heavy_wx

I'm up near the Albany area for this storm...I think it will be better here than where I'd usually be, along I95 in MD! My main concern is if the secondary mid-level (~700-mb) band stays just south of ALB, and we're stuck in the subsidence zone of the circulation during the period of heaviest snow.

There's a relatively good indication of 1-km AGL rotation from KLWX for the storm west of Baltimore City. Also some shear-induced size sorting evident in the relative placement of the ZDR and KDP maxima.

The new positives reported each day would eventually decrease if the infection rate of the virus slows (R0<1), even with increased testing. This happened in New York State, where they have seen both a decrease in # of positives and in increase in # of tests. https://covid19tracker.health.ny.gov/views/NYS-COVID19-Tracker/NYSDOHCOVID-19Tracker-DailyTracker?%3Aembed=yes&%3Atoolbar=no&%3Atabs=n

Sorry to hear. Hope you feel better soon.

As an example, NY state (as of the Governor's briefing today) has ~700 confirmed cases and 65 people currently in ICU beds. Beyond the confirmed cases, it's hard to know how many people are asymptomatic, so I take your point that the percentage could be lower when factoring in these unobserved cases. The troubling thing is that the number of confirmed cases increases exponentially with time, unless serious social distancing measures are implemented. Italy has *only* 24k cases but its health care system is overrun with COVID-19 patients in critical condition. 16 days ago, Italy had about the same number of cases NY has currently.

~10% of COVID-19 cases are serious enough to require ICU treatment. The US hospital system has a limited capacity to provide people with those resources so if there are too many cases at the same time, the system is overloaded and people will not be able to get the treatment they need. Social distancing measures to limit the number of cases occurring at the same time are essential to make sure we don't have that situation - essentially what is happening right now in Italy and Spain - here in the US.

Yeah, that was a terrible winter for State College; despite getting 7" from that storm, we tied the all-time record for lowest seasonal snowfall.

Light snow here in North Laurel.

Didn't see any snowflakes here.

Getting some relatively large aggregates with this squall here.

Measured a final total of around 2".

Moderate to large aggregates out there, though looks to be ending pretty soon. I could definitely see some pristine dendrites attached within some of the larger aggregates, so these low-density particles will help bump the snowfall accumulation/ratios here.

And the aggregates are starting to get bigger here. Coincides with a dendritic growth signature on radar, where ZDR and KDP are somewhat enhanced in the precip east of DC, farthest from LWX where the radar beam is higher. Another slightly more substantial dendritic growth signature is also visible over southern PA.

Getting a steady light snow now with wet but mostly frozen aggregates

Left work around 12:30 and just started to see rain around the 95-495 split near Beltsville, MD. Now getting some light flurries here in North Laurel.

Forecast wet bulb temperature profiles definitely look colder at low levels than a few days ago, with 18z NAM and GFS profiles below 0C everywhere above the immediate surface layer (see BWI forecast sounding below). A deformation zone between 800-600 mb is aligned relative to the temperature gradient such that there will be frontogenesis-induced lift within this region. Vertical motion in this layer will have pretty good overlap with temperatures favorable for dendritic growth, with the subsequent aggregation of these dendrites producing relatively large, low-density ice particles. These low-density particles should help to increase snow-liquid equivalent ratios, though surface temperatures at or slightly above freezing could counteract these enhanced ratios somewhat. It will be interesting to follow this tomorrow, and I kind of wish I had planned ahead to telework!

And even the operational 12z Euro has fairly mild boundary layer temperatures for the I95 region (see sounding below). Unfortunately not a great pattern for low-level cold air with the progressive 500-mb troughs in SE Canada/lack of a strong, cold anticyclone.

Measured about an inch of snow here in North Laurel. Currently sleet with a few snowflakes mixed in.

Large aggregates falling here in the last few minutes (since I woke up), with a coating of snow on the road.

Measured about 9.5" on the ground here.

Yeah, definitely high SLR.

Low-density fluff falling out there. Nice aggregates composed mainly of rimed dendrites.

I think the snow detected by the radar is > 500 m above the ground, so with the N wind, it has moved several km south by the time it reaches the ground. I noticed this as the band approached me in North Laurel, where the precip didn't become all that intense until the center of the band was above me.

Getting some moderate-sized aggregates now and reduced visibility within the band of 35-40 dBZ reflectivtiy.

Getting a steadier light snow here on the northern edge of the band approaching Howard county. Still relatively small flakes.