Our “First Guess Snowfall” map is now available for Sunday into early Monday morning. The latest overnight data continues to agree with an inland solution, and ensembles are in agreement with keeping the heaviest snow along and west of US Highway 29. An Upper-Level Low across the Tennessee and Ohio River Valley will meander to the west while the main area of low pressure either moves along or west of the Chesapeake Bay. The data continues to shift closer to an I-95 track. An icy mix is possible between US Highway 29 and Interstate 95. Snow or a wintry mix is likely for locations along I-95 and east but quickly changing to rain by the afternoon.
Numbers are lower across Northeast Tennessee, portions of Southwest, and Southern Virginia due to potential mixing issues with sleet or freezing rain. Across much of the Shenandoah Valley, the primary precipitation type will be in the form of snow, likely heavy at times during the day Sunday and into Sunday night. A fairly quick transition to rain will occur for locations east of Interstate 95.
Snow will develop across Southwestern and Central Virginia between 7:00 a.m. to 10:00 a.m. Sunday. Upper-Level Low across Northeastern Tennessee may change some of the snow into sleet or freezing rain (or possibly a period of rain) across Far Southwestern Virginia. Just north of the mix/snow line will be some very heavy snow across the Roanoke and New River Valleys.
By Sunday afternoon, heavy snow is likely along and north Interstate 64 in Central Virginia. Snow could change to sleet or freezing rain across the Southern Shenandoah Valley and Southern Piedmont. As low pressure moves into Eastern North Carolina, heavy rain is likely across Richmond Metro and southeast into Hampton Roads.
By Sunday evening into Sunday night, low pressure will be between Interstate 95 and the Chesapeake Bay. Heavy rain overspreads much of Eastern Virginia with heavy snow or heavy mixed precipitation across the Piedmont and Valley. Across Central and Western Maryland, the atmosphere from top to bottom will still support precipitation in the form of snow.
Wind: The strongest winds will be along the coast and in the mountains. Wind gusts 40 to 50 mph are likely along the Chesapeake Bay, Northeast North Carolina, and Lower Delmarva. Wind gusts across the Virginia Piedmont and Shenandoah Valley could gust 25 to 30 mph.
Flooding: Coastal flooding is certainly a possibility for locations along the Atlantic and the Bay.
Power Outages: There is an elevated risk for power outages due to a combination of snow and ice weighing down on trees and power lines. Gusty winds along the coast may also cause some power outages.
(Wednesday, January 12, 2022 – 4:00 p.m.)
Confidence is increasing for significant, plowable snow for locations WEST of Interstate 95. There remains too much uncertainty for locations along and east of Interstate 95. It all comes down to the Upper-Level Low to the west. The Operational GFS and Canadian models show a strong across the Tennessee and Ohio River Valley with a developing low pressure system moving from the Carolina’s into the Mid-Atlantic Region. The modeling shows the upper-Level Low strong enough to pull the coastal low inland and as far west as Interstate 95. Most locations would start as snow, but quickly change to rain across Eastern Virginia and Delmarva by Sunday afternoon or Sunday evening.
However, the GFS and European Ensembles are different. The Upper-Level Low to the west is much weaker and low pressure is much further east along the Delmarva Coast. There may still be some precipitation type issues due to high pressure sliding east and lack of a true cold air source, however, the heavier precipitation should allow most of the precipitation to fall in the form of snow.
The Weather Prediction Center appears to agree with a eastern track and has a modest 10 to 30 percent threat east of Intersatate 95 for wintry precipitation exceeding one quarter inch. Along and west of Interstate 95 is greater than 50 percent, with 70 percent across the Shenandoah Valley and Highlands. These areas will likely stay snow the longest (or possibly for the entire duriation of the event.)
WIND is going to be a concern along the coast and the potential for tidal flooding. Wind gusts over 40 mph is possible along with coastal flooding which will be dependent on the track of low pressure.
POWER OUTAGES is going to be another concern. This could end up being a heavy, wet snow for locations west of Interstate 95 before colder and drier air moves into the region.
We continue to use the ENSEMBLES. This is where there has been the most consistency with handling this system. The low pressure “mean” continues to be along the coast and we believe that the operational models are too aggressive in regards to the Upper-Level Low to the west. We’ll start to see more consistency in the models tonight due to new data and sampling of the upper air pattern.
Sunday’s FIRST GUESS on snow amounts
We are NOT making a map just yet, but using our new ThreatNet graphics across Virginia (other areas outside of Virginia will be posted on Thursday!) This just gives you a “broad idea” on percentages or confidence level from at least 2 inches, 5 inches, or more than 10 inches of snow. Since we are still 4 days out, we have trended HIGH on the low end of the accumulation and MEDIUM TO HIGH on the middle ground solutions. In order for the HIGH END of snowfall possibilities to happen, low pressure needs to be along the coast. If the low indeed comes as far west as Interstate 95, there will be ice concerns across the Virginia Piedmont and Shenandoah Valley.
Before reading the graphs, please take a moment to read this Public Service Announcement from Denver (and Madea.) The graphics had to be removed from the Facebook page last night becuase everyone “sees” a number and they think it’s in inches of snow. That’s not how our ThreatNet graphics work.