9N 129.6W 105 KT 120 MPH 96H 31/1200Z 15.5N 134.0W 115 KT 130 MPH 120H 01/1200Z 17.0N 137.5W 115 KT 130 MPH $$ Forecaster Berg NNNN