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Dec
12
2011

Hawaii Weather Overview

   Locally breezy, locally showery, chance of a heavy shower on some of the islands

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:  The last 24-48 hours found lots of rainfall in the state, at least in many areas. There were those especially wet spots that saw as much as 7.00″+ amounts of precipitation! This cloudy and wet reality was thanks to a rather complex set of circumstances…which included low pressure systems in our area, both at the surface and aloft. At the same time, blustery trade winds were blowing this past weekend, which acted as a conveyor belt, carrying fuel (in terms of moisture), feeding the numerous showers, and even a few thunderstorms that were present. All of this necessitated a flash flood warning, which was active over all the islands until early this morning.

The clouds are still around as we’ve moved into this new work week, although not as extensive as what we saw both Saturday and Sunday. This satellite image shows what’s left of the high and middle level cloudiness, which remains over Maui and the Big Island…leaving Oahu mostly free of these upper clouds, and Kauai completely clear of them. Meanwhile, there are lower level clouds too, although they pale in comparison to what we’ve seen lately. In order to see those lower clouds, or at least the rainfall they are bringing to the state, we have to turn to this looping radar image. Meanwhile, there’s been snow falling atop the Mauna Kea summit on the Big Island.

Peering into the future a bit further, the threat of thunderstorms has faded now, and will remain absent through the rest of this week. This doesn’t mean that we won’t see a few heavier showers through say Tuesday, although thereafter we are likely to grade into drier and more stable weather by mid-week. This more typical weather pattern will stick around through Thursday, with lighter east to southeast breezes blowing. These may or may not carry some volcanic haze up over the smaller islands, from the vent on the Big Island into Friday. Then, the forecast calls  for a mostly retired cold front to approach the islands from the north, bringing an increase in showers around Friday…mostly along our windward sides. As we get into the weekend, our trade winds will return with fairly routine weather conditions supporting one of the last weekend shopping periods before Christmas. 

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 1029 millibar high pressure system located far to the northeast of the Hawaiian Islands Monday afternoon.  This high pressure cell has an elongated ridge that runs from the center southwest, and generally westward across the International Dateline…into the western Pacific. This ridge is positioned to the north of the state, which will keep our trade winds blowing, although will be subdued to some extend by a trough of low pressure draped over the state now.

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

24                 Port Allen, Kauai – ENE
27                 Waianae, Oahu – SE
24                 Molokai – NE
12                 Kahoolawe – ENE
28                 Lipoa, Maui – NNE
09                 Lanai – NE
28                 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 Monday afternoon. Looking at this NOAA satellite picture we find that high and middle level cloudiness stretches across Maui County and the Big Island, leaving Oahu and Kauai much more sunny. We can use this looping satellite image to see this high level moisture streaming up from the southwest, over the eastern islands. This cloudiness masks the lower level showers that are being carried our way on the trade wind flow.   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  areas are coming into the  windward sides…although there are showers coming over the Big Island too.

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

1.90               Mount Waialeale, Kauai
2.49               Oahu Forest NWR, Oahu
0.06               Molokai
0.00               Lanai
0.02               Kahoolawe
3.25               Puu Kukui, Maui
7.27               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:   The north shores will be small to lower medium Monday into Tuesday…then rising again from the northwest. The west sides will be slowly lowering in height Monday into Tuesday…with another increase later Tuesday. Surf along the east shores will remain active, rough and choppy through Tuesday…then gradually smooth out and lower in size. South shores will be very small to locally flat 

North shores –    The most recent large northwest swell will gradually lower through Monday into Tuesday. The next northwest swell, although quite a bit smaller than the one that’s been active, will arrive Tuesday into Wednesday…lasting for a few days along these beaches. A second NW swell will arrive Friday, keeping the surf up into the weekend

West shores –    The northwest swell will keep these beaches breaking, although much smaller now than over the weekend and late last week.  The next batch of waves, although considerably smaller than the the most recent NW swell, will arrive Tuesday, with a second northwest swell approaching on Friday

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

East shores –    Surf will remain choppy and rough, as trade winds continue to bring large surf…high surf advisory conditions

NOAA animated wave model