Winter Weather - Diagnostics

Precipitation Type
Precip Type
Near-Freezing Surface Temps
Critical Thickness
Max WetBulb Temp

850 mb Temp Advection
850 mb Frontogenesis
850 mb Frontogenesis
800-750 mb EPV
850-700 mb Frontogenesis
850 mb Moisture Transport
700 mb Frontogenesis
700 mb Frontogenesis
650-500 mb EPV
700-500 mb Frontogenesis
Mid Level Lapse Rates

Mesoscale bands of heavy snow are favored where frontogenetic circulations are embedded within an unstable thermodynamic enviroment (slantwise or vertical) . 

  • Geostrophic Equivalent Potential Vorticity (EPVg) < 0 suggest parcels will be unstable to slantwise motions within that layer of the atmosphere. EPVg as an ingredient to mesoscale banded precipitation is best evaluated in a 50-100 mb layer directly above where frontogensis is being analyzed.
  •  If EVPg is < 0 in this layer, the ageostrophic frontogenetic circulation will be enhanced. If elevated CAPE or steep lapse rates are also present, the parcels unstable to slantwise motion will become unstable in the vertical, resulting in upright convection. 

Near Surface Freezing Temp
SFC Wet Bulb
Freezing Level
925 mb
850 mb
700 mb

DGZ Depth
DGZ Depth + RH

Lake Effect and Snow Squall
Lake Effect Snow 1
Lake Effect Snow 2
Snow Squall