Monday February 18 2019

The Winter Storm Watch now includes all counties west of the Chesapeake Bay and Susquehanna River in our region. The timing across the area varies as the storm will arrive from south to north, and those northern zones will stay colder longer with more icing on top of the snow. This post includes my first call for snowfall. It will snow and there will be sleet and freezing rain to follow. Timing that change is the hardest part to certify snow totals. In simplest terms, this will be a mess on Wednesday.

Also below is a look at the snow totals from various models and regional NWS Offices to compare. There is a wide range of expectations.

Winter Storm Watch

Maryland and VA begins Tuesday night and ends Wednesday night
PA begins Wednesday morning and ends Thursday morning
Cecil County and Delmarva- Your NWS Office has not issued anything yet.

Is Your County Not Included?

Either you may be too warm or your NWS Office has not posted yet. Click this map for more on the regional forecast zones

Storm Notes:

Wednesday morning most of the area will see snow. This includes Southern MD and Delmarva.
A burst of moderate to heavy snow could bring 1″/Hr at times.
Wednesday Afternoon: Snow will change to sleet and freezing rain from south to north. That change over will be around lunchtime between Washington and Baltimore.
Wednesday afternoon and evening: There will be icing across central Maryland
Wednesday night: The normally colder zones will have heavy icing
Thursday morning: It is possible that leftover ice has not fully melted or fallen off of trees in some areas even with warming and rain.

Storm Animation

More Below

Compare my call for snowfall to the model and NWS Office snow forecasts below the slider.

I am staying lower that possible due to the sleet. If the change over is later, then we could bust and end up with more snow.

Zone A:

3″ to 6″ of snow. The white circled region can get 6″ to 12″.
This area will have the most snow and heaviest icing Wednesday night

Zone B:

2″ to 4″ of snow. It will fall heavy at times in the morning.
Change over will be around lunchtime (between 11 AM and 2 PM).
I expanded this 2″ to 4″ zone to include Kent, Queen Annes, and Caroline Countes.
Moderate icing in sleet and freeing rain
Should change to rain between 3 PM and 7 PM Wednesday.

Zone C

1″ to 2″ of snow.
Faster change over to icing and then rain during the day.

Radar Simulation —> slider

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Thursday Morning Conditions

The is a chance some cold air lingers in pockets northwest of Baltimore.
Ice will be slow to thaw and also could be falling off of trees and power lines for a few hours after the change to all rain. This is what happened during last week’s storm.

How Much Snow?

Use the two sliders below to compare various models and NWS Zone Forecast Maps

Computer Models — > slider

The ECMWF an NAM 3 Km seem most reasonable.
The Canadian is low and the GFS is VERY HIGH. I think this is overblown and not accounting for the icing properly.

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Snow From NWS Offices For Their Zones —> slider

Notice northern Maryland seems higher than adjacent PA Counties.
I think NWS Sterling VA put a lot of emphasis on the GFS Model above

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Notes:

The potential to beat here might be on the higher side of snow. This all depends on the timing of the change over from snow to sleet, and freeing rain. Just plan for an icy mess. Morning snow rates will be high and able to stick on the pavement. The sets the stage for stickage for the middle of the day and afternoon.

Also remembering the ice storm last week. It is possible to change to plain rain, but have the effects of ice linger. This is due to longer time for it to melt and also fall off of trees and power lines. There is potential for 0.1″ to 0.25″ of icing on top of whatever snow falls.

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