Issued: 8pm on Sunday, December 15th 2024
Technical Forecast Discussion
Short-term Forecast (Sunday 12/15/2024 through Tuesday 12/17/2024):
A weak cold front continues to push through Southeast Ohio this evening, bringing scattered light rain showers. Precipitation will remain light and intermittent due to limited low-level moisture and weak forcing along the front. Showers will taper off by midnight as the front exits eastward, leaving mostly cloudy skies overnight. Post-frontal winds will shift to the northwest at 5-10 mph, aiding in slightly cooler conditions. Overnight lows will remain near seasonal averages. On Monday, high pressure centered over the Midwest will gradually build eastward, promoting subsidence and clearing skies. Expect a mix of sun and clouds during the day with light northwest winds. Temperatures will be slightly above seasonal norms due to weak warm advection in the mid-levels. By Tuesday, a warm front associated with an approaching low-pressure system will lift into the Ohio Valley. Clouds will thicken throughout the day as southerly flow increases, enhancing low-level moisture transport. A few isolated light rain showers may develop late Tuesday evening into the overnight hours as isentropic lift strengthens, particularly along and north of the frontal boundary.
Long-term Forecast (Wednesday 12/18/2024 through Saturday 12/21/2024):
A deepening low-pressure system tracking through the Midwest will dominate the midweek pattern. On Wednesday, a robust warm sector will extend into the region ahead of the system, driven by a strong southwesterly jet in the mid and upper levels. This setup will result in widespread rain across Southeast Ohio, with the heaviest precipitation likely during the afternoon and evening hours. PWAT (precipitable water) values will approach 1.0-1.25 inches, above the climatological mean for December, leading to moderate rainfall totals of 0.5 to 0.75 inches. South winds will increase during the day, with gusts of 25-30 mph possible in the warm sector. As the system progresses eastward Wednesday night into Thursday, colder air will advect into the region on the backside of the low. However, temperatures are expected to remain above freezing, keeping any lingering precipitation in the form of rain. Scattered showers may persist through early Thursday under wrap-around moisture and weak cyclonic flow aloft. Model guidance suggests surface high pressure will build in late Thursday, leading to clearing skies and cooler temperatures. By Friday, conditions should remain dry as the high settles over the region. A weak system could approach from the west by Saturday, but model discrepancies regarding its track and intensity introduce low confidence in precipitation timing and amounts. The most likely outcome is increased cloud cover and a low chance of light rain showers Saturday evening.
