Wind Advisory 20, NWS Honolulu, HI

957 
WWHW70 PHFO 022357
NPWHFO

URGENT - WEATHER MESSAGE
National Weather Service Honolulu HI
157 PM HST Mon Apr 2 2018


HIZ028-031300-
/O.UPG.PHFO.WI.Y.0020.000000T0000Z-180403T1500Z/
/O.NEW.PHFO.HW.W.0011.180402T2357Z-180403T1600Z/
Big Island Summits-
157 PM HST Mon Apr 2 2018

...HIGH WIND WARNING IN EFFECT UNTIL 6 AM HST TUESDAY...

The National Weather Service in Honolulu has issued a High Wind
Warning, which is in effect until 6 AM HST Tuesday. The Wind
Advisory is no longer in effect.

* WINDS...West 40 to 60 mph with localized gusts to 85 mph.

* TIMING...Through tonight.

* IMPACTS...Strong and gusty winds will produce difficult 
  driving conditions especially for high profile vehicles.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A high wind warning means that winds at the summits are expected 
to be at least 56 mph with gusts over 66 mph. Take necessary 
precautions to protect property. Travel to the summit areas should
be delayed until winds subside.


$$

Area Forecast Discussion
National Weather Service Honolulu HI
835 PM HST Sun Apr 1 2018

.SYNOPSIS...
A wet weather pattern unfolds next week across the Hawaiian
Islands with several low pressure systems track across the
state. Humid and Voggy southerly winds will continue into the
first half of next week. The first trough will move into the
islands from the west on Monday and Tuesday spreading clouds and
showers down the island chain to Maui County. A second trough
sweeps showers across the islands from the west starting on
Wednesday morning. Deep moisture will continue to hang over the
islands through the week with a weak cold front sweeping a third
round of showers through the state on Thursday and Friday. Trade
winds return briefly from late Friday into Saturday in a
continued humid and cloudy weather pattern.

&&

.DISCUSSION...
The East Pacific high remains locked in place off the California
coast as a broad area of low pressure moves through the Central
Pacific. A slow moving cold front lingers between these two air
masses dragging a nearly stationary remnant frontal boundary just
northwest of the Hawaiian Islands. Meanwhile tropical moisture
with voggy kona winds persists over the state. A complicated wet
weather pattern will develop this week with several upper level
short wave troughs passing west to east through the region. These
upper troughs will cause weak lows to develop along the northern
remnant front, lifting clouds and showers through each island as
they pass.

Monday and Tuesday...The first in a series of troughs moves into
Kauai from the northwest on Monday afternoon with upper level
forcing spreading clouds and showers eastward over Kauai and Oahu.
The trough continues to push into Maui County from Monday night
into Tuesday morning with enhanced showers reaching the Big Island
by Tuesday afternoon.

Wednesday through Friday...Meanwhile out west, a second stronger
trough moves into the picture passing eastward through Kauai and
Oahu on Wednesday morning. On Thursday high pressure moving across
the Central Pacific will help push another round of clouds and
showers into Maui and Hawaii Counties through Friday.

The long range outlook for next weekend still appears humid and
cloudy as a surface trough will linger over the state and another
upper trough and surface low move into the region from the west.
Weather model guidance continues to show kona winds replaced by
trade winds on Friday and Saturday, strong enough to blow all the
Volcanic fOG (VOG) away from the smaller islands. Another round of
showers is possible for the northern islands on Sunday.

The timing on precipitation impacts for each island remains
challenging in a complicated weather pattern. Overall we expect
periods of moderate to locally heavy rainfall through the upcoming
work week with higher chances over Kauai and Oahu on Monday and
Tuesday. The American (GFS) global weather model and the European
(ECMWF) model continue to struggle with the track and impacts
from these troughs. We will focus more on short term precipitation
timing and use a broader approach to shower activity for the
second half of the week. A blend of solutions using both global
models with mesoscale details will help identify short term
precipitation trends. Stay tuned for forecast updates this week as
the weather pattern evolves over time.

&&

.AVIATION...
A weak front just northwest of Kauai will nudge closer to the
islands through Monday. A weak surface wind flow will persist
across the island chain tonight, allowing night-time land breezes
to develop, with stronger southerly winds are expected across the
islands on Monday. VFR conditions will prevail across the area
through early Monday, though isolated MVFR lower ceilings and
showers may affect the area, especially for the western islands as
the pockets of moisture may move in from the south.

An AIRMET for TEMPO moderate turbulence continues between FL180
and FL260 over the entire state. The non-standard AIRMET for
TEMPO light icing remains in effect in the area between 160 and
FL250 due to the present of upper level moisture.

&&

.MARINE...
Local winds are forecast to remain in the light to moderate range
out of the south and southeast, which will continue to give way
to overnight land breezes and daytime sea breezes through Monday
near the coasts. The best chance for heavy showers will remain
over the northwest waters through Monday due to a front positioned
west of the state. Winds are forecast to shift out of the south-
southwest Tuesday through midweek and increase into the fresh to
strong category as low pressure develops and lifts northeast,
potentially dragging a cold into the area by Thursday. More of a
widespread rainfall threat will become a possibility Tuesday
through the second half of the week as the front begins to advance
down the island chain.

The anomalous pattern across the northern Pacific that has
suppressed our more typical swell energy from the northwest
direction since the second half of February has begun to shift.
The ridge over the northwest Pacific has broken down, which has
allowed the storm track to shift eastward. The latest model
guidance reflects this and depicts a series of gales setting up
over the northwest Pacific through the week that will bring
consistent surf out of the northwest (310-330 deg) to our north
and west facing shores through the upcoming weekend.

The current west-northwest (300 deg) swell that brought advisory-
level surf to exposed north and west facing shores early Saturday
will continue to slowly ease through Tuesday. A small
reinforcement out of the same direction associated with a gale
tracking eastward north of Midway around 30 to 35N this evening is
forecast to fill in locally Wednesday through Thursday.

Another gale is forecast to develop between 35N and 40N just east
of the date line Wednesday as it tracks southeastward aiming seas
at the local area out of 330 deg. Surf will respond from this
source Friday and persist through the weekend.

Choppy and short period surf along south facing shores will
become a possibility Tuesday through midweek as fresh to strong
south-southwest setup over the state.

&&

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

&&

DISCUSSION...Bohlin
AVIATION...Hui
MARINE...Lau