Last Updated on Monday, 01 September 2014 05:26
Winds Statewide in a glance ...go HERE (this link is also the 4th drop down under weather)
Sep 01, 2014 4:00 AM HST
A light east-southeast flow is expected to continue today with high pressure remains far northeast , and a surface trough near the islands. Heading towards midweek, light to moderate trades are expected to build in. The light winds will allow afternoon sea breezes to bring localized cloud buildups and a few showers over leeward and interior areas. As the week progresses and the trades strengthen, expect the limited clouds and showers to be focused over the windward slopes. Trade wind showers may increase by Friday as low level moisture rides in on the trades.
The overnight sounding at Hilo showed a low level inversion within 400 ft of the surface. This is similar to an inversion observed yesterday morning, but this morning's is not quite as strong as yesterday's. The strong low level inversion yesterday morning allowed smoke and odors associated with the relatively new lava flow in the Puna district to become trapped near the surface until mid morning when the heat of the day helped to dissipate the inversion. With the morning sounding showing the inversion again, even though not quite as strong, it's very likely similar events will be observed this morning, thus the mention of smoke in the grids. The weaker inversion today may mean it will break up a little sooner than yesterday.
No major changes to the forecast for this morning. The clouds over the Big Island last evening began to break up over the northwest half of the island shortly after midnight, leaving clouds and some showers over the slopes from Hilo to Cape Kumukahi to South Point. This batch of clouds is associated with a weak surface trough draped across the islands of Maui county and the Big Island. These clouds are moving to the west northwest, with the bulk of the clouds expected to pass south of the smaller islands today. The presence of this trough is disrupting the trade wind flow generated by the high pressure system far northeast of the islands.
The models are in good agreement with the high lingering to the far northeast of the islands through much of the week. The surface trough near the islands should start to dissipate and move away from the islands heading into mid week, which will allow the trades to make a return appearance. However, a low northeast of the islands, and a front passing northwest of the islands will help prevent more than light to moderate trades to build back in. As the winds increase, look for clouds and showers to become focused more over the windward slopes. The GFS and ECMWF both show limited low level moisture during the middle of the week, so expect shower activity to be on the light side.
Both models do show additional low level moisture being carried in on the trades at the end of the week. This increased moisture appears to be loosely associated with the remnant of Marie that is passing far northeast of the islands. As such, look for more showers at the end of the week than at midweek.
The near shore buoys continued to show steady readings overnight. The reinforcement to the current south swell started to make an appearance on the 51003 buoy overnight with periodic 15 second energy being picked up. Surf along the south facing shores is expected to remain elevated, but below advisory levels into Tuesday.
A very long period south swell, 20-25 seconds, is due to arrive Tuesday, and build through Wednesday. This swell will likely produce advisory level surf into Thursday.
The long period swell from the east should continue to trend down today. Winds and seas will remain below small craft advisory thresholds for at least the next several days.