| Current Conditions | ||
| Temp |  | 1.6 C |
| RH | | 81 % |
| Wind | | SSE 0 mph |
| Road | | Closed |
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Hawaiian Islands Synoptic Discussion and Guidance 567 FXHW60 PHFO 200633 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 833 PM HST Thu May 19 2022 .SYNOPSIS... Moisture along a weakening front will maintain higher shower chances for Kauai through tomorrow. The rest of the state will experience mainly spotty showers under decreasing southeast to south winds. High clouds will gradually diminish as humid conditions persist through Friday. Moderate trade winds will build during the weekend and will hold into next week. && .DISCUSSION... Radar shows a line of showers moving over Niihau and Kauai this evening, but the heaviest rainfall appears to be over the coastal waters to the southwest and south of Kauai. This will more than likely bring some additional light to moderate showers to the Garden Isle over the next few hours. CIMSS MIMIC satellite derived precipitable water (PW) shows a swath of moisture from Maui to Kauai between 1.90 and 2.05 inches, which matches closely to the afternoon sounding from Lihue which had 2.08 inches. A stationary front is near the western end of the state and continues to bring a humid, slightly unstable, and southerly flow over the islands. The atmosphere is becoming more stable with time. An upper level trough axis north of the state has swung to the east, resulting in the high clouds largely clearing the islands, with further thinning of the high clouds expected overnight. Dewpoints tonight in the low to mid 70s will keep humidity values high. Expect some gradual decline in dewpoints in a couple days. The moisture band is expected to linger near Kauai through Friday, with a land and sea breeze regime over the remainder of the state. Upper level ridging will slowly build in, but a lingering mid level trough nearby will maintain some instability. As a result, expect clouds and spotty showers, some briefly heavy, to develop over most islands in the afternoon and diminish during the overnight hours. Cloud cover and shower chances will remain highest over Kauai, with heavier rainfall possible Friday afternoon. That being said, not expecting any widespread flooding concerns. An increasingly stable trade wind flow will build during the weekend. High pressure far northeast of the state will strengthen, causing trade winds to slowly increase and push the deeper moisture west of the state. A mid level ridge will also build overhead and bring increased stability. The result will be a return to typical trade wind weather that will hold into next week. && .AVIATION... Showery weather will persist statewide, the result of a weak front stalled over the western end of the state. Low level winds will be mainly out of the south through the night with deep low level moisture concentrated over the smaller islands. On Friday, drier easterly flow will develop over the Big Island and spread across the remainder of the state by Saturday morning. The air mass over the state will gradually stabelize as the front decays. Nevertheless, locally heavy showers are still possible over Kauai and Oahu, especially in the afternoon and evening hours. Elsewhere, shower activity should remain light and favor south and east facing slopes and coasts. AIRMET Sierra for mountain obscuration remains in effect for Kauai. && .MARINE... A front stalled near Kauai this evening will continue to weaken and drift northward, resulting in a sharp drop in southerly wind speeds. A high pressure ridge will build back into the region on Friday with easterly trade winds strengthening from east to west this weekend. SCA conditions will likely return to the typical windier waters and channels around Maui County and the Big Island on Saturday and Sunday. Easterly trade winds with more stable weather conditions will continue into the middle of next week. Surf heights along south facing shores will remain elevated into next week as the current south swell becomes reinforced by additional long period south swells arriving on Saturday, Monday and next Thursday. In the long range, models continue to show quite a bit of activity in the southern hemisphere, which could translate to additional south shore surf events lasting into early June. Surf along north and west facing shores will remain slightly elevated through tonight as a small, medium-period northwest (300-320 degrees) swell holds. A return to small, summer-like conditions is expected over the weekend and into the first half of next week as this current northwest swell energy fades. && .HFO WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...M Ballard AVIATION...Bedal MARINE...Bohlin Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office |
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