February/March 2021 - Frigid or Flop? Pattern/Longterm Forecast Thread.

[Carvers Gap]

1 hour ago, AMZ8990 said:

This is a great breakdown Carver!!!  I appreciate you going into detail on this stuff.  

Just looking at the EPS this afternoon...looks like the pattern will repeat one more time.  NAO does re-fire d10-15.  Cold builds out West...bet it slides east as the GEFS extended had last night for the first week of March(late in that first week).  This has been the base pattern all winter.  Actually, November had the same pattern but climatology fought the cold coming SE.  Think Cosgrove is on the right track there.

[Daniel Boone]

2 hours ago, Carvers Gap said:

Just looking at the EPS this afternoon...looks like the pattern will repeat one more time.  NAO does re-fire d10-15.  Cold builds out West...bet it slides east as the GEFS extended had last night for the first week of March(late in that first week).  This has been the base pattern all winter.  Actually, November had the same pattern but climatology fought the cold coming SE.  Think Cosgrove is on the right track there.

Better hope for a Miller A for Eastern areas.

[Holston_River_Rambler]

On a positive note at least for me after my Banter post, that there seem to be some hints at the possibility of a front end WAA thump for the late weeks system, but that of course could evaporate in time. 

[Carvers Gap]

58 minutes ago, Daniel Boone said:

Better hope for a Miller A for Eastern areas.

My biggest snow this winter was actually from a lee side low.  Always the chance for a Miller A....no way to know this far out of course.

[Daniel Boone]

2 hours ago, Carvers Gap said:

My biggest snow this winter was actually from a lee side low.  Always the chance for a Miller A....no way to know this far out of course.

I agree Carvers.       March is getting late in the game. Without a ridge out West it'll be tough relying on just blocking,is basically what i was aluding to. Hopefully, we can get those in conjunction.

[Carvers Gap]

NE TN , SE KY, and SW VA folks might want to get a look at the 0z CMC, 0z RGEM, 0z GFS, and 0z Euro(trend on that one).  Worth a look.  Won’t add more unless the trend holds - might be a hiccup.  0z RGEM was  snow for most of E TN.  Colder.  

[John1122]

Still don't know that I believe it but that front end thump is dropping some extremely heavy snowfall in a short time over Eastern areas with .3 to .5 qpf blitzing down as snow.  It's showing a change over to rain on the GFS at hr 75 imby but the temp is 32. it's maybe half a degree C above freezing at around 900mb and 32 down to the surface below it with a best guess ptype as freezing rain. Euro had it but not as far east, the 06z RGem has it too.

[Holston_River_Rambler]

Who's ready to get sucked in for round 2???

 

 

0z EPS has 5 members that look anything like the above.  

[Holston_River_Rambler]

Looks like quite a bit of WAA on the NAM:

 

With no precip:

Just gonna say that it is probably underestimating the WAA precip

 

Something else to consider:

 

That is a left over piece of energy that could ride the front as it get pushed east by the Thurs-Fri storm. It's still digging and it has some friends to the north that could help it out, now that the TPV of Doom is retreating. Up through now, any N - S interaction has been squished by the TPV, but since it is on its way out, that opens the door for more changes in the next couple of days. 

If you run the CMC out past hr 84, you can see that energy interact with a N. stream piece and for a storm off the outer banks:

 

I think that since the TPV is still cranking over the Great Lakes, it is still impacting everything that happens afterwards. It should finally (thank God) be rolling out by Wed. evening and I bet there will be more changes, for better or worse, until go time with the late week system and whatever might follow up over the weekend, before we get to the Cosgrove Relaxation Period (like the Medieval Warm Period, but more Cosgrovish and recent) that Carver mentioned. 

[Holston_River_Rambler]

17 minutes ago, Holston_River_Rambler said:

Who's ready to get sucked in for round 2???

As you can tell, it's already happened to me.   

[Carvers Gap]

Regarding Weds night/TR the 6z GFS is a total mess...even messier than 0z.  RGEM is right there with it.  Agree with John on believability stuff.  That said, cold bleeding into the eastern valley and getting trapped is a legit option.  Whether it happens, anyone's guess at this point.  However, the 0z and 6z suites have some significant icing and snow for parts of E TN which did not for yesterday's model runs.  Again, the 6z GFS doubled down on its 0z run.  Worth a mention...may or may not happen, but a big change.  We will see where it goes.  

