394 
fxhw60 phfo 211953 
afdhfo 


Area forecast discussion 
National Weather Service Honolulu HI 
1000 am HST Sat Nov 21 2009 


Synopsis... 
some passing showers will affect mainly the windward or mountain 
areas tonight. Otherwise conditions are relatively dry and the 
atmosphere is stable. The fresh to strong trade winds will slacken a 
bit Monday and Tuesday as a strong low far north pushes the surface 
ridge nearer to the islands. 


&& 


Discussion... 
high clouds will clear today as the upper trough over the main 
Hawaiian islands shifts rapidly to the southeast. Rainfall was 
sparse through middle morning with most activity over the windward Big 
Island. Despite the high clouds blocking The View...some shower 
bearing lower clouds that stretch from east of The Big Island to 
just north of the central islands have a somewhat unstable 
appearance. Hence some showers tonight over windward sections and 
mountains with a few blowing to the leeward side. 


In general however mostly sunny weather is expected through the next 
few days. Conditions will be stable under ridging aloft and the 
continuing influence of the high to the northeast. Winds will back 
down to moderate strength Monday and Tuesday when a low presently in 
the far western Pacific moves into the central North Pacific as a 
very strong low late Sunday. The surface high will shift eastward 
and the surface ridge will move to about 200 miles north of 
Honolulu. 




Models show a cold front moving toward our islands Tuesday night and 
Wednesday but stalling before it can reach Kauai. Models do not 
depict enough support in the upper atmosphere to push it down across 
the main Hawaiian islands Wednesday or Thursday. Instead the low 
moves up to the Gulf of Alaska and a new surface high moves in 
behind again strengthening the trade winds. There is a 
chance...according to models...of some moisture being drawn up from 
the southeast onto The Big Island Wednesday and Thursday. 


The present forecast reflects a trade wind climatological pattern. 


&& 


Marine... 
a high surf advisory will likely be issued this afternoon for north 
and west Kauai and Niihau and for North Shores of Oahu Molokai and 
Maui to run through Monday. The low that will move into the central 
North Pacific late Sunday and Monday will produce an even larger 
northwest swell Tuesday night with the peak Wednesday. The swell 
will then continue as a large north northwest swell for several more 
days. 


&& 


Hfo watches/warnings/advisories... 
Small Craft Advisory until 5 PM HST Sunday for Kauai Channel- 
Kaiwi Channel-Maalaea Bay-Pailolo Channel-Alenuihaha Channel-Big 
Island leeward waters-Big Island southeast waters. 


&& 


$$ 


Hoag