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Hurricane Miriam Forecast Discussion Number 15
2018-08-29 22:44:28| National Hurricane Center (East Pacific)
Issued at 200 PM PDT Wed Aug 29 2018 895 WTPZ45 KNHC 292044 TCDEP5 Hurricane Miriam Discussion Number 15 NWS National Hurricane Center Miami FL EP152018 200 PM PDT Wed Aug 29 2018 The satellite presentation of Miriam has significantly improved over the past 12 hours or so. Several microwave images received since the release of the previous advisory revealed a significant increase in organization with convection wrapping nearly completely around the center. Recent visible satellite images have shown hints of an eye, but the surrounding convective tops have warmed somewhat. Subjective and objective Dvorak intensity estimates all support hurricane strength, and the initial intensity is increased to 65 kt for this advisory. Satellite fixes show that Miriam has slowed down and is moving westward or 270/8 kt. The hurricane is near the western edge of the subtropical ridge and is forecast to turn west-northwestward very soon. A large mid- to upper-level trough located northeast of the Hawaiian Islands should cause Miriam to turn northwestward, then northward over the next couple of days, and the dynamical models are in good agreement through 72 hours. After that time, model differences remain as the ECMWF continues to take a deeper cyclone much faster northward than the remainder of the guidance. The NHC forecast continues to lean toward the solution of a weaker cyclone turning northwestward or west-northwestward near the end of the forecast period. The updated NHC forecast is once again south of the model consensus at days 4 and 5 and is in best agreement with the GFS ensemble mean. Miriam has about another 12-24 h over warm water and within a light to moderate wind shear environment in which to strengthen. After that time, a significant increase in southwesterly shear is anticipated and Miriam is forecast to weaken fairly quickly between 36 and 72 hours. Miriam should reach SSTs below 26C by 96 h and should degenerate into a remnant low by that time. Miriam will move into the Central Pacific Basin shortly and this is last NHC advisory on this system. Future information on Miriam can be found in advisories issued by the Central Pacific Hurricane Center beginning at 5 PM HST (0300 UTC), under AWIPS header HFOTCPCP3, WMO header WTPA32 PHFO, and on the web at http://www.prh.noaa.gov/cphc FORECAST POSITIONS AND MAX WINDS INIT 29/2100Z 14.0N 139.7W 65 KT 75 MPH 12H 30/0600Z 14.4N 140.7W 70 KT 80 MPH 24H 30/1800Z 15.3N 141.3W 75 KT 85 MPH 36H 31/0600Z 16.7N 141.5W 70 KT 80 MPH 48H 31/1800Z 18.4N 141.5W 60 KT 70 MPH 72H 01/1800Z 21.5N 142.7W 40 KT 45 MPH 96H 02/1800Z 24.7N 145.5W 30 KT 35 MPH...POST-TROP/REMNT LOW 120H 03/1800Z 27.0N 149.5W 25 KT 30 MPH...POST-TROP/REMNT LOW $$ Forecaster Brown
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