| Current Conditions | ||
| Temp |  | -2.9 C |
| RH | | 16 % |
| Wind | | W 30 mph |
| Road | | Open (4x4) |
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Hawaiian Islands Synoptic Discussion and Guidance 479 FXHW60 PHFO 281329 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 329 AM HST Sat Nov 28 2020 .SYNOPSIS... Moderate to locally breezy northeast trade winds will prevail through the weekend, with clouds and showers favoring windward and mauka areas. Winds will become light Monday through mid week, with daytime sea breezes and overnight land breezes expected. Dry conditions will prevail through much of next week, with a few showers near the coast each night and over the island interiors each afternoon. Moderate trades and a more typical windward and mauka shower regime may return by Friday. && .DISCUSSION... Currently at the surface, a southwest to northeast oriented ridge of high located around 650 miles north of Kauai, is driving moderate northeasterly trade winds across the island chain early this morning. Infrared satellite imagery shows partly to mostly cloudy skies in windward areas and clear to partly cloudy conditions in leeward locales. Radar imagery shows scattered to numerous showers moving into windward areas with a few showers spilling leeward from time to time. Main short term concerns revolve around rain chances and trade wind trends. High pressure north of the state will keep moderate to locally breezy trade winds blowing through the weekend. The high will weaken as a cold front begins to approach from the northwest early next week, and this should ease the trades to light and variable levels by Monday, with daytime sea breezes and overnight land breezes common statewide. This land and sea breeze pattern should hold through mid week, with moderate to breezy trade winds possibly returning Friday of next week. As for the remaining weather details, pockets of moisture embedded within the trade wind flow will bring passing showers to the islands through the weekend, with showers favoring windward and mauka areas. A shortwave trough passing overhead from northwest to southeast may act to enhance the trade showers as it moves through today. The latest 12z soundings from PHTO and PHLI show significant dry air aloft, and this should keep any thunder from occurring over the eastern end of the state, so have removed the mention of thunder here. Dry conditions should set in statewide Monday through Thursday, with a few showers possible near the coast during the night and early morning hours, and over the interior areas each afternoon. A trade wind shower regime may return next Friday. && .AVIATION... A high pressure system north of the Hawaiian Islands will weaken today decreasing trade wind speeds into the more moderate range through the weekend. Enhanced shower activity will continue through the morning hours as unstable clouds associated with an old frontal boundary drifts over the islands from the north. These enhanced showers should diminish from west to east starting later this morning, with enhanced showers lingering near the Big Island and Maui through the afternoon hours. Periods of MVFR conditions are possible with heavier showers this morning mainly over windward and mountain regions. AIRMET Sierra issued for Tempo Mountain Obscuration above 025 for north through east sections of Molokai and Maui. This AIRMET will likely be cancelled later this morning. AIRMET Tango remains in effect for Tempo Moderate Turbulence below 080 for all areas immediately south through west of mountain ranges. This AIRMET will likely be cancelled later this morning as wind speeds decrease. AIRMET Tango remains in effect for Tempo Moderate Turbulence between FL270-370. A passing upper level trough will keep this AIRMET for Clear Air Turbulence in effect through the afternoon. && .MARINE... High pressure north of the islands will continue to move to the northeast through today, and we are expecting trade winds to weaken some into early next week. The SCA has been scaled back to just the Alenuihaha Channel for today. A moderate northwest swell is expected to peak today, with another northwest swell expected Sunday which will maintain moderate surf through Monday. A small northeast swell will maintain moderate surf along east facing shores through the weekend. Without support of this swell early next week and the lighter trades, surf will be smaller along the east facing shores. Surf will be small along south facing shores throughout the period, where a couple of long period pulses from the south- southwest and south are expected through next week. A large northwest swell is expected to arrive by next Tuesday and Wednesday, which will produce warning level surf along north and west facing shores. Surf would likely reach advisory levels on Kauai and Oahu on Tuesday, and warning levels by Tuesday night. The swell will spread down the island chain, peaking Wednesday followed by gradual decline through Friday. Tides are currently running about half a foot above predicted levels, and high tide Wednesday morning is predicted at 2.3 feet. The high tide and surf arrival will further increase the possibility of runup on roadways during this event. A Small Craft Advisory (SCA) will also be needed as seas exceed 10 feet as early as Tuesday afternoon for waters near Kauai, then quickly spread to other exposed waters Tuesday night. Seas are expected to fall below SCA levels Thursday afternoon. && .HFO WATCHES/WARNINGS/ADVISORIES... Small Craft Advisory until 6 PM HST this evening for Alenuihaha Channel. && $$ DISCUSSION...Jelsema AVIATION...Bohlin MARINE...Powell Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office |
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