[CG2]

Here are the latest runs of the GFS, RGEM, Euro, and para-GFS at onset and compared to their previous runs for comparison purposes.  New run is on the left.

 

[Holston_River_Rambler]

One thing I really like about this Thursday- Friday system (besides the fact that the cursèd TPV is gone), is that we will be in the "Frickin' Floodin' February" Pattern from the past couople of years, but with actual, real, arctic cold, somewhere in the forum area. :

 

Right entrance region of a jet streak, FTW. 

I picked the non-precip type image, just to show the intensity. Remember the firehose aimed at parts of the eastern TN valley the past couple of Febs? Imagine that, but with snow. 

 

 

[CG2]

As Holston noted, this is WAA scenario.  Again, this will depend on time of day and how far the cold bleeds over from the Plateau.  It is worth noting, because it is showing up on several models.  WAA means warm air advection for those who are new to this.  Basically, cold air gets trapped at the surface as warm air and precip move in at higher altitudes.  Usually, we see snow to sleet to freezing rain to just rain.  Going to keep an eye on this as some modeling, specifically the GFS and RGEM which have done well this year, are showing a longer duration WAA event than what we are used to.  Guess is the cold air trends north a bit...but the last two runs have trended south which is why I am mentioning it.  Here is the 6z NAM at range and is likely way overly amped.  Here is the 0z CMC.  Again, just watching trends.  New is on the left, and old on the right.

[Holston_River_Rambler]

6z Euro has the thump:

[CG2]

Yep, so pretty much all modeling is on board now with varying levels of WAA frozen precip for the eastern valley Weds Night/early Thursday.  Here is the side-by-side comparison of the 6z and 0z.  One can see the trend.   Again, something we will watch for the eastern valley....nothing set in stone. Just trend watching.  Of note, there is light snow just one frame prior to this for NE TN.

[PowellVolz]

Yep, so pretty much all modeling is on board now with varying levels of WAA frozen precip for the eastern valley Weds Night/early Thursday.  Here is the side-by-side comparison of the 6z and 0z.  One can see the trend.   Again, something we will watch for the eastern valley....nothing set in stone. Just trend watching.  Of note, there is light snow just one frame prior to this for NE TN.

What’s the trend? Is it colder or the track of the system?


.

[Sweetpea Farms]

All we have to do is get past Thursday and Friday here in southern Lincoln County and we are on our way to a springtime trend. 2/19 has been the inflection point since the beginning of the month and it seems to be working out. So looking forward to it. Temps here Tuesday, 2/23 should reach 60 and be in the high 50s the rest of that week. Those are right at average temps.

[dwagner88]

QPF on the GFS is really high. Nearing 4” here.

[Carvers Gap]

12 RGEM is again a messy onset but more so for NE TN this run with .43 ZR in Sullivan Thursday morning.   Looks like the RGEM is seeing the warm nose a bit better this run.  Powell was asking about the difference.  Ya'll check out the temps Wednesday AM over E TN without snow.  I had to look twice.  Those temps are going to set the stage for really cold rain or a mess Thursday night in eastern sections.

[Holston_River_Rambler]

para GFS for the late week system:

[Uncle Nasty]

None of the maps are loading for me with limited Verizon service at work. Is the frozen depicted showing up from Knoxville north and east or does any of it make it to the southern valley around Chatty?

Sent from my moto z4 using Tapatalk

[CG2]

The 12z GFS....through Thursday AM.  Can see a pretty good thump from TYS to SW VA.

 

[CG2]

12z CMC....Still keeping an eye on overnight Wednesday and Thursday AM.  We will see if the warm nose can scour this out, but a major CAD signal for North Carolina, and with a different set of dynamics, cold which is having trouble getting out of the way at TRI.  Sometimes modeling does not do well with identifying where the cold is that is just stubborn in leaving.

[Holston_River_Rambler]

About half the 12z GEFS members have a front end thump for TYS - TRI, as well as the control. 

[Holston_River_Rambler]

12z Euro has snow through I-40 across all of TN between 8PM and 2 AM Wed- Thurs.:

[Carvers Gap]

Euro is coming in HOT!  (well cold!)

[Holston_River_Rambler]

Snowfall through hr 90:

[Holston_River_Rambler]

Pivotal's version of events:

 

[Carvers Gap]

Let me dig out my CG2 account...will give you all some still shots.