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1/25–26 Coastal Storm Thread: Deep Cold + Moisture Feed = High-Impact Ceiling (Still Volatile)
Big picture: We’re heading into a major arctic outbreak with a cold high pressing across the northern tier, while a frontal zone + subtropical moisture plume sets up to our south. Guidance supports a significant winter storm from the southern tier into the Mid-Atlantic, with increasing signals that SNE is now in the envelope.
Over the last ~48h, there’s been a notable north shift in many solutions, tied to greater interaction/phasing between southern-stream energy and northern-stream energy over the Plains → deeper trough → stronger downstream ridging → farther north storm track. WPC notes this shift is broadly reflected across deterministic/ensembles/AI guidance, but also warns the unanimity could be partly a mirage due to unresolved shortwave details.
SNE baseline expectation (as of 1/21):
• Snow looks increasingly likely late Sunday into Monday, but exact track/gradient still low confidence.
• Ensemble spread still supports anything from “a few” to “10+” depending on where the coastal low tracks relative to the benchmark.
• With the arctic air mass in place, SLRs could be higher than climo for much of the region where snow verifies.
Things to watch:
• Track vs benchmark (suppressed / benchmark / inside runner)
• Degree of phasing (deformation/banding ceiling vs quick hitter)
• Coastal front placement (I-95 jackpot potential vs sharp cutoff)