Matthew Havin
EF2
Surface low pressure moving across the Dakotas overnight is progged to move into MN during the daytime tomorrow. 00Z NAM has sub-1000mb sfc low over central MN by 00Z Thu. Primary target for severe wx tomorrow will be ahead of the cold front that will extend from S.MN thru E IA and dividing Missouri from NE to SW.
Chase targets can be divided into 2 areas:
1. E IA/NW-WC IL/NE MO
2. SE KS/SW MO
1. Primary area of activity will likely develop ahead of the cold front in E IA-NE MO and into western IL north of Saint Louis (stay out of STL...we never get tornadoes in severe weather season). 00Z NAM has best colocation of 2000+ CAPE (mid 60s Tds) and 0-1km SRH 150-250+ m2/s2 near Quincy IL ....giving a model-based EHI of 3-5 by late afternoon. However, due to linear wind profiles, primary storm mode will likely be a squall line. Another big concern that is a negative is question of how much convective debris will be left over from overnight action in the area during the midday. What may make this area deliver, and a point the SPC brought up, was if any boundaries left over from morning convection are present...then they may trigger isolated pre-frontal storms that will have a fighting chance in this region.
2. Conditional secondary target of activity will be across SE KS/SW MO where more likely daytime surface heating will lead to 2500+ CAPE by afternoon. Wind profiles here will be less unidirectional...with SSW 850mb and WNW 500mb flow. Progged 0-1km SRH is lower (50-150m2/s2), and the cap in the area may supress storm development until early evening. However, with any assistance from mesoscale boundary interactions.....a few isolated supercells may be possible in this region where futher up north along the front in IA/IL it will be rather unlikely.
Chase targets can be divided into 2 areas:
1. E IA/NW-WC IL/NE MO
2. SE KS/SW MO
1. Primary area of activity will likely develop ahead of the cold front in E IA-NE MO and into western IL north of Saint Louis (stay out of STL...we never get tornadoes in severe weather season). 00Z NAM has best colocation of 2000+ CAPE (mid 60s Tds) and 0-1km SRH 150-250+ m2/s2 near Quincy IL ....giving a model-based EHI of 3-5 by late afternoon. However, due to linear wind profiles, primary storm mode will likely be a squall line. Another big concern that is a negative is question of how much convective debris will be left over from overnight action in the area during the midday. What may make this area deliver, and a point the SPC brought up, was if any boundaries left over from morning convection are present...then they may trigger isolated pre-frontal storms that will have a fighting chance in this region.
2. Conditional secondary target of activity will be across SE KS/SW MO where more likely daytime surface heating will lead to 2500+ CAPE by afternoon. Wind profiles here will be less unidirectional...with SSW 850mb and WNW 500mb flow. Progged 0-1km SRH is lower (50-150m2/s2), and the cap in the area may supress storm development until early evening. However, with any assistance from mesoscale boundary interactions.....a few isolated supercells may be possible in this region where futher up north along the front in IA/IL it will be rather unlikely.