December 2019 Med/Long Range Disco

[yoda]

Um... going to need to see that sounding at 102... cause precip says snow in DCA

[NorthArlington101]

Um... going to need to see that sounding at 102... cause precip says snow in DCA

 

Subzero 850s but the surface isn’t great. With rates it could make for a pretty scene.

 

eh actually it’s 33-34 and with the GFS’ UHI overestimation it’s close

[yoda]

Just now, NorthArlington101 said:

 

Subzero 850s but the surface isn’t great. With rates it could make for a pretty scene.

Full sounding at DCA says its snow at 32/33 degrees

[clskinsfan]

GFS is still loving Mappy land. Snow at 30 degrees works. We get skunked out here.

[NorthArlington101]

Snowing again at 138 in NE Maryland, getting a little deform action.

 

the weatherbell maps I’m using seem to be outputting a little different then the TTT maps, btw

[C.A.P.E.]

6z GFS develops a nice batch of precip with the upper low, but pretty toasty at the surface so its rain. The air mass is marginal at best even in the wake of the coastal. Ofc sometimes magic can happen under an upper low if its strong enough and we get intense precip rates. Not sure it's happening with this one. Climo and really no cold air is tough to overcome.

[showmethesnow]

Euro took a step backwards overnight. Very easily fixed problem though with a feature that the models mishandle all the time. Also shows the need for stronger ridging (greater height anomalies) located on the northern portion of the eastern ridge that I am sure some of you were shaking your head over when I mentioned it. ***Greater anomalies in the northern portion will not effect the flow through our region. But greater anomalies located in the southern portion will as they will push the boundary northward of us in advance of the system***

Below we have yesterday's 12z run. If you notice we have stronger height anomalies to the NE of the system running through the Midwest. These are important as they help to force the storm south as well as to help turn the trough axis the storm is embedded in. The stronger the better with this feature. These height anomalies are produced from the greater height anomalies we see earlier in the evolution in the norther portion of the ridge. As the ridge gets squeezed between the 50/50 and the incoming storm those higher heights get pushed northward.. Of note, also look at where the NS energy is located and pressing down (Black arrow).

 

 

Now look what we have on the latest run. Notice that we are seeing weaker heights to the NE of the system. These heights were on par with the previous 12z run earlier in the process but now they are being beat down by the NS energy which is now dropping farther west. As a result we are nor seeing the system dropping as far south as on the previous run. Pretty much shows you how important that these heights are. But as I said it is a very easy problem to fix with a feature that the models mishandle all the time up to and even inside of 24 hours.

 

 

ETA: Seeing the same issue with the NS on the EPS as well but not quite as extreme. Also seeing weaker heights in the northern portion of the ridge initially which is also translating to weaker heights to the NE of the storm later.

[showmethesnow]

19 minutes ago, C.A.P.E. said:

6z GFS develops a nice batch of precip with the upper low, but pretty toasty at the surface so its rain. The air mass is marginal at best even in the wake of the coastal. Ofc sometimes magic can happen under an upper low if its strong enough and we get intense precip rates. Not sure it's happening with this one. Climo and really no cold air is tough to overcome.

Looks to be the same issue as the overnight Euro. NS is dropping farther south and to the west of previous runs so we are seeing the higher heights to the storms NE breaking down. Also doesn't help that the system is a little slower so that is giving even more time for those heights to drop. Doesn't help for our front end chances that we are seeing greater height anomalies within the ridge creeping southward as well. But we always knew that this one would be a tough one to bring home. Still 3 1/2 days to work with before the over running sets in so let's see where this goes.

[C.A.P.E.]

9 minutes ago, showmethesnow said:

Looks to be the same issue as the overnight Euro. NS is dropping farther south and to the west of previous runs so we are seeing the higher heights to the storms NE breaking down. Also doesn't help that the system is a little slower so that is giving even more time for those heights to drop. Doesn't help for our front end chances that we are seeing greater height anomalies within the ridge creeping southward as well. But we always knew that this one would be a tough one to bring home. Still 3 1/2 days to work with before the over running sets in so let's see where this goes.

This has always looked like a bit of a longshot. I was never really enamoured with the setup esp given it's early Dec, but certainly worth tracking.

What else we gunna do? 

[Wonderdog]

Great write- up guys. Dumbing it down for me, is the track of the storm (nw to se) also a problem since the wind direction fails to tap any cold air? Seems to be acting like a clipper which we haven't had much luck with lately. 

[mappy]

8 hours ago, clskinsfan said:

GFS is still loving Mappy land. Snow at 30 degrees works. We get skunked out here.

this is good. i like this. 

[psuhoffman]

[PDIII]

I am looking for this thing to manufacture its own cold air.

[LP08]

Just now, psuhoffman said:

It’s pretty exciting to not be staring at a death ridge over us like the last couple of years leading up to the holidays and to not even have to hope the weeklies show a pattern change coming.  Even if the progression is rushed a tad, the pattern by both the EPS and GEFS should provide opportunities during the start of prime climo.

[psuhoffman]

Just now, LP08 said:

It’s pretty exciting to not be staring at a death ridge over us like the last couple of years leading up to the holidays and to not even have to hope the weeklies show a pattern change coming.  Even if the progression is rushed a tad, the pattern by both the EPS and GEFS should provide opportunities during the start of prime climo.

The best news is that the AO looks to quickly flip back after a short spike positive.  

[C.A.P.E.]

5 minutes ago, psuhoffman said:

The best news is that the AO looks to quickly flip back after a short spike positive.  

