Area Forecast Discussion
Issued by NWS Honolulu, HI
FXHW60 PHFO 291338
Area Forecast Discussion
National Weather Service Honolulu HI
330 AM HST FRI JUL 29 2016
A surface high to the north will keep trade winds blowing over the
islands through the coming week. The trades will carry areas of
tropical moisture over the islands while lows aloft will make the
atmosphere unstable. This combination will keep the weather rainier
than normal through next week.
A 1032 MB surface high 1680 miles north northeast of Honolulu at
43N145W will move west slowly with little change in strength through
tomorrow. The pressure gradient southwest of the high will keep
breezy trade winds blowing over the main Hawaiian Islands through
this evening. The atmosphere over the islands is dry and stable.
Balloon soundings at 200 AM showed a strong temperature inversion
sloping from 5200 feet at Lihue to 6600 feet at Hilo. This
inversion will limit cloud growth and keep rainfall light today.
Water vapor imagery shows a low aloft 740 miles east northeast of
Honolulu at 24N 147W moving toward the west northwest around 20 mph.
As this low moves by the islands tonight through early next week, it
will weaken the trade winds and raise the temperature inversions.
The higher inversions will mean that showers will become more active.
As the low aloft moves north away from the islands next Tuesday, the
trade winds will become breezy again. An area of tropical moisture
enhanced by the low aloft will help boost shower activity through
early next week. A bigger increase in showers is likely Thursday
when another area of tropical moisture moves over the islands.
Strong trade winds blowing over the mountains and strong low-level
temperature inversions will continue to produce low-level
turbulence. AIRMET TANGO remains in effect for low level turb over
and S through W of the mountains. VFR conditions will prevail, but
windward areas may experience isolated MVFR ceilings.
A high to the northeast will maintain strong to near-gale force
trade winds across the area today. A Small Craft Advisory (SCA) is
in effect for all Hawaiian waters through this evening. Winds will
taper off as a weak surface trough arrives from the east tonight
into Saturday. Some or all zones may drop out of the SCA this
weekend. The trade winds will strengthen again by the middle of next
The trade winds will produce choppy surf along east facing shores,
but surf is expected to remain below advisory levels. There will be
a series of small south swells into next week but surf will remain
below the advisory level along south facing shores also. Only small
surf is expected along north and west facing shores.
Small Craft Advisory until 6 PM HST Today for all Hawaiian waters.