Monday March 13 – The Winter Storm on the way is showing up on the national weather map this morning in two pieces. The primary piece is in the midwest now, but the coastal energy will be the main event by Tuesday morning. The main hesitation I had was where the rain snow line would set up. Considering the late season and warm Chesapeake Bay, there has been some fine tuning to the snow maps. I have bullet point notes, close up and wide view storm maps, and my final call for snowfall below.

Nor’Easter Alerts

  • Winter Storm Warning – Pink
  • Winter Weather Advisory – Purple
  • Wind Advisory- Orange
  • Coastal Flood Warning – Green


Freezing Line/Rain Line

As I have been mentioning for the past few days…. A shift of 50 miles could make a big difference with snow amounts. The Bay is warmer than a typical winter storm event, plus the track of the storm will add more mixing around I-95.  Also, when places that mix to slush or rain got back to snow, it will be during the day on Tuesday when the sun angle will be higher.

When and where the snow falls heaviest, it may be dropping at rates of 2 inches per hour.

Canadian GEM Model

This brings that mix line along I-95 and metro Baltimore Tuesday morning.


GFS Model –

Compare the same 8 AM time frame to the map above. The freezing line is through Ellicott City, Towson, and Bel Air. But the snow line is south. There may be a period of snow with warmer temps or mixing. This will depend on the specific wind direction and intensity of the precipitation to drag colder air down from aloft.


Also See:

March Snowstorm History In Baltimore

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Storm Simulation —> slider GFS Model

[metaslider id=45328]


Snowfall Maps

Computer Model



My Final Call For Snowfall

I will add in an arrival time and more maps to compare in my next report

  • Baltimore– I adjusted the beltway for 6 to 12 inches
  • Annapolis – I adjusted for 3 to 6 inch range due to more mixing, but will end with snow
  • North/West Suburbs – I adjusted 10 to 16 inches. I needed to drop just to account for compaction of the heavy snow and possible mixing. But this will be the sweet spot staying all/mostly snow: Carroll County, northern Baltimore County, and southern Pennsylvania.
  • Eastern Shore – More rain/mixing but will end with snow


Please keep my notes in mind with this major storm:

  • 8 PM Monday to Midnight—> Snow arrives from the south.
  • Tuesday Morning: Heaviest Snow- Freezing Line/Rain gets closest. 
  • Winds may be strong enough (35 mph) to warrant blizzard conditions and white outs for some areas
  • Heavy snow zone will get 2 inch per hour rates at times
  • Tuesday Afternoon:  Main storm moves north, but snow showers continue
  • Wednesday Morning:  Snow showers linger and temperatures will be below freezing. 
  • Canadian and European Model give the heaviest snow. If these verify, it would be the heaviest snowstorm in March history. The GFS model shows a closer track and more mixing in central Maryland. Still a respectable snowfall in any month for any year.
  • I need to consider the warmer than average Chesapeake Bay to influence the snowfall. 
  • Snow can fall while temps are above freezing in some areas.
  • Heavy, wet snow will compact and weigh down final totals. So ratios may be lower than 10:1 snow to liquid.

Temperature Outlook

Cold air and more ice likely to be an issue Wednesday morning. The Thaw/Refreeze cycle will be the case for a few days.



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