WRF and ROMS forecast summary for July 28

07/28/2009 - A more or less N-S oriented surface high pressure ridge is entrenched in the eastern GOA With pressure gradients relatively weak across the PWS, conditions would be expected to be near quiescent with weak, variable winds. However, the observed southeasterly winds have been moderate (10-20 knots) and fairly unpredictable in the short term, though longer term trends have provided better guidance. PWS-WRF has done an admirable job with the wind directions over the past 24 hrs. Since the Gulf is in a fairly stable pressure configuration, the ridge is forecast to last for the next few days and PWS-WRF forecasts indicate little change in the moderate east to southeast flow through the next 24 hours. The mean ocean surface flow within the PWS is also little changed from yesterday, continuing to be generally northward to northwestward with the near-surface waters entering the Sound through the Hinchinbrook Entrance and exiting through the Knight Island Passage/Montague Strait entrance. HF radar observations later in the day today began to suggest the possible formation of a smaller-scale cyclonic eddy in the central Sound. Comparison of a 16-member ensemble of ROMS simulated trajectories with an observed drifter trajectory over a period of 72 hours showed reasonable agreement, although after about 30 hours the spread among the simulated trajectories became increasingly large. Tidal ranges continue to be on the decrease, for example, at Valdez, the tidal range will be around 10 feet. High water (5 feet) will be reached at 19AKDT and low water (-4 feet) will be reached at 1AKDT. There were no significant operational issues today.