Moderate trades this morning will gradually strengthen each day over the next several days with widespread strong trades expected by Thursday and very windy conditions possible on Friday. The main focus for the weather this week will be the tropical cyclone development southeast or south of the Big Island over the next few days. While the potential wind impacts remain uncertain, the threat for flash flooding will increase over the Big Island during the second half of the week.
Breezy trade winds continue today. Moisture gradually increases tonight into tomorrow due to a disturbance southeast of Hawaii. Rain showers are likely to impact eastern and windward areas of the Big Island early tomorrow morning with periods of MVFR ceilings and visibility possible in heavier showers. Highest confidence in impacts at PHTO early Wednesday with impacts gradually spreading northwards late Wednesday into Thursday.
AIRMET Sierra is in effect for mountain obscuration and will likely be extended.
AIRMET Tango is in effect for low level turbulence downwind of island terrain and will likely be needed through the day.
The gradient between the subtropical high to the northeast a low pressure system (a developing tropical cyclone) to the southeast is causing moderate to fresh trade winds across the Hawaiian coastal waters today. A Small Craft Advisory (SCA) is in effect for the typical windy waters of Maui County and the Big Island through early Wednesday evening. The SCA will likely be extended and expanded to all coastal waters as trade winds strengthen during the second half of the week and this weekend as the tropical cyclone organizes and approaches the coastal waters from the southeast. Showers and thunderstorms will increase as the system nears, particularly across the eastern waters.
Surf along south facing shores will decrease into midweek as the current south-southwest swell fades. A moderate southwest swell will build in around Friday into the weekend building surf back up across south and west facing shores.
A small, short period, north northwest swell will fade through Wednesday. Another small northwest swell will fill in this weekend keeping surf slightly elevated along north and west facing shores.
East facing shores will maintain rough, short period windwaves generated from the breezy trade winds. As trades strengthen on Thursday through the weekend, surf will increase and become very rough and choppy, possibly nearing advisory levels.
Small Craft Advisory until 6 PM HST Wednesday for Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters- Maalaea Bay-Pailolo Channel.
