UPDATED 2pm 12/15: Severe Snowstorm Wednesday, Potential Cat 4 on the Winter Index Scale

2pm 12/15 – This is the last set up model maps I will show. I really don’t have much to add so I want to begin a live blog with updates about the current storm and what is going. The trend was to bring the snow west into the Appalachians. No surprise given the track of the storm and upper level low which by the way is very impressive, especially now in the Plains.

7am 12/15 Update – The models overnight have changed to the idea I have been saying that the storm will go inside Norfolk to The Delmarva then east through The Dalmarva to off NJ where it will loop while waiting for the upper level system to catch-up. Once it does, the storm will intensify to 990 mb and head east and out. The heaviest snows have shifted to the west into the Appalachians because of two reasons. One, the 850 mb jet is just screaming into the mountains causing upslope snows. Second, the thunderstorms the develop over VA and The Delmarva are forced north into central PA. I always say watch where the thunderstorms go for the heaviest snow rates.

The NAM and ECMWF models have remain consistent on the snow amounts while the GFS has shifted with each run. I like my snow map and will make changes today if needed but I think things are good so far. Max amounts of snow in central PA will be around 25 inches.

I did posts of the ice storm and severe weather as well yesterday.

4pm 12/14 Update – Made updates to the snow map. Also, I did a post on the severe weather in The Dalmarva.

1pm 12/14 Update – Nothing new to report. I did a post on the ice threat in North Carolina and Virginia Wednesday morning. Also did a post on the snow in the southern Plains Tuesday.

Models continue to stay steadfast on on their own snow amounts with no consensus on the amounts. I like the NAM for personal reasons….lol.

9am 12/14 Update : I plan to leave my snow map as is because I do like what I have out. As you can see by all the maps below, it’s just a matter of the track now. I remain firm that the track goes inside Norfolk then through The Dalmarva, loops of NJ while waiting for the upper level energy then heads out east. Impacts all remain the same but many areas will not have a heavy wet snow but more dry and powdery due to the drier and colder air coming into the storm. The big cities will probably have the wet snow and lower snow ratios due to the ocean influence.

Update 5pm 12/13 – Just wanted to post various model maps. I am leaning toward the NAM solution because I like the track inside of Norfolk, Va then out to off The Dalmarva where the storm will sit and loop before heading east. This still means the snow amounts shown are Ok but a little concerned that the top of 20 inches might now come about. Airmass ahead of the storm is going to be a lot colder and drier so the dry air may prevent some snow at first. Snow ratios will actually change as the storm becomes more convective with time. Very complicated storm with all the different types of airmasses running around.

1pm 12/13 – I updated the snow map to reflect the track. Thinking not is cuts inside Norfolk then loops off Nj before heading east. Do not think GFS was correct on latest run because it’s having issues with the track of the storm.

Update 7am 12/13 – I made a few minor tweaks to the snow map. So far the models continue to remain consistent with a severe winter storm hitting Wednesday into Wednesday night. Where the snow is heavy, you can count on a disruption of travel and activities. The big question are the snow ratios. Below is a map of snow ratios which shows 13:1 in the Appalachians to 7:1 near the I-95 corridor. That’s going to have major implications on snow amounts and will also mean power outages are possible due to the heavy nature of the snow. Keep in mind this will be a highly convective snow event with snow amounts ranging from 10 inches to 20 inches over a a few miles.

Updated 6pm 12/12 : Latest GFS shows a shift west and a lot of snow on top of that. ECMWF remains as is with big snows eastern PA into New England. Let the shifting start

The latest GFS and GEMS pretty much inline with each other on the snow amounts. I expect the ECMWF to come out and show a little west movement of the snow.

I think we have all seen the latest model maps with a major snowstorm. I have talking about this event for two weeks now that around the 15th was going to be the big event and even the 30 day mentioned the potential for a Big Daddy storm. Well it’s here and looking like it’s coming.

This will be my initial post on the storm, starting tomorrow, I will begin a LIVE BLOG that will just continually updated with new information as to now have to post multiple times on the same subject.

Winter storm index

Key points about the storm… https://members.weathermadness.com/weather-madness-pro-winter-storm-index/

  1. Highly convective storm with snow rates 1-4 inches per hour
  2. Thunder and lightning may occur over many locations within the snow area
  3. Major disruption to travel will occur
  4. Cat 4 on the winter storm index.
  5. Storm will hit the major cities with impacts late day and at night
  6. For snow plowers, this is a plowable snow event
  7. Temperatures 28-34 during the snow which will make it a heavy wet snow
  8. Snow ratios 8:1 to 10:1 depending on location



Henry slowly but surely it seems as though the snow shield is moving west, as a comparison in south eastern Ohio 2 days ago there was hardly anything and per your map today it’s now 4 inches. Also, do you think Philadelphia’s totals will be cut down because of a mix potential.

Lastly, for this storm how does it compare with the January 1996 storm beyond this storm not as cold?

Keep up the great work Henry!


Noon GFS is about a 200 mile difference further east in low placement vs the European, my bet at this time is the European has a way better handle on this storm on being west of the gfs track.


I am in NOVA (Springfield) and we have not seen a decent snow (over 4.5”) in almost two years. I would love a EPIC Snow however… am just concerned with all of the models I am seeing being thrown around and the Low is still in the Pacific. The One Old meteorological saying is wait until the storm hits the West coast. Anyway, thank you Henry for all you do sir. I have followed and will continue to follow you :).


Good morning, Henry & everyone. The Kuchera map sure is different with the temps so marginal. Here at my house, the model “consensus” is roughly 16 inches assuming 10:1 and closer to half that using Kuchera. As Spock would say, “fascinating.” Is Kuchera always better? I would not think so… ?

Weather Madness

The only map I could find with snow ratios.


    The next generation of crackerjack meteorology students…, one with a roommate with coding skills and a girlfriend who is a GIS wizard may get to have a cool thesis or dissertation topic. Baking ratios into model maps, in a way that is user-adjustable. A need seemingly exists…


Hello Henry, the NAM solution map for the big cities that you have advertised sure look pathetic for snow is that your thought? thanks again


Looks to me that the NAM brings in dry and/or warm air, pushing the big snows west into the Mountain. “Bust” for Balt-Wash. Euro and GFS could not be more different.

Winky Martingale

Already seeing mixed precip in Baltimore suburbs close to I-95.


So is there a negative tilt going on with the storm now? Possible a full blown blizzard for hudson valley?


As I mentioned this weekend I thought the storm was way to east, the Euro continues to shift west and Philly will see their snow cut down dramatically to more rain than anything, for people around Frostburg, md to duncannon, pa to tamaqua, pa that area looks like the big winners. Big power outages are guaranteed.

it will be Interesting to see the NAM around noon.


Looks like the ridge is weaken gonna push this storm north big time 🤬