Relatively weak trades will continue through Friday, with increasing wind speeds this weekend. A weak upper level trough will linger just northwest of the state, also through around Friday, bringing an increased chance of showers to the western end of the state. The main area for showers may shift to the eastern end of the state this weekend, but confidence is not high at this time.
Radar and satellite show mostly cloudy skies this morning, with trade wind showers most numerous over windward and mountainous areas on Oahu and in Kauai County. There are a few lighter showers making it over to leeward areas. Winds are weak, averaging just 5 to 10 mph sustained.
High pressure at the surface, centered well to our NNW, will keep trades going through the rest of the work week. However, the pressure gradient is weaker now than a few days ago, and will remain relatively weak through Friday. As a result, trades will be weak and a sea breeze effect will develop each afternoon. This will result in a few (mainly coastal) showers in leeward areas. Trades will increase this weekend, doing away with most of the sea breeze.
An upper level trough to our west and north will linger through Friday, bringing slightly more unstable air to the western end of the state. There may be a brief increase in moisture over mainly Kauai Wednesday. This weekend, another increase in moisture, this time over the eastern two counties, may occur. Models have a plume of moisture coming either over or very close to Maui and Hawaii County, but confidence is not that high at this time.
A weakening high pressure ridge far north of the state will keep moderate trade winds in the forecast. A passing low level trough passing from east to west across the Hawaii Region will bring enhanced clouds and shower coverage across the state today. Periods of MVFR conditions are expected through the morning hours, favoring northern and eastern windward mountain slopes of all islands.
AIRMET Sierra in effect for mountain obscuration above 020 for north through southeast mountains of Kauai, Oahu, Molokai, Maui and the Big Island. These conditions will continue well into the morning hours.
Moderate trade winds will prevail over the coastal waters for the next few days as the remnants of former Tropical Cyclone Genevieve continue lifting northward, well east of the area, and a front passes from west to east across the North Pacific. Winds are expected to remain below Small Craft Advisory levels through much of the week. Trades are forecast to restrengthen to locally breezy levels by the end of the week as what is left of Genevieve's remnants dissipate and high pressure expands north of the state.
Surf along south-facing shores will remain below seasonal averages through much of this week, though occasional small fluctuations can be expected as small background swells move through. By this Saturday, a small, long period south swell is expected to arrive, followed by a series of reinforcing south swells that will boost surf heights to near or above seasonal averages into next week.
Small, medium period easterly swell generated from former Tropical Cyclone Genevieve continues to linger, but will gradually ease for the next couple of days. Choppy conditions will remain, generated by the moderate trade winds.
Surf along north facing and west shores will remain flat to tiny through the forecast period, except for areas exposed to the easterly trade wrap.
None.
