Winter Wizard

All rain in Annapolis.

I don't buy the NAM verbatim (probably too dry), but it does show you how limited the window of opportunity there is for snow. Once that front moves through, dry air will rush in and shut off the precip pretty quickly from west to east. At this point, I think T-1 is a solid call for I-95 south and east. 1-3 possible in the climo favored areas with isolated higher depending on how strong the rates are.

Frontogenetic forcing on the GFS continues to look impressive. The 250 mb Jet steak is also sharper and puts us right in the right entrance region. I suspect we’ll see some pretty intense banding with this system, likely N and W of the cities.

I think what's important is both the GFS and the Euro (as well as ensemble guidance) have a strong antecedent cold air mass, west coast ridging and a shortwave tracking along and up the coast. The issue here is timing - if the system can arrive earlier and/or the high takes longer to retreat, then I suspect you could be seeing more favorable solutions. Lots to work out over the coming days, but for mid-December there are far worse looks we could be seeing.

Woke up to a wet ground. I'm guessing that band in NoVa died out before reaching Annapolis and/or temps didn't cooperate. Edit: yup, NAK and BWI both reported light rain. IAD recorded light snow.

Definitely the most unforgettable storm for me. It happened to occur on the day of my Bar Mitzvah and we always joked that it was a sign that meteorology was my destiny. I was probably the only kid not upset his party got canceled because he was so excited about the 18 inches of snow that day.

Last night's GFS was all in on the December '09 redux exactly 10 years later.

Nice little band of snow rotating into Cecil and Harford counties.

The surface depiction is just noise at this point, especially the GFS which had a totally goofy evolution. The features aloft have largely trended in our favor today in terms of seeing some front end frozen precip. The 500 mb vort depicted in today's ensemble guidance is close to being in a favorable spot for DCA, but would still need to be considerably farther south in order to get anything from the coastal. Otherwise, the best dynamics would take place farther north and it's a congrats SNE.

I wasn't alive for it, but 89-90 had one of the most dramatic pattern flips I've seen. Second coldest December on record in DC (-12.2 departure) to blowtorch January (+7.6) and February (+6.2). December 22-24 1989 was the biggest snowstorm on record for ILM and OBX (15 and 13 inches respectively) while our area was mostly shut out. We did have above average snow for the month but most posters would have been frustrated.

Vontaze Burfict got suspended for the season and Garrett's hit was undoubtedly worse. He should be suspended the rest of the season at least and probably the start of 2020 too.

We have flakes in Parole (west side of Annapolis)!

45 with rain in Annapolis. It'll be a pretty close call here for snow.

And what's more impressive is the cold that follows it. State College drops into the low single digits for at least three consecutive mornings next week on the GFS.

12z GFS is another pretty solid run for C-PA snow next week. Classic anafront situation.

Looks anafrontal to me. Obviously not as great as 6z but still eventually turns to snow everywhere but the MD/DE shore through 168.

Hour 132 shows frozen precip into central PA. The most notable change I see it northern stream vort isn't digging as much as on the 6z run. 144 has a mix for the N and W suburbs, rain for DCA and BWI

I agree that the 11/12-13 threat has much more potential. The late week storm threat seems more like a frontal boundary that could bring some snow on the backend to interior New England and maybe parts of western NY and PA. Even some mood flakes are possible in the far northern and western suburbs depending on the track. This would shift the baroclinic zone farther southeast, which could end up working out in our favor if all goes right. You have a highly amplified west coast ridge, a deep trough, fresh injection of cold air, and some semblance of Greenland blocking starting this weekend. Actually a fairly similar setup to November 2014 and 2018. We've seen D10 threats fall apart in the medium range, but this one is definitely worth monitoring. At the very least, a colder-than-normal November seems pretty likely at this point.

Congrats La Plata

Skins will never come close to a championship as long as Snyder is in charge. Beal is probably gone by next year, but at least the Wizards will suck enough to have decent draft capital.

This is a pretty classic high shear, low cape severe event. Anything that develops later this afternoon (should be around 0z in the Blue Ridge, 2z near I-95) should quickly congeal into QLCS. The biggest concern is definitely the straight-line wind threat, although a brief spin up is not out of the question, with very strong speed and directional shear near the surface and a cranking LLJ. Question is, can we overcome that mid-level capping inversion and mix down to the surface as shown in the 0z DCA sounding?

BWI: 23.2" DCA: 13.7" IAD: 25.1" RIC: 10.8" Tiebreaker SBY: 10.3"

Since 1950, there has been a -AO in November 38 times. Among those 38, 23 were also followed by -AO in December, but 27 featured a mean -AO for DJF. The average snowfall since 1950 at DCA is 16.1". Among those 38 Novembers, 23 had a strong -AO of <-0.5. 16 of those years (70%) also had a -AO for the winter. Interestingly, the last four times this occurred (2018, 2016, 2014, 2007), there was a +AO in the winter. Conversely, there have been 17 Novembers with strong +AO of >0.5. 11 of the following winters (65%) also had a +AO. The mean snowfall in -AO November years is 15.2", but in strongly negative years (<-0.5), the average climbs to 18.4". -AO Novembers where the winter also featured a -AO DJF have a mean snowfall of 17.7". In total, 12/38 (31.5%) of -AO November winters had above normal snowfall. Interestingly, the mean snowfall in +AO November years is above normal at 17.2". 13/31 of those winters featured above average snowfall (41.9%). Another interesting tidbit I found was in DC's top 10 snowiest winters, 5 of them had a -AO November, but only 2013-14 had a +AO November and +AO winter.

Yes, I was talking strictly December snowfall vs. rest of the season. Rest of season snowfall is about average with +AO Decembers.

Just ran through the numbers: Since 1950, there have been 33 winters with a positive AO in December. 25 of those winters featured 1 inch or less of snow in DCA and among those, 15 were complete shutouts. The average snowfall in +AO winters is just 1.2" while only 3 have featured 6" or more in December. However, the rest of those seasons averaged 12.7" which is in line with the long term average of 13.2". 12 of those winters featured a 6"+ snowfall at another point in the winter including 6 of the shutout winters. Conclusion? If the AO is positive then odds are very high December is doomed in DC. However, there is definitely still hope especially if the AO eventually turns negative, which was the case in most of above average winters.