National Weather Service Raw Text Product

905 
FXHW60 PHFO 090136
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
336 PM HST Mon Jul 8 2019

.SYNOPSIS...
The northern periphery of the remnants of former tropical cyclone
Barbara will pass by south of the state tonight with passing 
showers across the area especially for windward and mauka areas. 
Breezy to locally windy conditions are expected through tonight 
due to Barbara's proximity. A more typical trade wind weather 
pattern is expected Wednesday through Saturday with clouds and 
passing light showers favoring windward and mauka areas. Stronger 
trade winds are expected Sunday and Monday as a new high builds in
north of the area.

&&

.DISCUSSION...
The remnants of former Tropical Cyclone Barbara are presently 
centered about 120 miles south of the Big Island. It is currently 
moving toward the west at around 15 mph. Moisture associated with 
Barbara are providing for numerous showers to fall over windward 
sections of the Big Island and east Maui with just a few passing 
showers elsewhere mainly over windward and mauka areas of the 
other islands. The threat of widespread heavy showers over the Big
Island appears to have ended thus the Flash Flood Watch has been 
cancelled. The pressure gradient between high pressure northeast 
of the area and Barbara has caused trade winds to increase. Thus a
Wind Advisory is posted through the evening hours for portions of
the state mainly over and downwind of terrain as well as near 
coastal headlands. 

This area of moisture associated with Barbara will continue to
spread westward tonight with increasing rain chances for the 
remainder of the state especially over windward and mauka areas. 
Rainfall will begin to taper off from east to west on Tuesday as
the remnants of Barbara begin to move away from the area. Also 
winds will gradually diminish as the pressure gradient relaxes a 
bit. 

Moderate easterly trade winds are then expected during the
Wednesday through Saturday time frame as high pressure remains
centered far northeast of the area. Moisture embedded in the
trades will likely allow for passing showers to favor windward 
and mauka areas with just a few passing light showers expected 
over some leeward locations. By Sunday, a stronger high is
expected to build in north northwest of the area resulting in an 
uptick in trade winds speeds due to a tightening pressure 
gradient. These stronger trade winds will likely continue into
Monday.

&&

.AVIATION...
With the remnants of Tropical Cyclone Barbara passing just to the
south of the Big Island, easterly trade winds should be breezy to
windy through this period. Expect low level turbulence to the
south and west of the mountains on all islands. As a result, 
AIRMET Tango is will probably be in effect until at least Tuesday
morning.

There is a lot of moisture also associated with the remnants of
Tropical Cyclone Barbara and it will move from the southeast to 
northwest over the island chain as we progress into Monday night 
and early Tuesday. As a result, AIRMET Sierra is in effect for 
mountain obscuration on the windward and south sides of the Big 
Island, Maui, Lanai and Molokai. This should continue into Monday
night and possibly into the early part of Tuesday. These passing 
IFR conditions are expected to stay with Hawaii through the period
so the rest of the islands may see mountain obscuration later 
today and overnight Monday night into the early portions of 
Tuesday. Expect mainly MVFR conditions for the rest of the state.

&&

.MARINE...
A surface trough will be traversing the area from east to west 
through tonight. The trough is currently located southwest of the 
Big Island and is expected to pass south of Oahu tonight. Strong
to gale force easterly winds are expected for the Big Island
tonight and strong east to northeast winds are expected elsewhere. The
combination of strong to gale force winds and a large east swell 
will lead to dangerous and unsafe water conditions through 
tonight. A Gale Warning is in effect through 6 am HST Tuesday for 
the Alenuihaha Channel and waters south of the Big Island, while 
the Small Craft Advisory (SCA) with the similar time set as the 
gale warning, cover the rest of the islands near-shore waters. 
Winds should begin to decrease Tuesday to more typical summertime 
speeds as the trough moves away from the state and a ridge builds
north of the area later this week.

The large east swell from Barbara will continue to produce
dangerous surf along east facing shores of the Big Island. Earlier
today, we received a observation of 15 to 20 foot surf on a east
facing shore of the Big Island. The Hilo buoy continues to hold
strong this evening, but upstream buoys are indicating a steady
decline to begin tonight as the trough moves away from the area. A
High Surf Warning is in effect for east facing shores of the Big
Island through tonight and is expected to drop to advisory levels
on Tuesday. Elsewhere, a High Surf Advisory remains in effect for
east facing shores of Maui, Molokai, Oahu and Kauai through
tonight. Surf is expected to drop to borderline advisory levels on
Tuesday for these areas. 

The combination of a declining south-southwest swell and a steady
small southeast swell generated by the strong southeast trade
winds in the South Pacific last week will maintain surf at 
heights slightly above the summer-time average (5ft) through mid-
week along south facing shores. Towards the end of the week, a 
series of south-southwest swells is expected starting Friday and 
will likely reach advisory levels over the weekend. A tiny north-
northwest swell filled in today and is producing small surf along
north facing shores of some of the islands. A similar size 
northwest swell is slated for Wednesday night through Thursday 
night. 

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
High Surf Advisory until 6 AM HST Tuesday for Kauai Windward-
Oahu Koolau-Olomana-Molokai Windward-Maui Windward West-Windward 
Haleakala-Leeward Haleakala.

Wind Advisory until 8 PM HST this evening for Molokai Windward-
South Big Island-Big Island North and East-Kohala-Big Island 
Interior.

High Surf Warning until 6 AM HST Tuesday for South Big Island-
Big Island North and East.

Gale Warning until 6 AM HST Tuesday for Alenuihaha Channel-Big 
Island Leeward Waters-Big Island Southeast Waters.

Small Craft Advisory until 6 AM HST Tuesday for Kauai Northwest 
Waters-Kauai Windward Waters-Kauai Leeward Waters-Kauai Channel-
Oahu Windward Waters-Oahu Leeward Waters-Kaiwi Channel-Maui 
County Windward Waters-Maui County Leeward Waters-Maalaea Bay-
Pailolo Channel-Big Island Windward Waters.

&&

$$

DISCUSSION...Burke 
AVIATION...Chevalier
MARINE...Kino