6:25 p.m. update: A severe thunderstorm watch remains in effect until 11 p.m. An initial broken line of storms is moving through parts of the region, mainly concentrated over Carroll county where some hail is possible. Weaker activity associated with the same line is moving through Frederick, western Montgomery and eastern Loudoun county as well as to the south around central Fauquier county. There’s a bit of a split in the activity over the immediate metro region but some isolated activity could fire up over the next hour as the entire broken line pushes east. Behind it, a much more significant line is moving into eastern West Virgina which we need to watch for possible impact in the area between 8 and 10 p.m. tonight. That line, for which numerous warnings are in effect, holds the most potential for severe weather.
4:20 p.m. update: The Storm Prediction Center has issued a severe thunderstorm watch until 11 p.m. that includes primarily the western half of the area (see map). Storms now moving through West Virginia will approach as the evening progresses, probably arriving here around 7-9 p.m.
3:45 p.m.: It’s been a cool and dreary day thus far, but largely dry -- other than some drizzle -- as a low pressure system and attendant cold front move toward the area. Highs currently nearing 50 or just above are considerably warmer not too far south and southwest, and a bit more warm air may push in yet. That temperature contrast helps set the stage for more showers and potential strong to severe thunderstorms later.
Through Tonight: Clouds may temporarily break a bit before the risk of rain goes up this evening as an area of severe weather that has prompted a Tornado Watch to the west moves toward us. Fortunately, cool and fairly stable surface air should promote weakening of the storms as they move in. However, there’s still a risk of large hail and damaging winds. Most spots that see consistent rains could end up with about .50”, but some higher and lower numbers are also likely. The rain risk tapers after midnight, though showers are possible through morning. Lows reach near 40 to the mid-40s as a northeast wind blows around 5-10 mph.
Tomorrow (Thursday): There may be a few showers -- perhaps mixed with snowflakes or snowgrains north and west -- around into midday as upper-level energy passes by. It’s fairly cloudy again, but we should see some increased sun chances as the day wears on and the storm moves off to the northeast. Cold air keeps filtering in, so highs probably struggle to the mid-40s or near 50. With averages nearing 60, maybe a little painful.
Northeast Snow:The storm impacting us today is bringing some late-season snow to places north of here. As much as 12” total is expected in the higher elevations of the Poconos and Catskills into northern New Jersey, where over a half a foot has already fallen in some spots. Other locales such as Hartford (Boston might be on the northern edge) look to pick up a few inches. Even into NYC, a few flakes have fallen with additional expected, but the battle against springtime climatology is tougher to overcome in the coastal plain, and not much is expected to stick there.