Wildfire in Hawaii, February 10 to 12, 2018

Area Forecast Discussion
National Weather Service Honolulu HI
338 PM HST Sat Feb 10 2018

.SYNOPSIS...
A trough northeast of the islands will bring increasing clouds and
showers to the islands tonight and Sunday, focused over windward
and mauka areas. A cold front and upper level trough will
approach from the northwest early in the week, once again
increasing the chance for clouds and showers statewide.

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.DISCUSSION...
Winds on the Big Island Summits have begun to decline, in line
with the ECMWF and GFS. Winds have dropped to advisory levels
where they are expected to remain through a good chunk of tonight.
Have posted a Wind Advisory, replacing the warning through tonight
as a result.

A trough to the northeast of the islands a fair amount of clouds
and presumably some showers associated with it. The trough is
expected to move towards the islands tonight and Sunday, bringing
those clouds and showers to the area. As they interact with the
terrain, expect a few additional showers over land, primarily over
the windward and mauka areas. Precipitable water (PW) values from
the soundings this afternoon were 0.71 for Lihue and 0.93 for
Hilo. This marks an increase in PW for Hilo, while Lihue stayed
nearly the same since last night's sounding. This pairs well with
the satellite derived PW that shows 1.2 to 1.4 inch PW to the
northeast of the islands associated with the trough. As this
airmass moves over the islands, this will bring PW back near
normal for February.

Expect a few showers to form over windward and mauka areas
overnight. Not expecting any significant rainfall totals from this
system.

The models are in good agreement with the next weather feature to
bring rain to the islands. A low currently more than 1200 miles
northwest of Kauai has a cold front associated with it, with the
front about 950 miles northwest of Kauai. The models move the low
to the east, while the front moves towards the islands. A new low
develops along the low to the northeast of the islands. The latest
runs bring the front near Kauai Monday afternoon. This will bring
southerly winds to most of the islands ahead of the front.
Expect an increase in shower activity with the front, mainly from
Monday night through Wednesday night.

The low is expected to linger north of the islands through the
remainder of the week, so showers could linger, but high pressure
building in over the islands could limit rainfall totals.

&&

.AVIATION...
Low-level NW to N winds will diminish overnight and become light
and variable Sunday as a trough to the NE moves over the area, and
AIRMET Tango for moderate low-level turbulence has been
cancelled. While VFR conditions will prevail in the short term,
persistent MVFR conditions over the SE portion of the Big Island
have prompted the issuance of AIRMET Sierra for mountain
obscuration.

Increased low-level moisture associated with the trough will
likely fuel an increase in SHRA and MVFR VIS/CIG later tonight
into Sunday, mainly along N and E facing slopes and coasts, which
may necessitate an expansion of AIRMET Sierra for mountain
obscuration.

&&

.MARINE...
Winds and seas are dropping across the western portion of the
main Hawaiian islands, allowing for cancellation of the Small
Craft Advisory (SCA) for waters west of Oahu. The SCA remains in
effect for remaining waters through this afternoon. Winds and seas
will continue to decrease into early next week.

A northwest swell will continue to lower gradually through
tonight. However, a moderate size northwest swell is expected to
fill in tonight and Sunday. A slightly larger, reinforcing
northwest swell is expected Monday with a second reinforcement Tuesday
into Wednesday.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until 6 AM HST Sunday for Big Island Summits.

&&

DISCUSSION...M Ballard
AVIATION...Birchard
MARINE...TS