Today: Mostly sunny with scattered showers. Highs around 80 near the shore to 64 to 69 at 4000 feet. Northwest winds up to 10 mph shifting to the east around 10 mph in the afternoon. Chance of rain 50 percent.
Tonight: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows around 63 near the shore to around 49 at 4000 feet. Light winds becoming northwest up to 10 mph after midnight. Chance of rain 50 percent.
Thursday: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs around 80 near the shore to 64 to 69 at 4000 feet. Northeast winds up to 10 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 50 percent.
Kona
Today: Sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs 79 to 84 near the shore to around 70 near 5000 feet. South winds up to 10 mph shifting to the west in the afternoon. Chance of rain 40 percent.
Tonight: Mostly cloudy with isolated showers in the evening, then mostly clear after midnight. Lows 63 to 69 near the shore to around 50 near 5000 feet. Light winds. Chance of rain 20 percent.
ARTICLE CONTINUES BELOW AD
ARTICLE CONTINUES BELOW AD
Thursday: Sunny early in the morning, then partly sunny with isolated showers in the late morning and afternoon. Highs 79 to 84 near the shore to around 70 near 5000 feet. Light winds becoming west up to 10 mph in the afternoon. Chance of rain 20 percent.
Waimea
Today: Mostly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs around 79 near the shore to 70 to 77 near 3000 feet. East winds up to 15 mph. Chance of rain 40 percent.
Tonight: Partly cloudy with isolated showers. Lows around 62 near the shore to 48 to 56 near 3000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.
Thursday: Mostly sunny with isolated showers. Highs around 79 near the shore to 70 to 77 near 3000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.
Kohala
Today: Mostly sunny. Isolated showers in the morning, then scattered showers in the afternoon. Highs around 79 near the shore to 70 to 77 near 3000 feet. East winds up to 15 mph. Chance of rain 40 percent.
ARTICLE CONTINUES BELOW AD
Tonight: Partly cloudy with isolated showers. Lows around 62 near the shore to 48 to 56 near 3000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.
Thursday: Mostly sunny with isolated showers. Highs around 79 near the shore to 70 to 77 near 3000 feet. East winds 10 to 15 mph. Chance of rain 20 percent.
South Big Island
Today: Breezy. Sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 82 near the shore to around 71 near 5000 feet. Northeast winds up to 20 mph shifting to the east 10 to 20 mph in the afternoon. Chance of rain 20 percent.
Tonight: Partly cloudy. Lows around 65 near the shore to around 49 near 5000 feet. Northeast winds 10 to 15 mph.
Thursday: Breezy. Sunny in the morning, then partly sunny with isolated showers in the afternoon. Highs around 82 near the shore to around 71 near 5000 feet. East winds 10 to 15 mph becoming up to 20 mph in the afternoon. Chance of rain 20 percent.
Puna
ARTICLE CONTINUES BELOW AD
Today: Mostly sunny with scattered showers. Highs around 80 near the shore to 64 to 69 at 4000 feet. Northwest winds up to 10 mph shifting to the east around 10 mph in the afternoon. Chance of rain 50 percent.
Tonight: Partly cloudy in the evening then becoming mostly cloudy. Scattered showers. Lows around 63 near the shore to around 49 at 4000 feet. Light winds becoming northwest up to 10 mph after midnight. Chance of rain 50 percent.
Thursday: Partly sunny in the morning then becoming mostly sunny. Scattered showers. Highs around 80 near the shore to 64 to 69 at 4000 feet. Northeast winds up to 10 mph increasing to 10 to 15 mph in the afternoon. Chance of rain 50 percent.
Waikoloa
Today: Sunny in the morning, then mostly cloudy with scattered showers in the afternoon. Highs around 81 near the shore to 65 to 72 above 4000 feet. Southeast winds up to 10 mph shifting to the northwest in the afternoon. Chance of rain 40 percent.
Tonight: Mostly clear. Isolated showers in the evening. Lows around 67 near the shore to 45 to 53 above 4000 feet. Light winds becoming east up to 10 mph after midnight. Chance of rain 20 percent.
Thursday: Sunny. Highs around 81 near the shore to 65 to 72 above 4000 feet. Northeast winds up to 10 mph shifting to the north in the afternoon.
Detailed Forecast
Synopsis
Trade winds will fluctuate between light and moderate strength through the weekend as a series of fronts pass north of the state. Stronger trades will be possible early next week. Showers will continue to be focused over windward slopes, with an increase in rainfall possible this weekend.
Discussion
Have made some minor tweaks to the forecast with the morning package, but no change to the general forecast philosophy. An overnight ASCAT pass showed moderate to locally trades over the waters near the Big Island. This corresponded well with the model depictions for the winds at the time of the ASCAT pass, boosting confidence in the general wind forecast.
As expected, lighter winds are found over Kauai and Oahu as a surface ridge sinks southward towards the islands. A stable air mass overhead is limiting rainfall totals. A front behind the ridge is moving to the east, and helping to push the ridge closer to the islands. Expecting winds to ease some more, and shift to the southeast today over Kauai and Oahu, which will also allow for some afternoon sea breezes to set up. The remaining islands will see light to moderate trades holding in place, but they too could see some localized sea breezes in places where the winds go light. With any afternoon sea breezes there is the possibility for some cloud development along with a few isolated showers over interior and leeward areas.
Expecting another brief return of light to moderate trade winds Thursday as the ridge lifts northward. However, another front moving in from the northwest will push the ridge back towards the islands Friday weakning the winds. Winds are expected to increase over the the weekend, though a lingering surface trough to the north could limit some of that increase.
Satellite derived precipitable water (PW) confirms what we have observed with the overnight soundings – a relatively dry air mass remains over the islands. PW values are slightly higher over/near the Big Island. The GFS and ECMWF are showing a possible increase in showers Thursday and again during the weekend. The GFS and ECMWF models are showing the ridge aloft eroding during the weekend, which could enhance rainfall.
Trade winds may strengthen again early next week. There is some uncertainty, since the GFS and ECMWF models have recently advertised stronger trade winds that have not materialized at longer time ranges.
Aviation
A band of broken mid and upper lvl moisture will drift over the western islands this morning, in advance of a weakening cold front slowly approaching from the west. Otherwise, an area of high pressure remains centered northeast of the state which will continue light east to southeast winds across the islands through tonight. This pattern will allow for afternoon sea breeze circulations again across leeward interior locations. Moisture will remain limited through the TAF period, with isolated showers and a majority of cloud cover focused on windward slopes and inland along afternoon sea breezes. VFR conditions will prevail across the state with brief periods of MVFR cigs possible in developing showers.
No AIRMETs are currently in effect. However, a period of tempo light ice IC conditions may develop across Kauai and Oahu after 1800z, as the band of mid and upper level moisture slowly pushes eastward.
Marine
Trades over the island waters will fluctuate from light to moderate levels through the upcoming weekend, due to the ongoing progressive pattern across the northern Pacific – featuring a series of fronts passing close enough to shunt the ridge southward into the area periodically. Moderate to locally fresh trades will hold into Thursday, transition to the light category Thursday night into Friday, then return to the moderate to fresh category over the weekend. For the periods with light winds, expect localized land and sea breeze regimes to become established near the coasts.
Surf along exposed north and west facing shores will continue to lower today as the swell that surged well above guidance Tuesday (led to warning-level surf) moves out. Offshore buoy observations to the northwest reflect this and are now in line with the predicted levels this morning on the tail-end of this swell. This energy extrapolated out in time suggests surf heights will dip below the advisory levels by daybreak today, then continue to lower through the day. This combined with seas dipping below the Small Craft Advisory level (10 ft) has led to the cancellation of the advisories for surf and seas over exposed waters and coasts.
The lowering trend will continue into Thursday with surf heights dropping well below average for February. A new, west-northwest swell (310 deg) is forecast to arrive late Thursday into Friday, followed by a larger west-northwest swell Saturday out of the same direction. Surf will respond and may near advisory levels Friday for exposed north and west facing shores of the smaller islands, then likely exceed the advisory-levels with the second swell through the day Saturday.
Surf along east facing shores will trend up through the second half of the week as a small, easterly swell from a batch of fresh to strong trades upstream fills in.
Surf along south facing shores will rise once again Thursday into Friday as a new, out-of-season, long-period southerly swell arrives from a recent gale passing east to southeast of New Zealand within Hawaii's swell window. The active pattern across the southern Pacific has continued over the past couple of days, which supports another small bump clipping the local area as it passes by early next week.
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