Current Conditions
Temp2.2 C
RH46 %
WindNE 21 mph
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Hawaiian Islands Synoptic Discussion and Guidance

FXHW60 PHFO 160710

Area Forecast Discussion
National Weather Service Honolulu HI
830 PM HST Mon Jul 15 2019

Trade wind weather will prevail through the week into early next
week, thanks to high pressure far north of the area. Passing clouds
and showers will favor windward and mauka areas. Lee sections of the
Big Island will see clouds and showers mainly during the afternoon
and evening hours.


Trade wind weather continues over the islands this evening, as a
high pressure persists far north of the state. Moderate to breezy
trade winds are expected as pressure gradient remains somewhat
tight across the area. Moisture embedded in the trades is providing
some passing showers, mainly along windward and mauka areas.
Lingering convection over the lee areas of Big Island is decreasing,
and will slowly clear out overnight. There are not much low clouds
in the island vicinity, thus expect mainly fair weather will
continue over rest of the area for rest of the evening.

Water vapor imagery along with model guidance showed a broad mid
and upper level trough just east of the Big Island. This trough will
drift westward over the next few days, passing over the islands.
This will bring a little airmass instability to the area. A small
area of enhanced moisture can also be seen on satellite imagery a
few hundred miles east of the area. Latest guidance indicates that
this area of moisture will reach the Big Island Tuesday, then
advance westward across rest of the area later Tuesday into early
Wednesday. An uptick in windward and mauka shower activity is
expected with the passage of this feature. The trades will also be
strong enough to carried some showers to the leeward locations of
the smaller islands.

The surface high to the north is forecast to strengthen during the
middle and latter half of the week. Expect an uptick in trade wind
speeds across the area. Meanwhile, the upper feature will have
weakened and moved to just north of the state. Thus breezy trade
wind weather is expected. The high will weaken a bit over the
weekend with a slight drop off in trade wind speeds.


High pressure north of the state will keep a breezy to locally
windy, easterly trade wind flow in place through over the next
several days. Relatively dry conditions will prevail with a few
light showers affecting mainly windward and mountain areas. Brief
MVFR cigs/vis are possible as showers move through, but VFR
conditions are expected to prevail statewide over the next 24

AIRMET Tango remains in effect for moderate, low-level turbulence
over and downwind of the higher terrain of all islands below 6
thousand feet. These conditions are expected to continue for the
next couple of days.


A weak trough of low pressure just northwest of Kauai, will lift
northeast and dissipate over the next couple days, as high pressure
north of the islands strengthens. This will lead to strengthening
trades across the state through Wednesday, with fresh to strong
trades then expected through the end of the work week. The trades
could ease slightly over the weekend, as high pressure to the north
weakens. A Small Craft Advisory (SCA) remains in effect for the
typically windy waters around the Big Island and Maui. The SCA will
likely need to be expanded to include additional zones around mid

The current south swell will continue to slowly subside through
mid-week, with only small background south and southwest swells
expected for the end of the work week and over the upcoming weekend.
A High Surf Advisory remains in effect for south facing shores
tonight, and will likely be cancelled with the morning forecast
package. The locally strong trade winds will produce choppy waves
along east facing shores but the fetch will be short for the next
couple of days so wave heights will remain relatively small. East
shore surf will increase by mid-week as the fetch becomes longer.
Only very small surf is expected along north facing shores during
the next 7 days.


High Surf Advisory until 6 AM HST Tuesday for Niihau-Kauai
Windward-Kauai Leeward-Oahu South Shore-Waianae Coast-Molokai
Leeward-Lanai Makai-Kahoolawe-Maui Leeward West-Maui Central
Valley-Windward Haleakala-Leeward Haleakala-Kona-South Big
Island-Big Island North and East.

Small Craft Advisory until 6 AM HST Saturday for Maalaea Bay-
Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big
Island Southeast Waters.




Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office