Area Forecast Discussion
Issued by NWS Honolulu, HI
FXHW60 PHFO 080707
Area Forecast Discussion
National Weather Service Honolulu HI
830 PM HST Wed Dec 7 2016
The weather will become a bit more unsettled over the next few days
due to another trough of low pressure aloft approaches the state
from the west. Shower activity is expected to increase and continue
off and on through the weekend. Mainly light winds will continue
through the rest of the week with widespread daytime sea breezes and
nighttime land breezes. A frontal boundary may reach the state later
this weekend and stall out in the island vicinity.
Rather light winds with minimal showers across the islands this
evening as a broad weak surface pressure pattern resides across the
state. A broad upper level trough centered several hundred miles
west are bringing high clouds from the convection southwest of the
state, keeping skies rather cloudy.
Weather is expected to take a turn for the worst again as the
aforementioned upper level trough moves slowly towards the islands
in the coming days. As this upper level feature advances closer to
the area, a corresponding weak surface trough will setup in the
island vicinity. In fact, lower level winds have already turned more
southerly as indicated by latest radar data. A rather dry airmass
over the western islands as revealed by Lihue afternoon sounding
will become more moist under the increasing southerly winds. Hence
atmospheric conditions are becoming more conducive for heavier
rainfall to develop though the next few days as well as a slight
chance of thunderstorms on Thursday. A Winter Weather Advisory
remains posted for the Big Island summits due to possible wintry
weather at times. Shower chances will increase but will be hard to
pin-point the timing and location due to the rather weak low level
forcing. Mainly light southerly winds are expected as well, with
land and sea breezes developing during night and day. In all,
expected active weather for the islands through Saturday with
scattered showers, locally heavy at times.
Model runs hinted the upper trough may finally push across the
islands by Sunday, though there is a timing difference between
models. This will result in a more stable airmass returning to the
state. On the other hand, all models show some kind of front-looking
band lingering in the island vicinity over the early part of next
week. This still points to possible a further increase in showers
for the area. Looks like the wet weather will stay around in the
island vicinity early next week.
A weak pressure pattern will remain in place tonight and Thursday,
keeping winds light across the area. An upper level disturbance
will approach the island chain from the west tonight and move
overhead on Thursday, bringing some unsettled weather and the
potential for thunderstorms. Mainly VFR conditions are expected
through the overnight hours, with MVFR conditions expected to
develop around daybreak Thursday in many areas, particularly west
of the Big Island. MVFR cigs/vsbys are then expected to linger
across much of the island chain through the day on Thursday, with
some improvement expected Thursday evening.
AIRMET Tango is in effect for upper level turbulence due to strong
jet stream winds. These conditions will likely continue through
AIRMET Sierra and AIRMET Zulu may be needed late tonight and
Thursday for mountain obscuration and icing respectively across
much of the island chain.
A moderate northwest swell will peak overnight, bringing well below
advisory levels surf along north and west facing shores. This
current swell will decline on Thursday, with no other significant
swell is expected through the weekend. A moderate north swell is
possible early next week.
As the winds remain on the lighter side, and with no major swell
expected, small craft advisory conditions are not expected for the
coastal waters through the next few days. But then, locally heavy
downpours as well as a slight chance of thunderstorm may bring
rough conditions at times.
Winter Weather Advisory to 6 AM HST Friday for Big Island Summits.