Hawaii Weather Synopsis: A strong high north of the area will maintain locally strong and gusty trade winds. The winds will gradually weaken starting tomorrow as the high moves east and weakens. Meanwhile, a low aloft will remain near the islands and keep the weather unsettled. The trailing end of a frontal band will move over the islands tonight and produce increasing showers and possible thunderstorms through Friday. The threat of heavy showers will decrease starting Saturday.
A Winter Weather Advisory is in effect from this evening through Friday morning for the summits of Mauna Kea and Mauna Loa.
A High Surf Advisory is in effect through Sunday afternoon for east facing shores of Kauai, Oahu, Molokai, Maui and the Big Island.
A Wind Advisory is in effect this afternoon for Molokai windward, Lani, Maui windward west, Maui leeward west, Maui central valley, leeward Haleakala, south Big Island, Big Island north and east, Kohala.
A Gale Warning is in effect through this afternoon for Pailolo and Alenuihaha channels and Big Island southeast waters.
A Small Craft Advisory is in effect through Friday afternoon for all remaining coastal waters.
Click on the following link for the latest National Weather Service advisories and warnings: Wind/Surf/Flood related advisories or warnings
Broad Overview of Hawaii’s Weather
Based on the NWS Area Forecast Discussion for Hawaii, issued 10 Nov 2011 at 1000am HST
A strong 1035mb high lies about 1150 miles north of Kauai near 38°N 156°W. The global models are in good agreement showing the high remaining nearly stationary and weakening slightly through Friday night, then moving away slowly to the east. A wind advisory for windy areas of Maui county and the Big Island and a gale warning for the Pailolo and Alenuihaha channels will remain up through this afternoon. As the high weakens a bit and the winds weaken over night we expect to be able to cancel the wind advisory and gale warning, but it will remain quite breezy and the small craft advisory will remain up.
Meanwhile, water vapor imagery and upper air analyses show a blocking pattern aloft with a high about 700 miles north of Kauai near 33°N 160°W and a low about 275 miles south of Oahu near 17°N 159°W. The low is forecast to move slowly north northeast over the next several days. Cold air aloft associated with the low is making the atmosphere unstable over the main Hawaiian islands.
The instability over the islands has been making the weather rather showery, since clouds riding in on the strong trades can built up high enough to produce locally heavy showers. There are currently no well organized low level features over the islands to focus shower activity, but that will change tonight. A band of showery low clouds and towering cumulus clouds associated with a shear line is north of a line from 22°N 150°W to 225 miles north of Hilo to 60 miles north of Kauai. This cloud band will reach the islands late tonight bringing more and heavier showers. The increased low level moisture will also bring a slight chance for thunderstorms tonight and Friday and an increased chance of snow on the summits of Mauna Kea and Mauna Loa. We have issued a winter weather advisory for the summits.
As the low aloft moves northeast and weakens, temperatures aloft will become less cold and the atmosphere will become more stable. As the shear line breaks up and moves off to the southwest low level moisture will decrease. And as the strong surface high moves east the trade winds will gradually weaken. Moderate trade winds and a more typical trade-wind weather pattern will prevail for the first half of next week.
Marine Forecast: Gale warnings remain in effect for the Pailolo and Alenuihaha channels and southeast Big Island waters. The winds will continue to be funneled and accelerated around the terrain of the islands today. A small craft advisory is in effect for the remaining coastal waters due to the strong winds of 25 knots or greater and combined seas of 10 ft or greater. These conditions will persist today before starting to slowly diminish. The high surf advisory for east facing shores will continue through Sunday. Rough, wind-driven surf and an incoming north northeast swell will create hazardous conditions along exposed east facing shores.
The following numbers represent the strongest wind gusts (mph), along with directions Thursday morning:
28 Lihue Apt, Kauai – NE
28 Bellows AFB, Oahu – ENE
28 Molokai – NE
29 Lipoa, Maui- ENE
24 Lanai – ENE
37 Upolu Airport, Big Island – ENE
Here are the 24-hour precipitation totals (inches) for each of the islands as of Thursday morning:
0.53 Mt. Waialeale, Kauai
0.44 Mililani, Oahu
1.24 Puu Kukui, Maui
2.63 Waiakea Uka, Big Island
Here is the latest NWS rainfall forecast
Here are the latest available satellite images:
SURF ZONE FORECAST – OAHU
NATIONAL WEATHER SERVICE HONOLULU HI
900 AM HST THU NOV 10, 2011
A High Surf Advisory is in effect for east facing shores through 6 pm HST Sunday.
Surf along east facing shores will be 6 to 8 feet through Friday.
Surf along north facing shores will be 3 to 5 feet through Friday.
Surf along west facing shores will be 2 to 3 feet through Friday.
Surf along south facing shores will be 2 feet or less through Friday.
Outlook through Wednesday Nov 16: A long period north northeast swell will arrive Saturday and Sunday. The swell, plus the waves generated by the trade winds, will keep surf above the eight foot advisory level for east facing shores through Sunday.