Hawaii Extended Forecast Discussion NWS Weather Prediction Center College Park MD 301 AM EST Sun Dec 20 2020 Valid 00Z Mon Dec 21 2020 - 00Z Mon Dec 28 2020 Latest guidance agrees well for the the overall surface evolution through the period, along with a drier trend for the first half of the upcoming week as enhanced deep moisture moves away to the south/east and upper ridging strengthens overhead through midweek. However by next weekend models and ensembles diverge for important but lower-predictability details aloft, decreasing confidence for the amount of deep moisture that will be available to contribute to rainfall at that time. Within the agreed-upon drier trend during the first half of the week, expect trades to weaken as surface ridging initially north of the state continues eastward and a front approaches from the northwest. Windward/mountain shower focus should transition to a period of sea/land breeze influence. Compared to yesterday guidance appears to have come into better clustering for timing of the front reaching the main islands late this week, as well as the trailing high that which will support brisk northeasterly winds that will eventually turn more easterly (and renewing a windward focus for rainfall that should increase near the front). The 12Z ECMWF mean was still a bit slower than the current majority solution. By next weekend the past couple GFS runs are more aggressive than most other guidance for energy that could drop over/near the state from the southern fringe of the westerlies, leading to more moisture and rainfall. 00Z GEFS/CMC and 12Z ECMWF ensemble members show a lot of spread aloft for this time frame and the fairly small scale of this feature lends itself to low predictability. Thus confidence is well below average at this time. For now would prefer to lean away from GFS specifics while maintaining an intermediate amount of moisture/rainfall potential--between the 00Z ECMWF and drier ensemble means that show a more southward push of moisture. Rausch