Hurricane Hector Discussion Number 20
Wiki-Hurricanes Forecast Center
2:00 PM PDT Sun Aug 5 2018
Hector appeared to undergo some sort of internal reconfiguring this morning, perhaps not a typical eyewall replacement cycle, but one where a disconnected main eyewall connects and merges back into a secondary eyewall. This has historically been observed on some occasions within intense tropical cyclones on radar imagery. The hurricane has become more organized since that process completed, with the eye becoming more clear and distinct on visible and infrared channels. High resolution visible imagery reveals the presence of eyewall mesovorticies spinning about in the eye. Microwave data shows that Hector has taken a fairly simplistic two-fold structure: the storm is primarily a strong central dense overcast and a tightly bound rainband to its north. An occasional ring of -70°C cloud tops has completely encircled the eye, reflective of intensification. UW-CIMSS ADT estimates have increased once again T6.0/115kt in reflection of recent satellite improvements. A supportive SATCON consensus of 112 kt and consensus SAB and TAFB estimates of T6.0/115kt give plenty of rationale to increase Hector to 115 kt once again, making it a Category 4 hurricane.
There are no new developments to speak of regarding track and intensity forecasts. We continue to anticipate the same west-northwest to west track noted in earlier advisories, shaped by a weakening and restrengthening of the subtropical ridge north of Hawaii. Hector has kept a more direct westerly path for slightly longer than expected, but is well in line of the ensemble spreads and thus no change is anticipated. The most likely scenario remains a 50-150 nautical mile pass south of Hawaii, and gusty winds, fringe rainband effects, and rough surf are the current expected slate of impacts for Big Island, with rough surf for all Hawaiian islands anticipated.
Conditions remain marginal for development, but Hector is doing well with the current environment. The next 24 hours provide the best opportunity for short-term strengthening before the hurricane tries to hold steady in challengingly dry conditions as it nears Hawaii. As models refine their track assessments south of Hawaii, it appears that there are some indications that Hector could avoid downsloping winds from Big Island and find itself in more favorable conditions, and some synoptic guidance immediately starts to intensify Hector after passing the islands. With some minor tweaks, the intensity forecast philosophy is carried over from the previous advisory.
FORECAST POSITIONS AND MAX WINDS
INIT 05/2100Z 115 KT 130 MPH
12H 06/0600Z 120 KT 140 MPH
24H 06/1800Z 120 KT 140 MPH
36H 07/0600Z 115 KT 130 MPH
48H 07/1800Z 105 KT 120 MPH
72H 08/1800Z 95 KT 110 MPH...CLOSEST APPROACH TO HAWAII
96H 09/1800Z 85 KT 100 MPH
120H 10/1800Z 90 KT 105 MPH