Heavy Rain in Hawaii, January 24 to 25, 2017

Area Forecast Discussion
National Weather Service Honolulu HI
345 AM HST Tue Jan 24 2017

.SYNOPSIS...
A high northeast of the area will maintain locally breezy trade
winds through mid-week. A trough aloft and remnants of a front will
keep windward areas showery through tomorrow night. During the
second half of the week a surface ridge will shift south near the
islands. The ridge will bring light winds and dry weather. A band of
showers along a new front will move across the islands next weekend.
Trade winds will return early next week as a new high moves east
behind the front.

&&

.DISCUSSION...
A 1028 mb surface high 1250 miles northeast of Honolulu is forecast
to move east at 10 mph over the next few days. The high will
maintain locally breezy trade winds over the islands through mid-
week. The trades will push some clouds over the islands through
tonight, so windward areas will remain showery. Cold temperatures
and fog may produce ice on the summits of Mauna Kea and Mauna Loa
this morning. The road to the summit of Mauna Kea may be
slippery until the sun burns off the fog and melts the ice.

As the high moves east, a surface ridge north of the islands will
shift south closer to the islands during the second half of the
week. Winds over the islands will weaken and daytime sea breezes and
nighttime land breezes will develop. A ridge aloft will build
eastward over the area and make the atmosphere quite stable, so
rainfall will be minimal.

A new front will move southeast over the islands next weekend,
reaching Kauai by Saturday evening and moving down to the big Island
by Sunday evening. The front is expected to bring widespread
showers, but moisture along the front will likely be too shallow for
heavy rain. A new high will move east behind the front and produce
breezy trade winds through the first half of next week.

&&

.AVIATION...
Remnant clouds and showers from an old front will linger over east
sections of the islands today. AIRMET Sierra is in effect for TEMPO
MTN OBSC. VFR conditions will prevail for leeward areas. No other
AIRMETs are expected through Tuesday.

&&

.MARINE...
A high northeast of the area is maintaining locally strong easterly
trade winds across some areas of the Hawaiian waters. Also, in some
areas seas remain above 10 feet due to a north swell and waves
produced by the strong trade winds. The trade winds and the
associated elevated seas will gradually subside today. A large
northwest swell building today will keep seas elevated in areas
exposed to the swell.  Please see the latest Marine Weather Message,
MWWHFO, for further details.

The strong trade winds and a short-period north swell continue to
produce surf above eight feet along east facing shores, so we have
extended the high surf advisory through noon today. This surf is
expected to drop below eight feet this afternoon. The large new
northwest swell arriving today will produce surf well above the
advisory threshold along north and west shores of the smaller
islands by this afternoon.

Another large northwest swell may produce surf well above high surf
advisory threshold along north and west facing shores of the smaller
islands starting Friday night. A reinforcing swell may push surf
above the 25 foot warning threshold by Sunday night.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until noon today for ice on the summits of
Mauna Kea and Mauna Loa.

High Surf Advisory until noon today for east facing shores of Kauai
Oahu Molokai Maui and the Big Island.

High Surf Advisory from noon today through noon Wednesday for north
and west facing shores of Niihau Kauai Oahu and Molokai and north
facing shores of Maui.

Small Craft Advisory through Wednesday for a combination of strong
trade winds and seas above 10 feet.

&&

Donaldson