Wednesday, March 21, 2018

What changed and what's next? 
SHORT TERM UPDATE FOR 8 am - 12 pm WED 3/21
7:30 AM 3/21 - WHAT CHANGED, WHY AND HOW MUCH TO GO? The attached image above is an 18-hour projection from the NOAA Short Range model depicting latest additional snowfall expected through 8 PM today. Current radar below, and below is our analysis.

Like you, we were expecting widespread snow cover from DC on north to Baltimore and east to Annapolis by now. So why not? Many areas north of I-70 and above the 695 beltway have the snow, but not what was expected. Despite the overnight timing, the reality of two back-to-back Lows obviously created a gap in precipitation that:
  • Lasted longer than forecast, and should close up by 8 AM;
  • Allowed for a warm pulse of air to embed in the lower levels overnight right where snow usually forms (around 5000 feet);
  • As seen on radar, the heavier snow pushed north of I-70 and stayed in place, whereas south of I-70 to DC, gaps opened up and allowed temps to drop, making for a glaze on most untreated surfaces. 
  • Oddly enough, snow cover would have been easier to manage, as slush can be handled better by tires and plows than a sudden glaze of ice. So where the snow cover *did not* occur as forecasted -- we are seeing the crashes and road closures more so than it seems areas with more snow cover.

WHEN WILL SNOW REALLY START TO CRANK? (For those in Frederick, Carroll, northern Baltimore, Harford and southern PA, it's more like .. when will this END??)