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Nov
25
2011

Hawaii Weather Overview

A weak cold front will bring showers tonight into Saturday night, with unusually strong northeast winds flooding into the state in its wake.

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

Hawaiian Weather Synopsis:  The main thing that we’ll need to look out for this weekend will be the gusty northeast winds, which will feel a bit cool too. These will trigger small craft wind advisories over all of our local coasts and channels…along with possible gale warnings in at least some of the major channels around the state. The islands themselves won’t be immune from these blustery and chilly winds, with wind advisories possible over at least some part of the state, and even up high over the mountains on both Maui and the Big Island. This isn’t your ordinary strong and gusty wind event, which happens so often here in the Aloha state. This looks like it could be one of the possible strongest blows we seen in a while. It’s not often that the NWS talks about gale warnings and wind advisories in the same breath.

As this weather map shows, we have a big near 1033 millibar high pressure system up to the northwest, which will quickly blast eastward. This moderately strong high pressure cell will be in the area north of Hawaii by this time Saturday. The clockwise rotation of this high  will bring air down from the area near Alaska, thus the good chance of cooler weather this weekend. At the same time we need to bring the words wind chill into play as well, and the very dry character of the winds too. These will team up to drop our air temperatures both Saturday and Sunday several degrees below what would be considered normal for this time of year. It won’t be shocking by any means, although most folks might notice that its a little on the cool side soon. This tropical cool snap will begin to fade by early in the new work week ahead, as the winds calm down and turn more to our more customary easterly direction.

Meanwhile, we have that high pressure shown above getting ready to push a weak cold front down through the islands too. This is being noted all the way down here on the page, after the windy news above…as it will be rather insignificant as far as cold fronts go. Here’s a big satellite image showing this rather diffuse frontal cloud band to our north and northwest. If after scrolling around and finding the islands outlined in blue, you may be wondering where is the cold front? There are quite a few bands of clouds up to our north, and that’s why this particular cold front is being called diffuse. It’s not easy to pick out from the various bands up that way. At any rate, it will arrive on Kauai first, early Saturday morning, and not too long after that on Oahu. It will take a while for this front to push down through the islands of Maui County, and then across the Big Island. It will bring some showers, but nothing anywhere near flooding in nature. It should fizzle out rather quickly, although drizzle or mist could stick on the north and northeast facing slopes for a while, hung up there by the gusty winds blowing through.

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 strengthening 1033 millibar high pressure system located to the northwest of the Hawaiian Islands, with a second weaker 1025 millibar high pressure cell to our northeast Friday afternoon.  At the same time, there’s an area of  low pressure  to the north-northeast of Hawaii…with a weak cold front to the northwest through north of our islands.  Our trade winds are light to moderately strong, at least so far. The forecast continues to call for our local trades to surge this weekend, with strong and gusty trade winds riding in behind a cold front…into early in the new work week ahead.

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

21                 Mana, Kauai – NW
20                 Makua Ridge, Oahu – SE
27                 Molokai – NNE
42                 Kahoolawe – E
18                 Lipoa, Maui – NE
29                 Lanai – NE
23                 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 Friday afternoon. Looking at this NOAA satellite picture we find that high and middle level cloudiness is located to the north, northeast, east, and southeast of the state…as over the state too. We can use this looping satellite image to see low cloud bands being carried over the islands on the trade wind flow. 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. 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 Friday morning:

0.07               Moloaa Dairy, Kauai
0.40               Oahu Forest NWR, Oahu
0.20               Molokai
0.00               Lanai
0.07               Kahoolawe
0.04               Puu Kukui, Maui
0.36               Piihonua, 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:   Smaller surf along the east shores, then begin to rise again later Saturday. The north shores will become slightly smaller, then up again later Saturday into Sunday. The west sides will get gradually drop, although then rising very locally later Saturday into Sunday, and south shores will be small to very small through the early part of the new week ahead

North shores –   Small north to northwest swells will keep our surf breaking through most of Saturday. A much larger north-northwest swell arriving late Saturday into Sunday…into early next week

West shores –   These beaches will be active when small northwest swells arrive this week…and will come up locally along those more northerly exposures as the new NNW swell arrives

South shores –  Small to very small surf through the week into early next week 

East shores –   Surf remaining active with wind swell waves breaking…rising and becoming rough and choppy later Saturday for several days

NOAA animated wave model