WTPZ45 KNHC 080247

800 PM PDT THU AUG 07 2014

Despite a marginal environment, Julio has become better organized over the past several hours with warming temperatures in the eye and strong convection in the eyewall. Subjective and objective Dvorak estimates from all agencies suggest that the intensity has increased to at least 100 kt, so the initial wind speed is raised to that value.

With few outer bands and a symmetric structure around the eye, Julio now appears to have become an annular hurricane, much like Iselle in the same general area a few days ago. While guidance is generally showing a steady or quick weakening, these hurricanes are known to be more resilent to marginal environments than most. Since little change is expected to the SSTs or shear for the next day or so, it makes sense to go above the model guidance at that time with the current annular structure, and the NHC prediction is raised from the previous one. An increase in westerly shear after that time could cause Julio to transition into a more conventional cyclone structure, so the intensity forecast is blended with the previous interpolated forecast and the model consensus. At long range, although the SSTs are forecast to rise, there could also be an increase in shear. With the large uncertainty, little change is made to the extended-range intensity prediction.

Julio is moving at about 280/14. There has been no change to the forecast synoptic pattern with the hurricane expected to remain south of the subtropical ridge for the next few days, with a westward turn at long range due to the ridge strengthening. Track guidance is in better agreement than the last cycle, with even the GFDL model, formerly an outlier solution near Hawaii, shifting northward away from the islands. The new NHC prediction is adjusted a bit to the north at longer range, close to the model consensus, although most of the better performing individual models are still farther north. It should be noted that data from a NOAA G-IV jet synoptic surveillance mission for Julio should be included in the 0000 UTC model runs.

Julio is expected to move into the Central Pacific Hurricane Center's area of responsibility by 0900 UTC and will issue the next advisory on this system.


INIT 08/0300Z 17.4N 139.1W 100 KT 115 MPH 12H 08/1200Z 17.8N 141.4W 100 KT 115 MPH 24H 09/0000Z 18.5N 144.3W 95 KT 110 MPH 36H 09/1200Z 19.4N 147.1W 85 KT 100 MPH 48H 10/0000Z 20.6N 149.9W 75 KT 85 MPH 72H 11/0000Z 22.9N 154.7W 65 KT 75 MPH 96H 12/0000Z 24.2N 159.2W 60 KT 70 MPH 120H 13/0000Z 25.0N 163.0W 60 KT 70 MPH

$$ Forecaster Blake