| Current Conditions | ||
| Temp |  | 5.1 C |
| RH | | 16 % |
| Wind | | NNE 22 mph |
| Road | | Open (4x4) |
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Hawaiian Islands Synoptic Discussion and Guidance 807 FXHW60 PHFO 211924 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 924 AM HST Fri Jan 21 2022 .SYNOPSIS... Winds will remain on the light side today, with trade winds beginning to filter in later today and tonight. Trade winds will strengthen this weekend and into next week. Pockets of moisture will ride in on the trade winds, shifting shower activity back to the more typical windward and mountain areas. && .DISCUSSION... A cold front northwest of the islands is expected to dissipate before reaching the islands. Meanwhile, a surface ridge over the main Hawaiian islands continues to bring light winds to the area, with daytime sea breezes expected again this afternoon. The ridge is expected to erode today, allowing for some light trade winds to filter into the western end of the state by late in the day. A low pressure system to the northeast will be moving to the southwest over the next couple of days with little impact on the local weather. The sea breezes today will allow for some cloud and shower development over the interior of the islands. As trades begin to filter back in, look for those areas to see the clouds and showers once again focus over windward areas. Assuming winds remain on the light side tonight, there will be some land breezes that will help to clear out the interior of the islands. Although the above mentioned front will be dissipating, some leftover moisture from the front could reach the islands (particularly Kauai and Oahu) beginning tonight. Northeasterly trade winds are expected to increase Saturday with the high pressure system setting up north of the island, and the low pressure stays to the east of the islands. The leftover frontal moisture is expected to peter out Sunday. Trades are expected to pick up further during the first part of the new week, and moisture from the low to the east will be picked up in the trade wind flow. An upper level system will brush the Big Island Sunday increasing winds over the Big Island summits. && .AVIATION... A ridge of high pressure will remain over the islands through the TAF period, while a cold front weakens as it approaches from the northwest. Weakly organized sfc winds continuing into this afternoon, will allow for some sea breeze circulations mainly over the sheltered leeward side of the islands, while an overall transition to easterly trades begins today and continues through Saturday. Showers remain limited across TAF locations today, with only an isolated shower possible along sea breeze and trade wind developments. Shower chances increase in areal coverage Saturday along favored windward slopes as trade winds settle in. No AIRMETs are currently in effect, and none are anticipated. && .MARINE... One more day of light winds should be expected today before trades winds start to make their return tonight and this weekend. Locally strong winds could return to the typically windier waters around the Big Island and Maui County by tonight. The Small Craft Advisory (SCA) may need to be expanded tonight or tomorrow for these areas due to winds. The current SCA configuration covers the coastal waters around Kauai and north of Oahu for the building west-northwest swell and expected combined seas above 10 feet. For the building west- northwest swell, we just started seeing the long period energy arrive at NDBC Buoys 51001 and 51101, a few hours behind guidance. This swell should peak near the islands late tonight into Saturday at extra-large levels. A High Surf Warning (HSW) is posted for the exposed north and west facing shores of the smaller islands. As the swell builds today, it is also expected that the HSW will be expanded with afternoon package to cover the west shores of the Big Island. The SCA will likely be expanded down the island chain as the combine seas build as well. Although a downward trend is expected through the second half of the weekend, another long-period, west-northwest pulse arriving by Sunday night will support a return of advisory-level (if it dips below Sunday) surf Monday. Heights are expected to fall below advisory levels for north and west facing shores Tuesday through the second half of next week. Surf along east facing shores may trend up over the weekend in response to a tight gradient that has setup between low pressure centered more than 1000 miles east of Hilo and high pressure to its north. Recent ASCAT data showed a packet of strong- to gale-force winds focused at the state north of the low. Guidance has this easterly swell arriving by Saturday night, then lingering into early next week before easing. Current guidance is showing the surf staying just below the Advisory levels for east facing shores. && .HFO WATCHES/WARNINGS/ADVISORIES... High Surf Warning until 6 PM HST Saturday for north and west facing shores of Niihau-Kauai-Oahu-Molokai. And north facing shores of Maui. Small Craft Advisory until 6 PM HST Saturday for Kauai Northwest Waters-Kauai Windward Waters-Kauai Leeward Waters-Kauai Channel- Oahu Windward Waters. && $$ DISCUSSION...M Ballard AVIATION...SWR MARINE...EATON Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office |
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