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Dec
06
2011

Hawaii Weather Overview

Gradually strengthening trade winds,  windward biased showers for the most part…larger surf along our north and west facing beaches.

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:  As was the case yesterday, and which will remain the case through the rest of this week…the trade winds are in force of our local weather circumstances. These moderately strong winds are being anchored by a couple of high pressure systems, one located far to the northeast, and another closer to the islands, to the north. At the same time, we find a weak low pressure system to our north, with its associated cold front draping down in a classic comma shape, not far to the north of Kauai. This can all be seen if one takes a quick glance at this weather map.

This weather chart also shows a deep 969 millibar storm low pressure very far northwest of the Hawaiian Islands. This storm is heading into the Bering Sea now, although has been spinning in the northwestern Pacific the last several days. The strong winds blowing on the ocean surface have generated a large swell train of waves pointed in our direction. It will arrive later Wednesday into early Thursday. This will be a larger than normal swell, which may not quite reach high surf warning levels, but will keep high surf advisory level waves breaking through Friday…gradually lowering in size this weekend.

A bit more about this swell, it will be larger than normal, and as such, will be dangerous to those folks who aren’t used to this big stuff…especially our visitors. At the same time that this swell arrives, we’re expecting our local trade winds to be picking up in strength too. The combination of the high surf and the stronger winds will trigger advisories in many coastal and channel waters…especially along our north and east facing beaches. The east facing beaches will come into play as the trade winds increase, which rough and choppy conditions developing there too.

As for precipitation, it will be somewhat drier than normal for the time being, with most showers falling along our usual windward sides. As the trade winds pick up over the next couple of days, a few of these showers may travel across the islands into the leeward sides…on the smaller islands. The computer models have been fluctuating between drier conditions early next week, to a wet reality. The latest iteration comes down on the side of dry weather however, so time will tell which way the weather pendulum swings then. For the time being however, pretty nice weather will prevail through the rest of this week, with those high and middle level clouds overhead at times.

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 strong 1035 millibar high pressure system located far to the northeast of the Hawaiian Islands Tuesday afternoon.  This high pressure cell remains offshore from the Columbia River mouth, between the Oregon and Washington borders.  Meanwhile, we see a weaker 1024 millibar high to the north of the islands. At the same time, we see a 1017 millibar gale low pressure system to the north of Hawaii…straddling the 40 degree line of latitude. This low has a frontal cloud band extending from its center south and southwest, to the north and northwest of the island of Kauai.

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

22                 Port Allen, Kauai – E
28                 Honolulu, Oahu – NE
27                 Molokai – NE
00                 Kahoolawe – E
23                 Kahului, Maui – NE
00                 Lanai – NE
24                 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 early Tuesday afternoon. Looking at this NOAA satellite picture we find that high and middle level cloudiness are located over the ocean to the east, and over most of the state from a second area to our north through northeast. 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 southeast over the ocean.  Checking out this looping radar image we see showers over the ocean, most of which are in the light to moderately heavy category. The most active precipitation areas are coming into the  windward sides..especially on Oahu, Maui, and to the southeast of the Big Island. 

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

0.30               Mount Waialeale, Kauai
0.11               Maunawili, Oahu
0.04               Molokai
0.00               Lanai
0.08               Kahoolawe
0.27               Puu Kukui, Maui
0.61               Glenwood, 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 Tuesday and Wednesday…generally on the small side or a little larger. The north shores will be rising from the northwest during the day Tuesday, gradually lowering Wednesday. The west sides will be rising Tuesday, lowering slowly Wednesday. South shores will be very small to flat through Wednesday.

North shores –    The current north-northwest swell will gradually lower. The next larger northwest swell will arrive during the day Tuesday…remaining active for several days. A following larger west-northwest swell will arrive Thursday, remaining large into the weekend. The largest surf late Tuesday in those best aligned spots will reach 10-16 foot…wave faces.

West shores –  A new northwest swell will rise Tuesday…with another larger west-northwest swell Thursday into Friday and Saturday. The largest surf late Tuesday in those best aligned spots will reach 6-8 foot wave faces.

South shores –  Surf will be small to very small for the time being.  

East shores –  Surf remaining small with wind swell waves breaking…through the first part of this week. The trade winds will increase Tuesday through Thursday…with rising wind swell into the weekend.

NOAA animated wave model

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