| Current Conditions | ||
| Temp |  | 4.7 C |
| RH | | 14 % |
| Wind | | NE 2 mph |
| Road | | Open (4x4) |
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Hawaiian Islands Synoptic Discussion and Guidance 047 FXHW60 PHFO 270627 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 827 PM HST Mon Sep 26 2022 .SYNOPSIS... Trade winds will strengthen to light to moderate this week which will focus low clouds and showers across mainly windward areas. Winds may be light enough at times to allow localized afternoon sea breezes to generate clouds and a few showers across leeward areas. && .DISCUSSION... Radar this evening shows only scattered to isolated showers across the islands, with a majority of showers lingering west of the state in an area of deeper moisture. Otherwise, satellite data shows limited cloud cover this evening, as drier air continues to stream in from the east. Overall expect limited clouds and showers to influence the islands through early Tuesday, as dry and stable air moves westward. A surface boundary about 400 miles north-northeast of the islands will further weaken as it slowly drops southward toward the state into Wednesday, while the surface ridge north of the state gradually reestablishes itself. This pattern will maintain a weak pressure gradient and light to moderate easterly trade wind flow across the islands this week. These winds will direct showers to mainly windward areas in a typical trade wind weather pattern. However, localized sea breeze clouds and showers remain possible for some leeward areas this week. The airmass will differ across the state this week, as the front sagging southward maintains a layer of deeper moisture over the western islands, while much drier and more stable air continues to filter in across the central and eastern islands through much of this week. Forecast moisture depths and inversion heights will remain around 7k feet across the eastern half of the state with PW values generally around 1.25 inches or less. Deeper moisture depths between 8k-10k feet and PW values over 1.60 inches or greater, are forecast over the western end of the state. This pattern will limit the areal coverage of showers for Maui and the Big Island into Friday, while the areal coverage of showers increasing across Oahu and Kauai. Current trends support a weaker pressure gradient redevelops once again this weekend, as another surface boundary drops southward. The weakened surface pressure gradient could allow for localized afternoon and early evening sea breeze showers across some leeward areas and island interiors this weekend. && .AVIATION... A ridge of high pressure passes north of Hawaii this evening producing gentle to moderate trade winds. Trade winds will strengthen slightly to more predominantly moderate levels on Tuesday. Few to scattered clouds around the islands will decrease in coverage overnight with benign weather expected on Tuesday. VFR conditions will prevail over the next 24 hours and no AIRMETs are expected. && .MARINE... A front will remain in place between a high to our north and the main Hawaiian islands. This will keep trade winds in the light to moderate range over the next several days for most waters. However, terrain-induced acceleration may briefly boost winds to Small Craft Advisory threshold Tuesday and Tuesday night across typically windy waters around Maui and the Big Island. South swell will continue to lower through Wednesday. Another small longer period south swell will fill in Wednesday night and Thursday with a slight reinforcement expected Friday and Saturday. A slightly larger long period south swell may arrive around Sunday. No significant north or northwest swells are expected through Thursday night, with a small short period northwest swell expected Friday and Saturday. Another small but longer period northwest swell may arrive on Sunday. Short period choppy surf will remain rather small over the next few days across east-facing shores, with a slight increase possible later in the week and on into the weekend. && .HFO WATCHES/WARNINGS/ADVISORIES... Small Craft Advisory from 6 AM Tuesday to 6 AM HST Wednesday for Maalaea Bay-Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters. && $$ DISCUSSION...SWR AVIATION...Foster MARINE...Powell Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office |
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