| Current Conditions | ||
| Temp |  | 8.2 C |
| RH | | 30 % |
| Wind | | W 1 mph |
| Road | | Open (4x4) |
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Hawaiian Islands Synoptic Discussion and Guidance 089 FXHW60 PHFO 250158 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 358 PM HST Sat Sep 24 2022 .SYNOPSIS... Light southeast flow and sea breezes will enhance showers across island interiors this weekend. A ridge of high pressure reestablishing north of the islands next week, will promote the gradual transition from light trades early, toward a moderate to locally breezy trade wind pattern through next weekend. The strengthening trade wind pattern will redirect showers toward windward areas next week. && .DISCUSSION... A persistent pattern will remain anchored over the region this weekend, with an area of high pressure well northeast of the state and a weakening surface low lingering northwest near Midway. This pattern will maintain a weak pressure gradient southeast flow across the islands, allowing for the continued development of afternoon and early evening sea breeze showers across leeward areas and island interiors into the beginning of next week. Current radar trends show showers developing across the islands this afternoon and expanding in areal coverage across leeward zones. As expected, plume development has once again organized, especially the Molokai and Lanai plumes, as winds remain generally light southeast. Rainfall intensity has begun to pick up some late this afternoon, which combined with the showers slow movement and training pattern, and CIMSS based data showing total precipitable water estimates around 1.55 inches streaming in from the east, keeps heavier showers a possibility into this evening. The airmass across the state is forecast to remain basically unchanged through the remainder of the weekend (precipitable water values ranging between 1.40 to 1.60inch). Therefore expect the areal coverage of showers will expand across the islands Sunday in a similar pattern as today. However, the depth of moisture forecast for Sunday is slightly lower compared to today, which may tend to limit rainfall rates somewhat to end the weekend. Next week begins the transition toward strengthening trades. A weakening surface boundary well north of the state will drop southward toward the islands, maintaining lighter southeast background flow, while increasing moisture and enhancing rainfall chances over the westerns islands into Wednesday. These lighter winds, will keep afternoon sea breeze showers a possibility for leeward locations into early next week. The ridge north of the state begins to reestablish itself by midweek, with easterly trades increasing to moderate before further strengthening to locally breezy by the weekend. Models still differ some with respect to the exact timing of when trades finally strengthen across the islands. The trade wind pattern developing mid week will diminish chances for afternoon sea breeze showers leeward, and once again redirect showers to mainly windward areas in a typical trade wind weather pattern. Drying airmass streaming into the region from the east through next week, will eventually decease the areal coverage of windward showers, as precipitable water values drop to around 1.25inches or less. && .AVIATION... Sea breezes have brought in increasing clouds and a few showers over island interiors this afternoon that will linger until sunset. Brief mountain obscurations will occur with these showers. Have added AIRMET Sierra for mountain obscuration for windward portions of the Big Island over the next few hours as cloud build ups have been a bit more extensive there, otherwise VFR conditions will prevail elsewhere. This AIRMET will likely be cancelled around or just after sunset. Land breezes will set in a keep cloud cover and showers offshore. Expect a similar weather setup for Sunday with building clouds and showers through the day. && .MARINE... A low far northwest of the main Hawaiian Islands will continue to weaken the ridge just north of the state. Expect light to moderate east to southeast winds through tomorrow. Models show a front will stall north of the region by Tuesday, keeping light to moderate winds in the forecast through the first half of next week. Wind speeds may approach Small Craft Advisory thresholds by the end of next week. South swell will remain elevated through tomorrow, then decrease tomorrow night, leaving only background south swell through the first half of next week. A small north-northwest swell will keep north shore surf elevated today before fading on Monday. Another small north- northwest swell is forecast to arrive Tuesday and Wednesday. West facing shores will see a small increase in surf from the south swell and, to a lesser extent, the north-northwest swell. Light trade winds will keep small surf in the forecast along east facing shores through at least next Wednesday. && .HFO WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...SWR AVIATION...Foster MARINE...Powell Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office |
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