If you don’t like reading or like to criticize the time and effort, here is the abridged version.
“Storm possible Sunday-Monday, details unknown”
For the rest of you… the majority…. It’s nerd time!
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Social Media Hype Machine?
Ahhhh. The social media drama of a large storm signal is upon us!
Every forecaster from hobbyist to professional sharing model images of their choice, some from experience of which model serves them the best, or which one gives them the most snow, or which ones makes for better clicks and sensationalism. We too were once hobbyists, if nine-year-old me had access to weather models, I’d def be posting the most apocalyptic runs I could find! For any forecaster, it’s hard sometimes to push down the passion, love for extreme weather, or whatever your type of weather preference is, and just share the facts.
With that said… We are in what forecaster Bernie Rayno would call the “Windshield Wiper” part of this forecast. The forecast models continue to try to grapple with all of the dynamics of this upcoming setup and spit out an endgame that trends north, then south, drier and wetter, snowier and snowless. Which is why forecasting with individual models, or getting committed to individual runs every 6-12 hours is futile.
We look for trends, stay grounded in what we know and aware of all we don’t know.
Here’s what we know-
- There will be a high impact, extremely disruptive storm across the country to the east coast this weekend.
- It will be very cold out ahead of the system.
- There will be an axis of 12”+ snowfall amounts.
- It may be a longer duration event.
What we don’t know-
How far north will the moisture of this storm reach. Which depends on:
- Position of arctic boundary,
- strength and position of High pressure,
- how multiple pieces of energy that haven’t even arrived on the west coast interact with each other and how this in return impacts the jet stream downstream.
- Even the timing of the arrival of the system which has slowed in the last 24 hours will impact the outcome.
Other items that keep this forecast quite complex for our region.
- We don’t need the northern most track to produce impacts across the region, the airmass pouring into the region of Friday is bitter cold. A track to our south will keep air temps in the teens during the event. This would lead to incredibly high snow ratio’s the fluff factor would allow moderate to heavy snowfall amounts even from low amounts of moisture.
- Cold airmass to our north not only supplies cold air, but also dry air, with a storm passing to our south we often see a sharp cut off of precipitation and a northern edge that can underperform. For that reason it’s possible that our region may be the dividing line between a moderate to little snowfall with a track along the southern envelope.
Now what?
We wait.. we look for trends.
Focus on the ensemble’s (multiple blends of model runs) not single models. Wait for energy to come ashore on west coast for better sampling to be ingested into the models. Look at upper air setup and identify subtle changes from run to run that may point to a broader trend towards an outcome.
Below is an example of “trends” this is the GFS (American) Model Ensembles, the model runs 30 scenarios and creates a forecast by blending them all together. This is 24 hours worth of data, what we can see is a flatter, strung out, overrunning event, which has slowly evolved into a more amplified and NW trend with a more expansive shield of precipitation further north. At the same time, other guidance has some southern trends to it, so it’s about knowing each models biases and communicating the threat, not the specifics.
18 hours ago…
12 Hours Ago….
6 Hours Ago….
Currently…
Notice how every 6 hours… with each new run of the ensembles, the area of dark blue expands northward and looks more impressive? That’s the ensemble data beginning to have much more agreement in the details with regard to where the heaviest snow falls from this storm system.
As we continue… things will begin to clarify… and we will be here to communicate it. Until then, just keep calm and weather on.