At the surface low pressure will be located over NW Kansas. Another area of low pressure will be over the Dakotas with an associated cold front. There is still yet another low pressure moving across the southern tier of Canada with a warm front extending towards the east from that low pressure area. These lows along with the cold front are generally going to move towards the east allowing the cold front to move towards the ESE.
A dry line will extend from the Ok/TX panhandle and run South/Southwest to SW TX. We do not have any part of TX in the severe zone because the 700 mb RH is relatively dry but ..there could be some isolated severe in the SW side of TX up towards Amarillo and Lubbock area...For the most part however we think that area should remain severe free..
Severe Parameters in Place for the Severe Zone are as follows:
Temperatures 70s to 90s depending on where you reside..
http://www.twisterdata.com/data/models/nam/221/maps/2012/05/19/00/NAM_221_2012051900_F24_TMPF_2_M_ABOVE_GROUND.png
Dew Points in the 60-70 range
http://www.twisterdata.com/data/models/nam/221/maps/2012/05/19/00/NAM_221_2012051900_F24_DPTF_2_M_ABOVE_GROUND.png
CAPE 500 to about 3500 depending where you are
http://www.twisterdata.com/data/models/nam/221/maps/2012/05/19/00/NAM_221_2012051900_F24_CAPE_SURFACE.png
Lift Index 0 to - 9 depending on where you reside...
http://www.twisterdata.com/data/models/nam/221/maps/2012/05/19/00/NAM_221_2012051900_F24_PLI_30_0_MB_ABOVE_GROUND.png
EHI is generally low
http://www.twisterdata.com/data/models/nam/221/maps/2012/05/19/00/NAM_221_2012051900_F24_EHI_1000_M.png
However.. EHI does increase but not until later in the evening and this would be across Western Ok and North Central Wisconsin.
Helicity highest is over Canada and then also over Minnesota but this does not coincide with any areas of highest EHI...
http://www.twisterdata.com/data/models/nam/221/maps/2012/05/19/00/NAM_221_2012051900_F24_HLCY_1000_M_ABOVE_GROUND_0_M_ABOVE_GROUND.png
Shear from OK northwards 30 knots plus
http://www.twisterdata.com/data/models/nam/221/maps/2012/05/19/00/NAM_221_2012051900_F24_SHRM_500_MB.png
So we do have parameters in place for severe weather to occur across the highlighted zone. Main threats will be hail and wind... with the tornado chance being 2% in the mentioned above areas where the EHI increases later in the evening...
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