Issued: 8am on Thursday, December 19th 2024
Technical Forecast Discussion
Short-term Forecast (Thursday 12/19/2024 through Saturday 12/21/2024):
A weak warm front will lift through the region on Thursday, bringing increased cloud cover with the potential for light drizzle or scattered rain showers during the afternoon as moisture from the southwest interacts with the boundary. Upper-level support is limited, so any precipitation will remain light and localized. By Friday, a cold front associated with a broad upper-level trough over the Great Lakes will advance southeastward. This front will bring enhanced low-level convergence and a deeper moisture profile, resulting in a transition to snow showers by late Friday as colder air filters in behind the boundary. While snow accumulations are expected to be minimal due to a lack of significant moisture, some slick spots may develop on untreated surfaces. Post-frontal conditions on Saturday will feature cold, northwest flow under cyclonic upper-level support. Persistent low clouds will dominate, with occasional flurries possible given residual boundary layer moisture. Temperatures will be well below seasonal averages, and a modest pressure gradient will support breezy conditions, further enhancing the cold feel. Surface high pressure begins to build in late Saturday night, leading to improving conditions.
Long-term Forecast (Sunday 12/22/2024 through Wednesday 12/21/2024):
By Sunday, a surface high will expand into the Ohio Valley, promoting a drier air mass and clearing skies. Subtle ridging aloft will aid in moderating temperatures slightly, though conditions will remain cold, particularly in the morning hours due to efficient radiational cooling under mostly clear skies. Monday will see continued tranquil weather as the high remains overhead, but by Tuesday, a shortwave embedded within a strengthening upper-level jet will begin to approach from the west. This feature will bring increasing mid- and high-level clouds as warm advection strengthens ahead of an associated surface low. The system is expected to deepen as it tracks northeastward into the Great Lakes by Wednesday, bringing a surge of moisture into the Ohio Valley. A strengthening low-level jet ahead of the cold front will transport warmer, more humid air into the region, resulting in the potential for light rain showers beginning late Tuesday and continuing into Wednesday. Precipitation coverage and intensity will depend on the exact track of the low and the strength of the warm sector, which will require closer monitoring in the coming days.
