384 
fxhw60 phfo 081336 
afdhfo 


Area forecast discussion 
National Weather Service Honolulu HI 
400 am HST Thursday Jan 8 2009 


Synopsis... 
high pressure will remain north of the islands bringing trade winds 
today. Winds will weaken and shift to the southeast tonight as a 
cold front approaches the islands from the northwest. The front will 
move through the islands Saturday night and Sunday...bringing 
isolated thunderstorms and locally heavy rainfall. 


&& 


Discussion... 
clouds and showers embedded in the trade winds continue to affect 
mainly the windward and mountain sections of the islands this 
morning. Rainfall totals from the gages around the state remain 
on the lighter side...with less than a tenth of an inch reported 
except for a few windward and mountain spots. High pressure far 
north of the state will provide trade winds to the area one more 
day. Morning Lihue and Hilo soundings depict a drier and stable air 
mass...with inversion height ranging from about 5k to 8k feet. 
Expect trade wind weather to continue through today...with passing 
clouds and showers affecting mainly windward and mountain sections. 


Winds will be shifting southeast and becoming lighter tonight as an 
approaching cold front from the northwest pushes a surface high 
ridge near the islands. Land and sea breezes will become more 
prominent under the light wind regime...and the islands will 
experience a more convective type weather regime...with clearing 
overnight under night time cooling while clouds and showers develop 
mainly over interior sections under day time heating. Air mass over 
the area is expected to remain stable...and thus precipitation will 
remain on the lighter side. 


Winds will turn more south by Saturday and strengthen as the front 
moves closer to the northern islands. The main rain band associated 
with the front is still expected to reach Kauai Saturday night...and 
advance southeast through Oahu and Maui counties Sunday. Isolated 
thunderstorms as well as locally heavy rain are expected during its 
passage. The movement of the rain band would be swift enough such 
that the threat of flooding is lowered. This front is expected to 
weaken when it reaches The Big Island by late Sunday...but there may 
be enough air mass instability for thunderstorms as well as locally 
heavy rain to develop over the southern islands. 


Forecasting models continue to disagree on what will happen over the 
area right after the frontal passage...with the European model 
keeping westerly winds over the islands while GFS has trade winds 
returning briefly. Forecast confidence is low for that 
period...though there seem to be better agreement between models 
beyond the extended period as they all hint possibly more fronts 
affecting the islands. 


&& 


Marine... 
the next northwest swell expected by Sunday may produce above the 
advisory level surf across north and west facing shores through 
Monday. Surf along east facing shores will continue at moderate 
levels today under the winds...then slowly subside tonight through 
Friday as the winds decrease. 


&& 


Hfo watches/warnings/advisories... 
none. 


&& 


$$ 


Hui