ZCZC MIATCDEP3 ALL TTAA00 KNHC DDHHMM HURRICANE JIMENA DISCUSSION NUMBER 12 NWS NATIONAL HURRICANE CENTER MIAMI FL EP132015 800 AM PDT SAT AUG 29 2015 Convective cloud tops in the central dense overcast have warmed since the last advisory, but the 10-15 n mi wide eye remains distinct. An 0913 UTC GCOM overpass clearly indicated that the formation of a secondary outer eyewall was almost complete, which could be a harbinger that Jimena will soon go through an eyewall replacement. Dvorak Current Intensity estimates at 1200 UTC were 6.0/115 kt from TAFB, 6.5/127 kt from SAB, and 6.8/135 kt from the CIMSS ADT, and the initial intensity is held at 130 kt. This advisory continues to show the possibility of Jimena reaching category 5 intensity during the next 24 hours since the environment remains conducive for strengthening. However, if Jimena does go through an eyewall replacement soon, then fluctuations in intensity are likely to occur, and the hurricane could actually weaken a bit in the short term. The intensity forecast is somewhat challenging after 24 hours. Vertical shear is expected to remain low, and sea surface temperatures remain above 26C through the forecast period, but the hurricane models show a general decay to a category 1 or 2 cyclone by day 5. On the other hand, the global models, particularly the GFS and ECMWF, seem to take more advantage of the favorable environment and retain central pressures that would support a category 3 or 4 hurricane through day 5. Therefore, the NHC intensity forecast shows a much slower decay than indicated by the hurricane models, keeping Jimena as a major hurricane through day 4. Jimena's eye has been wobbling around, but the longer-term motion estimate is 275/7 kt. The ridge to the north of the hurricane appears to be weakening, and Jimena is expected to turn west-northwestward later today. This trajectory should continue through day 5, with a decrease in forward speed by days 4 and 5 when the steering currents become much weaker. The track guidance is still in good agreement on the future track, and the updated NHC forecast is similar to, but slightly faster than, the previous forecast after 24 hours. FORECAST POSITIONS AND MAX WINDS INIT 29/1500Z 12.5N 125.6W 130 KT 150 MPH 12H 30/0000Z 13.0N 127.0W 135 KT 155 MPH 24H 30/1200Z 13.9N 129.1W 140 KT 160 MPH 36H 31/0000Z 14.7N 131.5W 135 KT 155 MPH 48H 31/1200Z 15.4N 133.9W 130 KT 150 MPH 72H 01/1200Z 16.5N 137.9W 115 KT 130 MPH 96H 02/1200Z 17.1N 140.5W 100 KT 115 MPH 120H 03/1200Z 17.6N 142.1W 90 KT 105 MPH $$ Forecaster Berg NNNN