Weather Service Report


359 
FXHW60 PHFO 231951
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
951 AM HST Sun Feb 23 2020

.SYNOPSIS...
Winds will be generally light today as a front approaches from the
northwest. The front will stall and dissipate early this week 
just north and west of Kauai while a new high passes by far to our
north resulting in moderate trade winds returning. Mostly dry 
weather today will transition into a typical shower pattern 
favoring windward and mauka areas. A new strong high will build in
north of the area toward the end of the week and on into next 
weekend with trade winds becoming rather windy. An upper trough 
will also move over the area resulting in a wetter trade wind 
pattern. 

&&

.DISCUSSION...
High pressure is centered far northeast of the area with a ridge 
extending west southwest to a position just north of the state. 
Meanwhile, a weakening cold front is approaching the area from the
northwest. Winds a rather light with sea breeze circulations 
expected to prevail today across most areas. The airmass is rather
dry and stable so just a few showers are expected today mainly 
over interior areas. 

The front is forecast to stall just to the north and west of Kauai
on Monday, then gradually dissipate on Tuesday. A new high will be
passing by far north of the area during that time with light to
moderate trade winds returning. Moisture embedded in the trades
will provide for some passing showers over windward and mauka
areas with a few showers possible over select leeward locations. 

By Wednesday and Thursday, surface high pressure will be centered
far northeast of the area. Aloft, an upper low is expected to be 
centered several hundred miles east of the Big Island while an 
upper level ridge axis lies just west of Kauai. Moisture embedded 
in the trades will provide for passing showers over windward and 
mauka areas with the trade winds sufficiently strong enough to 
blow some brief passing showers over leeward areas at times. 

Models are in good agreement with some changes occurring as we 
head into next weekend. A new strong high will build in to our 
north while an upper level trough develops across the area. Trade 
winds will pick up and become rather windy across some areas. The 
upper trough will destabilize the airmass especially over the east
end of the state. The upper trough is forecast to cut off near 
the Big Island over the weekend. Thus a windy and rather wet trade
wind pattern is setting up for next weekend. Details will be fine
tuned as we get closer to the event. 

&&

.AVIATION...
Most of the area has variable low level winds due to the weakening
front to the north of the state. The winds are weak enough to 
where a daytime sea breeze/nighttime land breeze scenario will be 
in place through tonight. As the front washes out and high 
pressure begins to nudge in, expect northerly winds to pick up 
through the day on Monday, starting with Kauai, then moving 
southeast. Therefore, the winds are not much of a factor. Due to 
the sea breezes, there is a chance of interior showers and some 
areas of MVFR conditions, especially up against the mountains, but
most of the state will have VFR a majority of the time through
this forecast period.

There are no AIRMETs currently in effect.

&&

.MARINE...
Have cancelled the Small Craft Advisory (SCA) for the remaining 
waters with the morning package. An overnight ASCAT pass showed 
winds below SCA levels over the area, and the small area of 10 ft
seas to the northeast of the Big Island early should be on the
decline. SCA level winds are expected once again Monday night,
with SCA level seas filling in on Tuesday. 

The ridge to the north of the islands this morning will be pushed
closer or over the islands later today as a front to the 
northwest moves to the east. The front is expected to stay north
of the islands, but light winds will continue through tonight. 

High pressure will strengthen north of the islands starting
Monday, allowing trade winds to increase. As mentioned above, SCA
level winds are expected to enter the typically windier areas near
Maui County and the Big Island, as well as some additional nearby
waters, as early as Monday night. Winds are expected to strengthen
further through the week, so expect additional coastal waters to
be under a SCA by the end of the week.

The current northwest swell will gradually lower through Monday. A
large northwest swell is expected to arrive Monday night, with
seas reaching SCA levels filling in on Tuesday. The surf from this
swell is expected to peak Tuesday well above advisory levels, and
could reach warning levels for north and west facing shores. It
will then gradually subside through Thursday, with a new northwest
swell arriving. This new swell will peak Thursday night and Friday
near advisory levels, before gradually decreasing next weekend. 
Surf along the east showers will be trending up this week as the
trades increase, and may reach advisory levels by the end of the
week. 

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

DISCUSSION...Burke
AVIATION...Chevalier
MARINE...M Ballard

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