Hawaii Weather Synopsis: Light trade winds will remain through Wednesday with widespread afternoon sea breezes expected over leeward coastlines. Rainfall will remain light. Trade winds with windward showers will return Thursday into early Saturday, before diminishing again on Sunday.
A High Surf Advisory is in effect until 6 pm HST Tuesday evening for Kauai windward, Oahu Koolau, Olomana, Molokai windward, Maui windward west, windward Haleakala, Big Island north and east.
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 18 Oct 2011 at 10:02am HST
A cold front 550 miles northwest of Kauai has reduced the trade winds over the State (see latest weather map). Morning radar shows a few showers moving along with the light trades, but most of the state is under clear skies. This afternoon, clouds will increase as the islands heat up and isolated showers are expected over interior island locations. The synoptic pattern remains in place and light trade winds and sea breezes are in the cards again Wednesday.
The global models have been a bit squirrelly with the location of an upper low on Thursday. Previous runs had the cold pool over the western half of the state, meaning enhanced cloud tops and showers. However, recent model runs have placed the cold pool aloft farther and farther west, and now looks to have little effect on island weather. The current forecast would bring only high clouds over Kauai and Oahu on Thursday.
Trade winds will increase Thursday as high pressure builds far northeast of the state, and windward showers will increase in turn. Moderate trades will remain through Saturday before another cold front approaches the islands from the northwest. This front will again diminish the trades with a possibility of light southeast winds early next week. Forecast confidence is low for this long term forecast due to the aforementioned challenges the models have had recently.
In the marine environment, a northeast swell will bring high surf to east-facing shores through today, but will diminish this evening. A long-period northwest swell is expected Sunday, lasting into next week.
The following numbers represent the strongest wind gusts (mph), along with directions Tuesday morning:
13 Princeville, Kauai – E
15 Bellows AFB, Oahu – N, and Kahuku, Oahu – N
04 Molokai – N
18 Kahoolawe – ESE
15 Kahului, Maui – NNE
09 Lanai – W
21 South Point, Big Island – E
Here are the 24-hour precipitation totals (inches) for each of the islands as of Tuesday morning:
0.47 North Wailua Ditch, Kauai
0.47 Luluku, Oahu
0.05 Kepuni, Maui
0.38 Kahua Ranch, 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 TUE OCT 18 2011
HIGH SURF ADVISORY FOR EAST FACING SHORES
Surf along east facing shores will be 6 to 8 feet today, decreasing to 4 to 6 feet Wednesday.
Surf along north facing shores will be 4 to 6 feet today, decreasing to 3 to 5 feet Wednesday.
Surf along south facing shores will be 3 to 4 feet with locally higher sets through Wednesday.
Surf along west facing shores will be 2 to 3 feet through Wednesday.
Outlook through Monday Oct 24: The current northeast swell will maintain surf around the 8 foot advisory level across east facing shores today. The swell will steadily decline tonight and Wednesday and fade on Thursday. The current south swell will produce moderate surf into Thursday then decline Friday and Saturday. Another small, late-season south swell is possible Monday. A northwest swell will build on Sunday, with north shore surf possibly reaching the 15 foot advisory Sunday night and Monday.