**New feature to the site will be the dot in the above image. This is where I would place myself if I was chasing tornadoes (topography and road network not factored in). This is just another way to raise awareness and to try out new methods for tornado forecasting (not to scare anyone near these areas). The thoughts and opinions in this blog are mine and not an official forecast. For an official Severe Weather Outlook please visit www.spc.noaa.gov. ***
This area has the best potential for significant severe weather, but a lot of uncertainty for initiation. The strong convergence along the cold front will aid in the development for storms to fire. Strongest mid level flow moves out early and progresses towards the Midwest areas. This will decrease vertical shear over the vicinity, but models show subtle s/w energy moving in during max heating with a band of 30-35kt mid level flow that will support storm organization. Given the extremely unstable environment and forcing associated with s/w and convergence along the front should support messy storm mode. However further south in KS/MO into southern portions of NE/IA will have a better chance for discrete supercell with presence of EML. As the cap erodes it will lead to SBCAPE values exceeding 5000J/Kg!!! These extreme values combined with favorable dynamics for supercells will be the reason the "dot" is placed in this area. The other reasons include strong low level vertical shear to 20kts and backing sfc winds ahead of dryline bulge coinciding with MLLCL heights around 750m AGL. Large Hail up to 4" in diameter and damaging winds are the main threats with a few tornadoes possible.
The most defined s/w will move across the Midwest with the risk for a more widespread severe weather day. The combination of marginal instability with strong uni-directional wind shear will lead to a few bowing segments that will support the threat for damaging winds. In addition to the damaging winds, large hail and brief spin ups are possible in mesovorticies along the line. This area does not have the strongest instability, but will have the best chance for severe weather. The forcing from s/w, sufficient deep layer shear, and weak cap will lead to storms congealing into MCS(s) and moving across the best threat area. PWAT values approaching 1.50" in tall thin updrafts will lead to precip loading and downward transport of stronger mid level winds and with unidirectional shear this will be sufficient for bowing segments with damaging winds. Hail is not the biggest factor here and will most likely reach marginally severe levels given the precip loading. Heavy rain/flash flooding are possible in these storms, but fast storm motions should cut down on this threat.
Southern stream s/w will move over top the dryline across portions of OK during peak the diurnal heating max resulting in a threat for convective initiation in a very unstable environment. Supercells will be possible as a belt of sufficient mid level winds accompany this disturbance resulting in 0-6km shear values increasing to 30+Kts. During this same timeframe low level winds will back and strengthen further increasing threat for large hail and damaging winds in any storms that can develop. Elevated Mix Layer will do its best to prevent this instability from being released and models are favoring a "no go" on severe storms just yet. But given the close call I highlighted this area.
Eastern US/Ohio Valley
A few areas of possible convection tomorrow in the Eastern US. Mesocale Convective Vortex from convection in the Southern US will drift northward and interact with an area of instability (MLCAPE 1500-2000J/Kg) sufficient enough for severe storm development. Threat would be isolated across the Ohio Valley/Middle Atlantic into the South.
Along the warm front a few showers and storms could pop up in the late afternoon hours and push east. Although mid level winds are rather weak, potential exist for some organization of multicells to form small scale line segments. Threat is low and would be short-lived for the most part.
New York late in the nighttime hours as stronger mid level forcing overspreads the vicinity associated with low level wind max/associated convergence/ for a few small scale line segments. Main threat would be for strong gusty winds.