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Hurricane Hector Forecast Discussion Number 12
2018-08-03 16:47:32| National Hurricane Center (East Pacific)
Issued at 800 AM PDT Fri Aug 03 2018 753 WTPZ45 KNHC 031447 TCDEP5 Hurricane Hector Discussion Number 12 NWS National Hurricane Center Miami FL EP102018 800 AM PDT Fri Aug 03 2018 The satellite presentation of Hector has degraded over the past several hours, with only occasional hints of an eye in the latest imagery. More notably, an AMSR2 microwave pass at 0945Z shows a secondary eyewall structure beginning, with a ring of convection noted at about a 30 n mi radius. All these data indicate that Hector has weakened, so the initial wind speed is conservatively reduced to 80 kt, near or just above the latest Dvorak estimates. The current northeasterly shear is forecast to abate by the numerical models during the next 12 hours, which would normally lead to a restrengthening of Hector. However, the secondary eyewall formation throws a wrinkle into the forecast, since that process usually takes longer than that amount of time. As a compromise, gradual intensification is shown starting tomorrow, with a small uptick on Sunday as Hector reaches warmer waters in a light-shear environment. The HWRF and HMON still show Hector becoming a major hurricane, so it is too soon to abandon that forecast. The new forecast is a blend of the latest corrected-consensus guidance and the previous forecast, resulting in about a 10-kt reduction from the last NHC prediction. Slow weakening is shown at the end of the forecast due to cooler SSTs and potential entrainment of drier mid-level air. The initial motion remains 270/10 kt. A large subtropical ridge should steer the hurricane westward for the next couple of days, then a weakness in the ridge develops, which should cause a more west-northwestward track. The model guidance suite is a little slower than yesterday, about 1 or 2 kt overall. While that doesn't sound like much, over the course of a forecast that could change the final cyclone position by a few degrees, so it is meaningful. In this particular case, a slower solution turns Hector to the west-northwest earlier in the forecast, since the hurricane feels the developing weakness to the north-northeast sooner. The new NHC track forecast follows the trend of the model consensus and is adjusted slightly to the north. FORECAST POSITIONS AND MAX WINDS INIT 03/1500Z 14.1N 128.8W 80 KT 90 MPH 12H 04/0000Z 14.2N 130.4W 80 KT 90 MPH 24H 04/1200Z 14.2N 132.4W 85 KT 100 MPH 36H 05/0000Z 14.1N 134.5W 90 KT 105 MPH 48H 05/1200Z 14.2N 136.6W 100 KT 115 MPH 72H 06/1200Z 15.1N 141.4W 100 KT 115 MPH 96H 07/1200Z 16.3N 146.7W 90 KT 105 MPH 120H 08/1200Z 17.0N 152.0W 85 KT 100 MPH $$ Forecaster Blake
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