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Hurricane Norman Forecast Discussion Number 14
2018-08-31 16:38:59| National Hurricane Center (East Pacific)
Issued at 800 AM PDT Fri Aug 31 2018 619 WTPZ41 KNHC 311438 TCDEP1 Hurricane Norman Discussion Number 14 NWS National Hurricane Center Miami FL EP162018 800 AM PDT Fri Aug 31 2018 Norman appears to be undergoing an eyewall replacement cycle. Although a lack of earlier microwave imagery hasn't helped to support this speculation, enhanced infrared BD-Curve images, however, revealed a collapse of the inner core in the northeast quadrant several hours ago. Currently, that portion of the eyewall has begun to fill in with a solid ring completely surrounding the eye, albeit, rather thin. Consequently, subjective and objective T-numbers, as well as an earlier SATCON analysis, support a slight decrease of the initial intensity to 115 kt. Further slow weakening is forecast through the entire period, although there could be fluctuations in the short-term due to the aforementioned inner core structure evolution. There also appears to be some modest northeasterly shear impinging the northeast portion of the cyclone, which could hamper strengthening. The Decay SHIPS intensity model indicates that the shear will persist during the next couple of days. Through the remaining part of the forecast, decreasing SSTs and the intrusion of a more stable/drier environment from the north should lead to further weakening. The NHC forecast is similar to the previous one, and follows the NOAA-HCCA and IVCN intensity consensus models. The initial motion is estimated to be west-southwest, or 245/7 kt. The cyclone's motion is currently influenced by a northeast-southwest oriented mid-to-upper tropospheric ridge residing between Hurricane Miriam to the west, and Norman to the east. This current motion is expected to continue for the next 36 hours, or so. Afterward, the ridge between the two tropical cyclones is expected to weaken as Miriam continues on a generally northward track. This change in the synoptic steering pattern should cause Norman to turn to the west and then west-northwest with an increase in forward speed. The official forecast has changed little over the past 6 hours and is based on a blend of the HCCA and TVCN consensus models. FORECAST POSITIONS AND MAX WINDS INIT 31/1500Z 16.7N 120.8W 115 KT 130 MPH 12H 01/0000Z 16.4N 122.0W 105 KT 120 MPH 24H 01/1200Z 16.2N 123.8W 100 KT 115 MPH 36H 02/0000Z 16.3N 125.9W 95 KT 110 MPH 48H 02/1200Z 16.8N 128.6W 90 KT 105 MPH 72H 03/1200Z 18.3N 134.4W 80 KT 90 MPH 96H 04/1200Z 19.5N 140.0W 70 KT 80 MPH 120H 05/1200Z 20.5N 144.0W 60 KT 70 MPH $$ Forecaster Roberts
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