Current Conditions | ||
Temp | ![]() | -4.3 C |
RH | ![]() | 27 % |
Wind | ![]() | NE 34 mph |
Road | ![]() | Closed |
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Hawaiian Islands Synoptic Discussion and Guidance 697 FXHW60 PHFO 280624 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 824 PM HST Wed Jan 27 2021 .SYNOPSIS... High pressure north of the state will keep breezy trades in place through Saturday, with a slight easing in the trade wind speeds expected on Sunday. Showers will favor windward and mauka areas with a few showers reaching leeward areas from time to time. An old front will likely bring an increase in showers to the islands on Friday however. The trades will diminish and shift southerly early next week in advance of a cold front. The cold front is expected to bring a more widespread rainfall event Tuesday through Wednesday of next week, with cooler and breezy conditions behind the front. && .DISCUSSION... Currently at the surface, a 1030 mb high is centered around 1050 miles north-northeast of Honolulu, and is driving breezy trades across the island chain this evening. Infrared satellite imagery shows partly to mostly cloudy conditions across the state, with cloud cover most prevalent in windward areas. Meanwhile, radar imagery shows scattered showers over windward slopes and coasts, with a few showers making the trip over the mountains into leeward locales from time to time. Main short term focus revolves around trade wind trends and an increase in showers associated with old frontal remnants moving through on Friday. High pressure will build slowly southward and closer to the islands tonight through Thursday night, before becoming absorbed into a new re-enforcing high building southward far to the north of the state Friday through the weekend. The gradient will remain rather tight across the islands through the period. Breezy conditions are expected through Saturday, before the trades slowly ease to the moderate levels by Sunday. The trades are forecast to diminish further Monday, then become disrupted and shift southerly next Tuesday in advance of a cold front. Breezy northerly winds are then expected following the cold frontal passage Tuesday night and Wednesday, ushering in some cooler air. As for the remaining details, typical trade wind weather is expected tonight through the weekend. Showers will favor windward and mauka areas and a few showers will reach leeward areas from time to time. We expect an increase in shower coverage on Friday however, particularly over windward areas, as both the GFS and ECMWF show some old frontal remnants sliding southward through the islands. This would likely send a few more showers into leeward communities as well. Drier trade wind weather is expected for Monday, with fewer windward and mauka showers. The lighter winds will also allow for some leeward shower development in the afternoon hours as a result of localized sea breeze development. A cold front will likely bring more widespread rainfall to the islands Tuesday through Wednesday of next week, with the potential for some locally heavy rainfall and thunderstorms. && .AVIATION... Breezy trade winds will carry in clouds and showers into tonight bringing tempo MVFR/isolated IFR conditions along windward slopes. In the very near term, AIRMET Sierra for tempo mountain obscuration is in effect for windward areas, but is expected to expire on schedule at 07z/9pm HST. Fewer clouds and showers are expected by Thursday. AIRMET Tango remains in effect for low-level mechanical turbulence leeward of all islands due to strong low level winds. && .MARINE... A strong high far north of the state will keep breezy to locally strong easterly trade winds in place through Friday. A slight decrease in trade winds into the moderate to breezy range will develop by this weekend, as a weaker high passes by far north of the island chain. Large surf along east facing shores will continue through Friday morning. The easterly trade wind swell will gradually decrease from Friday afternoon through the weekend as the high pressure system north of the area weakens. A Small Craft Advisory (SCA) for all Hawaiian waters is in effect through early Friday morning. A High Surf Advisory (HSA) for exposed east facing shores is in effect through Thursday afternoon. This HSA may need to be extended into Friday with continued strong trade winds. The current small northwest swell will continue to hold through Thursday with a slight reinforcing bump Thursday night. A new moderate, long-period northwest swell will spread across the area late Friday, and continue through Saturday night. Northwest swell heights will slowly lower from Sunday into early next week. Forerunners of a small, long-period north-northeast swell will likely arrive Thursday and continue through the weekend. The current small out-of-season southwest swell will slowly drop tonight through Friday morning. Otherwise, expect small background south swells Friday afternoon into early next week. && .HFO WATCHES/WARNINGS/ADVISORIES... High Surf Advisory until 6 PM HST Thursday for Kauai Windward- Oahu Koolau-Olomana-Molokai Windward-Maui Windward West-Windward Haleakala-Big Island North and East. Small Craft Advisory until 6 AM HST Friday for all Hawaiian waters- && $$ DISCUSSION...Jelsema AVIATION...JVC MARINE...Kinel Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office |
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