Ed, snow and hurricane fan

Not as much snow, but still snow on the backside of the Monday storm in NCTX Tuesday morning on today's CMC (2-4 inches). Still in a 15% risk I-10 corridor from near San Antonio to Alabama with that storm Monday. Euro and GFS show limited surface instability (near/less 500 J/KG ML) but close to 1500 MUCAPE with about 50 knot LLJ Monday mid-day.

Might get lucky with recon for the ATL, Gulf and Pac.

Day 17 15% from SPC. I was looking at Friday, but it doesn't look like instability will be there for strong/severe. Winds for Monday system look impressive.

Cool and dry has been pretty boring (HGX AFD's main concern tonight is firework smoke will make local fog after midnight worse, then a half to an inch and a half Tuesday night into Wednesday with a coastal low) but maybe Friday afternoon/evening has a severe threat near and S of I-10. 850 mb winds are not from the SW, but the S. Severe rarely happens near I-10 w/ a SW flow because of capping, but that doesn't look to be the issue. Of course, CAPE is on the low side, but that can change.

Network news on cold weather, and I think TWC, routinely use windchill maps showing temps in the teens and twenties to hype cold outbreaks. Because actual cold outbreaks where people live just don't get cold enough anymore. Semi-related, GEFS means for next Friday would seem to support snow maybe as close to BOS as 495 with the cold air chasing the back edge of precip to the coast.

I noticed that a long time ago and assumed it was because day length and sun angle can be described fairly well as a sine function, or a third of the way from the Solstice to the Equinox everything is half way to late March. Why, if I understand, the Saturnalia is the 25th, not the 21st, the rate of change is so miniscule in late December, it takes 4 days past the Solstice to notice the day lengths are increasing. Although that would seem to imply the Romans were behind most cultures if it took them over half a week to notice the increase in day length. EDIT TO ADD: If the SSW is 2 weeks away, and the cold follows ~3 weeks later, if it follows, ensembles looking warm in 2 weeks isn't a season cancel, no?

There is someone on the tropics threads who posts 16 day op GFS to prove the Atlantic is dead. @GaWxknows his or her name.

Is there any real way of knowing where in the Northern Hemisphere the cold following a SSW happens?

It appears WPC isn't really buying it, but 0Z and 6Z Euro have a 2 to 4 inch rain bullseye general vicinity of Houston Christmas Eve. GFS has the heaviest rain toward NC Texas.

On the one hand, the Earth has been warming for several hundred years. OTOH, all time temperature records in polar regions of North America and Asia is a little concerning. Record Atlantic ocean temps as well last Summer. It looks like there is anthropogenic influence superimposed on the normal climate change. I'm no liberal, I haven't voted Dem since 1992, and have been solid R except for 2016, I voted 3rd party. But not Dem.

I know the general nature of ensemble modeling, petroleum reservoir engineering involves mass balances and radial diffusivity and multiple phase fluid flow in heterogeneous and anisotropic materials. Seismic modeling gives general depths and shapes of underground reservoirs, the rest is data gathered from individual oil wells, and even as just an undergrad, models in the 80s ran what was called 'Monte Carlo' variation of data, because engineers have so little data they actually know, they must run the models with varying inputs, assign probabilities to changes from the best guess, and finding a mean and range of likely outcomes. The solution of the radial diffusivity equation is so complex simplifying assumptions are made and transforms are used. I still loathe my 'systems of linear differential equations' class at UT. I remember being tormented trying to convert things in LaPlace space back. Back in the day, oil companies had the most expensive super-computers. What I meant by empirical, a French sewage engineer named D'Arcy did experiments and came up with an equation for fluid flow as a function of differential pressure, size, length of porous media and viscosity of the fluid from that data. Darcy's Law, the key to aquifer and petroleum engineering, was not based purely on physics. I assume in weather many things are based purely on physics, I wondered if somethings were best fit data derived from experiments and observation. I think the below answers that (empirical formulas are used), or changes in the base state, warmer oceans seems like the most significant, will affect model performance.

How much empirically derived equations go into those forecasts as compared to strictly dynamics/physics. If something in the base state has changed, maybe warmer oceans globally, empirical based predictions that worked before won't work as well now.

If nothing is happening short term besides a wind/rain/far interior elevation snow in the near term, all there is to discuss, besides that, is medium range and beyond forecasts. Pimping ensemble products? What does that even mean. I don't know too many people who don't use ensembles for 500 mb pattern or things like the NAO, ENSO, strat warms and the such. I like mets discussing those things because I am weak on my correlations and thus like seeing discussions on them.

On the one hand, I wonder what the NMME verification is at 8 months lead time, probably not particularly high. OTOH, El Nino should go neutral early in the season, and I see forecasts for the Atlantic to be cooler next season. 2024 thread will be interesting.

GFS and Euro have rain, but it doesn't look that good for severe, but we are days away.

Per Twitter, 1938 was last time a team gave up 10 or less losing 3 straight games.

I was reading the NE and NYC forums the Friday before Boxing Day 2010 (born in Queens, family near Boston, time spent both places) and the gloom and doom was so bad. At the time, there were a lot of Sabbath observant people in Brooklyn (I think many have since made aliyah) who logged off with crushing disappointment and logged back on Saturday evening to blizzard warnings. It was such a happy thing to see. People verbally dancing in joy.

Even in the cold 76-77 Winter the first real snow was Christmas night. Snow on the ground Christmas morning in the NYC metro (and I suspect most of I-95) wasn't that common. It will only get worse as it seems like the offshore Atlantic waters are getting warmer.

Models never really suggested enough instability for enhanced, but in fairness to SPC, they stated it was very conditional, and I think you'd rather have an enhanced that busts than a marginal with several EF2 or greater tornadoes.

Enhanced risk N part of HGX CWA, my house on the edge of Enhanced, Houston and S is Slight. Looking at 3k NAM and FV3, I don't think the 10% tornado probability area will verify. Shear and vorticity are there, instability is not that exciting. Maybe some cold season brief EF-0 and EF-1s. I guess we'll see if the Enhanced is still there at the mid day update.

How does this El Nino end as forecast to in Summer 2024? Looking at the forcing posts earlier, the change in the Walker Circulation would cause weak Easterlies or WWBs forever. But obviously it doesn't, because El Nino's do end. What is the key signal I should be looking for next Spring/Summer to know Nino is ending?

Larry Cosgrove, retired met, seems to think Modoki:

I was home from college in Bedford, TX, about 5 mile W of S end of DFW airport. IIRC, there was a little thunder. I remember another sleet storm in DFW when I was in college which had fairly frequent lightning. Probably during one of my ~1 month long Christmas breaks,

Living in Texas the last 40 years, Houston area the last 23, the idea of a Texas perma-drought being a whoops is not correct. It has definitely been dryer since 2011, even with events like the 2017 floods.

It is starting. https://radar.weather.gov/station/KPOE/standard