Area Forecast Discussion
Issued by NWS Honolulu, HI
Issued by NWS Honolulu, HI
500 FXHW60 PHFO 170647 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 847 PM HST Mon Sep 16 2024 .SYNOPSIS... Locally breezy trade winds will continue to bring humid and somewhat wet conditions tonight, especially for windward areas. Drier trade wind weather will filter in Tuesday into the weekend, with moderate showers focused over windward slopes. && .DISCUSSION... CIMSS precipitable water imagery continues to show an area of enhanced moisture moving over the state. Precipitable water remains quite high, between 1.6 to 2 inches based on satellite and sounding data. Latest satellite and radar imagery shows an area of enhanced clouds and showers just east of the state that will increase in shower in the next couple of hours over windward areas and persist into the early morning hours. A drier trade wind flow moving in from the east will undercut the moisture, rainfall totals should be significantly less than last night. However, expect humid conditions to linger as dew points remain elevated in the low to mid 70s. The deeper moisture will move off to the west on Tuesday, bringing a less active shower pattern. Surface high pressure north of the state will drive moderate to locally breezy trade winds, with a brief decline in the trades possible around Thursday and Friday. While a ridge aloft will bring stability, the mid- level trough will linger nearby into Wednesday, which will keep shower chances a bit higher than normal. However, dew points will fall into the upper 60s over most leeward areas, bringing some relief from the humidity. Drier conditions are due Thursday and Friday and likely into Saturday. While a ridge aloft will maintain stability over the islands through much of the week, an upper-level trough will persist to the west. The main effect of this feature will be periods of high clouds overhead. Models suggest that a low aloft may develop Sunday and Monday and north of Kauai. At this time, it does not look like it will affect local weather significantly. && .AVIATION... Moderate to locally breezy trades are expected through the forecast period. Scattered showers and low ceilings over windward areas will bring temporary MVFR conditions tonight through Tuesday morning. Elsewhere and otherwise, VFR conditions are expected to prevail. With locally breezy trade winds prevailing across the state, AIRMET Tango remains in effect for low-level turbulence over and downwind of terrain. This AIRMET will likely continue through Tuesday. && .MARINE... High pressure north and northeast of the state will maintain moderate to locally strong trade winds through Wednesday. The trades may ease off ever so slightly Thursday and Friday as the high to the north weakens, before rebounding back to moderate and locally strong levels this weekend. A Small Craft Advisory (SCA) is in effect for all waters surrounding Maui County and the Big Island through tonight, and for the typically windy waters around the Maui and the Big Island 6 AM Wednesday. The SCA will likely need to be extended in time with the morning forecast package. East shore surf will hold near seasonal levels through Wednesday, then slowly lower Thursday through early next week. A mix of southeast, south and southwest swells will keep some small surf rolling into south facing shores through the weekend. A slight bump in south shore surf is possible early next week as a slightly larger southwest swell moves into the islands. North shore surf will remain very small through the weekend. A nice bump in north shore surf is possible early next week as a long period northwest swell arrives. The combination of high astronomical tides and water levels running around 0.6 to 0.7 feet higher than predicted will produce localized coastal inundation around the time of high tide Tuesday afternoon. A Coastal Flood Statement remains in effect highlighting these conditions. && .HFO WATCHES/WARNINGS/ADVISORIES... Small Craft Advisory until 6 AM HST Tuesday for Kaiwi Channel- Maui County Windward Waters-Maui County Leeward Waters-Big Island Windward Waters. Small Craft Advisory until 6 AM HST Wednesday for Maalaea Bay- Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters. && $$ DISCUSSION...Almanza AVIATION...Shigesato MARINE...Jelsema