paulythegun

You just inspired me. Prepping some steaks and shrimp

Trust me, I'm kind of weirded out!

Roads not fully caving yet in DC. Some sort of new mutant salt

Seeing snow in DC, near the foothills of the mighty Mt. Hamilton

I wasnt expecting anything more than flurries before midnight. I'll wait until then to throw a tantrum...(Not here...in some group chats!) The column is saturating - fairly quickly based on the dew points. All good!

Trying to be positive. Trying SO HARD haha.

Yep! Not a big deal. Will fill in

Mrs. PacMan, as expected. Everything is on schedule. Waiting until about midnight for this to fill in

My guess...they have like 6+ other hires models to look at that are better than NAM, if you include all the experimental ones.

Capital Weather Gang just did the exact opposite. https://bsky.app/profile/capitalweather.bsky.social/post/3md4fnulpvc24

https://repository.library.noaa.gov/view/noaa/53067 Analysis of Model Thermal Profile Forecasts Associated with Winter Mixed Precipitation within the United States Mid-Atlantic Region This paper looked at overrunning events in a CAD setup in the mid-atlantic and found a warm bias for NAM and NAM3k. Money part:

SLEETY SAYS "Don't forget to include sleet!"

I've got one of those Segway e-scooters. I plan to take it out late Sunday with tons of padding (and a helmet) and skid around some parking lots. Done it before, it's the greatest thing ever. Falling down doesn't hurt either.

FV3 buries DC with snow. Very late changeover. NAM3k brings a very early changeover. NWS' forecast looks much more like FV3 (high snow totals). See the other thread. I asked ChatGPT to discuss the models' strengths and weaknesses (LOL). Here's what it told me (EXACTLY WHAT I WANTED TO HEAR, SHOCKER! but an interesting read): This is a classic Hour-40–60 Mid-Atlantic fork, and the way you described it already hints at which solution is more plausible versus more diagnostic noise. Here’s how forecasters would parse exactly this setup. What the disagreement really is NAM solution Introduces a 700-mb warm nose after ~40 hr Overruns CAD → sleet/freezing rain inland Produces a fall-line snow cliff (DC ~4", south much less) FV3 solution Keeps the column colder Maintains deep isothermal profiles Allows widespread synoptic snow, including south of DC Matches the current forecast thinking from National Weather Service This is not subtle disagreement — it’s a structural difference in storm evolution, not just a few degrees. Why the NAM solution is suspect at 40–60 hr The NAM’s warm nose is a known bias At this lead time, the NAM often: Over-advects mid-level warmth ahead of strengthening southern stream systems Especially above CAD, where it erodes cold air too early Invents sleet/freezing rain before the synoptic forcing is mature This is textbook NAM behavior in overrunning setups. A 700-mb warm nose at hour 48 does not mean it will verify — it often means “the model is ahead of itself.” Sharp fall-line cutoffs scream “fake precision” At 3-km resolution, a knife-edge cutoff near the fall line at Day 2–2.5 usually means: Convective or feedback-driven thermal noise Poor handling of ageostrophic ascent CAD erosion happening too abruptly Real storms: Transition gradually Evolve over multiple cycles Rarely stop snow exactly at the fall line at this lead time FV3 matching NWS matters — but why matters more It’s not just that FV3 agrees with NWS — it’s what it agrees on: Cold column integrity Broad ascent Synoptic-scale snow shield That alignment tells you: The conceptual model is consistent across guidance. That’s far more important than any single snowfall number. What’s likely happening physically Most likely evolution given current signals: CAD holds longer than NAM suggests Warm nose (if it arrives) is: Later Weaker South/west of DC Snow extends well south of the fall line initially Any mix issues become: Late-stage South-focused Elevation-dependent NAM is probably correct that warm air exists aloft eventually FV3 is probably correct on timing and impact How forecasters would weight this right now At Hour 40–60: Reject the NAM snowfall cliff Flag the NAM warm nose as a risk, not an outcome Lean FV3 for: Snow extent Cold-air durability Early & mid-storm evolution If future NAM runs: Delay the warm nose Soften the cutoff Trend colder That’s convergence toward FV3, not the other way around. Bottom line (plain language) The NAM is likely too warm, too fast, and too sharp The FV3/NWS solution is meteorologically cleaner At this range, widespread snow is the higher-probability outcome Mixing concerns are real but premature This is exactly the kind of setup where: NAM scares you early FV3 ends up closer on the big picture If you want, next we can: Walk through what would need to change for the NAM solution to win Identify the specific upstream feature that decides this Compare this setup to Jan 2016 / Jan 2018 / Jan 2000-style cases Just tell me where you want to go next.

HAPPY CONVECTION ALLOWING DAY to those who celebrate

Sticking this here since it's SREF: 8(!!!!) SREF Plumes out of....I don't know, 25(?) bring the temp above freezing at DCA Sunday. THREE (!!) are above 40F. (the snowmean is like 19" though hahaha)

GFS ingested the Baja Recon data. Instead of waiting an hour, it became impatient after about 15 minutes and ingested MORE Baja Recon Data. Amateur hour.

GFS was not informed about the slightly anomalously cold temps in a tiny area of the Pacific. Once it learns, it will Make Less Snow For Us* *Source: SCIENCE

Dumb Dumb NAM

SREF OUT!

It's really quite funny if you reread it.