Will It Blizzard? Or Will It Be A Major Blizzard Failure; American Vs International Models This Weekend

Confidence is starting to grow that a winter storm will impact the region Sunday into Monday, bringing the potential for widespread accumulating snowfall. However, while the threat for some sort of snow is becoming clearer, major questions remain regarding just how significant this system will become. Forecast guidance remains in general agreement that low pressure […]

Confidence is starting to grow that a winter storm will impact the region Sunday into Monday, bringing the potential for widespread accumulating snowfall. However, while the threat for some sort of snow is becoming clearer, major questions remain regarding just how significant this system will become.

Forecast guidance remains in general agreement that low pressure will develop off the Southeast or Mid-Atlantic coast late Saturday night or Sunday, then strengthen as it moves offshore into Monday. What remains highly uncertain is how close the storm tracks to the coast and how intense it ultimately becomes.

Model solutions continue to vary widely. Some guidance depicts a stronger storm tucked closer to the Mid-Atlantic coastline, which would support heavier snowfall, stronger winds, and a higher risk of coastal flooding. Other solutions keep the storm weaker and farther offshore, which would result in lighter snowfall totals and potentially even some rain mixing in at the onset.

There has been a subtle westward shift in some of the midday model runs, particularly with the ICON and UKMET, suggesting a slightly closer track. Meanwhile, the ECMWF has come into better agreement showing at least light snowfall accumulations across the entire area. Ensemble guidance, however, still shows significant spread, highlighting the continued uncertainty.

It is worth noting that while some mid-range American models such as the GFS and NAM have hinted at an extreme scenario featuring 2 to 3 feet of snow in parts of the region, that solution currently appears to be an extreme outlier. At this time, confidence in a historic blizzard scenario remains very low. The overall snow threat is real and it is increasing, but the most extreme projections do not appear to be the most likely outcome.

High-resolution guidance is also offering important insight. Some CAMs, including the MPAS, show a significant reduction of snowfall on the backside of the system due to weaker phasing of upper-level energy. The timing and interaction of shortwave energy from the Midwest and West Coast will ultimately determine how amplified the upper-level trough becomes and whether the system achieves a more neutral or negative tilt. A stronger, phased system would support heavier snow, while weaker phasing would favor a more modest event.

Another key factor will be boundary layer temperatures. The air mass ahead of the storm is not particularly cold, meaning surface temperatures will play a critical role in determining how efficiently snow accumulates. Even with a weaker solution, increasing northeasterly winds could develop Sunday into Monday, especially near the coast, raising at least some concern for minor coastal flooding.

The bottom line: confidence is high that precipitation will occur Sunday into Monday, with an 80 to 90 percent chance of measurable precipitation. Confidence is increasing that a chuck of that is snow. However, it is too early to lock in specific totals or buy into extreme scenarios. Expect forecast adjustments as newer data continues to refine the storm’s evolution.