| Current Conditions | ||
| Temp |  | 2.8 C |
| RH | | 58 % |
| Wind | | NNE 2 mph |
| Road | | Open (4x4) |
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Hawaiian Islands Synoptic Discussion and Guidance 610 FXHW60 PHFO 231401 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 401 AM HST Mon Nov 23 2020 .SYNOPSIS... Breezy trade winds will persist through Tuesday, while gradually diminishing. High clouds are expected to linger over the islands, and trade winds will continue to focus showers over windward areas. Showers will be more active on the windward slopes of the Big Island and Maui today. As an upper level feature moves over the islands tonight through Tuesday night, a few thunderstorms will be possible. Moderate trade winds and a decrease in showers are expected for most areas on Thanksgiving Day. Increasing trade winds will likely push a dissipating front over the state on Saturday. && .DISCUSSION... Have made some tweaks to the forecast throughout the forecast period, but no major changes. A band of moisture continues to ride in on the trade winds and has been impacting primarily the Big Island and portions of Maui overnight. The band extends several hundred miles to the east of the Big Island, and is expected to continue to bring showers to over the next couple of days. Most of the showers yesterday and overnight have reached upslope, with lower rainfall totals at the coast. Coastal areas are seeing an uptick in stream levels as the result of the upslope showers, and this could cause some nuisance flooding in and around Hilo as time goes on. A 1032 mb high pressure system far north-northeast of the islands will continue to bring breezy trade winds to the region today and tomorrow. Winds have been gradually diminishing after the stronger trades were seen over the weekend. Moderate trade winds are expected to be found by Thanksgiving Day. An upper level trough to the west of the islands is helping to spread some high clouds over the islands from the west. This upper level feature is expected to move to the east, and as it does so, the bulk of the high clouds will shift to the south and east. This upper level trough will be part of the catalyst for some possible thunderstorms Monday night through Wednesday morning. The area of thunderstorm possibility remains unchanged, and follows closely the location of the upper level trough as it moves in from the west and then stalls over the central islands Tuesday night/Wednesday morning and weakens. A drier and more stable airmass appears to move overhead for Thanksgiving and Friday as the upper level trough moves east of the islands. This will allow a mid level ridge to move over the islands which will help cap the showers and largely confine them to the windward sides of the islands. High pressure building to the northwest will allow trade winds to gradually increase heading into the weekend. The building trades may push a dissipating front over the islands late Friday or Saturday, leading to a period of increased in showers. && .AVIATION... A zonally oriented band of moisture will remain focused on the Islands bringing periods of widespread MVFR and showers through this morning, especially for windward areas. Some improvement is likely this afternoon before conditions deteriorate again late this evening. Gusty winds will also remain a focus of the aviation forecast as strong trades will very gradually weaken through the day. AIRMET Sierra for mountain obscuration remains in effect for Windward Oahu through Big Island. AIRMET Tango for lee turbulence remains in effect for the entire area. && .MARINE... A strong high far northeast of the area will maintain easterly trade winds over Hawaiian waters through the week. The trades are currently quite strong, with near gale force winds in the windier areas around the Big Island. The strong winds plus a moderate northwest swell are also producing seas above 10 feet. A Small Craft Advisory is in effect for most waters from Oahu to the Big Island. Winds will subside over the next few days as the high weakens. A long fetch of strong trade winds has generated large waves. A High Surf Advisory is in effect through this evening for east facing shores of all islands except Lanai and Niihau. Surf along the east facing shores will subside over the next few days as the trade winds weaken. A moderate northwest swell that peaked overnight will subside through Wednesday. A new moderate-sized northwest swell is expected over the weekend. Some of the large trade-wind swell is wrapping around into south facing shores. Otherwise, surf along south facing shores will remain small through the week. && .HFO WATCHES/WARNINGS/ADVISORIES... High Surf Advisory until 6 PM HST this evening for Kauai Windward-Oahu Koolau-Olomana-Molokai Windward-Maui Windward West- Windward Haleakala-South Big Island-Big Island North and East. Small Craft Advisory until 6 PM HST Tuesday for Maalaea Bay- Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters. Small Craft Advisory until 6 PM HST this evening for Kaiwi Channel-Maui County Windward Waters-Big Island Windward Waters. && $$ DISCUSSION...M Ballard AVIATION...JVC MARINE...Donaldson Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office |
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