An active weather pattern continues across the Mid-Atlantic, and are now monitoring the potential for a coastal storm to impact the Delmarva Peninsula during the second half of the weekend.
While details remain uncertain, confidence is increasing that a developing area of low pressure will track west to east across the region late Sunday before strengthening offshore along the northern Mid-Atlantic coast. But there is also key details I’m not very fond of trusting.
Storm Track Will Determine Impacts
Most computer models show a storm developing and passing near the region Sunday. However, the exact track and strength of the surface low will ultimately determine how impactful this system becomes for Delmarva.
Recent trends in both deterministic and ensemble guidance have nudged the system slightly farther south and east. That shift could reduce overall impacts totals locally if it continues. Still, there remains a signal for a widespread precipitation event across the peninsula.
If the storm tracks close enough to the coast, stronger dynamics could enhance precipitation rates. At this stage, it is too early to determine rain and even snowfall amounts or pinpoint exact impacts.
Cold Air Will Be Key
The amount of cold air in place ahead of and during the storm will play a major role in determining precipitation type and accumulation potential.
Forecast guidance suggests that sufficient cold air may be present for accumulating snow across Delmarva if the storm tracks favorably. However, small shifts in the storm’s path could significantly change the outcome.
Relying On a Norlun Trough & Dynamic Cooling Never Fair Well For Delmarva
A Norlun trough is a narrow, elongated area of low pressure that can develop between two larger weather systems, often in New England or the northern Mid-Atlantic.
These features often form in cold, unstable air behind a departing coastal storm or between competing pressure systems. They can be difficult to forecast because they are small-scale and highly sensitive to subtle atmospheric changes.
On Delmarva, Norlun troughs are less common than in New England, but similar narrow deformation bands can produce comparable localized snowfall.
Dynamic cooling refers to a process where strong upward motion in the atmosphere causes temperatures to cool rapidly, sometimes enough to change rain to snow.
If precipitation falls heavily enough, it can also contribute to cooling through melting and evaporation, reinforcing the transition to snow.
Much Colder Air Early Next Week
Behind the potential weekend storm, a notably colder air mass is expected to settle into the region early next week.
High temperatures Monday and Tuesday may struggle to climb out of the 30s across Delmarva, with overnight lows dropping into the teens in many locations. The colder conditions could lead to icy spots lingering if snowfall occurs over the weekend.
