Beware the ides of March…. In this case for making a late season snow forecast. It’s difficult after a long winter to even consider that we have one more event as I sit here and type on a sunny 60 degree Saturday. At least I already got a soccer game in with my oldest son.
March and even April snowfall is more common than you might think in Baltimore. In face just last winter we had a snow event on March 25th that brought 3.2 inches to BWI. That was welcome by more since the winter was rather slow. If you wonder what is possible, it was the blockbuster 21.9” in Baltimore on March 29th that holds the record for the month. But that was way back in 1942.
If you really want to see the wide variety of weather we can get this time of the year, check out the past two decades of Orioles opening day weather story I wrote last year. Late March and early April can often swing back and forth from summer heat to late winter snow.
The more I look at this, the more I think this will end up like the March 3rd event. I busted that with a projection too high, but I took extensive notes and learned from it. This is not the same exact event, the ground is warmer, the arctic boundary is not as intense, but the end results may be quite similar. Please remember that storm did produce lower snow totals, but the conditions were bad during the morning travel. This will be the same!
Rather than complete geek out on the dynamics of what is creating this storm, I want to provide three things now:
1. Compare a few weather models
2. Show the factors that will help and hurt accumulation
3. Give my first call (which you already see, but at least explain my thinking)
Anyone that has followed my forecasting success this winter, has seen my leniency on the Canadian Computer Model. I was let down with a bust early this month, but I still agree with its solution. This was THE FIRST to call this storm, and it has been consistent every day for the past 4.
On my Facebook page back on Tuesday March 11th, I compared the Canadian to the GFS which was dry. Now even that model is rather aggressive with a modest snowfall for Maryland. The higher resolution NAM model actually has this storm cutting off a sharp edge near or just south of Baltimore.
The last event and bust on my part does lend to some important lessons.
- In short, the NAM model will fluctuate and should not be the one of choice, especially on the north end.
- The Canadian did properly project the northern edge of the snowfall region, but overdid the amounts.
- Most models hinted at much more snow than we actually got.
- Regardless of what models show could 'fall' as snow, not all will accumulate
Factors that will help and hurt stickage/accumulation:
NOTE---> NOT ALL THAT WILL FALL WILL LAY AND STAY.
*Most of the snow will fall at night. The most optimal time for March snow to stick.
*Arrival 7-10 PM Sunday
*Finish- mid day to afternoon Monday
*Temperatures should DROP into the mid and lower 20s by Monday morning.
*The trend has had the bulk of recent events in central and southern MD, central VA, and into DE.
*The ground will be warm thanks to the 60 degree Saturday.
*Solar angle this time of year is equal to late September. Even on cold and cloudy days, solar radiation gets absorbed by the ground and can lead to more heat retention.
REPEAT: ---> NOT ALL THAT WILL FALL WILL LAY AND STAY.
*Wasted flakes on the front end until the ground can cool down. More will stick on the grass before the roads.
*No stickage AFTER 9 am Monday (thanks to March sun angle) So the flakes will be wasted on the back end too.
My snowfall is a lower than NWS on the south side, as I see potential for the storm to shift a little north and put the rain/melting line closer. The northern edge is pretty close. See both in the slide show.
*Where the rain line sets up. Following my trusty Canadian- it would include Calvert and parts of St. Mary's Co in MD, but the trend has been for storms to verify 50-100 miles north of model projections at the very end.... That would shift the rain line and heavy snow band north.... This is my lowest confidence one.
*Along Rt. 50 is my general focus for the main hit. Metro Baltimore and Washington right in the middle, but more just south! Moderate snow will include southern PA with a sharp cut off farther norther. It goes back to Garret Co and Winchester... east to Dover, DE, Philadelphia, and Atlantic City, NJ.
I called for a cold and snowy winter based on many reasons and now with over 30 inches in Baltimore, we are 50% above normal. It has been active ever since the record early start for the local ski resorts the day after Thanksgiving, helping to prove validation for my atmospheric memory theory. I wind more than I lose and I will certainly be out to do it again.
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