Carvers Gap

I posted this on Nov 21st about the first and second weeks of November. Look at the second paragraph. That standing wave was replaced by a trough. Is that standing wave over the SE a feedback error on the EPS and Euro?

Temps are 48, but the wind chill is 34 in this howler. Absolutely freezing my tail off.

One last comment about the 12z suite…when looking at the ensembles, be sure to look at the number of solutions depicting a certain solution. The warmer options are skewing the mean drastically when the median would look quite different. This recently occurred with early December.

The 12z Euro has actual temps in the mid to upper teens by Sunday afternoon with windchills below zero along the northern border of Tenn.

Understandable but still wild....some big swings in the d+10 range. The left is the new GFS run. IF Alaska has a block like that, that trough likely corrects eastward. In that trough is very cold air. At 0z, the pattern was less amplified and blocky. The left has an east based NAO and a full fledged Alaskan block. As a result, the 12z GFS finds a cold front on Christmas Eve. It isn't huge, but interesting to see it parked right in the middle of the warm-up.

The CMC and GFS at 12z are a great example of the conundrum. The CMC has the December 20th cold front. The GFS does as well, but it is more seasonal. If that Canadian Yukon air can find a mechanism southward, those d10+ forecasts could change rapidly.

At 195 on the CMC, the air over the Canadian Yukon is -79F. The GFS isn't quite that cold, but it is impressive as well. With that type of cold air sitting upstream, that is why we have to keep our eyes open.

This is the Chinook mentioned above...It will race eastward.

On the GFS at 246, you can really see the Chinook blowing over the peaks of Colorado's Rockies. That "should" be followed by a cold air mass diving down the Plains behind it. Let's see if it can make it SE. About half the model runs shunt it across the northern border. About half, it's a jailbreak.

The 12z Canadian(even for the cold bias CMC) has a very cold air mass for early next week. Wind chills in many places are below zero w/ temps in the single digits. Portions of TRI are in the low single digits (or slightly bz) by Monday morning.

It is gonna take me forever to remember this PowellVolz. LOL. I have said it before, but glad to see you back posting here.

I am watching the 12z GFS roll in right now. Through 174, it is much colder across the NA continent. Let's see if that trend continues to hold for the rest of the run. This fits the trend of modifying warmer air masses. Looks like it has the post Dec 20 cold front rolling down the Canadia Prairies. Let's see if it can push all the way SE - I am still 50/50 on whether it can make it. Nice push SE on this run.

Thanks for posting that. I could see that get expanded into W NC overnight. They almost meet the criteria.

For kicks and giggles, take a look at the blizzard warning posted for West VA.

Just looking at yesterday’s Euro weeklies which have been the source of much gnashing of teeth and have the worst possible of all the outcomes. Warms up Christmas and is back to this current colder pattern by mid Jan. Wash, rinse, repeat. Actually, temps return to seasonal abruptly during the second week of Jan. Seasonal during that time frame will get the job done.