Breezy trades continue well into next week. Showers will generally favor windward and mauka areas, particularly during the overnight through early morning hours each day. An uptick in moisture next week could increase shower activity. Tropical Storm Lowell remains far SE of the main Hawaiian Islands, and uncertainty in its track, timing, and intensity forecast remains high at this time.
The early morning 12z soundings from Lihue and Hilo showed a slightly elevated inversion at around 6500-8500 feet. This, combined with a band of moisture seen on regional satellite imagery embedded within breezy trades, has resulted in an uptick in low clouds and showers during the overnight through early morning hours. Surface observations show that several windward locations, particularly across Maui and the Big Island, picked up between a half inch and one inch since yesterday evening.
A drier trade wind pattern will resume today as mid- and upper level ridging remains anchored near the area and the band of moisture that moved through overnight exits the region. Breezy trade winds will prevail for the next several days as strong high pressure becomes nearly stationary north of the main Hawaiian Islands. Occasional showers embedded within the trades will favor windward and mauka areas, particularly during the overnight through early morning hours each day. As the previous discussions have mentioned, an uptick in moisture by the middle of next week could increase trade wind showers once again.
The National Hurricane Center in Miami continues to track Tropical Storm Lowell, which as of the 11 PM HST advisory was located about 1430 miles ESE of Hilo, moving west around 8 mph. Lowell is expected to strengthen into a hurricane early next week as it continues to move westward. There is a great amount of uncertainty in the forecast thereafter, as it remains to be seen how Tropical Storm Karina (also in the East Pacific) could influence Lowell's steering flow. Should steering flow weaken as depicted in some global models, this would delay any potential arrival to/around the Hawaiian islands to beyond the 7 day forecast period.
For 12Z - Nocturnal showers under moderate trades bringing mostly VFR to occasional MVFR conditions overnight. Generally, VFR through the TAF period and occasional MVFR conditions due to passing showers/lower CIGs, highest chances this afternoon and overnight. Expect low CIGs and SHRA over windward and mauka slopes most areas and with VCSH for those TAFs.
AIRMET Tango is in effect for mod low-level turb lee of terrain and may be needed for a few days.
The subtropical ridge will remain locked in place north of the Hawaiian Islands through much of next week keeping moderate to locally strong trade winds in the forecast for the foreseeable future. A Small Craft Advisory (SCA) has been extended for the windier waters and channels around Maui County and the Big Island through Sunday afternoon. These SCA conditions look to persist through the first half of next week.
Tropical cyclone Lowell may move into the Hawaiian Region potentially bringing an area of hurricane force winds into the southern offshore waters by the end of next week.
The south swell that peaked just below advisory thresholds on Friday, will slowly decline over the next few days. Another south swell will increase surf heights starting on Tuesday, peaking on Wednesday near High Surf Advisory levels, then slowly fading into the end of next week.
Surf along east facing shores will remain choppy in response to the locally strong trade winds over and upstream of the islands. A small medium period east swell from Tropical Storm Iselle has filled in and will hold through the day.
Small Craft Advisory until 6 PM HST Sunday for Maalaea Bay- Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters.
