| Current Conditions | ||
| Temp |  | 3.5 C |
| RH | | 12 % |
| Wind | | NNE 17 mph |
| Road | | Open (4x4) |
|
Menu of Text Products for the Hawaiian Islands and the Tropical Pacific/Atlantic Oceans: |
|
Narrow the Menu List Select Time Limit: 12 hours | 24 hours | 48 hours | 72 hours | No time limit Select Product Type: All | Routine Bulletins/FCSTS | Warnings/Watches/Advisories | HAWN Weather | Tropical | Marine | Aviation | Daily Obs | Special |
|
|
Hawaiian Islands Synoptic Discussion and Guidance 096 FXHW60 PHFO 251341 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 341 AM HST Fri Sep 25 2020 .SYNOPSIS... Fairly typical trade wind weather is expected through Saturday, with showers favoring windward and mauka areas and a stray shower spilling leeward from time to time. The trades will become light Sunday through Monday, with a few showers continuing to affect windward areas and a shower or two developing over leeward areas during the afternoon hours each day. A land breeze and sea breeze pattern is expected to take hold Tuesday through late next week, with showers limited to coastal areas at night and during the morning, and interior locations during the afternoon and evening hours. && .DISCUSSION... Currently at the surface, a 1023 mb high is centered around 900 miles north-northeast of Honolulu, and is driving moderate to locally breezy trades across the island chain early this morning. Meanwhile, Tropical Storm Lowell remains far to the east of the state over the cooler east Pacific waters. Closer to home, infrared satellite imagery shows scattered to broken low clouds pushing into windward areas with the trades, with partly cloudy skies in most leeward areas. Radar imagery shows scattered showers moving into windward areas, with a few of these showers spilling into leeward areas. Main short term concerns revolve around trade wind trends and rain chances during the next few days. High pressure north of the islands will keep moderate to breezy trades in place today. The trades will then ease over the weekend as the high north of the state slides into the far east Pacific and a trough of low pressure develops north of the islands. A further easing of the trades is expected next week, as the remnant low of tropical cyclone Lowell approaches from the east, and a cold front approaches from the west. This is expected to drop trades into the light range Monday through late next week, with a sea breeze/land breeze pattern likely in leeward areas each day. As for the day to day weather details, fairly typical trade wind conditions will prevail through Saturday. Showers will favor windward and mauka areas, particularly during the night and early morning hours, with a stray shower reaching leeward areas from time to time. The forecast becomes a bit more uncertain Sunday and Monday, as the ECMWF shows a band of moisture ahead of the remnants of Lowell pushing into the islands, while the GFS keeps this band of moisture northeast of the state. With the lightened wind regime anticipated, we should see showers limited to windward areas and locations near the coast during the night and morning hours, with a few daytime heating and sea breeze driven showers possible in leeward areas each afternoon. Tuesday through Thursday, the trades will be largely cut off, and this should result in a fairly dry land breeze/sea breeze driven shower pattern. During this time, showers should favor coastal areas overnight and during the morning hours, and interior sections of the islands during the afternoon and evening. && .AVIATION... Locally breezy trades will remain relatively dry through the forecast period. Prevailing VFR is forecast with only isolated/brief instances of MVFR expected within heavier windward and mauka showers. AIRMET Tango is in effect for tempo low-level turbulence over and south through west of the mountains of all islands. Conditions will likely continue through today. && .MARINE... Fresh to strong easterly trades will continue through tonight, then gradually trend down over the weekend, potentially enough for a localized land and sea breeze pattern to set up near the coasts beginning as early as Sunday. The Small Craft Advisory has been extended through tonight for the windier waters around Maui County and the Big Island. For the upcoming week, guidance shows the light winds continuing each day in response to a weakness developing in the ridge as a series of fronts pass to the north. Surf along north facing shores will remain up today due to the first sizable swell of the season arriving out of the north yesterday. The swell will begin to ease through the weekend. The active pattern across the northern Pacific is expected to continue over the weekend through early next week with back-to- back systems diving southeastward across the Date Line from the western Aleutians. If this scenario materializes, the first swell will arrive Wednesday and peak Thursday with the second one arriving Friday. The first of the two could approach the advisory level by Thursday. Surf along south facing shores will remain up over the weekend as a new, long-period south-southwest swell arrives and slowly fills in today. Heights will near the advisory level (8 ft faces) by Saturday as it peaks. A gradual downward trend is expected Sunday into early next week. For the long range, the active trend is expected to continue down south around New Zealand within Hawaii's swell window. The latest guidance depicts a broad, storm-force low bottoming out at 929 mb south-southeast of New Zealand late this weekend. A large area of gale- to storm-force winds setting up within our swell window will drive seas into the 35 to 40 ft range. If this evolves as predicted, expect a large south swell by the end of the first week in October. Surf along along east facing shores will remain small through the weekend. A small easterly swell from tropical cyclone Lowell in the eastern Pacific can't be ruled out early next week, especially for the eastern end of the state. Water levels will gradually trend down each day into the first week October. && .HFO WATCHES/WARNINGS/ADVISORIES... Small Craft Advisory until 6 AM HST Saturday for Maalaea Bay- Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters. && $$ DISCUSSION...Jelsema AVIATION...JVC MARINE...Gibbs Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office |
|