George BM

Happy June-like start to April, Weather family.

May 21, 2026 3:56PM EDT Tornadic supercell over Winchester, VA already responsible for at least two confirmed tornadoes in eastern WV continues to move just south of due east into a more favorable environment characterized by extreme instability (5000+ J/kg MLCAPE), strong effective SRH (300-450 m2/s2) and strong effective bulk-shear (60+kts). With low LCLs owing to surface temps around 90F with dewpoints around 80F, the environment is set for cyclical potentially strong to violent tornadoes as this supercell or any others that manage to form through the cap (warm-layer aloft) near the warm front move E to ESE. This an unusually dangerous situation for the Greater DC metro region as this is where the warm front is slowly lifting through from southwest to northeast. Take any tornado warnings or potential tornado emergencies issued this afternoon and evening especially seriously. The greatest potential of any particularly intense tornadoes will be between now and about 8-9pm when the subtle shortwave responsible for this supercellular storm activity exits to the east. Outside of the tornado threat any storms this afternoon and evening will be capable of dropping up to 4 inch diameter hail as well as producing significantly severe wind gusts (80+ mph) thanks to the steep 8+C MLLRs and fairly large downdraft CAPE available. There will be a lull in severe activity by the late evening hours before another round of more widespread storms, possibly in the form of an MCS or to move in from the west as a result of a stronger shortwave moving around the crest of the ridge of high pressure draped over the southeastern US. Despite the late night/ pre-dawn timing of these storms (midnight-6am) there could still be a decent severe wind threat as well as a risk of severe hail and a couple tornadoes owing to MLCAPE still around 2500-3000+ J/kg, 50-60kt effective bulk-shear and still strong low-level shear (Effective SRH in excess of 250m2/s2). Friday will introduce a still hot but less humid day with only a slight chance of isolated afternoon storms, mainly in the mountains.

One things for sure... The common non-weather folks sure weren't expecting thunder last night. ...

Yes can confirm. weather.us Always like that site for figuring out how powerful certain lightning events were.

Yeah. A 401kA positive bolt would certainly do that.

Dang!

Yeah pretty sure I just heard a deep rumble near 5 minutes ago all the way down in Herndon, VA.

Rain/sleet/snow mix in Herndon, VA. Wintry Mix.

Could this have been the June 4, 2008 event?

Honestly, if there was a MOD+ risk severe day and you didn't make an appearance here I would send out a BOLO for you to every agency around.

Well hello there pinned severe thread. First time we've done one since February 25, 2017 IIRC when Ian made one for that event (That event produced an EF-1 in La Plata IIRC).

Sky has a bit of a hazy look with an orange tinge to the sunlight.

IAD has peaked at 86F so far!

And IAD as well it would seem.

IAD has hit 85F so far!

You gotta drive over there.

