National Weather Service Raw Text Product

834 
FXHW60 PHFO 082130
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
1130 AM HST Mon Jul 8 2019

.UPDATE...
Upgraded The High Surf Advisory to a High Surf Warning along east
facing shores of the Big Island. 

&&

.SYNOPSIS...
The remnants of former tropical cyclone Barbara will pass through
the area today through Tuesday resulting in increased shower
chances. 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 by Sunday as a new high builds
in north northwest of the area.

&&

.PREV DISCUSSION.../ISSUED 1000 AM HST Mon Jul 8 2019/

The remnants of former Tropical Cyclone Barbara are presently 
centered about 120 miles south southeast 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 over windward areas of the other islands. A 
few of the showers over the Big Island have been briefly heavy. A 
Flash Flood Watch is currently posted for the Big Island due to 
the heavy rainfall potential. Also, daytime heating may allow for 
a few thunderstorms to form over the Big Island slopes this 
afternoon. The pressure gradient between high pressure northeast 
of the area and Barbara has caused trade winds to increase. Thus a
Wind Advisory is posted 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 late today and 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 Barbara begins 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 may build
in north northwest of the area resulting in an uptick in trade 
winds speeds due to a tightening pressure gradient.

&&

.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 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, 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 near the Big 
Island and is expected to pass south of Oahu tonight. Ahead of the
trough, we should see strong to gale force northeasterly winds 
near the Big Island and strong northeast winds elsewhere today. 
Behind the trough tonight, winds are expected to veer east and 
maintain similar speeds to today. 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. 

The large east swell from Barbara will continue to produce 
elevated surf along east facing shores of most islands through 
tonight. A High Surf Warning is in effect along east facing shores
of the Big Island. A High Surf Advisory is in effect for east 
facing shores of all other islands 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 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. A tiny 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 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 Warning until 6 AM HST Tuesday for South Big Island-
Big Island North and East.

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

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...
MARINE...