George BM

67/36 at IAD 2:45pm est.

Neat. Was this at the same place that you lived during "The Spooky Scary Goose Whiteout" nearly 5 years later?

In any other case of severe potential that we’ve had in recent years around here I too would be cautious about jumping all in on a severe threat in these parts. But today is different… very different. I very highly doubt that this line of storms will fizzle out or even weaken much at all as they move in. In fact, they may very well do the opposite. Yes, legit severe is DEFINITELY extremely hard to get in these parts. But we are into the low/mid 90’s with dewpoints into the mid 70’s everywhere now. There is already a confirmed large tornado with the southern supercell, the northern Montgomery county supercell already has signs of strong rotation. Also, based on the 20z mesoscale analysis mid-level lapse rates are around 7.5C/km yielding MLCAPE of 4000+ J/kg everywhere. The biggest thing for me to note is that low-level lapse rates are steep (near 9C/km) now. The main line of storms approaching from the west is steamrolling it east at around 65mph and is moving perpendicular to the flow. Now with those steep low-level lapse rates that I just mentioned downdraft winds will easily be mixed down to the surface. So, a lot of areas should see max wind gusts of at least 65mph. BUT… with decent downdraft CAPE as well (1000-1300+ J/kg) coupled with the very strong to extreme instability and high PW values (1.75”+) we could see strong downbursts bring down much stronger wind gusts on a more local basis. Now as for the line of storms holding together through our region, effective bulk shear is strong for this time of year (around 50kts). This will allow the storms to remain very well organized and perhaps even strengthen a bit as the get east of the mountains and into the highest CAPE. Low-level shear is very decent for the time of year as well (effective SRH of 150-300m2/s2) hence the tornadic supercells developing ahead of the main line of storms. A few QLCS tornadoes are also possible with the main line. This is the best that I’ve felt about a severe threat in these parts in a long time… perhaps even “ever”. I just very glad that we finally seem like we’re going to score a bigly areawide severe event. Even work has brought @WxWatcher007 back to DC for this one. However, RIP this afternoon's and evening's rush hour though. BTW, Here's the new 2000z Convective Outlook from NWS George BM headquarters: 2000z update Mid-Atlantic region: A few supercells have developed within the last hour or so affecting the WV panhandle, northern/central VA and northern MD. These storms could become tornadic with a strong tornado not out of the question given the 150-300m2/s2 effective SRH with very large hail and severe winds also a threat with these storms. The main line of storms associated with the severe MCS/derecho now stretch from PA through western MD and eastern WV and is now moving over the mountains and into northern and western VA and is moving east at around 55kts. This line may further strengthen as it moves east of the mountains into an airmass with MLCAPE of 4000+J/kg, 1000-1200+J/kg DCAPE and effective bulk-shear of around 50kts. Widespread severe winds w/ some significantly severe gusts, severe hail and a few QLCS tornadoes will be the main threat with these storms through the afternoon and evening hours before they all move out into the Atlantic by 2z. Tornado: 10% (Enhanced) Wind: 45% hatched (Moderate) Hail: 30% hatched (Enhanced) The threat for this upcoming Saturday also looks very decent for our standards especially near the MD/PA border. What a fun week of severe weather tracking.

Woo storms! 31/28 at IAD.

Next year will be a-buzzin'!

Woo storms?

From last night.

@PrinceFrederickWx Lovin' it! I'd be very curious to see these same graphs over the past 100+ years... or since record keeping began at the local airports.

Is anyone going to try and see whether two dead satellites collide over Pittsburgh at 6:39pm est tonight? The chances of a collision are very low (1/20-1/100) but still... maybe we may see something if they do collide. They will be 560mi above Pittsburgh so you'd have to look up high.

That storm had a super deathband with crazy rates early in the morning of the 13th. Probably comparable to the Feb 1983 storm... nah that storm had 5"/hr rates according to some and the Feb 1979 storm had 4"-6"/hr rates.

@mappy I see that you're a @WxUSAF now.

A very cool story. Thank you for sharing. How was the Jan 25, 1985 whiteout at your location?... How much lightning and wind was there with that event?

He isn't. 49/40 with rain approaching.

Which of those rides most reminded you about storm-chasing?

You'll be forgiven and then some if you can bring us our Category 5 up the Potomac.

Close indeed. Just get a slightly stronger push of warm and humid air and it could be a nice high shear/low cape convective event for some. Still have over a week for it to trend better..... or worse.

I feel..... young-ish? I guess because I'm still fairly young-ish (early 20's) I get this preconceived notion that everyone who I haven't seen in person yet or who's general age I don't know is fairly close to my age. I think there are just two posters that I know of on here (from what they've said) who are actually younger than me. *shrugs* I know there are probably more people on here who are aob my age who just don't post much. Happy Martin Luther King Jr. Day.

Maybe we get our dues all at once? ...

32F with rain and 0.04" of ice accretion on the trees.

DC, Maryland, Virginia.

Snow started just after 6:05am and became moderate/heavy within ten minutes. Fine small flakes. It's tapering off now. Herndon, VA.

There is the potential for some ice accretion. URGENT - WINTER WEATHER MESSAGE National Weather Service Baltimore MD/Washington DC 133 PM EST Fri Jan 17 2020 MDZ503-504-VAZ028-030-031-052-053-501-502-505-506-WVZ052-053- 180245- /O.NEW.KLWX.WW.Y.0003.200118T1200Z-200119T0000Z/ Northwest Montgomery-Central and Southeast Montgomery- Frederick VA-Warren-Clarke-Prince William/Manassas/Manassas Park- Fairfax-Northern Fauquier-Southern Fauquier-Western Loudoun- Eastern Loudoun-Berkeley-Jefferson- 133 PM EST Fri Jan 17 2020 ...WINTER WEATHER ADVISORY IN EFFECT FROM 7 AM TO 7 PM EST SATURDAY... * WHAT...Snow, sleet and freezing rain expected. Total snow and sleet accumulations of up to one inch and ice accumulations of up to one tenth of an inch. * WHERE...Portions of central Maryland, northern and northwest Virginia and eastern West Virginia. * WHEN...From 7 AM to 7 PM EST Saturday. Precipitation will begin as snow before transitioning to sleet and freezing rain. Precipitation will change to rain late in the day. * IMPACTS...Plan on slippery road conditions. PRECAUTIONARY/PREPAREDNESS ACTIONS... Slow down and use caution while traveling. When venturing outside, watch your first few steps taken on steps, sidewalks, and driveways, which could be icy and slippery, increasing your risk of a fall and injury. && $$ Hope that helps.