11/30/2025: T (A mix of rain/sleet from the 4am hour through about 9am. Intensity got up to light/moderate intensity at times. Temps: low/mid 30s 12/02/2025: T (Probably had a brief period of sleet w/ rain sometime between 4:30am and 5am when precip started before quickly changing to a cold rain that became moderate at times during the morning.) 12/05-06/2025: 1.4" (Flurries/very light snow starting in the 4am hour intensifying to light snow between 6am and 10am (light/moderate at times). Flurries to very light snow showers continuing through the rest of the morning ending during the 12pm hour. ETA: Another few bursts of sometimes moderate snow with big aggregates between 10:30pm and around midnight or so dropping an additional 0.2".) 12/11/2025: T (A few flakes in the air during the morning on a northwesterly surface wind.) 12/14/2025: 0.9" (Mixed rain/snow starting after midnight on the 14th, changing over to snow sometime during the 3am hour and lasting through about 6:30am. Snow was moderate at times between 4am and 5:45am. It was graupelly in consistency.) 12/26/2025: T (A mix of light rain/sleet between 10:30am and 12pm. It was briefly freezing rain/sleet as temps fell to 31F during the precip.) 1/01/2026: 0.1" (A squall of heavy snow blew through between 5:18am and 5:35am with visibilities dropping to <= 1/4 mile briefly between 5:21am and 5:25am. Note: could have been 0.2" but the wind 25-30mph gusts made it difficult to tell.) 1/11/2026: T (A few wet flakes with a dying snow/graupel squall around 1:30-1:45pm.) 1/17/2026: 0.4" (Flakes started falling around 8:45am. At 8:48am intensity rapidly jumped from flurries to moderate+ within 15 seconds. Between 9-9:05am the snow was fairly heavy at times. Snow tapered off to flurries by 9:15am. There was a snow/graupel mix that briefly got up to light/moderate intensity around 10am. Snow/graupel tapered off by 10:30am as the last flakes concluded.) 1/18/2026: T (Off and on light rain, probably mixed in with mangled flakes predawn (1:30am-6:30am). An afternoon round of flurries between 4 and 5pm.) 1/24-25/2026: 8.0" (Flurries starting in the 11pm hour on the 24th intensifying into a light snowfall after midnight. Snow becoming moderate at times through the predawn hours. Some moderate+ rates in the 6am hour, then light/moderate through 7:30am when sleet mixes in. Back and forth between sleet and snow/sleet mix through 8:10am when sleet takes over for good. Sleet was moderate at times with snow grains mixed in throughout the morning. Waves of heavy sleet moved through during the afternoon (mainly between 1:30pm and 4pm). Sleet continued in light/moderate intensity afterwards until 5:30pm when it became light. Light sleet continued until precip wrapped up around 7pm. Snow grains were mixed in w/ the sleet (especially before 3pm.)) 2/06/2026: 0.3" (Flurries starting after midday becoming a period of light snow between 2:30pm and 4:30pm. Snow tapering off to flurries afterwards and ending by 5:20pm.) 2/07/2026: T ( Flurries/light snow showers associated with a strong cold front that moved through from NW to SE in the 2am hour.) 2/22/2026: 2.6" (Snow starts mixing in with rain around 2pm. More mixes in until it’s a moderate wet snow by 4pm. Snow becomes moderately heavy during the 5pm hour. Snow tapered off to light intensity during the 6 and 7pm hours. Became moderate again with the western snow band by 8pm w/ increasingly gusty winds. Snow lightened up during the 9pm hour and stopped with the exception of a few flurries throughout the night by 10pm.) Snow totals as of March 2nd, 2026: 13.7"

Forecast Discussion Tuesday, March 17, 2026 1:53PM EDT Severe Thunderstorm Watch in effect until 8PM EDT Tuesday, March 17, 2026 SPC Outlook Tornado: 5%, Wind: 90% CIGI 1, Hail: 5% Unseasonably warm and humid conditions remain in place throughout the region early this afternoon with upper 70s to mid 80s surface temps and low to mid 60s dewpoints. This is allowing for MLCAPE of 500-800+ J/kg. Strong ridge of high pressure remains entrenched over the southeastern US with a stationary front draped just to our north. Between the high to the south and lower heights to the north there is a belt of strong 50-60+ kt deep-layer flow (400-700mb). A well-developed severe MCS/derecho w/ an associated cold pool/ rear-inflow jet is currently located over eastern WV and will move across the entire region over the next several hours. Steepening low-level lapse rates and sufficient CAPE should allow this MCS to survive the trek over the mountains and cruise through the area. Widespread severe winds are, by far, the main threat with these storms, though a few QLCS tornadoes are certainly a threat given some fairly decent low-level shear (effective SRH in excess of 250 m2/s2). The Storm Prediction Center in Norman, OK has placed the entire area under a 90% wind risk w/ a level one CIGI which correlates to a moderate (level 4/5) risk. Moderate risk days from the SPC are rare as we’ve only had two such days previously in the last 13 years. Widespread wind gusts of 60-80 mph w/ a few locally higher gusts are expected as the line moves through at around 55-60kts. Skies will clear through the evening with temps holding in the 60s throughout the night before another round of potential severe storms tomorrow with the cold front pushing through from northwest to southeast as a more potent shortwave moves just to our north. Temps and dewpoints will be similar to today ahead of the front.

Warmer weather awaits. Welcome to Meteorological Spring peeps!

Remember... the new type of convective outlooks come out starting next week with the 1630z Day 1 March 3rd outlook. https://www.spc.noaa.gov/exper/conditional-intensity-information/

Into the norlun I go. Herndon, VA. Snowy and kinda windy.

1.9" so far in Herndon, VA.

Grass whitening under moderate snow. Herndon, VA

Hello neighbor! Snow mixing in here nicely in Herndon.

11/30/2025: T (A mix of rain/sleet from the 4am hour through about 9am. Intensity got up to light/moderate intensity at times. Temps: low/mid 30s 12/02/2025: T (Probably had a brief period of sleet w/ rain sometime between 4:30am and 5am when precip started before quickly changing to a cold rain that became moderate at times during the morning.) 12/05-06/2025: 1.4" (Flurries/very light snow starting in the 4am hour intensifying to light snow between 6am and 10am (light/moderate at times). Flurries to very light snow showers continuing through the rest of the morning ending during the 12pm hour. ETA: Another few bursts of sometimes moderate snow with big aggregates between 10:30pm and around midnight or so dropping an additional 0.2".) 12/11/2025: T (A few flakes in the air during the morning on a northwesterly surface wind.) 12/14/2025: 0.9" (Mixed rain/snow starting after midnight on the 14th, changing over to snow sometime during the 3am hour and lasting through about 6:30am. Snow was moderate at times between 4am and 5:45am. It was graupelly in consistency.) 12/26/2025: T (A mix of light rain/sleet between 10:30am and 12pm. It was briefly freezing rain/sleet as temps fell to 31F during the precip.) 1/01/2026: 0.1" (A squall of heavy snow blew through between 5:18am and 5:35am with visibilities dropping to <= 1/4 mile briefly between 5:21am and 5:25am. Note: could have been 0.2" but the wind 25-30mph gusts made it difficult to tell.) 1/11/2026: T (A few wet flakes with a dying snow/graupel squall around 1:30-1:45pm.) 1/17/2026: 0.4" (Flakes started falling around 8:45am. At 8:48am intensity rapidly jumped from flurries to moderate+ within 15 seconds. Between 9-9:05am the snow was fairly heavy at times. Snow tapered off to flurries by 9:15am. There was a snow/graupel mix that briefly got up to light/moderate intensity around 10am. Snow/graupel tapered off by 10:30am as the last flakes concluded.) 1/18/2026: T (Off and on light rain, probably mixed in with mangled flakes predawn (1:30am-6:30am). An afternoon round of flurries between 4 and 5pm.) 1/24-25/2026: 8.0" (Flurries starting in the 11pm hour on the 24th intensifying into a light snowfall after midnight. Snow becoming moderate at times through the predawn hours. Some moderate+ rates in the 6am hour, then light/moderate through 7:30am when sleet mixes in. Back and forth between sleet and snow/sleet mix through 8:10am when sleet takes over for good. Sleet was moderate at times with snow grains mixed in throughout the morning. Waves of heavy sleet moved through during the afternoon (mainly between 1:30pm and 4pm). Sleet continued in light/moderate intensity afterwards until 5:30pm when it became light. Light sleet continued until precip wrapped up around 7pm. Snow grains were mixed in w/ the sleet (especially before 3pm.)) 2/06/2026: 0.3" (Flurries starting after midday becoming a period of light snow between 2:30pm and 4:30pm. Snow tapering off to flurries afterwards and ending by 5:20pm.) 2/07/2026: T ( Flurries/light snow showers associated with a strong cold front that moved through from NW to SE in the 2am hour.) Snow totals as of February 22nd, 2026: 11.1"