Current Conditions
Temp2.3 C
RH82 %
WindE 11 mph
RoadClosed
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Hawaiian Islands Synoptic Discussion and Guidance

619
FXHW60 PHFO 210152
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
352 PM HST Tue Aug 20 2019

.SYNOPSIS...
A surface ridge north of the area will maintain locally breezy
trade winds over the islands.

&&

.DISCUSSION...
The 2 PM surface analysis shows a surface ridge extending from a
high far northeast of the area near 30N133W and another high
about 700 miles northwest of the area near 31N164W. A weak trough
south of the Big Island is moving west around 10 miles an hour
and weakening.

The ridge north of the islands will maintain easterly trade winds
across the area. A poorly organized area of showery low clouds
associated with the trough south of the Big Island has been moving
over the islands. Most of the showers have moved off to the west
of the islands, but some showers remain upstream of the Big Island
and Maui. These showers will clear the islands this evening.

Trade winds will strengthen a bit through tomorrow as the high
builds northwest of the islands. A front about 1000 miles north of
the islands will move south through Thursday and cause the trades
to weaken. On Friday, the front will move off to the west and the
high will build northeast. Trade winds will strengthen again and
become locally breezy over the weekend.

&&

.AVIATION...
A ridge north of the state will help to maintain moderate easterly
trade flow overnight. Isolated showers, mainly concentrated along
windward areas and over elevated terrain, will become scattered
after sun down. Expect MVFR conditions at times tonight due to
low clouds and SHRA.

No AIRMETs are currently in effect.

&&

.MARINE...
High pressure will strengthen north of the area providing an
uptick in trade winds speeds. Small Craft Advisory conditions are
expected beginning tonight over the typically windy waters around
Maui County and the Big Island.

Data from the PacIOOS buoys show the new long period south swell
continues to build. Advisory level surf can be expected through
Wednesday night. This swell will hold steady through Wednesday
then lower gradually Thursday and Friday. A series of smaller long
period southerly swells are expected early next week.

A small west to northwest swell will linger over the next few
days providing some out of season surf along exposed shorelines.
Strengthening trade winds over the next several days will cause
short period choppy surf to increase along east facing shores
through the remainder of the week and on through the weekend.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
High Surf Advisory through 6 AM Thursday for south facing shores
of all islands.

Small Craft Advisory through 6 PM Thursday for Maalaea Bay, the
Pailolo and Alenuihaha Channels and waters south of the Big
Island.

&&

$$
DISCUSSION...Donaldson
AVIATION...Thomas
MARINE...Burke

Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office