**The Storm Prediction Center has issued a moderate risk for severe weather, effective tomorrow, March 2nd.**
The Storm Prediction Center has issued a rare Day 2 moderate risk area for the Ohio Valley into the nation's Midsection and South Central US.
Have tried to pinpoint exactly when the instability will be highest and shearing the strongest. After determining that timeframe, I have found the jet stream to be raging at 140 knots, which equates to 160 MPH. You may not know it, but 160 MPH for a jet stream is extremely similar to the strength that was present for the April 2011 Superoutbreak of tornadoes.
Low Level Jet stream at 700mb level will also be screaming at 70 knots, which is roughly 80 MPH. Again, this is unusually strong for a lower level jet stream, and will only increase to the worry factor for this situation. An atmospheric cap will be virtually nonexistent, meaning any storms that fire will quickly break any cap present and proceed to strengthen.
As for shearing, SFC-700mb shearing will be fairly high, with the maximum values in the 70 knot ranges. SFC-850mb values are lower, coming in at a maximum 50 knots. SFC-925mb shearing maxes out at 30 knots. These amounts seem pretty insignificant, but all this shearing could very well set the stage for an extremely active day tomorrow.
And then there's the issue of deep layer shearing (difference between surface and 500mb winds). Check out the forecast deep layer shear (DLS) for the timeframe I am using:
This amount of deep layer shear is incredible to me- values of 100 knots+ are possible per the 6z GFS! Deep layer shear is one of a few main things needed for tornadoes, and the fact that there is this much shearing worries me.
Another worrying thing is how the Storm Prediction Center has put in the wording "Long Tracked/Significant Tornadoes Are Possible".
Tomorrow is likely to be the crash course into the 2012 severe weather season. That said, be ready if you are in the moderate risk area. The moderate risk area is nothing to fool around with- almost every time, I have seen tornadoes come out of these moderate risk situations if they were declared for tornadoes. It looks like this moderate risk will be for tornadoes as well.