| Current Conditions | ||
| Temp |  | 3.3 C |
| RH | | 12 % |
| Wind | | NE 22 mph |
| Road | | Open (4x4) |
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Hawaiian Islands Synoptic Discussion and Guidance 843 FXHW60 PHFO 200144 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 344 PM HST Fri Apr 19 2019 .SYNOPSIS... Moderate to locally breezy trade winds will prevail through much of the week as surface high pressure holds north of the state. Rather stable conditions will remain in place, leading to a typical pattern of mainly windward and mauka showers. && .DISCUSSION... A stable, moderate to locally breezy trade wind flow persists. The trades are being generated by strong high pressure located far northeast of the state and its associated surface ridge sitting nearly 350 miles north of Kauai. A mid level ridge overhead is producing stable conditions and a fairly strong strong inversion between 4,000 ft to 6,000 ft according to afternoon soundings and recent aircraft data. Moisture in the trade wind flow is generally near April normal, which has resulted in modest rainfall (less than 1/4 of an inch) across windward terrain today. Leeward areas have remained mostly dry. A typical trade wind weather pattern is expected through much the upcoming week. We will likely see a brief uptick in trade winds during the weekend as the ridge to the north strengthens. Trades will drop back into the moderate to locally breezy range on Monday and persist through at least Thursday as surface high pressure prevails to the north of the state. Stable conditions will dominate through much of the week as the mid level ridge will remain parked overhead, and generally, precipitable water will be near normal, suggesting that showers will be modest and confined to windward slopes. As random pockets of low level moisture move through on the trade wind flow, expect brief and localized increases in showers. Aside from afternoon showers on the Kona slopes of the Big Island, leeward areas will be mostly dry. The GFS and ECMWF differ on the details, though both models show an advancing front weakening the trade winds next Friday. && .AVIATION... A high pressure ridge north of the state will keep the islands in a moderate to breezy trade wind weather pattern through the weekend. Near surface wind speeds are strong enough to support moderate low level turbulence over and south through west of mountain ranges of all islands. Scattered shower activity will favor windward and mountain sections with brief periods of MVFR conditions mainly during the overnight hours. AIRMET Tango remains in effect for tempo moderate turbulence below 080. This AIRMET will likely remain in effect through the weekend. && .MARINE... Fresh to strong trades will continue into early next week as a ridge remains north of the islands. The Small Craft Advisory (SCA) remains posted for the typical windier areas near Maui County and the Big Island through Sunday afternoon. Models indicate an uptick in the winds Saturday as the ridge strengthens, so windward Maui and Big Island, as well as the Kaiwi Channel were added to the SCA for that time period. It also remains likely that the SCA for the typical windy zones will be extended into next week. The current north-northwest swell is expected to peak today below advisory levels, then slowly decline through the weekend. A small, west-northwest swell is possible early next week, but again remain below advisory surf levels. Background south-southwest swells will keep surf small along south facing shores through the weekend. An upward trend is expected early next week though, due to recent activity southeast of New Zealand, and should correlate to above average south shore surf continuing into midweek. Surf along east facing shores could see a bump over the weekend with an uptick in the trades. See the latest Oahu Surf Discussion (SRDHFO) for additional details on surf and swell. && .HFO WATCHES/WARNINGS/ADVISORIES... Small Craft Advisory until 6 PM HST Sunday for Maalaea Bay- Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters. Small Craft Advisory from 6 AM Saturday to 6 AM HST Sunday for Kaiwi Channel-Maui County Windward Waters-Big Island Windward Waters. && $$ DISCUSSION...Wroe AVIATION...Bedal MARINE...TS Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office |
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