Tom Johnston BLOG: (Back) On Track for March Monstah

Weather. It moves, evolves, changes. Part of the reason you're seeing a different snowfall potential map this morning. It's my first OFFICIAL offering, and yes, I'm bullish on a strong showing by the mid-March nor'easter. At the same time, we're still 48 hours out to event. So I expect some tweaking by the Team up to it.
Maybe it could use some nooks and crannies. But then again, sometimes a broad-brush effort like 12-20" nails it.
To me, the storm's always looked amazingly dialed in. Ironically, that's what's made me cautious in putting out an official forecast map until today (Sunday). It's also complex (*reference easterly wobble on Saturday). That stuff throws you for a loop. More wrinkles may arrive after I write this.
All the while, you've seen my Facebook LIVEs and broadcasts while Todd and Keith have provided blogs and broadcasts. It's all in an effort to inform you to the best of our ability. Perhaps the final tally falls somewhere in between, but it looks "big" to me. In other words, it has the promise to affect daily lives, especially Tuesday/Wednesday, regardless of the final snow amount.
Before we even get to our in-house maps, look at what the EPS has issued.


It's saying that Portland has a 90% chance of more than A FOOT. That is a STRONG signal this early in the game.
I realize that you have to buy into the EURO, which made that little jaunt out to sea on Saturday.
So why trust it?
For me, it's about what I've seen over the course of this process. It's overall stayed the course. Other models: GFS, NAM, GEM, RPM, etc. are more or less on board for significant snow.
That, plus that negative tilt that I believe WILL happen, you gotta think it'll be held a little closer to Maine's coast. Stay the course...


As a side note, Mainers are not the only ones getting lambasted.
Check out the extent of the WINTER STORM WATCHes in blue.


Meanwhile, Long Island and Southern New England under Blizzard Watches.
**By the way, we have to watch for Blizzard alerts here**


These are my latest headlines, including estimates on wind:


Here's more on the hour-by-hour timeline, so you can plan accordingly.




A couple things to address at this point...which could interfere with blockbuster snow totals...at least some.
1. Dry air wrapping into it (dry-slotting)
and 
2. Mixing along the coast
With the system forecast to be in "POSITION A" for a nor'easter, I don't anticipate a whole lot of mixing. Sure, it'll be close, especially MidCoast. But I just don't think it's a big enough player.
Boundary layer (lower-level temps where we roam) temperatures will likely be 27-33 during the storm. That's borderline mixing. And I expect we'll experience some. But in the expected prediction, winds will go from NE to NW, and that should limit mixing. Also, nor'easters tend to pull down colder air from aloft.
**On that note, snow type should be medium to wet for a while, then get "fluffier" as you go inland AND as the nor'easter churns along.
The "dry air entrainment", if it occurs, would cut off the snow to the south and west (like near the ME/NH border earlier than I'm expecting).
Still think 8"+ is a lock.
Here's my forecast for snowfall potential:


What's cool now is that the parent system(s) are now over land (North America), and this lends to more pinpointed input into the computer models.


"The little acorn that becomes the great oak". In this case, two acorns. It's a multifaceted phasing of systems.
National Weather Service Offices in the region of the waves/pressure systems can launch radiosondes (weather balloons) up into the air to collect data which will in turn help to initialize the computer models.
This is partly responsible for higher confidence within 48 hours, which will help us moving forward.

BOTTOM LINE: It's still coming. Do what you do. And realize that spring is just over a week away.

~ TJ Thunder

 

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