Models are notoriously unreliable on the placement of risks while systems remain over the Pacific. We’ll start to see things become much clearer over the next 24 hours now that the system is entering the upper-air sampling grid.
Here’s a comparison of the 3 main models showing the evolution of the low from where it is coming ashore near the Washington/Oregon state line until it exits the east coast. If you watch all 3 loops together, you can see there are some fairly large differences in how the details play out in each model — from the path of the low to the development (or non-development) of a lead lee-side low in southeast Colorado, to just where the northern and southern jet streams will come close to or interact with one another. Looking at the surface you see noticeable differences between the amount, type and duration of moisture.
At this point, we know something is going to impact the US from the Rockies to the Atlantic coast. But timing and the type (mode) of impact are just enough difference to rate a moderate uncertainty in the forecast. That’s why I say we’ll see changes in the next 24 hours. The models will start to converge on a solution once they all have good data in their ingest for a couple of cycles (so by the 0z — 6pm CST — run tonight). At that point we’ll be able to say with more confidence where impacts should happen and how large an impact we expect. Still, forecast snowfall totals will move around into mid-day tomorrow.
What you can expect form KSStorm Info
We will post our first outlook on the storm tonight, after the evening models come in. We’ll be ready then to say whether snow accumulation will be light, moderate or heavy, and whether we expect any severe storms ahead of the front. But it’ll be tomorrow’s update before we release our snowfall projection numbers.
In terms of threat to life an property, this system holds the biggest punch for areas south of the Mason-Dixon line, from eastern Oklahoma through the Mid South and the Ohio River valley. But if a few things come together just right, some parts of Kansas could see more snow this week than they’ve received in the previous storms. Our best hope for a drought-easing rainfall would come from a track on the low about 100-150 miles north of where models presently have it. We’ll see how it resolves over the next day…