wxmeddler

If you are in the lower elevations near the choptank or you are surrounded by fields you could make up that 3F easy with just radiational cooling.

This back door font originating air mass is so dry that while it's temperature was modified by the sea, the dew point was not raised high enough to condense into the normal back-door effect.

I got a tiny burn on my neck but I had that sweatshirt on, had nothing else. First burn of the season! Station coming "online" later today!

Fresh (ie. still fluffy) snow is way more effective at longwave radiation emission than hardpack snow.

Even if Feb is normal, we would still be way below normal for DJF.

The dew points would indicate most of the area above the fall line could get to zero by morning if you have good snow cover.

Hi. I actually do meteorological instrumentation as my profession. Temperature measurement is are actually very reliable and is the easiest of the weather parameters to measure. The mercury thermometers made 100-200 years ago were very accurate (to within 1°F). As far as calibration, traditional ice water and a boiling water stove provide an accurate 2 point calibration that is still used today. Now is is true that modern thermometers are more precise. We can reliably measure temperatures to 0.01°F in laboratory settings and 0.1°F in natural settings. But for climatology that is all you need.

Really obvious where the heavier snow fell:

Heavily rimed snow / graupel in Silver Spring.

This is unfolding about how I thought it would. Maybe slightly more NW (30 -ish miles) than expected but that may change as we pivot and it comes east.

0z Euro pretty much aligns with my thoughts perfectly. 18z AIFS nailed my thinking though.

I'm just sitting here leaning on the Euro/EPS general 1-3. I think if a band sets up anywhere it will be Loudoun / N. MoCo / S. Fredrick / Carroll / N. Balt / York. Somewhere should get 6.

Yeah, it took a hot minute for it to saturate down.

Amazing

The H5 over upper midwest has been sheared out into a big + tilt trough, not what we're looking for.

More positively tilted and a bit of a wave disconnect in over the northern GL's at 90 hrs.

18z Euro Ensemble has some members with a tucked in surface low close to the coast at h120. Waiting on graphics.

1-3... "hmm" or "hey" Otherwise this is solid. 10+ for FOLKS seems like a decent threshold.

It's a tad bit more progressive than 12z but it still is a major hit.

Officially 10:1 at DCA

I have to say I’m a bit disappointed in the flake quality. Not nearly supersaturated enough upstairs to get the dendritic growth. This is mostly looking like plates. The kuchera stan’s are gonna get a surprise when they stick their ruler in for this part of the storm. 8:1 to 11:1 Edit: It should get better when we get to the firehose stage of the storm in 4-6hrs from now.

Everything south of I-70 should get flakes in the next 20-30 min.

IAD reporting -SN and 7SM vis

A bit of a radar artifact. There is the main snow push coming through S NoVA and Charles/St.Mary's county, then a band developing in a line from about Point of Rocks to BWI. That band has not quite made it to the surface yet as LWX radar would have you think. BWI is still reporting 30/8 with 3800ft ceilings.

This is why looking at "1km simulated reflectivity" for a start time is a bad idea. Gotta look at 1-hr QPF. We're still on track.