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Hurricane ORLENE Forecast Discussion Number 9
2016-09-13 04:49:17| National Hurricane Center (East Pacific)
Issued at 800 PM PDT MON SEP 12 2016 000 WTPZ41 KNHC 130249 TCDEP1 HURRICANE ORLENE DISCUSSION NUMBER 9 NWS NATIONAL HURRICANE CENTER MIAMI FL EP162016 800 PM PDT MON SEP 12 2016 Orlene's rapid intensification episode has been interrupted. Satellite imagery indicates some erosion of the cyclone's deep convection, primarily over the northeastern quadrant of the circulation. The eye has also become cloud-filled and indistinct. A 2324 UTC SSM/I overpass suggested that an eyewall replacement is underway, which could be the reason for the cyclone's somewhat degraded satellite appearance. The latest satellite classification from TAFB was T4.5/77kt and the UW-CIMSS ADT is around that value. A blend of these data with Dvorak CI-numbers yields an initial intensity estimate of 90 kt. Orlene has wobbled a little east of due north during the last several hours, but an estimate of the cyclone's longer-term initial motion estimate is 360/05. The hurricane is about to enter a col region, which should result in a northward or north-northwestward drift during the next 24 hours or so. The subtropical ridge is expected to re-strengthen in about 2 days, causing Orlene to turn south of due west with a substantial increase in forward speed. By 120 hours, the model spread begins to widen, with the ECMWF farther north and slower compared to the faster and more southern GFS. This difference arises due to the models' handling of a strong mid- to upper-tropospheric cyclone around 140W. The ECMWF shows this feature farther south and stronger while the GFS maintains the subtropical ridge north of Orlene. The NHC track forecast is not much different than the previous one, but a little slower by day 5 as a result of the increasing track uncertainty. With an eyewall replacement in progress, Orlene should continue to slowly weaken. The cyclone will likely not be able to recover either since it should come to a halt over a region where the oceanic heat content rapidly drops off. Orlene's slow motion should induce significant oceanic upwelling, which could accelerate the rate of weakening during the next day or two. After that time, the cyclone will encounter an environment of critically low moisture, which should promote additional slow weakening. The new NHC intensity forecast is reduced relative to the previous one and is near the latest multi-model consensus. FORECAST POSITIONS AND MAX WINDS INIT 13/0300Z 18.7N 119.1W 90 KT 105 MPH 12H 13/1200Z 19.2N 119.1W 90 KT 105 MPH 24H 14/0000Z 19.7N 119.2W 80 KT 90 MPH 36H 14/1200Z 19.9N 119.7W 70 KT 80 MPH 48H 15/0000Z 19.8N 120.9W 60 KT 70 MPH 72H 16/0000Z 19.3N 125.0W 50 KT 60 MPH 96H 17/0000Z 18.9N 130.2W 45 KT 50 MPH 120H 18/0000Z 19.0N 133.7W 40 KT 45 MPH $$ Forecaster Kimberlain
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