Hawaii Extended Forecast Discussion NWS Weather Prediction Center College Park MD 819 AM EDT Sun Mar 24 2019 Valid 00Z Mon Mar 25 2019 - 00Z Mon Apr 01 2019 Guidance still displays similar ideas for the overall pattern evolution during the period. Primary differences involve the amplitude of individual shortwaves and associated impact on surface front/moisture band location. High pressure initially to the north of the state and promoting moderate to brisk trades will weaken and sink southeast toward 30N 150W during the day Tuesday followed by an eastward acceleration. Thus expect winds to trend lighter with time. Windward-focused showers early this week will tend to be on the light side, though a band of moisture drifting toward the islands from the north/northeast along with shortwave energy dropping down from the northwest may serve to enhance activity a bit. By Wednesday winds may be sufficiently light to support a land/sea breeze regime. GFS/ECMWF runs and their ensembles agree well for the amplitude of early week shortwave energy but the CMC and their ensembles are still somewhat flatter. At this time preference would go to the GFS/ECMWF cluster. After midweek the models/ensembles agree in principle on establishment of mean troughing over and north/northeast of the state but differ on some of the details. A leading shortwave reaching the area by early Thursday will bring a cold front into the main islands. Latest GFS runs (06Z version in particular) are bit more amplified than the guidance average for the upper shortwave. Then toward Friday-Saturday there are some valid times when GFS runs and some GEFS members are on the amplified side of the spread for amplitude of trailing energy feeding into the overall trough. Operational runs and their ensemble members appear to be more mixed for another possible shortwave around next Sunday. Based on the full array of guidance aloft, the cold front may not reach quite as far southeast as seen in the GFS late this week. On the other hand a guidance average may be called for toward next Sunday as subtle differences in the next shortwave will determine how far the front or at least its remaining moisture band may get pulled back to the northwest (ECMWF/ECMWF mean farther northwest than the GFS/GEFS mean). By Friday-Sunday confidence in any specific solution decreases given typically low predictability of medium-smaller scale shortwaves. Most rainfall, tending to focus over northeastward-facing terrain, should be in the lighter half of the spectrum though moisture returning from the southeast could provide at least a modest increase later in the weekend. Rausch