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Dec
14
2011

Hawaii Weather Overview

Still chance of a few localized heavy showers over parts of the Big Island, and perhaps Maui, gradually increasing trade wind speeds Friday into the weekend…rising high surf Friday on the north and west facing beaches…then easterly shores this weekend.

PDC Global Hazards Atlas displaying cloud cover and 3 hour precipitation accumulation...over and around the Hawaiian Islands

Hawaiian Weather Synopsis:  The long lasting high clouds are now exiting the state to the east, which will finally allow more sunshine to beam down, especially along our leeward beaches into Friday. The shower and even heavy rain producing troughs of low pressure, which have been around for the last five days or so, are beginning to lose their influence over the Aloha state. Today should be a transition day for only the eastern side of the chain, with Maui County and the Big Island still prone for at least a few heavier showers…especially during the heat of the afternoon hours. The western islands of Kauai and Oahu are likely free of these showers, or at least the heavy ones.

The winds today are generally in the light to moderately strong range, coming in from south of east in many locations. As the trough(s) of low pressure shift further away, we’ll see our winds rebounding from the trade wind direction…on Thursday. As we get into Friday, and even more so by the weekend…our trade winds will become quite strong and gusty again. As is often the case, we’ll see small craft wind advisory flags being hoisted over those windiest coasts and channels around Maui County and the Big Island. The latest forecasts keep these blustery trades blowing right on into next week. These winds will carry showers onto our windward sides, and perhaps even a few leeward areas on the smaller islands from Kauai to Molokai.

Prognosticating into the future, very likely too far for much accuracy, the Navy’s NOGAPS computer model suggests that we will have good weather, with the trade winds blowing steadily through about the 22nd of December. Checking with the GFS model, it shows the tail-end of a cold front bringing a few windward showers on the 17-18th, this weekend…and then again around the 21st and 22nd…next Thursday and Friday. We can’t put much stock into believing the models that far out into the future, although we can at least think in terms of nothing too unusual coming our way. These things can change of course, especially as we get deeper into these last few days of deep autumn.

Click on the following link for the latest National Weather Service advisories and warnings:   Wind/Surf/Flood related advisories or warnings

Details of Hawaii’s Weather – Wind/Precipitation/Surf

As this weather map shows, we find a 1030 millibar high pressure system located to the northeast of the Hawaiian Islands Wednesday afternoon.  This high pressure cell has an elongated ridge that runs from the center west-southwest to the north and northwest of the state, which will keep our winds blowing. They have taken on a more east-southeast to even southeast orientation, although will gradually become more easterly trade winds through Friday…then strengthening from the trade wind direction this weekend into early next week.

The following numbers represent the strongest wind gusts (mph), along with directions Wednesday afternoon:

15                 Port Allen, Kauai – SE
24                 Bellows, Oahu – ENE
20                 Molokai – NE
20                 Kahoolawe – SE
25                 Kahului, Maui – SE
12                 Lanai – SSE
25                 Upolu Point, Big Island – NE

We can use the following links to see what’s going on in our area of the north central Pacific Ocean Wednesday afternoon. Looking at this NOAA satellite picture we find that just a little of the high and middle level clouds stretch across  a very small part of the Big Island now. We can use this looping satellite image to see this high level moisture streaming up from the southwest…which continues to shift eastward.  Otherwise, skies are clear to partly cloudy elsewhere, with some cloudy areas too. Checking out this looping radar image we see showers over the ocean, most of which are in the light to moderately heavy category, moving over the islands in places locally. Rainfall has backed way off compared to the last several days.

Here are the 24-hour precipitation totals (inches) for each of the islands as of late Wednesday morning:

1.53               Mount Waialeale, Kauai
1.63               Oahu Forest NWR
0.42               Molokai
0.00               Lanai
0.02               Kahoolawe
1.00               Puu Kukui, Maui
1.58               Pahoa, Big Island

Here is the latest NWS rainfall forecast

Here are the latest available satellite images:

Hawaii Infrared satellite image
Animated Satellite image of Hawaii region
Latest satellite image – Close-in visible satellite view
Latest radar image – Looping

SURF OUTLOOK:  The north shores will gradually rise into Thursday. The west sides will gradually rise into Thursday as well…smaller. Surf along the east shores will remain active Wednesday…although gradually smooth out and lower in size into Thursday. South shores will be small to very small.  

North shores –    A new northwest swell will arrive during the day Wednesday into Thursday…lasting for a few days along these beaches. A second NW swell will arrive Friday, keeping the surf up into the weekend.

West shores –    A next batch of waves, although smaller than what we’ll find along our north shores, will arrive later Wednesday into Thursday, with a second northwest swell arriving Friday into the weekend.

South shores –   Surf will remain small to very small on these leeward shores.

East shores –    Surf will remain choppy, although gradually lowering in size and becoming more smooth. As the trade winds increase this weekend, so will the wind swell into early next week.

NOAA animated wave model