11:55 AM (Friday) | **Energetic atmosphere this afternoon/evening to bring rain and/or snow showers, strong wind gusts, and perhaps a thunderstorm with small hail**
Paul Dorian
Satellite image at mid-day highlights the coastal low and cloud bands associated with an approaching wave of energy in the upper atmosphere; courtesy NOAA, College of DuPage)
Overview
While low pressure is pulling off to the northeast at this hour along the New England coastline, a strong wave of energy in the upper atmosphere is dropping southeast over the Great Lakes and it will make it quite volatile here in the Mid-Atlantic region later this afternoon and evening. The combination of the intensifying and departing low pressure system and the strong approaching upper-level feature will help to produce wind gusts here to 40 mph or so this afternoon and evening, numerous rain and/or snow showers, and perhaps a few isolated thunderstorms which can generate small hail. Windy and cold conditions will stick around later tonight and through the day on Saturday, but noticeably milder and calmer weather is coming for Sunday.
An unstable Friday afternoon and evening
A strong wave of energy in the upper atmosphere will drop into the Mid-Atlantic region later today accompanying a blast of cold Arctic air and this will lead to quite unstable conditions. The result of this combination and the intensifying coastal storm will be wind gusts to 40 mph or so this afternoon and evening, numerous rain and/or snow showers, and perhaps even a few scattered thunderstorms. Latest radar echoes show clearly the precipitation associated with the departing coastal low (rain along the coast, snow across interior higher elevations) and the precipitation associated with the approaching upper-level wave of energy. Any thunderstorm that forms later today/early tonight can quite easily generate small hail as freezing levels will be quite low in the lower part of the atmosphere.
12Z NAM forecast map for mid-afternoon which features a wave of energy at 500 mph nearing the Mid-Atlantic; courtesy NOAA/EMC, tropicaltidbits.com
The windy and cold conditions will stick around in the Northeast US and Mid-Atlantic region later tonight and Saturday and despite plenty of sun tomorrow, afternoon temperatures will be confined to the below-normal 40’s for highs. Noticeably milder and calmer conditions are likely for Sunday in the DC-to-Philly-to-NYC corridor as high pressure edges in and temperatures could reach 60 degrees in DC and well up into the 50’s in Philly and NYC.
Latest radar features echoes associated with the coastal low (NE US) and upper-level energy (Ohio Valley); courtesy University of Wisconsin NEXRAD