Webberweather53
Meteorologist
The US snow cover extent is the big elephant in the room many are ignoring here, and its fairly atrocious for most of the southern US, minus areas at or well north of the I-40. We can hardly keep the southern extent of the snowpack inside the US/Canadian border &/or south of I-94...
Not only does this feeble snow cover feedback to moderating arctic air masses more quickly on their trek towards the southeastern US (as will occur next week), and setup a natural area of lower-level baroclinicity well to our north, but it has a directly link to the overall height pattern. Since the troposphere is heated largely via conduction at the surface, a dearth of snow cover (which when fresh reflects ~90% of incoming radiation) causes the ground temperatures to warm, therefore more radiation is absorbed @ the surface and conducted/mixed upward through the column, warming the troposphere and raising the height field... This physical concept is supported by the Hyposometric equation which states the thickness in an atmospheric layer are directly proportional to the mean temperature in the layer. Essentially what this means in a nut shell in this instance, less snow cover= warmer surface temps = more heat fluxed upward in the tropospheric column = higher heights/greater thicknesses (even @ 500mb) = stronger SER/storm track lifts northward. It's all connected... Definitely won't be impossible for us to get a canonical southern slider here, but the piss-poor snow cover is making it significantly less likely...
Oth, if a robust secondary or tertiary area of low pressure were to develop behind this first system (as the GFS/CMC depict with some wintry precip chasing the back end of the frontal boundary and associated (& weak) frontal wave), then that changes everything...
Not only does this feeble snow cover feedback to moderating arctic air masses more quickly on their trek towards the southeastern US (as will occur next week), and setup a natural area of lower-level baroclinicity well to our north, but it has a directly link to the overall height pattern. Since the troposphere is heated largely via conduction at the surface, a dearth of snow cover (which when fresh reflects ~90% of incoming radiation) causes the ground temperatures to warm, therefore more radiation is absorbed @ the surface and conducted/mixed upward through the column, warming the troposphere and raising the height field... This physical concept is supported by the Hyposometric equation which states the thickness in an atmospheric layer are directly proportional to the mean temperature in the layer. Essentially what this means in a nut shell in this instance, less snow cover= warmer surface temps = more heat fluxed upward in the tropospheric column = higher heights/greater thicknesses (even @ 500mb) = stronger SER/storm track lifts northward. It's all connected... Definitely won't be impossible for us to get a canonical southern slider here, but the piss-poor snow cover is making it significantly less likely...
Oth, if a robust secondary or tertiary area of low pressure were to develop behind this first system (as the GFS/CMC depict with some wintry precip chasing the back end of the frontal boundary and associated (& weak) frontal wave), then that changes everything...
