Another Model Run, Another Euro Snowstorm

Let’s preface this by stating the obvious, but no one should be expecting a foot of snow Sunday/Monday. The overnight model runs were good in that a storm looks likely beginning Sunday and lingering into Monday (or Tuesday. Seriously.). However, it isn’t a classic storm out of the Gulf of Mexico and hitting the outer banks of NC and then hugging the coast up to Maine, which all but guarantees us a whopper. But, instead, this is the deadly low traversing the country, then transferring to the coast, aka, the Gordon Barnes “double-barrel low” or the “rob Peter to pay Paul” low. Transfers are tricky and can end in miserable failure. When and where that transfer occurs is key for the mid-Atlantic and since we are still 4 days out, it would be wise to keep our expectations in check. Every model run this afternoon gave central MD some snow but the range is from about 2″ to upwards of 18″, and since we have been snow starved for what seems like forever, we shouldn’t be disappointed if we end up with 4″ of front end snow and then dry-slot to drizzle.

But man, the Euro is still pretty. The National Weather Service discussion this afternoon summarizes things way better than I ever could, so I’ve pasted it below and changed a little of the jargon to make it more readable. Anything in parenthesis are my words, but you can read the actual discussion here. I’ll update tomorrow.

Beyond (Saturday), attention turns to a system currently located just off of the West Coast. This system will move onshore tomorrow, and track across the (continental US) Friday into Saturday. By Saturday night the system will move into the Ohio River Valley. As it does so, warm air advection precipitation (ahead) of the (storm) will start to overspread the area either late Saturday night or early Sunday. Confidence is increasing that much, if not all of the forecast area will see at least some accumulating snow on Sunday in association with this round of warm air advection precipitation. Confidence in the details of the forecast decreases thereafter. The low is expected to progress very slowly toward the east Sunday night through Monday as a system over the Atlantic Ocean blocks its forward progress. Meanwhile, an additional disturbance descending down from the Upper Great Lakes in northwesterly flow will act to reinforce the backside of the trough as the first piece slowly progresses to the east. As the first piece progresses eastward, the primary surface low over the Ohio River Valley should eventually transfer to a developing coastal low off the Eastern Seaboard. Additional snow may be possible with this coastal low, but a lot of uncertainty remains with respect to the eventual strength and placement of this low pressure and its associated precipitation shield. Either way, at least some snow shower activity will remain possible on Monday, but the potential is also there for a more substantial snowfall with this round as shown in the deterministic 12z Euro. Ensembles continue to signal significant spread during this time period, which illustrates the high level of uncertainty in the forecast for Sunday night through Monday. Depending on how the downstream block evolves, snow showers may even linger into the day on Tuesday. We`ll continue to assess trends and adjust our forecast as confidence gradually increases moving closer to the event.