881 
fxhw60 phfo 110707 cca 
afdhfo 


Area forecast discussion 
National Weather Service Honolulu HI 
830 PM HST Friday Oct 10 2008 


Synopsis... 
trade winds and windward showers will persist through the weekend... 
but a front approaching from the northwest will turn the winds 
southeasterly over most of the state on Monday...and bring periods 
of rain to Kauai and Oahu through midweek. 


&& 


Discussion... 
local data from around the main Hawaiian islands showed light to 
moderate trade winds blowing. As is typical in such cases...rainfall 
was concentrated over windward slopes...and had diminished 
considerably through the day. However...substantial rainfall had 
accumulated last night and this morning...even spreading leeward in 
places. Together with high precipitable water as measured at 
Lihue...and a middle-level trough north of the state...this recent 
history of wet trades hinted at the possibility of a repeat later 
tonight. 


Guidance predicts the trades to persist with little change through 
Sunday. However...by Monday a front is expected to approach the 
islands from the northwest...supported by a fairly deep middle-level 
low diving toward the southwest over the state at the same time. It 
remains to be seen just how vigorous the front and trough will be... 
but the season for such events approaches rapidly...so they deserve 
serious attention. 


The latest solutions predict the front to stall out near the Kaiwi 
Channel around early Tuesday morning before retreating westward 
under the influence of the rapidly departing low aloft. This 
scenario represents a change in timing from earlier solutions...and 
likely will be superceded by later ones. From a practical 
standpoint...it looks like most of the rain and northerly winds from 
this event will remain north of the Kaiwi Channel...while the rest 
of the state experiences light southeasterlies with only a few 
prefrontal convergence bands. 


Although the low aloft includes an impressive cold pool...at this 
time temperatures over the islands are not expected to drop low 
enough to produce thunderstorms. However...lightning may well occur 
well offshore to the west of Kauai. 


Guidance brings trades back to most of the state as early as 
Wednesday afternoon...but this timing may be a little fast even if 
the front lifts out promptly. Still...light to moderate trades can 
be expected again by the end of the week. 


&& 


Marine... 
the first large northwest swell of the season may arrive soon from a 
large storm low over the eastern Aleutian Islands. Surf likely will 
exceed the 15-foot high surf advisory threshold along north-facing 
shores from early Sunday through Tuesday at least. 


&& 


Hfo watches/warnings/advisories... 
none. 


&& 


$$ 


Ryshko