912
FXHW60 PHFO 221327
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
327 AM HST Fri Nov 22 2024

.SYNOPSIS...
Trade winds will weaken today and become light and variable
during the weekend. The atmosphere will be stable and rather dry
with minimal rainfall expected. A shallow and dissipating front
move may across portions of the island chain Sunday night and
Monday, bringing only modest showers and likely maintaining light
winds. Light trades may return by the middle of next week.

&&

.DISCUSSION...
A stable and rather dry trade wind flow will diminish through
Saturday. Trades will continue to drop as a surface high,
currently sitting roughly 250 miles north of Oahu, moves east and
weakens. With trades on the decline, localized overnight land
breezes and daytime sea breezes occurring today will become more
prevalent on Saturday. A weak mid-level ridge will maintain
stability, and swath of rather dry low-level air around the region
will keep precipitable water below an inch. As a result, expect
minimal windward rainfall, and leeward sea breezes will produce
afternoon clouds over terrain, but little, if any, shower activity
is expected. Dew points will hold in the lower 60s, helping to
push overnight low temperatures into winter-like range of the mid
to even lower 60s in some locations. In addition, a developing
weak jet streak aloft will generate increased thin high clouds
today and Saturday.

Sunday and early next week, the overall pattern favors light
disrupted trade winds and a weak front passing over the northern
end of the island chain. For Sunday, trades will become light and
variable or northerly as a weak front approaches. A dry land and
sea breeze pattern is likely, though a small pocket of moisture
could produce some active showers on the Big Island. Timing in the
deterministic GFS and ECMWF have come into better agreement,
showing a weak front bringing modest showers to windward and
northern slopes of Kauai Sunday night and to Oahu and possibly
Molokai on Monday.

Details become elusive by Tuesday due to model differences. The
GFS and ECMWF are showing the potential for another weak front
passing near or over the state followed by an upper-level ridge
moving westward into the region around Wednesday. Ensemble
guidance shows that the potential for significant rainfall is low,
with light northerly winds becoming trade winds around Wednesday.

&&

.AVIATION...

Trades expected to be on the lighter side thought the weekend. In
the lighter trades regime we could see some localized land/sea
breezes. Any SHRA and low cigs should be confined to windward and
mauka areas. Brief MVFR conds can be expected in any SHRA but
otherwise VFR should prevail.

No AIRMETS are in effect.

&&

.MARINE...
A weak ridge of high pressure north of the state is producing
light to locally fresh winds. This ridge will gradually weaken and
shift south late tonight and over the weekend as a weak front
approaches from the northwest. In response, winds will gradually
become light and variable Saturday into early next week. A weak
transient high will build north of the state by the middle of next
week allowing gentle to fresh northeasterly trade winds to
briefly return.

A small, medium period, north northeast swell (010-030 degrees)
is filling at CDIP Hilo and Pauwela near shore buoys early this
morning. This should produce some small surf along north facing
shores today. Another more moderate, medium period pulse from the
same source is expected Saturday along with a similar size
overlapping northwest swell (320 degrees). These combined swells
will elevate surf along north and west facing shores just shy of
High Surf Advisory (HSA) criteria on Sunday before subsiding early
next week. A Marine Weather Statement remains in effect for
harbor surges, particularly at Hilo and Kahului harbor, generated
by the more northerly swells.

Surf along east facing shores will see some energy from the
northeasterly swell wrap today into the weekend. Surf along east
facing shores will become more elevated over the weekend,
especially Saturday into to Sunday as the swell peaks and shifts
more easterly, wrapping into exposed areas.

&&

.FIRE WEATHER...
KBDI values remain high across the state, and an overall dry
weather pattern is expected through at least Sunday over most
islands. With dry air moving overhead, relative humidity values
will have the potential to drop below the critical 45% threshold
during the late morning and afternoon hours. However, lighter
winds will mitigate fire weather concerns.

&&

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

&&

$$

DISCUSSION/FIRE WEATHER...Wroe
AVIATION...Walsh
MARINE...Almanza