| Current Conditions | ||
| Temp |  | 1.1 C |
| RH | | 26 % |
| Wind | | E 11 mph |
| Road | | Open (4x4) |
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Hawaiian Islands Synoptic Discussion and Guidance 340 FXHW60 PHFO 060631 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 830 PM HST Fri Jun 5 2020 .SYNOPSIS... Breezy trade winds will ease somewhat Sunday and Monday, and then strengthen again next week. The trade winds will deliver increasing clouds and showers to windward areas beginning later tonight, likely continuing through Saturday night. && .DISCUSSION... After a mostly dry day statewide, latest satellite images show an area of increased showery and stable low clouds approaching the islands from the E. Model guidance continues to indicate a weak 700 mb trough supporting this area, with the trough expected to sharpen as it moves W over the islands through Saturday night. PWAT is expected to increase to 1.4" (currently near 1.0"), with the net effect being an increase in mainly windward showers. Otherwise, the forecast philosophy presented earlier is congruent with latest model guidance. Clouds and passing showers riding moderate/breezy trade winds will mainly affect windward and mountain areas, with an occasional shower reaching leeward locations. High pressure centered far northeast of the islands extends a ridge along 30N across the central Pacific, providing our island trades. Over the weekend the high will move slowly E turning our winds slightly S of due E Sunday and Monday. This alignment will allow for lighter winds over leeward sections of Kauai and Oahu with the Big Island and Maui County partially blocking the easterly trade winds. Winds over the eastern islands look to remain at moderate to locally fresh speeds. Afternoon soundings from Lihue and Hilo depict a 8 degree F temperature inversion between 6000 and 9000 feet. This inversion is capping the trade winds showers, and visible satellite imagery bears this out showing clouds banking up along the windward slopes. The strong inversion is expected to remain in place into the weekend with some weakening expected Sunday and early next week as a midlevel trough moves overhead. Trade showers and cloud top heights may increase a notch in response to the weaker inversion. All that being said, trade wind weather will continue into the foreseeable future with small/moderate fluctuations in wind speeds and rainfall. && .AVIATION... High pressure to the northeast of the state will once again generate moderate to occasionally breezy easterly trades tonight. Expect scattered showers along the windward coasts and with occasional showers over the elevated terrain. Periods of MVFR conditions will likely accompany this aforementioned shower activity due to low ceilings and reduced visibility. AIRMET TANGO remains in effect for over and immediately south through west of mountains below 8000 feet for tempo moderate turbulence. && .MARINE... A ridge of high pressure is roughly 600 nm north of Kauai this evening. The ridge belongs to a high located 840 nm northeast of the islands. These two features will maintain breezy to locally strong trade winds through the first half of the weekend over the eastern end of the state. A Small Craft Advisory (SCA) is in effect to until late Saturday afternoon for the typically windy areas of Maui County and south of the Big Island. Another extension to this SCA is possible, that is through Sunday. A front passing far to the north will bring the ridge a little closer to the islands, so by Sunday night or Monday, the trades would be weaker, resulting in the cancellation of the SCA. This lull could be short-lived, with SCA likely returning Monday night to the typically windy waters, and continuing through at least the middle of next week. This comes about as the front falls apart, allowing the ridge to move north and the expansion of trade winds.long- period pulse fills in by Saturday The latest south swell continues to trend down, although a reinforcing small but long period swell is expected to fill in by Saturday. This will result in surf at about summer time average through the weekend. This will begin lowering Sunday into early next week. A small swell from the Tasman Sea is expected by Wednesday. A mid-size bump is expected for our south facing shores. Surf along east facing shores will remain small but choppy on Saturday. Surf could be a foot less between Sunday and Monday, due to the weaker trades locally, but will be building back up as the stronger trades return by the middle of next week. The north facing shores will have small surf through the weekend, and into next week. && .HFO WATCHES/WARNINGS/ADVISORIES... Small Craft Advisory until 6 PM HST Saturday for Maalaea Bay- Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters. && $$ DISCUSSION...Birchard/Morrison AVIATION...Thomas MARINE...Lau Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office |
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