Issued: Mar 08, 2014 4:00 AM HST
A cold front near the Big Island will continue to bring clouds and precipitation to the state toady. Rainfall chances will remain highest along windward terrain. Trade winds will spread across the the state behind the front and will persist through most of next week. Another frontal system may reach the area next weekend. Large and hazardous surf is expected along north facing beaches through the weekend.
Even though much of the cloud band associated with the cold front is covering mainly the smaller islands early this morning, vertical wind profile data from radar on the Big Island suggested the front has already reached that island. The front did bring measurable precipitation to the smaller islands, though not enough pose any problem. Looks like Big Island will see the least of the rainfall amounts from this system. There are still moisture persisting across the island chain, and will provide some showers, especially for the windward and mountain areas today. The mid and high level clouds associated with the system are expected to slowly clear the state from the east later today, as the associated upper level trough moves east of the islands. Northerly winds behind the front will spread across the islands as well, and will turn more easterly as a surface high pressure currently northwest of the state moves east later today.
Trade wind weather is expected to return to the islands next week, with clouds and showers affecting mainly windward and mountain areas, while afternoon convection may affect the lee areas of the Big Island as well. Forecast charts still indicate an upper level trough will deepen east of the state beginning Tuesday, though its main axis will locate a little further east than earlier model runs. Therefore its effect on the islands weather will be limited, with possible enhanced rainfall for the state Monday and Tuesday. The strong upper level jet expected along the western flank of the deepening system may bring windy conditions to the Big Island summits as well.
Trade winds are expected to weaken a tad Monday, as the surface high pressure moves far northeast of the state. Another surface high pressure from the northwest will pass the islands later next week, and will provide stronger trade winds to the islands beginning Tuesday.
Model runs still suggest another frontal system will approach the state next weekend, bringing possible wet weather to the islands again. The difference with this pending system from the others is that it looks more like a shear line when it reaches the state, with the present of a strong surface high pressure system behind the front. Both the european model as well as GFS are in quite good agreement on this weather scenario. Therefore trade winds are expected to hold even as this system approaches the islands, and become rather strong over the state by the later part of next weekend.
The incoming northerly swell has reached Oahu early this morning and will continue to spread to the rest of the islands through the today. In fact, this swell is expected to peak today then slowly subside tonight. A high surf warning remains in effect through early Sunday morning for north and west facing shores for most of the smaller islands.
A small craft advisory remains posted for all waters exposed to the incoming northwest swell through noon Sunday. Trade winds may become strong enough by the later part of next week to bring small craft conditions to the coastal waters, at least in the channels. The islands will probably see strong enough trade winds to warrant small craft advisory for all waters by next weekend, with possible gale conditions for the usual windy channels.
Weakening frontal boundary has stalled over the state this morning. An upper trough passing overhead continues to produce broken to overcast layered clouds in the vicinity of the front from Kauai to the Alenuihaha channel. The trough is moving east and Kauai should be seeing a decrease in clouds later this morning. Expect the central islands to continue seeing some MVFR and isol IFR ceilings and visibilities through today with improving conditions tonight.
Airmet sierra for mountain obscuration currently remains in effect from Kauai to Maui with Kauai expected to be the first to improve later this morning. Soundings still indicate enough moisture in the mid levels to lead to some light to moderate icing, mainly between 15k and 18k ft. Thus airmet for icing exists for Maui county and Oahu.
High surf warning until 6 am HST Sunday for Niihau, Kauai windward, Kauai leeward, Waianae coast, Oahu north shore, Oahu Koolau, olomana, Molokai, Maui windward west, windward Haleakala.
Small craft advisory until noon HST Sunday for all zones except Maalaea Bay.