Monday January 29 2018

Do you remember the few days in the 60s last week and Saturday? Well, the ground does. Snow will arrive early Tuesday morning, but the freezing temperatures will be delayed for metro areas. The front expected to pass through on Tuesday morning will bring a band of snow, and the timing early in the morning could have an impact on travel. But not for everyone. Below is look at two models comparing the timing of the snow and the hourly temperatures. Even when the 32ºF mark arrives, the ground needs to chill. That can take time and waste flakes to melting. This looks like a classic minor snow event that will be marginal for metro Baltimore and Washington, but most likely wet roads especially farther south. Check it out:

6 AM Tuesday Snapshot: HRRR Model

This model is updated every hour. I wanted to pick this plot to show my point on conditions. I will post an HRRR hourly simulation slider this evening. 


This shows the leading edge of the front and snow burst reaching Baltimore and Annapolis at 6 AM. Light snow may linger for an hour or two behind this…


Temperatures at 6 AM

This shows the freezing line in the typical north/west suburbs. The ground is still warm so the initial snow for Frederick/Westminster/York might melt, but have a chance to ice up and lead to travel and school delays. But metro Baltimore/Washington/Annapolis are more likely to stay warmer longer and lead to wet pavement while some snow adds up on the grass. That also makes the snow forecast totals hard to gauge… 

NAM Model Sliders

This model has done a good job with many of our small events this winter. I am showing these hourly sliders to compare. This is a little slower with the timing but the idea of delayed freezing air is the same…

Radar Simulation —>

This is a little later than the HRRR. Please consider a 1 to 2 hour buffer with these plots.

[metaslider id=57334]


Hourly Temperatures —>

[metaslider id=57359]


My SnowCast

A:  Snow 1/2″ to 2″

Best chance for roads to get icy. This area will be colder with a little more snow allowing for a better opportunity to freeze the ground and get stickage. The hills and valleys will range in totals a bit. If there are school delays, it is more likely in this zone.


B: Snow Dusting to 1″

Marginal stickage on roads… Many will be wet, but some including elevated bridges and overpasses will briefly get slick between 6 and 9 AM.

This area will have the colder air arrive a little later after the snow arrives. Flakes will be wasted to more melting. This region has a lower chance for school delays,  but any speeding up of the timing will get more snow to fall in the dark hours and possibly slick up the ground sooner.


C: Snow Dusting On The Grass

This area is most likely to have wet roads.


Snowfall Forecast From NWS Regional Offices





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Also See:

My Winter Outlook 2017-2018 for more snow

Maryland Winters

La Nina Formed: What it could mean to our winter

NOAA Winter Outlook: Not The Best But Not The Worst For Snow

Two Farmers Almanacs Winter 2018 Outlooks

Winter Weather Folkore: Suggestions from Animals and Crops

First Frost and Freeze Dates For Maryland (southern PA and northern VA)

My Preliminary Winter Outlook Notes

Low Snow Winters In Baltimore: To Repeat Or Not Repeat

NOAA Ranks Blizzard 2016 4th Worst Snowstorm On Record

Blizzard 2016 Record Top Snowstorm: Area Totals

Extreme Weather of 2015 balanced out on both ends