Short-period windswell and a slightly longer period easterly swell are combining to bring rough and elevated surf to Maui’s east facing shores, and a High Surf Advisory remains in effect through 6pm Sunday evening. The advisory may need to be extended again as tradewinds are expected to stay elevated east of the state well into next week. Wave heights should come in around head-high levels along the better exposed east and northeast facing breaks. North and northwest facing shores may see sloppy surf in the knee to waist-high range at most exposed breaks but some areas may see slightly larger sets from time to time. Tiny to small leftover surf from the south-southwest may still be found along select south facing shores, but it is on the way out. Some south facing shores may pull in wrapping windswell as well. No other significant swells are expected until a long-period northwest swell arrives on Tuesday, peaking Wednesday with a slow fade through Thursday. This northwest swell is expected to peak near advisory levels along exposed north and northwest facing shores. With the windswells from the east continue to arrive, these combined seas may exceed 10 feet in the better exposed areas at the peak of the swell, potentially requiring an advisory. Low pressure developing juest west of the dateline this weekend is forecast to strengthen over the next few days while tracking directly toward Hawai`i. The resulting swell should arrive Wednesday, likely peaking at the upper end of moderate levels. High pressure is again expected to take over the region to the north and northeast of Hawai`i which will limit swell production throughout the forecast period. As mentioned above, no other significant swells are expected. Actvity to the east-northeast of New Zealand this weekend will send up some minor late-season swell out of the south-southwest which would likely arrive around Friday or Saturday this week. The long-range models hint toward the potential for another small out of season south swell developing around mid-week, but the odds are low at the moment.
East and northeast facing shores may pull in sloppy windswell in the 4-7+ foot range at the better exposed breaks. North and northwest facing shores may still have surf in the 2-4 foot range with slightly higher sets possible in select areas. Upper West shores will be smaller at 1-3 foot but some areas may pull in an occasional higher set. South facing shores may still see surf around the lower end of 1-4 foot as a south-southwest swell fades away.
Wind and Tide Information
High tide at Kahului was 2.5 foot at 4:14 AM early this morning, dropping to a low of 1.0 foot at 10:41 AM this morning, then rising to a high of 1.4 foot at 2:55 PM early this afternoon, before once again dropping to a low of -0.1 foot at 9:24 PM late this evening
The sunrise was at 06:34 am this morning and will set at 05:46 pm this evening. The Moon is currently 3 days old, and is in a Waxing Crescent phase. The next First Quarter will occur at 6:28 AM on Thursday, November 19th.
The stronhg easterly tradewinds will continue in the 20-30 mph range over the weekend with gusts reaching near 50 mph in some areas. We should expect a slight decrease as we head into the upcoming week but wind speeds will still remain above moderate levels until late next weekend.
Sunset: 5:43 PM
Weather Outlook for Saturday
Trade winds will be wet and rather strong through the weekend, and a wind advisory is in effect for all islands due to the gusty trade winds. Lighter winds and fewer showers are expected early next week. The light east to southeast winds from Monday through Wednesday will give way to slightly stronger trade winds from Thursday into next weekend, with increased showers possible again by Thursday.
Currently, a relatively strong 1034 mb surface high is centered about 1400 miles N of the islands, having recently replaced a slightly weaker ridge that was a little further S on Friday. A surface cold front currently lies between the new high and the islands, thus keeping the pressure gradient far N of the area a little looser than it might otherwise be, while the gradient at the latitude of the islands has apparently changed little while this process unfolded over the past 6 to 12 hours. Water vapor imagery shows an e-w oriented trough aloft about 200 miles N and NE of the island chain, with a weak low embedded in the trough centered about 250 miles NE of the Big Island. This low and trough have been drifting slowly southward over the past 12 to 18 hours.
Early morning soundings continued to show the effects of the trough, as a fairly unstable and moist profile is seen in the lowest 15 to 20 thousand feet of the Hilo sounding while the Lihue sounding showed a shallower layer of moisture and a lower inversion height. With the strong trade winds blowing over nearby ocean waters that remain nearly 2 degrees celsius /about 4 degrees f/ warmer than normal, and cool temperatures aloft associated with the trough, satellite and radar show numerous showers moving over the islands within an unstable low cloud field, while the orography of the islands is also driving cloud and shower formation. While maximum 24- hour rainfall totals at gages in windward areas of the smaller islands are 1-2 inches, wettest windward Big Island gages have received 5-7 inches of rain. Latest imagery shows broken bands of showers in the trade wind flow, with one band now traversing the chain, with a bit of a break until another band is noted, currently about 200 to 300 miles NE of the chain. Thus a reduction in showers may occur from later this morning through this afternoon between these two bands.
