|Sunday, May 13, 2007 - 4:15AM EDT
Forecast update for May 13
A small but potent-looking trough is now showing up on the models for the May 22-24 period, affecting the northern Plains from Nebraska to North Dakota. This feature looks strikingly similar to the one that we covered in late May of 2006. As such, I'm not too excited about it. After the prolonged ridge, moisture will be lacking that far north, just as it was last May. While a tornado event can't be ruled out with this system, I feel the probabilities will be too low to warrant the extra-long drive to the northern Plains.
The models still trend toward a western troughing scenario for May 26 and beyond, though the newest model runs are keeping it too far to the west over the Pacific ocean through May 29. This pattern still keeps ridging/northwest flow persisting over the Plains. The GFS even suggests the start of an omega block pattern on May 28-29 with troughs in the east and west and a ridge over the Plains. Interestingly, this model forecast also was seen in May of 2006. That would be a cause for concern if that pattern keeps steady on future model runs. More likely than not, though, we're dealing with a 'flop' in the 'flip flopping' of the models - so we won't get excited/worried yet, or even change our probability table at this point.
Based on the current outlook, this probability table charts the chance of our trip starting on a particular date:
|2007 Weather Expedition - Departure Date Probability as of May 13|
|May 26-June 2||42%|