Friday, April 6, 2018

Like a dagger in the heart of Spring
  • MAPS: Below are projected surface maps for 8 AM Saturday.

  • WHAT: A reinforcing Arctic air mass will build into the region starting Friday night as waves of low pressure move northeast from the Tennessee Valley along the Arctic front.
  • WHEN: Early Saturday into daybreak, rain will mix with and change to snow from north to south, eventually overspreading the region by mid-morning.
  • HOW: Despite a strong April sun angle, high snowfall rates and dropping temperatures by mid-morning Saturday may produce light accumulations grassy & untreated surfaces. Some refreezing is likely as sub 30 F temps are expected Saturday night into Sunday AM.  
  • OPTICS: Liquid equivalents of 0.25" to 0.50" from DC to Baltimore and Philly as temperatures are dropping Sat AM indicates brief periods of heavy wet snow. It may even look like March 21 for a time, though most roads are likely to remain wet. Still, it's this kind of news that feels like a dagger to the heart of Spring....

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??)

Monday, March 19, 2018


It will be everything but the

FAKE VS. REAL: Can you tell which forecast is true? 
(Wonder why weather forecasting is harder than predicting politics, or teenagers? Now you know.)

SINK SCENARIO A: "Rain and sleet before 11 am, then rain, snow, and sleet between 11 am and 2 pm, then snow and sleet likely, possibly mixed with freezing rain after 2 pm. High near 36. Northeast wind 13 to 15 mph, with gusts as high as 23 mph. Chance of precipitation is 90%. Little or no ice accumulation expected. New snow and sleet accumulation of less than a half inch possible. 


SINK SCENARIO B: "Rain and snow before 2 AM, then changing to rain, sleet and snow between 2 am and 5 am, possibly mixing with freezing rain before 8 am, then rain through 11 am. High 35. Snow, freezing rain and rain likely from 11 am to 4 pm. Wind 8 to 13 mph, with gusts as high as 21 mph. Chance of precipitation is 80%. Little or no snow and sleet accumulation."

(Either way, powder cats won't be happy with it.)

  • OPTION 1: Don't Steal My Sunshine. With tropical road temps of 75-80 F today and a mid March sun angle, light precip amounts and marginal air temps in mid 30s suggest the weather impacts would be as minimal as the applicant list for a job at the White House this year. 
Any snow / sleet or freezing rain that would fall in daytime hours would quickly melt away like ice sculptures at an Australian Christmas Party. A 50% chance this comes true, with a varied collection of school districts delaying, others open on time, and everyone else complaining about something.
  • OPTION 2: Come and Get Your Love. The "ping-ping" of sleet on your window around daybreak Tuesday is first indication this day will not go as planned. Better get the high octane Starbucks. Upper level thermal profiles indicate you (if you = east of 270) get sleet- stormed for 6 hours while trying to drive on oil-greased ball bearings all over the road. 
Then you're hit with the kitchen sink of "rain and sleet, or "freezing rain, sleet and snow"; or "rain, snow and sleet" or "snow and sleet" or -- ok you get it. Either way, it's a total hot mess of a day, and then there's a Winter Storm Watch thrown in there for 3-6" of more snow starting Tuesday evening. What's not to love about this, since it has a 40% chance of being your wrinkle in time?
  • OPTION 3: Total Eclipse of the Heart. Like many famous busts in Marches gone by, you awake to the sounds of ... nothing. No precip, no rain, sleet or kitchen sink. You grudgingly head into work or school dragging your arms like Wreck-it Ralph wondering why we even bother having a winter. 
You check airline ticket costs for a romantic weekend getaway to Duluth, MN while rain and then partly cloudy pile up outside your office or classroom window. Meanwhile, this has a 10% chance of happening, since we have two Low pressures coming -- at least ONE of them will deliver frozen precip to someone in _________ (insert desired school district you prefer to be closed Tue or Wed).
  • Expect a surprising amount of change and intensity with precipitation types throughout Tuesday, with some early dismissals, delays or closures.
  • Plan for heavy, wet, wind-driven snow on Wednesday as the region will grind to a halt much like January 26, 2011.
  • Anticipate widespread refreezing and delays on Thursday as temperatures fail to cross 30 F before late morning.
- Forecaster Foot and the FF Winter Stormcasters