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SHORT-TERM WEATHER FORECAST Robert Glancy National Oceanic and Atmospheric Administration National Weather Service We are in the highly volatile time of year when weather can change on short notice (my caveat) but it does not appear that any significant snows can be expected in Colorado over the next week. Much ofthe week will feature a closed upper low over southem Califomia, with mostly dry northwest flow over much of Colorado. The unknown is when the upper low will begin drifting east...the best guess is for sometime this weekend. When it moves it will also be weakening...so it will spread some snow to the high country...but it does not look like a big storm. Temperatures will be moderating this week, with another cold outbreak and possible upslope conditions after the Thanksgiving weekend. The 8 to 14 day forecast, which was produced November 231'(1, was indicating the highest likelihood for near seasonal temperatures and near seasonal precipitation for December 1 st to the 7 . LONG-TERM WEATHER OUTLOOK Klaus Wolter National Oceanic and Atmospheric Administration Climate Diagnostic Center Executive summary (27 November 2002) 1. El Nino has stabilized at a moderate level during this month, just as expected. Moderate to strong El Nino conditions are predicted through the winter season, while the outlook into and beyond next spring remains somewhat uncertain. There is a small chance that this event could last into next summer, as last witnessed in the early 1990s. 2. Historically, El Nino has been associated with wetter than average conditions for November, March, and May in Colorado, often translating into decent early season skiing conditions, as well as a prolonged wet spring. These relationships are strongest over the plains of eastern Colorado, and weakest for the highest elevations of the north-central mountains. Ironically, it seems that November has been comparatively wetter over the mountains than the plains, which may yield three months in a row above normal for the high country. 3. Wet weather returned to Colorado in September, with quite a few locales exceeding their normal precipitation totals for the fall season as a whole. As predicted, the early ski season is off to a better-than-average start, but we still have a long way to go before this drought can be considered over. Compared to the last forecast update, mainly New Mexico's tilt of the odds towards wetness remains in place, while quite a few of the other regions appear either undecided or go against historical El Nino-precipitation associations. Clearly, the current El Nino is not strong enough (yet) to overwhelm all other regional influences. In the case of the north-central mountains of Colorado, the newly computed tilt towards wetness is obviously most welcome, but should be taken with a grain of salt until future updates reveal its stability. The lack of a tilt towards wetness for Arizona is another significant departure from El Nino expectations. Next month's update may be more eagerly awaited than some others in the past. 4. Bottomline: The extraordinary Colorado drought of 2002 may have reached its peak in August. A wet fall has been the first wet season in more than one year, but has obviously not ended the drought. Based on continued El Nino conditions, a further easing of the drought appears most likely for the Arkansas valley this winter, and for the eastern half of the state next spring. Based on a variety of seasonal prediction tools beyond ENSO, there is hope that the north-central mountains of Colorado may exceed the low expectations due to El Nino. However, 18