Winter Wizard

One quick note: it's definitely a stretch to call December 2013 a torch. Most places in the Mid-Atlantic finished the month right around average and that was largely skewed by a torch around 12/20. The first half of the month was below normal and the week of 12/8 brought three separate snow events to the Baltimore/DC metro, all of which featured WSW in the LWX zones. In fact, going off of the discussion yesterday in the medium/long range discussion thread, it's a good example of when having a strong SE ridge works in our favor since it shifted the baroclinic zone northward enough to get us in the action, but thanks to the strong -EPO, we remained on the right side of the gradient.

The trend is not your friend.

Interestingly the 12z GEFS has jumped considerably NW in the SLP track and ensemble mean. Now shows 0.5"+ for everyone south and east of Frederick.

Looks like the final total here in Annapolis was right around 1.2".

Yellow-banded here in Annapolis. RadarScope estimate has us around 0.4” so far today.

Looks like it's all from the primary low, especially N and W of DC. As soon as the transfer occurs, precip shuts off rapidly from W to E. Huge dry slot through central PA and NW Virginia. Let's hope this storm isn't a sign of things to come in the winter.

So far it's advancing at a pretty steady pace. As of October 11, Siberia had the second highest coverage over the past decade trailing only 2014.

Essentially a Miller B. The latest GFS has the primary vort holding strong all the way to Ontario before fully transferring off the coast of Mass. We all get some rain from the initial low but re-development is way, way too late for us to get in on the good stuff. The Euro, on the other hand was much closer to rainier solution as it had an earlier transfer (DE coast) and stronger secondary low, which brought the deluge into PHL and even far northeastern MD. Will be interesting to see the trends at 12z. I do wonder if the GFS is being too progressive, especially since the 6z GEFS re-developed the secondary farther south and west than the operational.

Had a decent band of rain earlier today in Annapolis, which brought us 0.11” in total. Photo is from Instagram but there was pretty significant coastal flooding near the Bay, which made things extra interesting for the Boat Show this weekend.

Another deluge of 0.01” here in Annapolis overnight.

Pretty stark contrast between last night's 0z GEFS and EPS runs for next week. EPS is much weaker with the troughing over the central US, which allows the southeast ridge to flex its muscles out ahead of it and torches the east through the 17th. The GEFS meanwhile continues to show a strong trough over the northern Plains that gradually moves east, which would put us solidly below normal through the 19th or so.

Yup, we actually were under a solid band for a bit around 11 last night. Tonight is a pretty tricky forecast but I think there's a decent chance we see at least some rain.

Looks like we had a whopping 0.05" of rain last night here in Annapolis. Solid deluge.

If all else fails, persistence forecasting is usually the way to go, though it's nearly impossible to predict the NAO this far out with any kind of skill.

I would exercise caution about using summertime NAO as a means to predict the wintertime NAO. I looked back at the NAO index from 1989-2018 and of those 30 years, just 13 had a pos/pos or neg/neg relationship, which is good for an r-value of just 0.09. Aka no correlation. Additionally, there have been 9 summers prior to 2019 (1993, 1998, 2000, 2008, 2009, 2011, 2012, 2015, 2016) where the NAO index has averaged less than -1. Among those years, a -NAO in DJF was observed in only 2 of the subsequent winters.

Both the latest EPS and GEFS have a fairly strong signal of a -NAO locking in around the 10th or so while the PNA returns to a neutral state and the MJO meanders between phases 8 and 1. Analog guidance is pretty bullish about a flip to a colder-than-normal pattern by mid-month.

Ended up at an astounding 98 degrees in Wilmington yesterday. Not only was this the warmest day in October on record, it was also the warmest day of all of 2019.

A muggy 72/67 here in Annapolis.

Pretty clear where the warm front is located right based on METARs...54 right now in Clearfield and State College but 75 in Indiana, 71 and Johnstown, and 63 in Altoona.

DCA: +5.5 and 0.25", good for 2nd warmest and 3rd driest IAD: +4.6 and 0.41", good for 3rd warmest and 2nd driest

Yup that one was a coastal that was way too far east for us. But brought a swath of 6+" to Norfolk/Virginia Beach to Chincoteague as well as eastern Long Island and Mass. Looks like DC didn't even see flakes from that one.

That was a backloaded winter if anything, which is typical of weak El Ninos. DCA temps and snowfall by month: DEC: +0.4 (0.1") JAN: +0.1 (6.4") FEB: +0.6 (5.2") MAR: -3.7 (0.8") Big storms that winter were the KU in January 2005 and back to back coastal storms in late Feb. January 2005 was a classic Miller B screwjob for the DC/Baltimore metro that crushed everyone north and east of Cecil. February 24-25 was a fast moving coastal that brought a wide swath of 6+" to Maryland east of DC although DC itself was a relative min. I don't recall the exact details of February 28-March 1, but I believe this was a storm where the primary low redeveloped too late, which kept the heaviest the snow well north and east of the metro. So as a result, it ended up being an average winter for DC and Baltimore, above average for Philly and NYC, and an all timer for Long Island and SNE including Boston.

BWI: 11/7 IAD: 11/7 DCA: 11/25 RIC: 12/2 Tierbreaker: 10.24"

Gaithersburg is probably the ideal spot if you want convenience to DC. As was mentioned before, the farther north and west you get from DC and the Beltway, the better you do especially in marginal setups. This is the farthest northwest spot you can go while still being close to the Metro (Shady Grove on the red line). It's also considerably cheaper than NoVa or anywhere inside the Beltway. This area also jackpotted during the 2016 Blizzard with just under 40 (!) inches.

Writing was on the wall last night for this to underperform. The Ohio Valley shortwave was much farther south and less robust than CAMs guidance showed 24 hours ago. GFS actually caught on to this first followed by the HRRR and finally the NAM. Persistent cloud cover has greatly limited our instability - CAPE is less than 1000 J/KG for most N of DC at the moment. For southern Virginia, though, where there has been clearing, CAPE is over 3000 J/KG and there is sufficient speed and directional shear to support isolated supercells. However, the total coverage will be far less than what we expected 24 hours ago. Unfortunately, this scenario plays out time and time again in this region. I was really looking forward to chasing today after work, oh well