Day 5 (Saturday), is our best chance for this outbreak and the SPC has the area of concern bulls-eyed right over us. Why is this and why is it just coming up now? Well this upper level low that has been giving us the nice cool weather over the past few days is wanting to move west, contrary to normal movement here. A high pressure system in the west is wanting to push east. So the wrestling arena for these two air masses is right here in the Ohio Valley on Saturday. The models say that the upper level low will lose this battle and shift eastward to be absorbed into a larger air mass with similar cyclonic rotation. As the low is absorbed, the high pressure system out west will become unstable due to all of this pushing and mixing of air types. According to the SPC's statement, it seems as if the sheer force of this movement is really going to stir up activity on Saturday.
The answer to why this is just coming up (instead of a week's notice) is because this low pressure system has been very difficult to forecast. If you remember my earlier discussion on tweaking my forecast, then you know that the 90's I forecasted on Saturday for later this week are now totally out of line. It was impossible to tell which way and when this low was going to move. Now that we know that its sticking around for a while longer, so I can pinpoint temps easier. The many unknowns about this low pressure system has shortened the length of long range forecasting accuracy. That's why the severe chances are just being publicized now.
Now, I will be out of town starting on Saturday afternoon. If this thing hits in the early or mid morning, I'll be able to cover it. The GFS paints a morning line of storms over us, but I don't buy it. The last time I trusted the GFS for accurate timing this far out, I ended up looking silly. By Friday I'll be able to see if I will be in town for this and I'll give my final marching orders to everyone on how to prepare for this thing if it looks real bad.
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