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Marine Weather and Tides Hilo, HI Version 3.4

NOTICE 8/26/2020 The 7 day forecast is taking about 5 seconds to load but it will eventually load. NOAA is still working on it. 8/18/2020 NOAA continues to have trouble. Wind guest will occasionally be left off graphs. I am working with NOAA to resolve the issue. 12/16/2019 NOAA is having trouble with requests that include wind gusts. I am posting graphs without wind gusts until it gets fixed. 10/9/2019 Updated the Marine Zones. 9/4/2019 Fixed the weather maps due to NOAA moving them. 7/25/2019 New feature in the Airports section gives a link to 5 minute updates for data reports.

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Sunrise 6:56AM

Sunset 6:08PM

Saturday January 23, 2021 8:18 AM HST (18:18 UTC)

Moonrise 2:02PM

Moonset 2:39AM

Illumination 79%

NOTE: Some of the data on this page has not been verified and should be used with that in mind. It may and occasionally will, be wrong. The tide reports are by xtide and are NOT FOR NAVIGATION.

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7 Day Forecast for Marine Location Near Hilo, HI

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Area Discussion for -

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FXHW60 PHFO 231330 AFDHFO

Area Forecast Discussion National Weather Service Honolulu HI 330 AM HST Sat Jan 23 2021

SYNOPSIS. Strong and gusty trade winds will deliver passing clouds and showers through the weekend, mainly dampening windward areas while a few brief showers spread leeward. More widespread rainfall may develop Monday into Wednesday as winds remain strong and shift to the southeast. Breezy trades and fewer showers are expected after mid- week.

DISCUSSION. Windy and locally wet trade wind weather will prevail through the weekend, with most clouds and showers focused over windward areas. The strong trades will blow showers leeward on the smaller islands, leading to prime rainbow weather. Strong winds will shift to the southeast late Sunday, increasing the potential for widespread cloudiness and rainfall starting on Sunday over the Big Island, spreading to the other islands Monday and Tuesday, then diminishing after mid-week. A Flood Potential Outlook (ESFHFO) has been issued to highlight the potential for flooding rainfall.

Low clouds have increased in coverage upstream of the islands over the past 12 to 24 hours, with a fair amount of open-celled showery cumulus embedded in a strengthening trade wind flow. A surface high centered far NE of the islands is in the process of being reinforced by a stronger high, and is expected to build to near 1042 mb over the next 24 hours before moving S and slowly weakening. A Wind Advisory is in effect for a large portion of the area in anticipation of the resultant increase in trade wind speeds.

Low-level moisture coming in with the trades will extend as high as 8-10 thousand feet through the weekend, due to the presence of weak troughing in the mid- and upper-levels, which has led to a weakened subsidence inversion. This will keep windward showers active, especially during nights and mornings, with the strong trades driving some raindrops leeward. However, most leeward communities will receive little in the way of accumulation.

The development of a deep-layer low to the distant W and NW of the islands is expected to cause the winds to veer to the SE late in the weekend, while an associated moisture convergence band extending SE from the low creeps towards the islands from the S. Latest guidance indicates this band will move over portions of the islands from late Sunday into Wednesday - bringing PWAT close to 2", layered cloudiness, and the potential for widespread rainfall. Another key ingredient typical of past flood events includes the presence of a negatively-tilted upper trough that guidance concurrently depicts.

While abundant moisture is expected, the atmosphere is expected to be only modestly unstable. In light of this, heavy showers have been added to the forecast, while thunderstorms have been omitted. Some mid-level warming may preclude the development of winter weather on the Big Island Summits, but this is a low confidence forecast, and may require significant changes. A drying trend is generally expected after mid-week as the convergence band shifts W of the area. High pressure to the distant NE will continue to support locally strong trade winds.

AVIATION. Breezy to locally strong trades will continue through the forecast period. Windward showers will be common throughout this time with frequent leeward drift of showers continuing through at least early this morning, especially over Oahu. Further, the latest ground and satellite observations support issuance of AIRMET Sierra for mountain obscuration for Windward Oahu through Maui this morning. Further expansion to Windward Kauai is plausible, but otherwise MVFR conditions are expected to abate by late this morning. The trade inversion will then begin to lift and weaken this afternoon in response to an approaching trough, a trend that will accelerate into tonight. Greater coverage of showers accompanied by a higher probability for MVFR is forecast for tonight.

AIRMET Tango is in effect for moderate mechanical lee turbulence and areas of strong surface winds.

MARINE. A surface high far northeast of the area is generating moderate to locally strong trade winds. The high will strengthen today, increasing trade winds across the entire area through the first part of next week. A Small Craft Advisory is in effect for all coastal waters through Tuesday for strong to near gale force trade winds as well as building seas from the trade wind swell and a large west- northwest swell. A Gale Watch has also been issued for the Alenuihaha Channel beginning Sunday evening.

