Area forecast discussion
National Weather Service Honolulu HI
400 PM HST Tuesday Jun 18 2013
Synopsis...
typically quiet June weather will continue as Spring gives way to
Summer. High pressure to the north will keep trade winds blowing.
Showers will be focused over windward areas...and these showers will
be most active during the nights and mornings. There may also be
some afternoon showers over leeward areas of The Big Island and
Maui...but rainfall will be light.
&&
Discussion...
Summer will start Thursday evening at 705 PM HST. This is usually
the driest time of year for most areas of the main Hawaiian islands.
Satellite and radar loops and surface observations show typically
quiet weather this evening. There are patchy scattered to broken
low clouds over the islands with scattered low clouds upstream.
Radars show only isolated light showers moving over the islands from
the east in the locally breezy tradewind flow.
The computer models show the atmosphere becoming drier and the
low-level moisture getting shallower over the next 24 hours...so
rainfall is likely to be quite sparse tomorrow through Friday. With
trade winds continuing...what rainfall we do get will be
concentrated over windward areas. Climatology shows a summertime
peak in rainfall over south Kona...but it looks as if the leeward
side of The Big Island will remain quite dry.
Computer models continue to show a big low developing up near the
Aleutians over the next couple of days and show the subtropical
ridge weakening and shifting south. That should weaken the pressure
gradient over the islands and cause trade-wind speeds to drop off a
bit Wednesday night through Thursday night. The ridge will re-build
by the weekend and trades will likely become locally breezy again.
&&
Aviation...
there should be little change in aviation weather around the main
Hawaiian islands through at least the next 24 hours. Conditions will
remain mostly VFR except for isolated MVFR ceilings over windward
and mountain areas.
&&
Marine...
a Small Craft Advisory...sca...is now up through early Wednesday
evening for locally strong trade winds and rough seas in the windier
areas around Maui and The Big Island. Winds will subside slightly
Wednesday night through Thursday night...probably enough to allow US
to drop the Small Craft Advisory for a day or two. A Small Craft Advisory is likely to go back up
again Friday.
Surf will be generally small except for moderate surf along east
shores due to the trade winds. A small southeast swell may affect
The Big Island starting Sunday...but The Big Island will likely
block most of the swell from reaching the rest of the islands.
&&
Hfo watches/warnings/advisories...
Small Craft Advisory until 600 PM HST Wednesday for Maalaea Bay...
the waters south of The Big Island...and the pailolo and alenuihaha
channels.
&&
$$
Donaldson
