4pm Monday, February 17, 2025
Before attacking the snow forecast, remember that the James River in Richmond remains 4.5 feet above flood stage this afternoon, and is expected to rise about another foot before cresting Tuesday afternoon and slowly falling Tuesday night.
Water has already flooded parts of the James River Park System, the Virginia Capital Trail, and areas upriver to Robious Landing. But this is not enough water to close the flood wall or threaten the water treatment plant.
Through Tuesday night, the weather is quiet. Some cloudier spots from time to time, with afternoons in the 40s and nights in the 20s.
The window for snow opens around midday Wednesday and closes shortly after dawn Thursday. And the air looks cold enough for all snow during that time, staying in the 20s on Wednesday afternoon.
Why weather apps are all over the place
The initial problem, as is often the case, is in precisely knowing the strength of the storm and its specific track.
On top of that, there is no standardization across weather apps. Some have more human oversight than others. Some software is better than others. Some rely on just one dataset. It’s tough to know.
Let the buyer beware.
There is a reason for the broad downward shift in forecast totals over the last 24 hours. Most of the raw data has shifted the storm track south by several dozen miles, dramatically dropping the chance of a paralyzing snowstorm in Richmond (12”+).
That is not to say it will not snow at all, but something less epic is beginning to look more likely. For the moment, let’s go with 4 to 8 inches in that window, down a couple of inches from my first wild guess at the end of last week.
In keeping with policy, our colleagues at the NOAA National Weather Service in Wakefield have issued a Winter Storm Watch, as we are within 48 hours of the first flakes flying.
Spare a thought for them by the way. They are federal workers who have been dealing with a lot of unnecessary stress as a result of the (ahem) political situation.
Why the change?
Normally, big shiny snowfall totals on weather computer models 4-5 days ahead of time are not to be taken seriously. But in this case, the data across multiple simulations for a couple of days were unusually consistent in suggesting a plowable snow was coming to Richmond.
It is a reminder that small errors at the beginning of a computer forecast can, well… snowball… later in the forecast period.
I understand the grumpiest among us may want to call the whole thing off, but there is another issue to consider.
The type of computer modeling in the last 48 hours before a storm is different from the modeling several days ahead of time. In this shorter time frame, finer structures of a storm can be simulated better over a smaller area — we are about to get into that time frame.
And more than once, I have seen the data back off of storm totals, only to turn-tail in the last 24 hours and blow them back up again.
With that in mind, I would still hold the idea of 4-8 inches in that window between midday Wednesday and daybreak Thursday. Comforting to see that my colleagues in Wakefield agree.
But there is not a lot of wiggle room here, and I will not pretend to be absolutely certain. In fact, I would offer some odds:
10%: 12 inches or more
15%: 8-12 inches
35%: 4-8 inches
25%: 2-4 inches
15%: less than 2 inches
Travel may begin to get difficult around rush hour Wednesday afternoon. Start thinking about that now. You don’t want it to take 3 hours to get home in the evening — or worse — slide off of the road and get stuck half the night with snow coming down and temperatures in the 20s.
Could this change?
Yep. Do not expect this to be the last word. Be ready for another modification in the forecast on Tuesday afternoon.
Either way, once the storm is gone, the sky will clear by Thursday afternoon and temperatures will climb into the mid 30s.
What about after?
There will be no rain or snow Friday, Saturday, or Sunday. Just periods of sun and clouds.
Friday and Saturday are around 40 in the afternoon, then in the upper 40s Sunday.
Friday night is in the upper teens, then 20s Saturday and Sunday night.