| Current Conditions | ||
| Temp |  | -1.2 C |
| RH | | 79 % |
| Wind | | E 13 mph |
| Road | | Open (4x4) |
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Hawaiian Islands Synoptic Discussion and Guidance 483 FXHW60 PHFO 251415 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 415 AM HST Tue Jul 25 2017 .SYNOPSIS... As the last of the remnants of Fernanda moves out, a more comfortable trade wind regime continues to settle in. And this regime will persist into the upcoming weekend. A broad high pressure cell located far NE of the islands will maintain this trade wind pattern through the rest of the week, assisted by mid level ridging. A boost in the trade showers may come on Friday and Friday night as a band of showers is slated to move through. Otherwise, showers riding in with the trades will favor the windward and mountain areas, especially the nights and mornings. Lee areas of the smaller islands will be dry. Leeward Big Islands will get their usually afternoon and evening clouds and scattered showers. && .DISCUSSION... The trade winds with a drier air mass continues to spread westward across the island chain this morning. Dew points in the mid to upper 60's have reached Maui County, and should be reaching Oahu shortly. It is expected to reach Kauai by mid morning, nudging out the last of Fernanda. With the trade winds back, so are the trade showers. They will be most frequent during the nights and mornings. Satellite imagery shows the scattered showers are embedded in a huge sheet of stable stratocumulus clouds that is just about to cover the entire windward Big Island coast, and is advancing onto windward Maui. Do not know how far west this field will advance but once the sun comes up, the field will start breaking up. Once the sun starts going down, however, the clouds will begin increasing. The upper level trough that aided with the flare ups of thunderstorms early Monday morning is still some 200 miles west of Kauai. However, the models are weakening it today and thus, it will not be a factor to our local weather. Mid level ridging will help keep the air mass stable across the islands to about Thursday. Strength-wise, the return of the trades will be that of moderate to locally strong at first. The trades then drops off slightly to moderate speeds on Thursday. This is due to surface high becoming slightly weaker from 1031 mb to 1029 mb some 1300 miles NE of the islands. It is expected to remain at moderate speed into the upcoming weekend. But there is an outside chance that the trades may bump up to locally strong late in the weekend. The GFS solution points to another upper level trough digging 300 miles west of Kauai this Friday. It will likely bring a threat of thunderstorms to the offshore waters west of Kauai that day. At the same time, the marine layer deepens from 8 to 10k feet to 10 to 15k feet across the island chain as a band of clouds and showers, possibly remnants of an old front, to move through the islands between Friday and Saturday morning. Nice trade wind weather should return by Saturday afternoon. && .AVIATION... Moderate to locally strong northeasterly trade winds are returning to the islands bringing drier and more stable air to the region. Expect mostly VFR conditions with scattered showers over northeastern slopes of all islands, isolated shower activity elsewhere. There are no AIRMET's currently in effect. However, stronger winds may produce low level turbulence over and downwind of mountain ranges by this afternoon. && .MARINE... Trade winds will strengthen as a weak trough west of Kauai moves away and high pressure builds in. A Small Craft Advisory is currently in effect and will continue through Wednesday night for the typically windy zones around Maui County and the Big Island as trade winds become fresh to locally strong. The high to the northeast is expected to weaken Thursday, and this will result in slightly weaker trades that will last through the weekend. The surface trough has move a safe distance from Kauai where thunderstorms are no longer a threat to the coastal waters west through north of Kauai. Thunderstorms however, will remain a threat to the offshore waters west through north of Kauai today. There are presently active thunderstorms in progress in this area. No significant swells are expected through the week. Surf will likely remain below high surf criteria on all beaches. && .HFO WATCHES/WARNINGS/ADVISORIES... Small Craft Advisory until 6 AM HST Thursday for Maalaea Bay, the Pailolo and Alenuihaha Channels, and waters south of the Big Island. && $$ DISCUSSION...Lau AVIATION...Bohlin MARINE...Kinel Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office |
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