|Sunday, June 3, 2007 - 3:00AM EDT
The GFS models paint the picture of a classic strong, wide-area tornado outbreak from Texas to Nebraska on Wednesday if it comes close to actually happening as shown. Thursday and Friday look like potent setups as well. This is one of those 'too good to say no' setups that has breathed at least one last breath into the hopes for our 2007 Weather Expedition.
The main negative right now, and it is a big one, is the cap. The cap is a layer of warm air above the surface that prevents the buoyant warm, moist air below from rising to create thunderstorms. Normally, a strong cap is a good thing as it keeps storms from becoming too numerous too early. Too many storms will rob each other's needed balance to become fully organized, and a strong cap will keep storms more isolated. However, too strong of a cap can mean no storms at all, and this appears to be a likely case for Wednesday. The cap is usually forecast using the temperature plot at the 700mb layer.
A cap of 10 degrees C is considered a strong but breakable cap, but 12C and above is considered harder to break. The precip forecast for Wednesday confirms this concern, with only light precip returns plotted in the extreme northern section of the highest risk area.
In a nutshell, Wednesday looks like a classic tornado day in northern Kansas and Nebraska that would be well worth making a trip for - in the event that one or two supercells can break through the cap. If the cap remains as strong or stronger than forecast, then we may just sit this one out. If the trip is a go, we would need to leave early on Tuesday, with a likely return on Saturday or Sunday.
Non-weather factors will play a major role in this trip being a reality. Two out of our four-man crew will likely not be able to make a trip this week, so that will be an issue we'll have to address - especially with fuel costs so high. Secondly, my home central air conditioner's compressor died today - which may be a financial death blow to any more observing trips. I will probably have an estimate on repairs by Monday.
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 June 3|