Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Honolulu HI
330 am HST Sat Jul 4 2015
the prevailing light trades will gradually increase during the next
several days...but remaining weak enough to allow for a few showers
this afternoon as sea breezes develop. The trades will likely
become moderate to locally strong by Tuesday or Wednesday.
Intensifying high pressure north of the islands may bring even
stronger trades for the second half of next week.
the prevailing light trades are expected to gradually increase and
become more NE during the next several days as a ridge over the
island chain migrates north. Latest wind observations show the
background flow slowly increasing around The Big Island and Maui
County. However...pressure gradients should remain weak enough to
allow for another round of sea breezes and a few showers this
afternoon and early evening. The good news for the Independence day
celebrations is that a rather drier airmass is expected to be in
place today across the state...except for areas of enhanced moisture
just S/southeast of The Big Island. Thus...shower activity should remain
Models depict reinforcing surface high pressure north of the area developing
early next week...which should further strengthen the trades into at
least moderate levels. Meanwhile...model solutions also suggest the
development of a couple of low pressure systems far southeast of the Aloha
state during the second half of next week. Track-wise...the models
seem to keep both systems moving to the S of the islands. However...
low level moisture should increase and become deeper...particularly
with the low currently developing about 1100 miles east/southeast of The Big
Island. This could result in enhanced showers and locally stronger
winds as pressure gradients become tighter between the high to the north
and the passing lows to the S.
The National Hurricane Center in Miami is monitoring a couple of
areas over the east Pacific...the stronger located about 2250 miles
east/southeast of Hilo...which models also suggest some development next week.
And although it is still too early to embrace a particular model
solution...these areas will continue to be closely monitored
throughout the forecast period.
trade winds will continue to gradually strengthen as a nearby
surface ridge moves slowly north. While the trade winds will deliver a
few clouds and small rain showers to windward areas that will result in
brief and isolate MVFR vis/cig...VFR conditions will prevail...and
airmets are not expected. -Shra currently near phko should diminish
shortly...and leeward areas will be mostly clear this morning.
Clouds and isolate MVFR visible/ceiling in rain showers are expected to develop over
leeward Big Island slopes this afternoon...and potentially over
leeward portions of the smaller islands. Additionally...MVFR ceiling is
expected at phny from 20z-02z.
the light trades are gradually increasing over the coastal waters...
but should remain below advisory levels through the rest of the
weekend. By Tuesday...winds will be near or at Small Craft Advisory
levels across the typically windier waters around The Big Island and
Maui County...and possibly expanding into other areas as the trades
build further through the rest of the week.
A south swell will reach the islands Saturday night and into
Sunday...then slowly declining Monday. This swell could push surf
to near advisory levels along south facing shores. Another southerly
swell should reach the islands by Monday...peaking on Tuesday and
then gradually decline through the second half of next week.