Monday Evening Update January 28 2019

New information in this post might be good news for some snow lovers. The Winter Weather Advisory has two updates in central Maryland. The timing has been expanded to now begin at 4 AM. This fits with my early forecast for predawn snow an proven in the new HRRR Model simulation slider below. The advisory also now includes Washington County, Maryland. So Hagerstown has joined the party and is now included in this map.

The other update is the National Weather Service snow forecast increased for some areas. I am keeping my original forecast and you can compare them all below. The big winner might be between northern Carroll County into York and Lancaster Counties.

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.

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Snow Simulations

Morning Timeline HRRR –> slider

[metaslider id=72119]

Notice the last image at noon. This model shows more mixing but has trouble identifying the snow.

Compare this to the NAM 3 Km Model… Showing more snow, but also having a hard time pushing it east for a few hours. This may be a signal that Low Pressure along the front is slowing it down. But, it may also be adding moisture.

Afternoon and Evening Timeline NAM 3 Km –> slider

[metaslider id=72096]

Flash Freeze: Cold Air To Follow

Midnight Wednesday

Wednesday Morning

How Much Snow?

NAM 3 Km Snow Forecast

NWS Office Snow Forecasts

The Baltimore/Washington Office increased the snow for northern Carroll County. Compare to the Pennsylvania Office just over the line almost half the total. That can be confusing. I think there is upside potential, but I am keeping my original forecast. Compare that below.

Westminster/Northern Carroll County is showing in 4 to 6 inches

But the image below has nearby

Adams and York Counties in PA is showing 2 to 3 inches

Cecil County shows a range of 2 to 4 inches. Less south in Kent County/Chestertown.

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: