High Risk of Tornadoes across the Plains today / tonight

Tornado Prediction Center
Ontario Weather Service
Ontario, California
June 11, 2008– 7:00am PDT

Source: [link to www.owsweather.com]
[link to www.owsweather.com]
TPC model: [link to www.owsweather.com]

Central Plains / Iowa / MN

Cold front will not be the most active event tornado-wise today. TPC model suggests that the cold front will have very slight to slight risk tornado dynamics. The warm sector ahead of it and associated warm front across Nebraska/Iowa /Minnesota is probably the best bet for supercells containing the most moderate to high risk of tornadoes today and tonight.

By Afternoon TPC tornado model suggests a very small area of tornado dynamics across the USA. This is most likely due to a cap that will still be in place over much of the area. The cold front will be through Central Nebraska and Kansas at a NNE to SSW stretch. TPC model suggests anything forming out ahead of this frontal zone will be in high risk tornado dynamics. A pretty large area from Northern KS to Southeastern NE. The triple point will be high risk tornado potential as well as shown on the TPC tornado model centered over Northeastern NE to Northwestern IA.

By Later afternoon things start to get active. Out ahead of the cold front in an isolated area in Eastern KS near Topeka is an area of moderate convergence as shown on the TPC model. This area is also in moderate to high risk tornado potential. Now remember I said anything ahead of the cold front is a danger spot today. This area is a small area in KS with this high of risk but still should be watched. The most convergence / tornado dynamics will be from Southeastern Nebraska, extreme Southeastern South Dakota, Western IA, and Southern MN across the warm front. Indications of very slight to slight risk across Wisconsin as well so they are in the cards for tornadic as well however weaker than the rest mentioned.

By Evening and Sunset the cold front will be stretching from Eastern South Dakota through Eastern Nebraska and down into Northern KS. TPC tornado model suggests semi-fast motion into 50 miles North of Omaha with it by this time so damaging winds are likely with it as it enters that area. The tornadic potential remains at slight risk across the cold front. However, further North near the surface low and triple point to the warm front is where the risk goes up to moderate right along it. Would be extreme Northeastern Nebraska, Northwestern IA, and Southwestern MN. The interesting thing about the TPC model is that it shows possible isolated supercells along a strong convergence zone stretching West to East across Northwestern IA. This area should be watched because this model suggests strong convergence / high risk tornado in Northern IA by then, well away from the cold front (where shear is maximized).
The warm front will be active as well I believe. I believe MN will be at risk across Southern and Central portions with moderate tornado risk potential. This is clearly evident on the TPC tornado model for this time-frame.
The convergence zone in Northeastern KS is still firing on the model during this time. Had a supercell form there this afternoon it will take that path through KS as a long tracker.

By the night instability will be going down and cap will be getting stronger. For the early part of the night till just before midnight we will still have enough instability in. The cold front will be firing still from Western MN through Western IA and on down through Southeastern Nebraska and Northern KS. A bump of in the slight risk in Northern KS suggests slight risk tornado potential there. However, because the convergence zone is firing strong on the model we will scale back and say most likely linear at best with of course very slight tornado potential. The model is showing a strong push of the front into Northwestern IA. This leads me to believe that damaging winds are very likely the most possible in that area as it comes out of Northeastern Nebraska a few hours before. Tornado potential remains moderate - high out ahead of it. TPC tornado labs model suggests isolated supercell activity possible out ahead of this into Northern IA.
Eastern KS into extreme Western MO will be a slight risk tornado potential as well. However because this area is still showing moderate to high risk in a rather large area out ahead of the cold front, damaging winds and tornadoes are still possible, mostly in Northwestern MO by that time as the model loop does suggest outflow from the cold front storms into the area by then.



K. MARTIN