The interaction between island terrain, the strong trade winds and the upper trough is also bringing moisture to the summits and upper slopes of the Big Island, where temperatures are cold enough to allow freezing rain and show showers to develop. Thus a winter storm warning is in effect through noon today due to ice accumulations leading to hazardous conditions. Moisture could spread to the summits again tonight, and the warning may need to be extended, and/or re-issued if allowed to expire.
The high currently building far N of the islands will move rather quickly toward the ESE into early next week, and then remain nearly stationary far NE of the islands through the forecast period. As the front between the high and the islands dissipates today, the low- level pressure gradient near the islands is expected to tighten. Winds are expected to strengthen to the point that a wind advisory has been issued for all land areas through tonight. With the trough in the mid- and upper-levels remaining in place through the weekend, the island atmosphere will continue to be moderately unstable, and showers will continue to pepper island skies, both windward and leeward, except for leeward Big Island, where clouds and showers will favor afternoon hours. Gfs guidance responds by indicating bands of showers streaming over the islands from the ENE through Sunday.
Local winds are expected to diminish and veer toward the SE beginning early week. This is partially due to the high moving far NE of the area, but more due to the approach of a cold front that will push the ridge associated with the high southward to a location about 150 to 200 miles N of Kauai on Monday, where it will remain in place until early Wednesday. Winds on the W end of the island chain will veer to the SE and weaken significantly while moderate E trade winds prevail near the Big Island. A ridge building over the islands should combine with the reduced winds to lead to a much drier weather regime than the current one, at least for the first half of next week.
The powerful low that spawns the approaching cold front will lift NE quickly early next week, leaving the stalled boundary W of the islands, and allowing the northward-moving ridge to bring increasing trade winds to the islands by mid- to late-week. Moisture moving in from SE of the island chain may lead to increased showers for the second half of the week, and next weekend. Significant differences exist between the GFS and ecwmf with respect to island weather next weekend, but both are portending the potential for a wet weather regime. Longer range forecast grids represent a blend of the guidance from the GFS and ECMWF.
Central Valley (Kahului, Spreckelsville):
WIND ADVISORY IN EFFECT UNTIL 6 AM HST SUNDAY. Breezy. Partly sunny with scattered showers in the morning, then sunny with isolated showers in the afternoon. Highs 81 to 87. Northeast winds 20 to 25 mph with gusts to 50 mph. Chance of rain 50 percent.
Leeward West (Lahaina, Ka`anapali):
WIND ADVISORY IN EFFECT UNTIL 6 AM HST SUNDAY. Windy. Mostly cloudy with showers likely in the morning, then mostly sunny with isolated showers in the afternoon. Highs 77 to 82. East winds 25 to 30 mph with gusts to 50 mph. Chance of rain 70 percent.
Windward West (Wailuku, Waiehu):
HIGH SURF ADVISORY IN EFFECT UNTIL 6 PM HST SUNDAY…WIND ADVISORY IN EFFECT UNTIL 6 AM HST SUNDAY. Windy. Frequent showers in the morning, then partly sunny with scattered showers in the afternoon. Highs 65 to 83. East winds 20 to 30 mph with gusts to 50 mph. Chance of rain near 100 percent.
Windard Haleakala (Hana, Haiku, Makawao):
HIGH SURF ADVISORY IN EFFECT UNTIL 6 PM HST SUNDAY…WIND ADVISORY IN EFFECT UNTIL 6 AM HST SUNDAY. Breezy. Frequent showers in the morning, then showers likely in the afternoon. Highs around 82 at the shore to around 63 at 5000 feet. East winds 20 to 25 mph with gusts to 50 mph. Chance of rain near 100 percent.
Leeward Haleakala (Kihei, Wailea, Makena):
WIND ADVISORY IN EFFECT UNTIL 6 AM HST SUNDAY. Breezy. Mostly sunny with isolated showers. Highs around 84 at the shore to 66 to 74 upcountry. East winds 15 to 20 mph with gusts to 50 mph. Chance of rain 20 percent.
WIND ADVISORY IN EFFECT UNTIL 6 AM HST SUNDAY. Mostly sunny. Breezy. Scattered showers in the morning, then isolated showers in the afternoon. Highs around 56 at the visitor center to around 54 at the summit. East winds 15 to 25 mph with gusts to 50 mph. Chance of rain 50 percent.
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