Area forecast discussion
National Weather Service Honolulu HI
400 PM HST Friday may 24 2013
Synopsis...
surface high pressure north of the area will keep trade winds
blowing over the islands through next week. With the trades
blowing...showers will be focused over mainly windward areas except
for afternoon showers over the Lee slopes of The Big Island. A
trough aloft over the area will help keep the showers fairly active.
&&
Discussion...
a 1030 mb high about 1300 miles northeast of the islands will
maintain locally breezy trade winds through the Holiday weekend. The
trades will taper off a bit Tuesday and Wednesday as the high
weakens and moves closer to the islands. The trades will strengthen
again later in the week as a new high builds far northeast of the
area.
An east northeast to west southwest trough aloft remains about 250
miles northwest of Kauai. The trough is making the atmosphere a bit
unstable...especially near Kauai due to a low aloft within the
trough 540 miles west of Kauai. The atmosphere over the islands will
stabilize over the weekend as the trough moves southeast and the low
moves away to the west. The atmosphere may become more unstable
again early next week...especially near The Big Island as a new low
aloft forms east of the islands. It remains uncertain how big an
impact this will have on local weather. In the latest runs...the GFS
model shows more instability than the European model (ecmwf). It does not look as if
it will get unstable enough for thunderstorms over the islands...but
showers may get more active on The Big Island while the low aloft is
nearby.
&&
Aviation...
the Hawaii terminals will remain mainly VFR with isolated MVFR
ceilings and visible over windward areas. As the trade winds
strengthen...moderate low level turbulence may develop and require
an airmet.
&&
Marine...
the current northwest and south swells will both continue dropping.
No other significant swells are expected. The Small Craft Advisory
for strong trade winds will likely be extended and may also need to
be expanded to include the Kaiwi Channel since the winds are
expected to strengthen over the weekend.
&&
Hfo watches/warnings/advisories...
Small Craft Advisory until 6 am HST Sunday for the windier waters
around Maui County and The Big Island.
&&
$$
Donaldson