Long-period energy from an incoming west-northwest swell has arrived to Kauai and Oahu and should reach Maui later this morning. This swell is expected to peak later today with an 18 second period and surf potentially approaching warning level. A High Surf Advisory (HSA) for exposed north and west facing shores of the smaller islands is now in effect. The more westerly direction of this swell will allow west facing shores of the Big Island to experience high surf as well, likely by this afternoon, so they have been added to the HSA. Swell and surf will lower gradually Sunday and Monday, then become rather small for this time of year on Tuesday and Wednesday.

Trades will strengthen this weekend, resulting in rough, short- period surf. An HSA is now in effect for exposed east facing shores and may need to be extended as strong trades persist for several days.

Small, mainly background, southerly swells are expected over the next several days. A small bump in south-southwest surf is expected to gradually fill in Monday, peak Monday night and Tuesday, then lower Wednesday through Thursday.

HYDROLOGY. For the National Weather Service in Honolulu to issue a Flood Potential Outlook (ESFHFO), there needs to be a >50% chance of heavy rainfall leading to flash flooding in the next 2 to 4 days, with the event expected to affect two or more counties for at least 2 days. These criteria are purposely stringent to prevent an over-issuance of the product. The convergence band that is expected to develop appears ripe for the development of training-type rainfall, where heavy showers repeatedly form and move over the same areas. While there is a chance this band remains over waters S of the islands, the potential for it to bring an impactful rain event to the islands next week was deemed great enough to warrant the issuance of the Outlook.

HFO WATCHES/WARNINGS/ADVISORIES. Wind Advisory until 6 AM HST Sunday for Kauai Leeward-Kauai Mountains-Oahu South Shore-Oahu Koolau-Olomana-Waianae Mountains- Molokai Windward-Lanai Makai-Kahoolawe-Maui Windward West-Maui Leeward West-Windward Haleakala-Leeward Haleakala-South Big Island-Big Island North and East-Kohala-Big Island Interior.

High Surf Advisory until 6 AM HST Sunday for East facing shores of Kauai Oahu Molokai Maui Big Island, North and West facing shores of Kauai Niihau Oahu Molokai, North facing shores of Maui, and for West facing shores of the Big Island.

Small Craft Advisory until 6 PM HST Tuesday for Kauai Northwest Waters-Kauai Windward Waters-Kauai Leeward Waters-Kauai Channel-Oahu Windward Waters-Oahu Leeward Waters-Kaiwi Channel-Maui County Windward Waters-Maui County Leeward Waters-Maalaea Bay-Pailolo Channel-Big Island Windward Waters-Big Island Leeward Waters-Big Island Southeast Waters.

Gale Watch from Sunday evening through Tuesday afternoon for Alenuihaha Channel.

Small Craft Advisory until 6 PM HST Sunday for Alenuihaha Channel.



DISCUSSION . Birchard AVIATION . JVC MARINE . TS

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Weather Reporting Stations

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Stations	Dist	Age	Wind	Air Temp	Water Temp	Waves	Pressure	DewPt
ILOH1 - 1617760 - Hilo, HI	1 mi	49 min	SSW 1.9 G 4.1	68°F	78°F		1016.4 hPa
51206	7 mi	36 min			76°F	9 ft
KWHH1	45 mi	49 min	ESE 11 G 18	78°F	78°F		1014.8 hPa

Wind History for Hilo, Hilo Bay, Kuhio Bay, HI

(wind in knots)    EDIT      (on/off)   Help

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N3

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NE7 G11

NE9 G12

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E2 G5

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SW2 G7

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1 day ago

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W7 G10

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W3 G6

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SW1 G4

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NW1 G4

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2 days ago

SW2

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N11

W9 G12

SE6 G10

SW4 G7

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NW3

NW4

SW2

N8

W6

SW3

SW1

SW2 G8

S1

S3

S2

SW1

E7 G11

S2

SW2 G8

SW3

SW3

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Airport Reports

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Airport	Dist	Age	Wind kt	Visibility	Sky/Weather	Temp	DewPt	Humidity	Pressure
Hilo, Hilo International Airport, HI	1 mi	26 min	WSW 8	10.00 mi	Partly Cloudy	70°F	62°F	76%	1017.7 hPa

Link to 5 minute data for PHTO

Wind History from HTO (wind in knots)

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W8

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SW8

1 day ago

W5

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E6

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Calm

Calm

W6

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W6

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2 days ago

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NE10

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N7

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Tide / Current Tables for Hilo, Hawaii Island, Hawaii

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Tide / Current Tables for Kawaihae, Big Island, Hawaii (2)

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Weather Map

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GEOS Local Image of Hawaii    EDIT
NOTE: East coast views moved to GEOS-16. They are experimental and not well supported by NOAA so they may not be correct so be warned. This change required redoing a large amount of the GOES code. If the image you are expecting is not showing, please let me know. You may need to use the EDIT function to update your location.
Link to Loop

Other links: Northern Pacific     Contential US     Full GOES-East

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Ground Weather Radar Station

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