Forecast Discussion
Wednesday, November 23, 2022 11:58AM EST
NWSGeorgeBMHeadquarters
A very strong and compact mid/upper level-low will continue to move ENE-wards into our region during the afternoon and into the evening. Currently ahead of it much of the area is experiencing light drizzle. Temperatures have slowly climbed to around 40F or so across the immediate Greater Washington Metropolitan region with low/mid 40s in southern and eastern MD and mid/upper 30s in far north and western regions. The Greater Metropolitan region should peak in the lower 40s over the next few hours. Afterwards, by early/mid afternoon (18z-20z) heights will fall very dramatically (500mb height falls: 12-15 dam/ 6hrs) as the compact system moves in. This will create very strong lift through a deep-layer of the atmosphere resulting in two significant things taking place.
1. Heavy precipitation will develop leading to dynamic cooling of the column allowing a quick changeover from rain to snow. With some elevated instability some elevated thunderstorms may develop, especially near the leading edge of this area of strong lift. Some small hail may even be possible with the most intense storms. But, more importantly, the snowfall rates will be very heavy. Although the system should be in and out within 6 hours there could be 1.5”+ of liquid equivalent precip within that time, much of it falling as snow. Therefore, snowfall rates could be in excess of 3”/hr. Current snow totals look to be in the 8-14”+ range. The snow will be high in moisture content (~8-10:1 ratios) leading to the potential of power outages.
2. In response to this strong mid/upper level system a surface low will rapidly strengthen over the southern Chesapeake Bay and move NE-wards across the Delmarva and into the western Atlantic through the evening as it continues to deepen. This will result in winds increasing throughout the region. Northerly wind gusts as high as 35 mph will be possible.
With the very heavy snowfall rates coupled with the gusty winds, visibility will fall to below a quarter mile. A Winter Storm Warning is in effect for the region. Winds won’t be quite strong enough for Blizzard Warning issuances. Nonetheless, it will certainly seem blizzard-like throughout the late afternoon/evening. Overall, this will be a quick hitting and high impact event with snow departing the region by 3z tonight.
