| Current Conditions | ||
| Temp |  | 4.0 C |
| RH | | 28 % |
| Wind | | W 13 mph |
| Road | | Open (4x4) |
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Hawaiian Islands Synoptic Discussion and Guidance 679 FXHW60 PHFO 190141 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 341 PM HST Fri Jun 18 2021 .SYNOPSIS... Moderate trade winds are expected over the weekend, and into next week with showers favoring windward and mountain areas. Some showers will be heavy at times through Saturday, before normal trade wind weather returns Sunday and continues into next week. && .DISCUSSION... High pressure located far northeast of the area is providing the islands with moderate trade winds. An upper low centered about 150 miles north of Kauai is bringing some instability over the western half of the state and radar bears this out showing some enhanced afternoon showers over the southwest slopes of the Garden Isle and over the Waianae Mountains on Oahu. Otherwise over the islands, the weather is quite benign this afternoon with mostly clear skies over leeward locations and partly cloudy skies over windward areas with minimal showers activity. The upper low is expected to meander eastward through Saturday and spread limited instability over the state. The instability will allow for embedded downpours within incoming trade wind showers along with the possibility of a few thunderstorms over the Big Island slopes Saturday afternoon. Some of the heavier showers will also reach leeward locations. By Sunday the upper low is expected to head north as a ridge builds aloft. The ridge will cap our showers with a stabilizing temperature inversion, and seasonal trade wind weather will resume and continue into next week. && .AVIATION... No AIRMETs are in effect and none are expected this evening. A high far northeast of the area will produce moderate east winds over the main Hawaiian Islands. The easterly flow will carry scattered clouds and isolated showers over east sections of the islands. A low aloft north of Kauai is create some instability, so heavy showers are possible, but the atmosphere is dry, so any heavy showers will be very isolated. && .MARINE... A 1028 mb surface high pressure system lingers far northeast of the region this afternoon with a surface ridge extending southwest from the high center to an area roughly 600 nm north of Kauai. This high pressure ridge will weaken as a cold front moves into the Central Pacific basin. Moderate to fresh trade winds will gradually weaken into the weekend. Another front will move into the region north of the islands next week, pushing the weakening surface ridge towards the islands causing another decrease in coastal and offshore wind speed trends. No Small Craft Advisories are expected over the next 5 days due to decreasing wind speeds. A series of long-period south swells will move into the region through next week, with elevated surf forecast along south facing shores. South shore surf heights will increase this weekend peaking near the High Surf Advisory threshold from Saturday night into Sunday. Surf heights along south facing shores will gradually lower from Monday into the middle of next week. Surf along north facing shores will remain small through the next five days with just a small bump in surf heights late Sunday into Monday as a small northwest swell moves into the region. A weakening trade wind regime will keep surf heights small along east facing shores through the middle of next week. && .HFO WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Morrison AVIATION...Donaldson MARINE...Bohlin Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office |
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