000 WTPZ41 KNHC 130845 TCDEP1 HURRICANE ORLENE DISCUSSION NUMBER 10 NWS NATIONAL HURRICANE CENTER MIAMI FL EP162016 200 AM PDT TUE SEP 13 2016 Recent microwave images suggest that there has been some erosion of the southern portion of the eyewall overnight, and the overall satellite presentation of the hurricane has continued to gradually degrade. The eye has become cloud filled in infrared satellite pictures and the convective tops surrounding the eye have warmed overnight. Despite the recent loss of organization, a blend of the subjective and objective Dvorak T- and CI-numbers yields an initial intensity estimate of 90 kt. The leveling-off of Orlene's intensity appears to have been caused by 15-20 kt of south-southwesterly shear as diagnosed by a UW/CIMSS shear analysis. The shear conditions are not expected to change much today. Meanwhile, Orlene is forecast to move very slowly during the next 36 h, which is likely to cause upwelling of cooler waters. These conditions are expected to cause gradual weakening during the next day or so. After that time, the shear is expected to decrease, but less favorable thermodynamic conditions are likely to continue to contribute to weakening. The new NHC intensity forecast shows a little more weakening during the next 2-3 days, but is close to the previous advisory thereafter. This is in good agreement with the latest Florida State Superensemble and close to the IVCN consensus model. It appears that the hurricane is beginning to slow down as anticipated, with an estimated initial motion of 360/4 kt. Orlene will be within an area of light steering currents during the next day or so, and only a slow northward motion is anticipated today. By Wednesday, a subtropical ridge to the north of the hurricane is forecast to strengthen, which should begin to steer Orlene westward at a faster rate of speed. Near the end of the forecast period, the models begin to diverge, with the latest GFS now taking a stronger system more poleward, while the ECMWF shows a weaker Orlene moving more westward. Since this is a flip-flop in the models from the previous runs, the NHC track maintains the more westward solution, and is close to the GFS ensemble mean and the multi-model consensus. FORECAST POSITIONS AND MAX WINDS INIT 13/0900Z 19.2N 118.9W 90 KT 105 MPH 12H 13/1800Z 19.7N 118.9W 80 KT 90 MPH 24H 14/0600Z 20.1N 119.0W 70 KT 80 MPH 36H 14/1800Z 20.2N 119.7W 60 KT 70 MPH 48H 15/0600Z 20.2N 121.1W 55 KT 65 MPH 72H 16/0600Z 19.9N 125.6W 45 KT 50 MPH 96H 17/0600Z 19.7N 130.5W 45 KT 50 MPH 120H 18/0600Z 20.0N 134.3W 40 KT 45 MPH $$ Forecaster Brown