| Current Conditions | ||
| Temp |  | 4.0 C |
| RH | | 8 % |
| Wind | | WNW 0 mph |
| Road | | Open (4x4) |
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Hawaiian Islands Synoptic Discussion and Guidance 945 FXHW60 PHFO 221341 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 341 AM HST Wed Jan 22 2020 .SYNOPSIS... A cold front north of the island chain and another front approaching the islands from the northwest will keep the Hawaiian Islands in a dry and light wind weather pattern through Friday. The slowing forward motion on the northwestern cold front will cause this frontal boundary to stall out near Kauai on Friday and Saturday, bringing increasing clouds and showers to the Garden Isle. Trade winds will also return to the region on Friday spreading isolated to scattered showers to windward and mountain areas of all islands through Sunday morning. Another cold front moving through the Central Pacific basin, north of the state, will bring several days of a dry light wind weather pattern starting next week Monday. && .DISCUSSION... Most islands this morning are showing clear skies with few exceptions along southeastern slopes of Maui and the southeast to east slopes of the Big Island. A weak front roughly 400 miles north of Kauai will continue to drift eastward away from the state. The state remains under the southwest edge of the subtropical ridge keeping the islands in a light and variable wind pattern. When the large scale winds diminish, surface heating and cooling differences between islands and ocean produce overnight land and daytime sea breezes. Today through Friday, expect continued land and sea breezes for most islands with only isolated shower activity possible each day favoring the afternoon hours. Clouds will develop over island mountain and interior sections each day due to converging sea breezes, then clear out each night as diverging land breezes take over. A cold front will stall out over Kauai on Friday with increasing clouds and showers forecast over the Garden Isle into the weekend. Trade winds will bleed through the front on Friday with a brief northerly direction quickly veering towards the east by Saturday morning. Isolated to scattered windward and mauka showers will return with the trade winds through Sunday morning. On Saturday and Sunday, showers along the weakening frontal band linger over Kauai and the Kauai Channel on Saturday as easterly trade winds return to the state. Wind directions will veer to the southeast direction over the western half of the state by Sunday pushing the clouds and showers towards the northwest away from Kauai. This slight increase in trade wind shower activity will only last a few days. By Monday, the southwest edge of the subtropical ridge will move back over the islands as we transition back to several days of a dry land and sea breeze pattern. The southeastern slopes of the Big Island will benefit from enhanced showers during this period with a light background southeast wind flow. && .AVIATION... VFR conditions will prevail with light and variable winds. Outside of some afternoon clouds associated with the sea breezes, mostly clear conditions are expected. The best chance for any showers will be over windward (eastern end of the state) and interior areas in the afternoon. No AIRMETS are in effect and none are anticipated. && .MARINE... The main marine hazard the next couple of days will be related to a pair of large NW swells (and associated seas/surf), with the first swell in the process of arriving. Long-period forerunners (21-27 seconds) of this swell have been steadily building at buoys 51001 and 51101 to the NW of Kauai through the night, and are showing up at the nearshore buoys as well. Although surf along most N and W facing shores may start off on the smaller side this morning (with long lulls between sets), surf will steadily increase through the day, and peak at dangerously high levels tonight into Thursday before gradually lowering later Thursday into Friday. A High Surf Warning and a Small Craft Advisory remain posted for exposed shorelines/marine zones. See the Coastal Hazard (CFWHFO) and Marine Weather Messages (MWWHFO) for additional details, as well as the Oahu Surf Discussion (SRDHFO). The second large NW swell is expected to arrive Friday night and peak at warning level heights Saturday, then gradually diminish Sunday and Monday. A surface ridge will be near the islands into Friday, keeping winds generally light and variable, but favoring a southerly direction near Kauai, and an easterly direction near the Big Island. A weak front will move into the area from the N Friday into Saturday, pushed S by a high building NW and N of the islands. This high will support light to moderate trade winds over the weekend as the front stalls and dissipates near Kauai and Oahu. && .HFO WATCHES/WARNINGS/ADVISORIES... High Surf Warning until 6 PM HST Thursday for Niihau-Kauai Windward-Kauai Leeward-Waianae Coast-Oahu North Shore-Oahu Koolau-Olomana-Molokai-Maui Windward West-Maui Central Valley- Windward Haleakala-Kona-Kohala. Small Craft Advisory until 6 PM HST Thursday for Kauai Northwest Waters-Kauai Windward Waters-Kauai Leeward Waters-Kauai Channel- Oahu Windward Waters-Oahu Leeward Waters-Kaiwi Channel-Maui County Windward Waters-Big Island Windward Waters-Big Island Leeward Waters-Big Island Southeast Waters. && $$ DISCUSSION...Bohlin AVIATION...Gibbs MARINE...Birchard Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office |
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