National Weather Service Raw Text Product

765 
FXHW60 PHFO 081358
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
358 AM HST Mon Jul 8 2019

.SYNOPSIS...
Expect breezy to windy trades today as a trough associated with
the remnants of former tropical cyclone Barbara passes through the
islands. Deeper tropical moisture will continue to drift in from 
the east as the remnants of Barbara pass through the region 
through Tuesday. This low level remnant will increase clouds, 
showers and wind speeds statewide. Drier weather will return from
Tuesday into Wednesday as trade winds trend lower. Stronger trade 
winds are forecast to develop by next weekend.

&&

.DISCUSSION...
The remnants of former tropical cyclone Barbara continue to spin
roughly 300 miles southeast of Hilo this morning. Satellite
imagery this morning shows bands of unstable clouds radiating 
outward from the center of this remnant trough and drifting over
windward mountain ranges. Abundant and unstable tropical moisture
surrounding this trough will pass westward through the islands 
today and tomorrow.

Increasing clouds and showers are expected over the windward 
slopes of all islands today as strong trade winds lift unstable
tropical moisture over windward mountain ranges. Precipitable 
Water (PW) levels are elevated, showing a large pool of moisture 
ranging from 1.5 to 2.0 inches surrounding this system. Trade 
wind speeds will also increase, becoming breezy to windy today due
to stronger surface pressure gradients associated with the 
passage of this remnant circulation. A wind advisory was issued 
this morning for most areas on the Big Island and windward Molokai
through this evening. The main threats associated with this 
passing tropical remnant will be potential flash flooding, high 
surf, and strong gusty winds.

Trade wind speeds will decrease later tonight into Tuesday as 
the trough passes to the west and pressure gradients return to 
normal. Expect a more typical trade wind weather regime with 
passing windward and mauka showers through Friday. Long range 
models continue to hint at another round of deeper tropical 
moisture drifting in from the east by this weekend increasing 
showers over the southeastern side of the state. Trade wind speeds
will also increase as this weak disturbance passes south of the 
islands. Track and timing differences on this system between the 
American (GFS) and the European (ECMWF) models will lead to some 
evolution in this longer range forecast over the next several 
days. Stay tuned.

&&

.AVIATION...
Breezy to locally windy easterly trades will continue today,
before easing tonight as the remnants of former Tropical Cyclone 
Barbara approach, then pass by just south of the Big Island. Low 
level turbulence is expected peak today, then gradually diminish
tonight and Tuesday. AIRMET Tango remains in effect and will 
likely continue through tonight and possibly through Tuesday.

Deep tropical moisture associated with the former tropical 
cyclone will overspread the entire island chain today. Widespread
MVFR cigs/vsbys are expected to affect windward areas, with IFR 
conditions possible. The worst conditions are expected across 
windward sections of the Big Island and Maui, where IFR conditions
will be more likely. Conditions should begin to improve from east
to west across the state tonight.

AIRMET Sierra remains in effect for mountain obscuration across 
windward sections of the Big Island, Maui, and Molokai. These 
conditions will likely continue through the day. AIRMET Sierra 
will likely be needed for mountain obscuration across windward 
sections of the remaining islands later today.

&&

.MARINE...
The remnants of once tropical cyclone Barbara will be traversing
the area from east to west through tonight. There is no definable
surface circulation, meaning Barbara is now a north to south 
oriented trough located some 200 nm southeast of the Big Island
and moving west at 15 kt. It is located along 153W longitude 
between 19N and 14N. This trough is set to pass south of the Big 
Island late this afternoon and the rest of the islands tonight and
Tuesday morning.

In doing so, the trade winds will be strengthening, becoming 
quite windy across the area today. Seas will be becoming very 
rough as well, leading to dangerous and unsafe water conditions. 
A Gale warning is now 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. 

The large east swell from Barbara will continue to produce 
elevated surf along east facing shores of most islands through 
tonight. A High Surf Advisory is in effect for this east facing 
shores through tonight. The combination of the strong trade winds
and elevated surf will produce very hazardous conditions along 
east facing shores through early Tuesday. 

The long-period south-southwest swell has subsided to below
advisory level, thus the High Surf Advisory has been lowered for
the south facing shores.  The recent period of strong southeast 
trade winds in the South Pacific should maintain at or slightly 
above summer- time average through mid- week for the south facing
shores. Finally, a small north- northwest swell may bring a 
slight rise in the surf along north facing shores of some of the 
islands today. A similar size northwest swell is slated for 
Wednesday night through Thursday night.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Flash Flood Watch through late tonight for the Big Island.

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 Advisory until 6 AM HST Tuesday for Kauai Windward-
Oahu Koolau-Olomana-Molokai Windward-Maui Windward West-Windward 
Haleakala-Leeward Haleakala-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...Bohlin
AVIATION...Jelsema
MARINE...Lau