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Nov
30
2011

Hawaii Weather Overview

Light to moderately strong winds,  windward biased showers increasing some near Kauai and Oahu tonight into Thursday, building surf heights on our north and west shores later today…then even larger Thursday and Friday.

PDC Global Hazards Atlas centered on the central Pacific Ocean near Hawaii is displaying 3 hour precipitation accumulations over the last three hours

Hawaiian Weather Synopsis:  There continues to be a few tweaks to the ongoing forecast ideas through the rest of this week, which have now been extended into early next week. The weak cold front that has been slowly moving in our direction to the northwest, is still doing that this afternoon. It will reach Kauai first, bringing an increase in clouds and showers with it tonight, and on to Oahu into Thursday. The other islands will have some windward biased showers too, although they will be thanks to the moisture being carried our way on the generally northeast breezes…rather than the cold front.

Meanwhile, we see the broad swath of high cirrus clouds, which have been over the Big Island, and then south and east of there the last couple of days. This area of icy upper level moisture seems to be slipping further away at the moment, although it could pulse back westward towards us with time. It’s associated with the trough of low pressure that has been migrating westward towards us the last several days. Most of the high stuff over the islands this afternoon are part of the cirrus area to our north and west, which provided a nice colorful sunrise this morning…and will likely do that again for sunset this evening.

Several of the computer forecast models are showing a rather deep trough of low pressure forming to the west of the state later  this weekend. There are various iterations of how this will affect our islands, and especially the Kauai end of the island chain. It appears that that side of the Aloha state could eventually become wet, perhaps very wet. The dry side of the state then could be Maui County and the Big Island. It’s still a little early to be nailing anything down in this regard, so perhaps we should let the models spin out a few more ideas before we settle on one or the other. We still have several days to fine tune this possible rainy weather for early next week.

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 very strong 1042 millibar high pressure system located far to the northeast of the Hawaiian Islands Wednesday afternoon.  This high pressure cell is not too offshore from the Strait of Juan de Fuca, between Vancouver Island, BC…and Washington. This high pressure cell has an elongated ridge of high pressure extending southwest from its center, into the area northeast of our islands.  At the same time, we see a 1014 millibar low pressure system to the north of Hawaii. This low has a cold front front running from its center southwest to near the International Dateline. Finally, there’s a trough of low pressure just  to the east of the islands, which  is slowly migrating westward.

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

32                 Barking Sands, Kauai – NNE
14                 Kahuku, Oahu – ENE
18                 Molokai – NE
16                 Kahoolawe – E
15                 Lip0a, Maui – NE
30                 Lanai – NE
20                 Kealakomo, Big Island – NNE

We can use the following links to see what’s going on in our area of the north central Pacific Ocean early Wednesday afternoon. Looking at this NOAA satellite picture we find that high and middle level cloudiness is located in most directions, over the ocean…as well as moving over the state from the west too. We can use this looping satellite image to see low clouds being carried over the islands on the trade wind flow here and there. At the same time, we find a considerable amount of thunderstorm activity far to our southwest over the ocean, with high cirrus clouds flying off the tops of those clouds in a large swath moving by to the southeast of the Big Island. Checking out this looping radar image we see very few light showers falling locally over the ocean, not many of which are reaching our shores or mountains,

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

1.33               Kilohana, Kauai
1.11               Moanalua RG, Oahu
0.12               Molokai
0.00               Lanai
0.12               Kahoolawe
0.18               Ulupalakua, Maui
0.17               South Point, 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:   Surf along the east shores will remain active into mid-week…gradually dropping into Thursday. The north shores will be rising again Wednesday as a new north-northwest swell arrives into Thursday. The west sides will be rising Wednesday along those beaches that have a favorable northerly orientation. South shores will be small, gradually rising a bit.

North shores –  A new north-northwest swell will arrive during the day Wednesday into Thursday…reaching high surf advisory.

West shores –  These beaches will be on the rise as a new north-northwest swell arrives, lasting for several days…largest surf along those beaches that have a more northerly exposure.

South shores –   Small surf through mid-week prompted by an out of season south swell, becoming somewhat larger later Thursday or Friday…into the weekend 

East shores –  Surf remaining active with wind swell waves Wednesday…although gradually lowering in size.

NOAA animated wave model