Oahu residents can look to slowly drop their umbrellas and stow away rain boots over the weekend as the National Weather Service (NWS) in Honolulu forecasts a change in trade wind patterns and drier conditions. Citing the latest weather data, the NWS predicts trade winds will weaken today and will be replaced by light and variable winds during the upcoming weekend. "The atmosphere will be stable and rather dry with minimal rainfall expected," according to the most recent NWS Honolulu update.
The approaching weekend is set to not just bring in a break from the rains but also to introduce much cooler nights. The decline in trade winds is partially due to a surface high, which is currently estimated to be around 250 miles north of Oahu, anticipated to move eastwards and weaken. Those out and about at night can expect to experience winter-like lows potentially dropping into the lower 60s in some parts of the area. A weak mid-level ridge helping to maintain a stable atmosphere, and a dry low-level air mass around the region means that while afternoon clouds might form over the terrain, they're unlikely to produce any significant shower activity. Moreover, a "weak jet streak aloft will generate increased thin high clouds today and Saturday," a statement reported by the NWS Honolulu update indicates.
Heading into the next week, there's a degree of uncertainty looming in weather predictions. A shallow and dissipating front is expected to move across portions of the island chain Sunday night and Monday, but it is forecast to bring only light showers with it. For Sunday, locals should prepare for trade winds to grow light and variable or even turn northerly as this front nears. Models suggest light northerly winds could give way to regular trade winds by around Wednesday, but the specifics remain unclear. As the NWS points out, "Details become elusive by Tuesday due to model differences."
For those with maritime interests, the impact of weather changes will also be felt at sea. The aforementioned ridge of high pressure is causing lighter winds, which will become even more variable as the weekend progresses. A Marine Weather Statement addresses expected harbor surges in light of the northerly swells, particularly cautioning those at Hilo and Kahului harbors. Meanwhile, surfers might to want take advantage of the situation before conditions subside early into next week; the NWS forecasts a period of elevated surf along north and west facing shores, warning of activity "just shy of High Surf Advisory (HSA) criteria on Sunday."
Fire risks, while mitigated by lower wind speeds, still remain a concern for the NWS. Dry conditions across the state mean a high Keetch-Byram Drought Index (KBDI), indicating an increased wildfire risk, and the NWS advises that although relative humidity values might tumble below the 45% critical threshold, the calmer winds should help to alleviate immediate concerns over fire weather hazards. Residents and outdoor enthusiasts are advised to remain vigilant and informed about any updates to the weather as the week progresses.
