textproduct: Honolulu

SYNOPSIS

Strong high pressure far north of the state will continue to produce breezy to windy trades for the remainder of the week and into the weekend. Showers will primarily focus along windward and mauka areas. However, an increase in shower coverage and frequency is anticipated later this week and into the weekend, with higher rain accumulations likely occurring during the nocturnal hours.

DISCUSSION

Current radar and satellite imagery shower isolated to scattered showers moving into windward and mauka areas on the trade wind flow this afternoon, with more moisture focused over the eastern end of the state. This has been the short term trend with consistent rainfall over the northeast-facing coastal areas of the Big Island bringing 2 to 3+ inches of rain to those areas in the last 24 hours, whereas elsewhere across the state, windward areas have only seen a few hundredths to a couple of tenths of an inch over the same period.

Strong high pressure centered far north of the state will continue to drive breezy to windy trades across the region through the weekend. The typical windier areas across Maui County and the Big Island continue to flirt with Wind Advisory conditions this afternoon, with a few sites touching 30 mph sustained at times and consistently gusting to 40 mph. Elsewhere, winds have been around 20 mph gusting to 30 mph. Looking aloft, Hawaii will remain under weak ridging through early next week as it lies between two upper-level lows, one to the east, the other to the west.

The breezy to windy trades will generally focus clouds and showers over windward and mauka areas throughout the period. However, batches of deep tropical moisture will move across the area Wednesday night through Friday night, again Sunday into Monday, and more will follow next week. As these batches of deeper moisture move through with precipitable water values reaching 1.5 to 2 inches, the inversion will weaken and lift, increasing shower coverage and frequency across the state. In addition to the potential for an uptick in shower activity, dew points will be on the rise, leading to muggier conditions through the weekend.

AVIATION

Breezy to windy trades will continue through Wednesday and bring low clouds and scattered showers predominately to windward and mountain areas. There will also be isolated spillover into leeward sites. VFR will prevail for most sites, with occasional localized MVFR mainly for windward/mountain sites associated with the stronger showers.

AIRMET Tango remains in effect for moderate low level turbulence over and downwind of terrain for all islands. This AIRMET will likely continue through the next several days.

MARINE

Strong high pressure remains centered north of the state, which is driving fresh to strong trade winds across all coastal waters. An advanced scatterometer (ASCAT) pass from late morning revealed that these winds are still in place over large portions of the area, and although winds may shift a bit more easterly and ease slightly, decided to continue the Small Craft Advisory through tonight. A few zones may be drop out of the SCA by Wednesday, but most areas are likely to see an extension in time of the SCA through the next several days.

A moderate, medium- to long-period south southwest (190-200 degrees) swell continues to generate moderate surf below advisory criteria along south facing shores. This swell energy will gradually lower through the remainder of the week. Expect small surf for south facing shores leading into this weekend, with mainly background energy. Another moderate, long-period south southwest swell (210-220 degrees) is expected to fill in Sunday, but due to the direction of the source, could be more inconsistent than the current swell.

Surf along east facing shores will remain rough and choppy through the week as fresh to strong trades hold. A small, moderate period west (280 degrees) swell is expected to arrive this weekend and linger into early next week. No significant swells are expected out of the north or northwest.

Looking ahead, higher than normal high tides will be possible beginning during the second half of this weekend. Interests immediately along the coasts in low-lying or vulnerable areas should continue to monitor forecasts for possible coastal flooding due to the King Tides from Sunday through the first half of next week.

HFO WATCHES/WARNINGS/ADVISORIES

Small Craft Advisory until 6 AM HST Wednesday for Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters- Big Island Windward Waters-Kaiwi Channel-Kauai Channel-Kauai Leeward Waters-Kauai Northwest Waters-Kauai Windward Waters- Maalaea Bay-Maui County Leeward Waters-Maui County Windward Waters-Oahu Leeward Waters-Oahu Windward Waters-Pailolo Channel.