| Current Conditions | ||
| Temp |  | 3.9 C |
| RH | | 52 % |
| Wind | | NE 19 mph |
| Road | | Open (4x4) |
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Hawaiian Islands Synoptic Discussion and Guidance 102 FXHW60 PHFO 030657 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 857 PM HST Tue Jun 2 2020 .SYNOPSIS... Trade winds are expected to strengthen tonight and Wednesday, then remain locally breezy through the weekend. Frequency of the showers riding in with the trades will increase during the nights and mornings, favoring the windward areas, although a showers will drift downwind into the lee areas of the smaller islands. The Kona side of the Big Island will cycle through morning sun, followed by afternoon and evening clouds with isolated to scattered showers each day. && .DISCUSSION... The strength of the trade winds is in the light to moderate range this evening. Models are suggesting that it will be trending stronger in the next 18 hours, reaching locally strong, and holding into the upcoming weekend. There could be a delay to this onset as a low level trough, noted by a low level swirl 800 miles east- northeast of Maui, undercut the trades as it passing north of the islands tomorrow. So, we will monitoring the winds closely. Otherwise, the trades are being supported by a east to west oriented ridge of high pressure located 750 miles north of Kauai. The ridge extends to the parent high, stationed 1500 miles northeast of Kauai. this high is forecast to edge closer to the islands during the second half of the week, lending to the boost in the trades that will persist into the upcoming weekend. With this boost in the trades, it may bring on a slight uptick in trade showers. Satellite infrared imagery shows a loose area of cumulus based clouds with embedded showers, stretched out across the windward waters of all the islands. There isn't much low clouds directly east of the Big Island as well. With this said, the forecast package was updated to lower the POPs for especially this evening. The frequency of these showers should be increasing in the coming hours to showers likely over the windward and mountain areas of most islands. But we see about this as well. It could be drier than predicted. Satellite imagery do show a band of broken low clouds 150 miles northeast of Maui. Models have the bulk of this band staying north of the islands, but clipping Kauai starting at sunrise tomorrow and persisting through most of Wednesday. && .AVIATION... Moderate trade winds will continue overnight into Wednesday, then increase into the moderate to breezy category by Wednesday afternoon. Clouds and showers will favor windward and mountain areas each day, especially through the overnight and early morning periods as pockets of moisture move through. MVFR CIGS and VSBYS in and around these passing clouds and showers will be possible. Although mostly dry conditions will prevail over leeward locations, a few showers spilling over from windward areas can't be ruled out. No AIRMETs are currently in effect, though AIRMET Sierra may be needed for some windward areas later tonight into early Wednesday if cloud and shower coverage increase. && .MARINE... A High Surf Advisory (HSA) is posted for S facing shores of all islands through Wednesday, as a significant long-period S swell continues to build this evening. Overnight buoy trends will be monitored to fine-tune the surf height forecast, and may also lead to an extension in time of the HSA. Surf will likely remain below advisory levels along all shores into early next week once the S swell diminishes below advisory levels Thursday/Friday. However, surf will not be flat as a smaller long-period S swell is expected over the weekend, with another maybe early next week. A small relatively short-period NW swell is also expected Wednesday and Thursday. Minimal E shore surf is expected as trades deliver short-period slop. Trade winds are expected to trend stronger over the next day or so, but confidence is somewhat diminished in this occurring during the day Wednesday as a weak trade wind feature passes between the islands and the trade-wind-supporting high centered far NE of the area. A Small Craft Advisory (SCA) for the windier areas around Maui and the Big Island does not appear to be verifying currently, but with an uptick in wind speeds potentially occurring on Wednesday, it will remain posted. && .HFO WATCHES/WARNINGS/ADVISORIES... High Surf Advisory until 6 PM HST Wednesday for Niihau-Kauai Windward-Kauai Leeward-Oahu South Shore-Waianae Coast-Molokai- Lanai Makai-Kahoolawe-Maui Leeward West-Maui Central Valley- Windward Haleakala-Leeward Haleakala-Kona-South Big Island-Big Island North and East. Small Craft Advisory until 6 PM HST Thursday for Maalaea Bay- Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters. && $$ H Lau/Gibbs/Birchard Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office |
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