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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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