Carvers Gap

In my mind, it doesn't take much of a jump to get to a point to where we see an overrunning event such as ice due to WAA and cold air getting trapped in the eastern valley and then followed a few days later by an ana front. We could end-up just with dry cold, but there is a decent amount of energy in that northern stream along with WAA attacking periodically retreating cold air.

The 0z Euro has a very strong Arctic(?) front later in its run. It has had this pretty consistently for the past few days. I am sure agencies in the areas working where Helene hit are starting to prepare - sources for heat, warm clothes, food, and temporary trailers winterized. Transportation in many areas is still an issue.

Great info beavis, John, and Boone. We had 1-2’ drifts from that in Scott, Co, Virginia. The wind chills with that front in SW VA were insane. I don’t want to embellish, but maybe in the -50s? Our farm thermometer got to -26F.

I suspect the GFS woes from late last week were probably due to that model mishandling the MJO. The Euro Weeklies tonight should be interesting as the 0z run was very cold and didn’t have the PNA displaced into the Plains as yesterday’s 0z did.

Overnight model runs and 6z continue to paint a pretty cold picture over our region to begin January. Interestingly, the cold appears to have moved up to late in New Year’s Day. Instead of Jan 3. Though details are murky for individual events, the CMC has a pretty stout upslope event well inside of d10. Let’s see if that shows up in other modeling. The 6z GFS has brought back the slider for Jan 2. No other model has that…so proceed with caution.

Might have been a phaser where he was racing the northern stream in from St Louis? I normally don't use the CMC weeklies a ton, but I do look at them from time to time. Sometimes the CMC is the only model which can really handle very cold patterns. It does have a cold bias, so maybe scale that back a degree or two. GEFS ext is taking forever to load tonight.

Finally figured out how to make a tweet work. Just copy the twitter link, past it into notepad, change the x to twitter, and copy link into post - will automatically update. MA had shared this. Now, we certainly don't live in the Mid-Atlantic...but E TN and NE TN do sometimes cash-in on the beginnings of their storms.

I think in 2018, the issue was the EPO got so tall, we were just pulling cold, dry air from the Arctic. Modeling this time does hint at multiple short waves coming out of the northwest. These look like 1-2" quick hitters. I know you know this, but for others new to this.....in very cold air those shortwaves can have 15:1 or better rations. Was 84-85 northern stream driven? I was a high schooler at the time, and wouldn't have known the answer to that. It seemed northern stream driven as my dad was hauling a load from Missouri to Tenn. He was racing a massive snowstorm home - barely made it. He got the rig into to town, jumped in the care, and rolled in with about 4-6" of snow already on the ground. In my mind, that storm came from the northern Plains....

This is a 360 map from the Euro AIFS - proceed with caution. It was super warm at 0z, but has rapidly cooled off. This is 12z. We will see what 18z has in a bit. It ended with a setup that was sending and Arcitc air mass straight down the middle of the Canadian Prairies - due south. I think we are going to have some northern stream smaller systems and maybe we get an STJ system. Clippers appear to embedded in this. I will add(very cautiously), sometimes BN precip can reflect snowfall areas...and sometimes it is just dry. With this type of look as a potential...no way modeling has the details even remotely worked out. That is confluence over the Tenn Valley right there. Northern MS to DC would be happy with that setup and 200 miles either side of that line IMHO. We'll see.... Dig up some great snowstorm maps. Looks a lot like that.

I don't know if this January is that time, but one day we are going to track another memorable pattern and maybe historic pattern. That is why we show up each winter. Give me that above, and let's roll. We need the Euro to stay in the fold overnight!

Still rolling.....EPO, NAO(but slightly east so no WAR), trough east of Hawaii(important). Anyone have any daily PDO numbers? I heard it was approaching neutral last week. That look right there opens up the potential for the PV to be trapped.

Man. Can you draw it up any better? This is the 18z GEFS. The Weeklies from this morning looks almost exactly like this as well, and is out to 1/15.

I am going to use the GEFS ext weeklies today since the 0z weeklies were so wonky(back to normal at noon...so hopefully not a trend). The 0z runs are what the Weeklies are derived from. So far, the GEFS ext is about halfway out....frigid for Jan 7-14 and colder than yesterday's run.

GFS Happy Hour rarely disappoints.

It will be interesting to see how things play out. Both the 12z Euro and GFS have multiple events ranging from small to boomers. The Euro has a slider and an anafront. The GFS has 2 sliders and the fantasy land big dog. I would look for some snow in he air by the 3rd or the 4th. For me in E TN, this definitely looks like a nickel and dime pattern...but the 12z Euro gives me a bit more confidence this pattern will deliver at some point. It really is going to depend on confluence. There is some 14-15 in how this looks. Lots of small pieces of energy rotating through the northern stream as the EPO really locks in.

Last nights Euro/EPS was strange. The multiple runs before it and the 12z run after it - not the same. Had to have been some model input or a week. The 12z ensembles are about as cold as you can get at this range. Big signal for a very cold air mass. I am like Bob Chill in the MA...just give the cold, and let's roll the dice so to speak.

Real feels are in the -10s for NE TN late in the 12z Euro.

To clarify…apparent temp changes. Below zero for most of TRI…single digit actual temps. 60 degrees colder for apparent and 40-50 degrees colder for actual temps.

The 0z Euro must have had something go sideways overnight - was really warm compared to the past gazillion runs. The 12z run was SIXTY degrees colder after 300!!!

12z Euro is thus far back to general continuity after a weird hiccup at 0z

Two small events and one bigger event. I suspect we nickel and dime this, but a bigger storm would have snow on the ground for a while if the pattern stays as cold as the GFS portrays. Is it right?

Pretty respectable 5-15” of snow over the eastern forum area for that run. TRI had 10-15”.

Nice storm on the 12z GFS after 300. Pretty typical of what ensembles have been showing the past few days on their snow maps.

Now I am in the correct thread. Pretty decent 12z GFS run incoming. The CMC is similar temp wise but without the wave. The past two Euro AIFS runs have picked up on the ridge that slides past after the first in a series of probable cold shots. I think the AIFS is far too aggressive in pushing the PNA into the western Plains. The GFS and CMC look like a good progression to me. Is the GFS back to normal…that IDK. I suspect that little wave eventually gets suppressed, but something to watch for future runs. The second cold shot could be a doozy.

GEFS ext 30d 500 map...AN heights over Alaska, AN heights over the Davis Straits(need that a little to the northwest IMHO), EPO ridge, trough east of Hawaii, trough pushing into the Aleutians, and trough in the eastern half of the US. If forced to find a negative, it is that the negative NAO is too strong. But if you go back and look at some decent winter patterns, they look a lot like this. FTR, I suspect the NAO is overdone, and the EPO is underdone.