Daily WeatherJan 27, 2015 4:00 AM HST
Synopsis...A front 480 miles northwest of Kauai is moving southeast at 15 mph.
Light trade winds will become more southerly as a weak front approaches the state through Wednesday. From Thursday into Friday, this front will spread light rain and weak northwest winds across the state. Light trade winds will return, and conditions will dry, slowly over the weekend. A stronger front may approach the islands early next week.
Wind speeds dropped off rather quickly overnight around the state, but cloud motions upwind suggested that the trade winds might pick up a little by this afternoon, though remaining below the criteria for a small craft advisory. The longer trend should move toward even lighter winds through mid-week.
Aloft, broad ridging prevailed over the state, crushing the inversion down to below its usual height. The air mass remained quite dry, but stable stratocumuli persisting upwind moved ashore locally along windward slopes. These stable clouds produced little rain, limited almost exclusively to windward slopes.
Guidance predicted only gradual change today and tonight, but by Wednesday winds will turn southerly ahead of a feeble front approaching from the northwest. This feature should advance southeast across the state from Thursday into Friday. Consensus predicted little water vapor to accompany the front, and the broad mid-level trough expanding southeast over the islands at the same time will provide most of its support to the north of the islands. Thus, relatively little rain will accompany the front, and northwest winds behind it should be fairly light as well. Light trade winds will recover gradually over the weekend, but lingering moisture will continue to support showers, perhaps producing more rain than the front itself.
By Monday, most solutions predicted a second, stronger front to approach from the northwest, turning winds southerly again ahead of it. Guidance disagreed somewhat about how much support this feature will receive from aloft, but generally portrayed much more abundant water vapor accompanying it than the first front. More recent guidance also agreed better in predicting this second front to move southeast down the archipelago starting Monday night.
Vfr conditions will prevail across the state today. Windward sections of all islands may see isolated MVFR ceilings at times through the day, and Lanai could see periods of MVFR cigs this afternoon.
Airmet tango for low level turbulence remains in effect to the south through west of higher terrain on Maui and the Big Island. Models suggest that trade wind flow will continue to weaken today, and this airmet will probably be dropped sometime this morning.
Airmet sierra for mountain obscuration has been dropped, with ceilings running generally above 4000 feet across windward areas.
Wind speeds over the coastal waters diminished substantially overnight, and so the small craft advisory has been cancelled.
The next incoming northwest swell likely will produce advisory-level surf heights along north- and west-facing shores from tonight through Thursday. Another large northwest swell is expected to arrive Friday, and then continue through Sunday. In addition to the surf, these swells threatened to build seas to above the threshold for a small craft advisory.
Small craft advisory through 600 pm Thursday for all Hawaiian waters except Maalaea Bay.
Advisory and Warning Criteria
Location Advisory Warning
North-Facing Shores 15 Feet (8') 25 Feet
West-Facing Shores - Big Island 8 Feet (4'+) 12 Feet
West-Facing Shores - Remaining Islands 12 Feet (7') 20 Feet
South-Facing Shores 8 Feet (4'+) 15 Feet
East-Facing Shores 8 Feet (4'+) 15 Feet