Tuesday January 29 2019

This morning snow began to fall and even more was seen on radar not reaching the ground. This will continue to develop and be in flux all day. This has been a tough call for schools as we expect light snow this morning, then some warming and rain mixing in, and a transition back to heavier snow with colder air this afternoon and evening. Below are two sliders as a guide for when this may happen.

There is more moisture streaming along the arctic front. So as the cold air advances, the system will be developing… right on top of us!

Morning Water Vapor Satellite

Some light stickage is possible this morning. But late morning and mid day should be wet. THEN it gets complicated and ices up. Timing out when to send kids home safely has been a challenge for schools. The Winter Weather Advisories across our area are reflective of the advancing cold air and how the timing is not the same for all of us. I hope this breakdown helps to explain it.

Winter Winter Weather Advisory

Zones Explained

1 AM Tue to 1 AM Wed for Southern Pennsylvania:

Adams, York, and Lancaster… This area will stay below freezing for the entire event.

4 AM Tue to 9 PM Tue for Counties:

Washington-Frederick MD-Carroll-Northern Baltimore-Northwest Montgomery-
Northwest Howard-Northwest Harford

This area will have some snow and ice in the morning and more snow total with the afternoon round.

Noon Tue to 10 PM Tue for Counties:

Southern Baltimore-Central and Southeast Montgomery-
Central and Southeast Howard-Southeast Harford-
Prince William/Manassas/Manassas Park-Fairfax-Northern Fauquier-
Southern Fauquier-Western Loudoun-Eastern Loudoun-

This area may have some wintry mix in the morning. But should thaw, then turn back to snow noon to 2 PM. Roads will become icy.

3 PM to Midnight Wed for Counties:

District of Columbia-Prince Georges-Anne Arundel-Charles-
Arlington/Falls Church/Alexandria-Stafford-Spotsylvania-

This area will turn to snow mid afternoon and get stickage on the roads for the afternoon commute. Travel will be icy into the evening.

4 AM to Midnight Wed for Counties:

New Castle-Cecil-Somerset-Mercer-Delaware

This area should stay below freezing for most or all of the event. Some morning snow, then the harder hit will be afternoon and evening.

Snow Simulations

Morning Timeline HRRR –> slider

This is NOT perfect. It is a gauge for when the snow is most likely to spread. Northern counties were always expected to be colder longer, but we may have some mid day hours that thaw… in time for kids to be bussed home.

[metaslider id=72151]

Afternoon and Evening Timeline HRRR –> slider

This is NOT perfect. It is a gauge for when the transition to snow is most likely to spread. I highlighted (in purple) where the mix zones are likely to be, as the model may have trouble depicting that zone.

Metro Baltimore will transition back to snow between 2 and 4 PM. This is as the system develops right over us. Then the cold air will be on the move south and east. So most of the day should be wet for DC, Annapolis, and Eastern Shore. But this evening will turn snowy and icy!

[metaslider id=72166]

Scroll Down For The Cold Air To Follow

My Original Forecast

There will be some morning snow in the mountains. But the developing situation will be over our central are to the Delmarva.

Zone A:

Most likely to have morning impact, stay near or below freezing all day, and have the most snow.
Snow Totals: 2 to 4 inches. There is potential for some higher amounts.

Zone B: