Hawaii Extended Forecast Discussion NWS Weather Prediction Center College Park MD 249 AM EST Mon Nov 15 2021 Valid 00Z Tue Nov 16 2021 - 00Z Tue Nov 23 2021 Rain should continue to trend lighter with time as shortwave energy lifts northeastward to start the forecast period. Through midweek precipitable water values will remain above climatology and the surface trough associated with the initial weakening stalled front over the area may linger but heights aloft will be steadily rising (leading to an upper ridge by late week). Also during the first half of the week the relatively light background flow should promote a fair degree of land/sea breeze influence on any showers. From Thursday into the start of the weekend the model/ensemble consensus shows enough surface ridging to the north/northeast of the state to support more sustained trades from the east or southeast, though they may not be strong enough to preclude some land/sea breezes. During the rest of the weekend into Monday, guidance has trended closer together for a front that may reach close to the northwestern islands before stalling and then possibly retreating somewhat. There is also a decent signal in the guidance that an area of enhanced moisture will move into the state from the east-southeast, which would increase rainfall to some degree. Specifics would depend in part on what becomes of shortwave energy associated with the weakening front, and the small scale of this energy lends itself to low predictability this far in advance. At the moment there are various ideas for where a compact upper low could close off over or near the state by Sunday-Monday (18Z/00Z GFS and 00Z CMC runs), or the energy could just remain an open trough/shear axis (00Z ECMWF). Not surprisingly the individual ensemble members from the 00Z GEFS/CMC and 12Z ECMWF runs are quite diverse. There is better agreement at the surface as the front could dampen trades for a time near the northwestern islands but by Sunday-Monday trailing high pressure passing to the north would support easterly trades. Rausch