| Current Conditions | ||
| Temp |  | 4.6 C |
| RH | | 87 % |
| Wind | | ENE 10 mph |
| Road | | Open (4x4) |
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Hawaiian Islands Synoptic Discussion and Guidance 910 FXHW60 PHFO 012010 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 1010 AM HST SAT OCT 1 2016 .SYNOPSIS... High pressure northeast of the state will drive fresh trade winds through the weekend. Showers are expected to increase in coverage during the weekend, with locally heavy downpours becoming more likely early next week, as a moist airmass associated with the remnants of Ulika moves over the state. && .DISCUSSION... High pressure to the northeast of the state will maintain fresh trade winds across the region through Sunday. The high is expected to move to the east over the next few days, and the associated ridge will sink a bit closer to the islands. This would weaken winds near the islands, and turn them more southeasterly for Monday and Tuesday. Ulika remnants are about 400 miles southeast of the Big Island this morning with the bulk of the associated moisture to the northeast of the remnants near 18N 149W. As this system moves closer to the islands, precipitable water (PW) values will increase. The overnight soundings from Lihue showed near normal PW for October of 1.19 inches, while Hilo was above normal with 1.86 inches. The models are in good agreement with the influx of moisture through the start of the work week, with the highest PW values expected over and near the Big Island. Looking at the upper level temperatures, both the GFS and ECMWF indicate 500 and 700 temperatures will cool a little Monday through Tuesday, but remain near normal for October. The coolest temperatures remaining to the northwest of Kauai. This is in part due to an upper level low that the models form to the northwest of Kauai. The disconnect between the bulk of moisture to the southeast and colder upper level temperatures to the northwest introduces an uncertainty with the organization of this event. What is certain and agreed upon with the models is that the increase in moisture will bring an increase in rain chances, and the possibility of locally heavy rainfall. Some heavy rain could make it into the islands as early as tomorrow afternoon and overnight, but the greater chance begins Monday. The grids have the possibility starting Monday and at this time do not have overwhelming evidence to change that. At this time, the threat appears the highest Monday night. Will be monitoring future model runs to evaluate the situation. During the second half of next week, look for trades and trade wind showers to gradually return. && .AVIATION... Pockets of showery clouds over and upstream of the state will lead to occasional MVFR conditions, mainly across windward sections. Brief IFR visibilities are also possible in heavier showers. After an improving trend this afternoon, an additional area of moisture over the windward offshore waters will enhance showers and lead to an increase in MVFR conditions again tonight. Have expanded the AIRMET for mountain obscuration to include all windward sections, though if conditions continue to improve we may be able to drop Maui County and Oahu. AMDAR soundings from Honolulu and Kahului show up to 30 knots of wind below a strengthening inversion. We have not received any pilot reports with more than light turbulence near the islands. However, with winds as strong as they are it remains prudent to keep the AIRMET for moderate low-level turbulence in the lee of the mountains. && .MARINE... High pressure to the northeast will maintain fresh to locally strong trade winds through the weekend. As a result, a small craft advisory remains posted for the typical windier areas near Maui and the Big Island through Sunday. Winds and seas are expected to trend down early next week as the high moves further away and winds become more southeasterly. The trades will continue to bring rough surf to east facing shores into Monday...before trending down as the winds weaken. Elsewhere, small surf is expected through the upcoming week. Surf along north facing shores will likely build next weekend due to a gale that is projected to develop over the northwest Pacific by Wednesday. && .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. && $$ DISCUSSION/MARINE...M Ballard AVIATION...Bravender Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office |
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