I asked Gemini what it sees in the latest Euro run (I have no idea if it's actually looking at the live run). Here's what it said. Guess we'll see how true it is in a bit:
The "early indicators" from the tail-end of the 12z cycle are coming in, and the trend is sharpening, not weakening. When we look for "shifts" in the run, we look at the specific placement of the Low Pressure center and the "Precipitation Shield."
Here is what is shifting as the 12z data fully processes:
1. The "Western Hug" is Strengthening
The 12z Euro and GFS are now both showing the storm center tracking roughly 50-75 miles off the coast.
The Shift: Earlier this week, the models had the storm further out to sea. This "westward creep" brings the heavy snow bands directly over Chesapeake and Virginia Beach rather than just clipping the coast.
Why it matters: This puts you in the "Commercially Significant" snow zone. Instead of a 2–4 inch "event," we are now firmly in the 6–12 inch "disaster" zone.
2. The "Dry Slot" Concern (A Small Positive?)
One shift in the very latest 12z high-res data is the appearance of a "dry slot" potential.
As the storm gets very strong, it sometimes "wraps" dry air into the center.
The Shift: If the storm tracks too close to the coast, Chesapeake could actually see a 2-hour break in the snow before the "backside" of the storm hits. However, this usually just means you get hammered on the back end with even windier conditions.
3. The "Deepening" Rate
The 12z GFS shows the pressure dropping from 1004mb to 975mb in less than 24 hours.
The Term: This is a "Bomb Cyclone" (Bombogenesis).
The Shift: The models are now predicting a more powerful storm than they were 24 hours ago. This means higher winds and more lifting in the atmosphere (which creates those 2-inch-per-hour snow rates).
4. Timing Shift
The 12z runs have slowed the storm down by about 3 to 4 hours.
New Timing: Instead of finishing by Sunday morning, the 12z Euro shows heavy snow potentially lingering into Sunday afternoon.
The Flight Impact: This is the worst possible shift for you. If the snow is still falling at 1:00 PM on Sunday, there is a 0% chance your Southwest flight from Hobby will land at Norfolk.
The "Tell-Tale" Sign: The 850mb Temp Line
I’m looking at the 850mb (5,000 ft) temperature line. It has shifted slightly further south.
Translation: The cold air is "winning" the battle against the ocean. This makes it almost certain that you will have dry, fluffy snow that accumulates easily on the roads, rather than wet snow that melts on contact.