Hurricane Hector Discussion Number 30
Wiki-Hurricanes Forecast Center
5:00 AM HST Wed Aug 8 2018
Hector continues to very slowly taper off this morning as it tracks towards the west. The well-defined eye is still apparent on infrared imagery but is now clouded in. Nonetheless, the eye is still surrounded by an annulus of cold cloud tops below -70°C. Outflow, particularly poleward, remains quite impressive transverse cirrus banding extending well past Hawaii. The final pass of a reconnaissance mission into the storm that concluded at 1034Z found flight-level winds of 134 kt but only documented 102 kt surface winds to match. While the flight level winds would traditionally be supportive of a 120 kt intensity, the more marginal sea surface temperatures would indicate less mixing of winds near sea level. Still, strong gusts may occasionally reach the surface, as exemplified by a 9z dropsonde which indicated instantaneous winds of 134 kt in the southern eyewall. For now, Hector's intensity is held at 110 kt, blending between reduced flight-level winds and the observed surface wind assessment.
Satellite and reconnaissance data indicate that Hector has stopped gaining latitude, and in fact may have occasionally wobbled south of west. Steering at this juncture is largely governed by a 591 dm subtropical ridge centered approximately 300 miles northwest of Honolulu, Hawaii. A shortwave trough to the ridge's west is expected to compress the ridge, allowing for a northwest turn in around four to five days. At the end of the forecast window, Hector should be near the International Date Line.
A more chaotic downstream upper-air flow caused by the Hawaiian island chain could give a bit more impetus to Hector's currently slow weakening trend, brough along by marginal sea surface temperatures capping the storm's energy intake, as the hurricane passes south of the islands later today and tomorrow. However, sea surface temperatures are beginning to slowly trend upwards from marginal to favorable, and should be above 27°C in around 48 hours. This should allow Hector to begin anew as reintensification takes place. At around five days, a likely interaction with a tropical upper-tropospheric trough is expected to induce some unfavorable shear over Hector, precipitating in a weakening phase. Not much has changed with environmental parameters, so the intensity forecast provided is indentical to the last advisory.
MAXIMUM WINDS FORECAST
INIT 08/1500Z 110 KT 125 MPH
12H 09/0000Z 105 KT 120 MPH...CLOSEST APPROACH TO HAWAII
24H 09/1200Z 100 KT 115 MPH
36H 10/0000Z 105 KT 120 MPH
48H 10/1200Z 110 KT 125 MPH
72H 11/1200Z 115 KT 130 MPH
96H 12/1200Z 115 KT 130 MPH
120H 13/1200Z 105 KT 120 MPH...APPROACHING INTERNATIONAL DATE LINE