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Nov
28
2011

Hawaii Weather Overview

Gradually softer winds through mid-week, a few generally windward biased showers, lowering surf heights on our east and north shores through most of Wednesday.

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

Hawaiian Weather Synopsis: This past weekend found a high pressure system team up with a weak cold front, in such a way that our local winds became inordinately strong and gusty as a result. These gusty winds prompted small craft wind advisories, wind advisories, and even gale warnings in some of the major channels. At the same time, several different swells, one from the north, and the other a wind generated swell from the northeast, caused very rough and choppy conditions…with a high surf advisory in force then too.

Wind speeds gusted all the way up to 50 mph in a few places around the state, including the small island of Lanai, and the Kaupo Gap area on east Maui. Besides these top numbers, winds were blowing generally in the 20-40 mph in most areas. There were some lulls in the wind flow at times, although winds gusted right back unless there was blockage from the physical terrain features. These stronger than normal winds remain blustery today, with winds gusting up over 40 mph in those locally windiest areas.

The computer forecast models suggest that the winds will gradually ease up over the next couple of days, although not quit blowing by any means. The current small craft craft winds advisories will be pulled back to just those windiest areas around Maui County and the Big Island with time, or perhaps pulled altogether by Wednesday. The winds will increase again later Wednesday into the early part of the upcoming weekend, although not reaching such gusty proportions as what we saw this past weekend.

The models go on to describe a pulling back of the winds later this weekend into early next week. This is all fairly common, with the winds strengthening and then relaxing again thereafter. All this up and down is caused by the interactions of high and low pressure systems. At any rate, lets move on to cold fronts, of which we again had one this past weekend. This frontal passage was relatively mild, although there were 1-2″ rainfall amounts at a few of those wettest locations…with one 3.00+ inch accumulation.

Looking ahead, there’s expected to be a another cold front approaching from the northwest, likely reaching us at some point between Thursday and Friday into early Saturday. We’re expected to have a trough of low pressure, now to the east of Hawaii, migrating westward towards us at the same. This trough may be able to pick up not only the residual moisture from this past weekend’s cold front, now to the southeast and east of the islands…but also some of the moisture that’s sitting out to the east associated with former hurricane Kenneth, the last tropical cyclone in the eastern Pacific. Just how much of all this will actually happen is still a question, but as always time will tell. Even further ahead we should see drier weather by the weekend, until the next cold front reaches down in our direction from the mid-latitudes 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 strong 1034 millibar high pressure system located far to the northeast of the Hawaiian Islands, with a second weaker 1024 millibar high pressure cell to our north-northwest Monday afternoon.  The high pressure cell to our northeast has an elongated ridge of high pressure extending southwest from its center, in the area north and northwest of our islands. We see the bottom edge of the weak cold front that went through our islands this past weekend, just to the southeast of the Big Island. Our winds are expected to relax gradually through mid-week, then picking up again Thursday through Saturday or so…although not becoming nearly as strong as what we saw this past weekend.

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

31                 Lihue, Kauai – NE
33                 Kahuku Trng, Oahu – ESE
37                 Molokai – NE
42                 Kahoolawe – E
42                 Kaupo Gap, Maui – NE
33                 Lanai – NE
36                 Pali 2, 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 Monday 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 Monday morning:

0.48               Mount Waialeale, Kauai
0.04               Oahu Forest NWR, Oahu
0.00               Molokai
0.00               Lanai
0.00               Kahoolawe
0.05               Puu Kukui, Maui
0.21               Kawainui Stream, 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 be small although still rough and choppy Monday, gradually dropping into Tuesday. The north shores will be smaller and gradually lowering Tuesday. The west sides will be smaller Monday, and south shores will be small to very small through mid-week

North shores –   The north to north-northwest swell will drop for a day or two, then a new northwest swell will arrive mid-week…lasting for several days

West shores –  These beaches will gradually drop until a new northwest swell will arrive by mid-week lasting for several days.

South shores –   Small to very small surf through mid-week, followed by an out of season south swell by late Thursday or early Friday…into the weekend

East shores –  Surf remaining active with wind swell waves Monday. This wind swell surf will gradually drop thereafter for a couple of days.

NOAA animated wave model