Breezy east northeasterly trade winds will remain through the week and could ease slightly this weekend and become more easterly. Showers will favor windward and mountain areas, as well as the night time and early morning hours. Late this week into the weekend, an upper-level low could bring an uptick in trade wind shower coverage.
At the surface, a dominate high pressure system resides far to the north of the Hawaiian islands, and will keep east to eastnortheast trade winds blowing through the weekend and into next week. Most of the rain this evening has fallen over Kauai, with some showers upstream approaching the other islands. Showers will be pushed over the typical windward and mountain areas, favoring the night time and early morning hours.
By Friday through the weekend, models continue to show a mid to upper- level cutoff low moving over the region, bringing cooler temperatures aloft and increasing instability. Precipitable water values at that time are expected to climb to 1.5 to almost 2 inches over the eastern end of the state as moisture is drawn up from the south. Its hard to know at this moment how much rain could fall, as some dry air and ridging could linger, inhibiting showers. But localized heavy showers especially over the mountain ranges look like a possibility at this time. This upper low is also expected to usher in muggier conditions as dew points climb into the lower 70s and the extra moisture could linger into early next week.
High pressure far north of the islands will maintain a breezy trade wind pattern through at least Wednesday. Mid-level ridging will help to limit shower activity with a stable airmass in place.
Limited showers will continue to be carried in on the trade wind flow. At times these showers could bring some mountain obscuration to various islands, mostly at night and during the morning hours. Otherwise, VFR conditions are expected to prevail.
AIRMET Tango remains in effect for mechanical turbulence to the lee of the mountains due to the breezy trade winds. Expect this to remain in place through at least Wednesday
A slow eastern-moving area of high pressure north of the islands will maintain generally moderate to locally strong Small Craft Advisory level trade wind winds through Thursday. An upper level low dropping south in the wake of the east exiting high will increase north and west water shower chances from Friday into the weekend.
A small short to medium period northwest (330 degree) swell will slowly decline through tonight. A larger long period northwest swell will arrive late Wednesday and will peak on Thursday. This will push north-facing surf to near or slight over head high levels.
Very small, medium period south swell will occur through the remainder of week. A long period south bump arrives Saturday and this will produce slightly elevated south-facing shore surf. Enhanced trades will maintain above seasonable east-facing shore wind wave chop the next several days.
Small Craft Advisory until 6 PM HST Wednesday for Maalaea Bay- Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters.
