775 
fxhw60 phfo 191404 
afdhfo 


Area forecast discussion 
National Weather Service Honolulu HI 
400 am HST Friday Mar 19 2010 


Synopsis... 
a high pressure will pass far north of the islands in the next 
couple of days...bringing moderate trades across the area. Clouds 
and showers carried by the winds will favor windward and mountain 
slopes. A surface trough is expected to develop near the islands 
early next week...causing the winds to decrease. 


&& 


Discussion... 
moderate trade winds continue over the islands this morning as a 
high pressure remains far northwest of the area. Extensive 
low clouds continue in the island vicinity and will provide some 
showers to the area...specially windward and mountain sections. Some 
showers will reach the Lee areas on the smaller islands as well 
under the moderate winds. High clouds continue to cover the state 
this morning as well. Thus expect filtered sunshine today. Morning 
Hilo and Lihue soundings revealed a stable air mass...which is not 
favorable for heavier precipitation to develop. In fact...rainfall 
totals around the state for the past 12 hours have tapered off quite 
a bit. On the other hand...low level moisture reaching 9 thousand 
feet is deep enough for wetting rain. 


The high pressure that is responsible for the wind will pass far 
north of the islands in the next couple of days...maintaining 
moderate trades over the islands. Look for trade wind weather to 
prevail through most of the weekend...with clouds and showers 
favoring windward and mountain areas. 


Latest forecast charts still indicate a change in the weather for 
the islands by early next week as a front passes north of the 
state...while a surface trough develops near the islands. Expect 
the winds to decrease Monday and Tuesday with a convective type 
weather regime developing. Air mass is expected to be unstable as 
well as an upper level trough moves across the area. Models pretty 
much agree on this trend though there are differences in terms of 
the strength of this trough near the islands...with GFS the 
strongest while European model (ecmwf) only has a hint of it. Have based the extended 
forecast on the stronger GFS solution for now. Hopefully the drought 
stricken areas across the state may see a little more rain as this 
scenario develops. 


&& 


Marine... 
readings from the buoy far northwest of islands showed elevated 
significant wave heights for the few hours. In fact Waimea buoy 
readings indicated the swell has reached Oahu about a couple of 
hours ago. Do expect advisory level surf for north and west facing 
shores of Niihau and Kauai and north facing shores of Oahu Molokai 
and Maui through this evening. Surf is expected to begin to subside 
this evening. A large south swell is still forecast to arrive 
Saturday...and may bring advisory level surf to south facing shores 
over the rest of weekend. 


Current northwest swell and the waves driven by moderate trade 
winds...will keep combined seas above 10 feet for the coastal 
waters. Small Craft Advisory conditions will prevail across the 
coastal water areas through Saturday. 


&& 


Hfo watches/warnings/advisories... 
high surf advisory for north and west facing shores of Niihau and 
Kauai and north facing shores of Oahu...Molokai and Maui through 
6 PM HST this evening. 


Small Craft Advisory through 6 PM HST Saturday for all coastal 
waters. 


&& 


$$ 


Hui