| Current Conditions | ||
| Temp |  | 3.1 C |
| RH | | 9 % |
| Wind | | SE 6 mph |
| Road | | Closed |
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Hawaiian Islands Synoptic Discussion and Guidance 329 FXHW60 PHFO 190625 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 825 PM HST Fri Oct 18 2019 .SYNOPSIS... Trade winds will continue through the weekend and much of next week, delivering clouds and showers to windward areas, with a stray shower reaching leeward locales from time to time. High clouds of varying thicknesses will occasionally move over the islands through early next week. && .DISCUSSION... Currently at the surface, a 1028 mb high is centered around 1000 miles northeast of Honolulu, while a weak trough of low pressure is located around 450 miles south-southeast of the Big Island. The resulting gradient is producing moderate trade winds across the island chain this evening. Infrared satellite imagery shows low clouds moving into windward areas with the trades, with high clouds associated with a jet stream aloft spreading from southwest to northeast across the state. Radar imagery shows scattered showers moving into windward areas, with a stray shower drifting leeward from time to time. Main short term concern revolves around rainfall chances and trade wind trends over the next several days. Trade winds will prevail for the next 7 days, with only some minor fluctuations in speed expected. Moderate to locally breezy trades will hold in place though Sunday, then ease slightly late Sunday through Monday as a weakening cold front approaches from the northwest. The trades are expected to edge up late Monday through Wednesday as high pressure northeast of the state strengthens, before trending back down late next week as a new cold front approaches from the northwest. Fairly typical trade wind weather is expected to continue during the next 7 days, with showers favoring windward and mauka areas along with the occasional leeward spillover. Showers are expected to be most common between 6 PM and 10 AM each day. There could be a bit of a downward trend in shower coverage through the weekend and possibly into Monday, as the airmass remains fairly dry and stable. Slightly higher precipitable water values move in late Monday and remain in place through the end of the work week. This should increase shower coverage to more typical levels for this time of year. Periods of high cloud cover associated with a jet stream aloft will continue to move overhead through the weekend and into early next week, resulting in partly to mostly cloudy conditions. The high clouds should thin out Tuesday through late next week. && .AVIATION... Breezy trades associated with high pressure northeast of the state will continue through Saturday. Clouds and showers will favor windward and mountain locations, with the best coverage likely occurring through the overnight and early morning hours. No AIRMETs are in effect or anticipated at this time. Brief MVFR ceilings and visibilities are possible in and around passing showers. Otherwise, VFR conditions will prevail for all areas. && .MARINE... High pressure northeast of the state will maintain the fresh to strong easterly trade winds through Saturday afternoon, so the Small Craft Advisory (SCA) continues for the typical windier waters near Maui County and the Big Island. As a front moves closer to the state from the northwest late Saturday night, winds are expected to shift to the east-southeast. The front is expected to stay north of the islands, and will likely weaken the winds over the western half of the coastal waters. Winds are expected to shift back to a more easterly direction Monday. Surf is expected to remain below advisory levels through the forecast period. The current combo north and northwest swell will continue to gradually decline through the weekend. A new small long-period north-northwest swell expected Saturday will help maintain small surf along exposed shores. A gale low is expected to develop near the Kurils Saturday night into Sunday, and then track to the east toward the Date Line Sunday into Monday. This would generate a northwest swell that could reach the islands late next week. Last week, a storm force low far southeast of New Zealand tracked east with a captured fetch aimed east of the state. Due to angular spreading, we should see an increase in surf tonight through the weekend along south facing shores. Near-shore buoys are showing some long-period forerunners from the south this evening. Surf should increase to around the summer average on Saturday and hold through the weekend before dropping off early next week. The fresh to locally strong trade winds will maintain rough surf along east facing shores through Saturday. As the winds weaken Sunday, surf heights should subside and conditions should improve. && .HFO WATCHES/WARNINGS/ADVISORIES... Small Craft Advisory until 6 PM HST Saturday for Maalaea Bay- Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters. && $$ DISCUSSION...Jelsema AVIATION...Gibbs MARINE...Kino Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office |
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