(above) 5-Day Forecast Cone map issued at 11 p.m. HST on Saturday night, courtesy the National Weather Service.

HILO, Hawaii – A category 2 hurricane 1,565 miles east of Hilo is being monitored closely as it heads in the direction of Hawaii. With 110 mile per hour winds, Iselle is nearly a major hurricane, according to the National Weather Service.

“The overall satellite presentation of Iselle hasn’t changed much during the past several hours, with strong convection in the eyewall and an eye which is intermittently obscured by cirrus clouds,” wrote the National Weather Service in its 11 p.m. discussion. “Satellite intensity estimates have not changed significantly, so the initial wind speed will remain 95 kt.”

Meterologists predict the storm will weaken before its predicted arrival by the end of the week. The most recent 5-Day Forecast Cone map shows Iselle as a Tropical Storm when it meets the Big Island Thursday night / Friday morning. But meteorologists speak of possible “pitfalls” for that prediction in their discussion.

Although Iselle is probably near peak intensity, it still has a short window of time today to become a major hurricane. It is not likely to strengthen much, however, due to Iselle moving closer to a less favorable thermodynamic environment. Since wind shear is forecast to remain low, only gradual weakening is anticipated after today while Iselle moves over marginal SSTs for the next couple of days. One possible pitfall of this forecast is that, given the forecast storm environment, Iselle could evolve into an annular hurricane, which could delay the weakening during that time. Late in the period, an increase in both shear and drier air aloft will probably help to weaken the storm while it approaches the Hawaiian Islands. The official NHC intensity forecast is close to the previous one and the intensity consensus.

The cyclone continues to move westward or 275/9. A subtropical ridge north of Iselle should steer the storm on this general path for the next few days, with a slight deceleration expected in a day or so due to the ridge temporarily weakening. Guidance is in very good agreement through day 3, and the NHC forecast through that time us basically an update of the previous one. After that time, Iselle should move on a more west-northwestward heading at a faster forward speed due to the ridge rebuilding. The model guidance has shifted northward on this cycle, which seems reasonable given the forecast synoptic pattern, and the official forecast is moved in that direction. It should be noted that the bulk of the guidance is north of the latest NHC forecast at long range, and further adjustments in that direction could be required on later forecasts.National Weather Service

The State of Hawaii will be keeping a close eye on the storm over the next week.