|Friday, April 20, 2007 - 9:59AM
Going on alert - again!
I've all but decided to leave here on Sunday to observe storms a three-day setup that looks to be taking shape for Monday-Wednesday on the Plains. How's that for a change of plans? I knew better than to give April 21-30 a 0% percent on that last probability table. This trip, however, will not be our main 'weather expedition' but rather a solo one by me. If I end up observing next week, it will mean I'll be doing two separate trips out west - this one, followed by our main trip in May.
The outlook for tornadoes has improved for Monday-Wednesday, with a strong western trough, good moisture, and a surface low pressure system all in a good spot for a decent three-day event. It's too early to nail down the finer details, but it appears the synoptics (IE, the large-scale features) will be very favorable. My premilinary target for Monday's expedition is Amarillo, Texas, followed by Oklahoma City on Tuesday and central Arkansas on Wednesday. all of those will most likely change as the days get closer.
Now, on to May. A good-sized trough is showing up on the GFS for May 6:
May 6 GFS 500mb forecast
That's a good sign and something we'll be monitoring very closely for our main weather expedition. As I said before, models that far out are notorious for being flaky and flip-flopping, but what we can glean from this simply that we'll need to keep on watch.
Our probability table for this season is taking a beating already. I guess that's a good thing, since it means that things are getting active. Last year, our table was pretty consistent because we had such a long period of obvious downtime on the models (which verified). Now it's all over the place. Add to the fact that we're now looking at two separate trips, and I'm not even sure how to represent everything! For now, I'll show the main weather expedition with the red shading, and next week's prospects with blue and a separate percentage. That should cover it - for now.
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 April 20|
|Red - main expedition
; Blue - April 22-30