| Current Conditions | ||
| Temp |  | -0.1 C |
| RH | | 5 % |
| Wind | | WSW 17 mph |
| Road | | Open (4x4) |
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Hawaiian Islands Synoptic Discussion and Guidance 674 FXHW60 PHFO 191313 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 313 AM HST Wed Dec 19 2018 .SYNOPSIS... A weak front that has moved down the island chain overnight is forecast to stall and diminish over and around the Big Island today through tonight. Showers associated with the front will favor northern and windward sections of the islands early today, then potentially linger over the eastern end of the state into Thursday as the boundary stalls. Gusty northerly winds along with drier and cooler air will fill in across the western end of the state through Thursday. A return of a more typical trade wind pattern is expected Friday into the upcoming weekend. Increasing rainfall chances will become a possibility early next week as another front approaches. && .DISCUSSION... Gusty northerly winds along with drier and cooler air behind a cold front will continue to fill in across the state from west to east today. The front will reach the Big Island early this morning, then stall and diminish by Thursday. A shallow band of moisture associated with this boundary combined with northerly winds and the island terrain will continue to support numerous showers for the northern and windward sections of Maui County and the Big Island. The latest rainfall summary showed peak totals exceeding 2.5" at West Wailuaiki on windward Maui and up to 3.5" on Molokai over the past six hours as of the 2 am HST. Similar shower coverage will continue over Maui County and the Big Island today as the boundary begins to stall. Elsewhere, a drying trend is expected today. In addition to the shower coverage, gusty northerly winds with speeds exceeding advisory levels over portions of Maui County and the Big Island can be expected. This has resulted in a wind advisory for portions of Maui County (Lanai and Maui Central Valley) and the Big Island (Kohala and southeast Kau/Puna slopes) through tonight. Temperatures may struggle to reach the 80 degree mark through the afternoon hours today due to the drier and cooler air filling in. Dewpoints are forecast to dip into the upper 50s. A transition period is expected Thursday as the low-level flow shifts around to a more typical trade wind pattern. Residual moisture along the stalled boundary will support the best rainfall chances over the Big Island through the day Thursday. Otherwise, guidance supports trade wind conditions prevailing Friday into the weekend with clouds/showers focusing over windward areas. Rainfall chances may climb once again early next week due to a better source of moisture moving into the area and another cold front approaching from the northwest. More specifics will come in later packages as confidence rises. && .AVIATION... A weak front has been moving through the islands and bringing breezy to strong north to northeast winds and intermittent showers to most of the state. Brief to TEMPO MVFR conditions will occur in those areas exposed to the low level flow, mainly over mauka and north- and east-facing coastal sections. An AIRMET for mountain obscuration is now in effect for all isles except the Big Island. Also, an AIRMET for low level turbulence is posted covering the area to the southeast through southwest of the terrain for all islands. && .MARINE... The cold front over the eastern end of the state will hang up in the vicinity of the Big Island today then slowly dissipate tonight. Strong northeast winds will continue to affect the marine area today and tonight with the strongest winds along and behind the front. A Small Craft Advisory (SCA) is now in effect for all of the Hawaiian coastal waters through Thursday, due to a combination of strong winds and seas greater than 10 feet. High pressure will build well to the north of the islands on Thursday, shifting the winds around to a more typical east-northeasterly trade wind direction. Moderate to locally strong easterly trades are then expected across the marine area late in the work week through early next week, with the strongest winds in the typically windier waters around Maui and the Big Island. The current large long-period north-northwest swell will hold through the morning hours, then slowly decline this afternoon through the end of the week. A High Surf Warning remains in effect for exposed north and west facing shores of the smaller island through 6 PM this evening. Advisory level surf will likely continue for most of these areas through the day on Thursday, but surf along west facing shores of Oahu may drop below advisory levels by Thursday morning as the swell becomes more northerly. The High Surf Advisory for north facing shores of the Big Island is now in effect through 6 AM Thursday. Surf is expected to drop below the winter time average along north and west facing shores Friday through the weekend. A new small to moderate northwest swell will be possible early next week. && .HFO WATCHES/WARNINGS/ADVISORIES... High Surf Warning until 6 PM HST this evening for Niihau-Kauai Windward-Kauai Leeward-Waianae Coast-Oahu North Shore-Oahu Koolau-Molokai-Maui Windward West-Maui Central Valley-Windward Haleakala. Wind Advisory until 6 AM HST Thursday for Lanai-Kahoolawe-Maui Central Valley-South Big Island-Big Island North and East-Kohala. High Surf Advisory until 6 AM HST Thursday for Big Island North and East. Small Craft Advisory until 6 PM HST Thursday for all Hawaiian waters- && $$ DISCUSSION...Gibbs AVIATION...Kinel MARINE...Jelsema Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office |
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