Hopefully the CFS is as crappy a model as we all believe it to be, lol.

[WxUSAF]

What’s hurting us on this weekends storm (front end WAA chance) per the overnight runs is that the storm has slowed down a fair bit. The timing of last nights 18z gfs was sort of perfect, but it kept slowing down at 0 and 6z. Euro shows it too. That lets what meager cold air we have more time to retreat. Plus the WAA precip itself is looking skimpier. 

[cbmclean]

1 minute ago, C.A.P.E. said:

Hopefully the CFS is as crappy a model as we all believe it to be, lol.

Maybe we can hope that all of the seasonals are as painfully wrong this year as they were last year about the beautiful fantasy pattern that always happened just past week 3.

 

[frd]

1 minute ago, C.A.P.E. said:

Hopefully the CFS is as crappy a model as we all believe it to be, lol.

According to Don S it is entering the time period when it is more skillful. Well, I am not sure verification from this date, November 27 for the  next month, but I believe we are still going to warm up in time for the holidays.  As for how  warm, and how long, still hard to say. We lose the - EPO so maybe Pacific based air mass floods the country the third week of the month. 

I am liking January and Feb.and even March, the new winter month, thinking March holds above normal winter weather promise this go around.   

 

 

[SnowGoose69]

2 minutes ago, frd said:

According to Don S it is entering the time period when it is more skillful. Well, I am not sure verification from this date, November 27 for the  next month, but I believe we are still going to warm up in time for the holidays.  As for how  warm, and how long, still hard to say. We lose the - EPO so maybe Pacific based air mass floods the country the third week of the month. 

I am liking January and Feb.and even March, the new winter month, thinking March holds above normal winter weather promise this go around.   

 

 

The CFS is exponentially more accurate at day 25 than day 30.  So if you’re looking at a forecast for 12/25 today it’s likely to be more accurate by a wide margin on 11/30 than today.  I’ve seen cases where it flips 6-10 degrees on a 25 day forecast vs what it showed 4 days prior 

[showmethesnow]

22 minutes ago, psuhoffman said:

So that's what a AO+++++++++++++++++ looks like? Would have never guessed.

Was looking over the strat this morning and I have to wonder if we are on the doorstep of a SSW. The extreme warmth that we will see at 10 mbs which will be centered over the pole is now looking to propagate down to at least the 50 mb level. Have yet to find a site for the 100 mb or 200 mb level to get a read there.

[psuhoffman]

7 minutes ago, frd said:

According to Don S it is entering the time period when it is more skillful. Well, I am not sure verification from this date, November 27 for the  next month, but I believe we are still going to warm up in time for the holidays.  As for how  warm, and how long, still hard to say. We lose the - EPO so maybe Pacific based air mass floods the country the third week of the month. 

I am liking January and Feb.and even March, the new winter month, thinking March holds above normal winter weather promise this go around.   

 

I am pretty sure we are going to "warm up" by around Dec 7th-10th as we briefly lose the pacific and the TPV is moving across the pole creating a brief but extremely positive AO.  What I am looking at is whether we can flip back cold again sometimes mid December in time for the holidays.  

[frd]

Just now, SnowGoose69 said:

The CFS is exponentially more accurate at day 25 than day 30.  So if you’re looking at a forecast for 12/25 today it’s likely to be more accurate by a wide margin on 11/30 than today.  I’ve seen cases where it flips 6-10 degrees on a 25 day forecast vs what it showed 4 days prior 

I hold no real value in the CFS, but I appreciate your post. I too have seen it actually be in the forecast month and calling for significant warm anomalies and the country is already cold and only getting colder. Maybe use it for trends and know it is extremely volatile. Never hang your hat on the CFS, unless maybe you are attempting bias in your point of view. Same thing for the weeklies. 

However, I still believe we warm up prior to favorable changes in the MJO, and other factors. Using lagged MJO composites and relevant analogs there seems to be a good case for blockiness to reestablish itself in early January, ( maybe as early as the last week of December  ) along with another -NAO interval.  Some of these analogs indicate the cold locking in and persisting in time. The greatest -EPO in these are Jan targeted and the deepest -NAO is mid Feb.            

[poolz1]

5 minutes ago, showmethesnow said:

So that's what a AO+++++++++++++++++ looks like? Would have never guessed.

Was looking over the strat this morning and I have to wonder if we are on the doorstep of a SSW. The extreme warmth that we will see at 10 mbs which will be centered over the pole is now looking to propagate down to at least the 50 mb level. Have yet to find a site for the 100 mb or 200 mb level to get a read there.

yeah...would love to see what is predicted below 50 also.  As it is, 50mb is on fire over the pole.....

[C.A.P.E.]

20 minutes ago, showmethesnow said:

So that's what a AO+++++++++++++++++ looks like? Would have never guessed.

Was looking over the strat this morning and I have to wonder if we are on the doorstep of a SSW. The extreme warmth that we will see at 10 mbs which will be centered over the pole is now looking to propagate down to at least the 50 mb level. Have yet to find a site for the 100 mb or 200 mb level to get a read there.

This is pretty interesting.

The tercile-category anomaly of the lower-stratospheric polar vortex, defined by the 100 hPa 60°N zonal-mean zonal wind, has been used as a diagnostic for the behaviour in the ‘coupling layer’ between the stratosphere and troposphere.

 https://simonleewx.com/polar-vortex-forecasts/

[showmethesnow]

7 minutes ago, C.A.P.E. said:

This is pretty interesting.

The tercile-category anomaly of the lower-stratospheric polar vortex, defined by the 100 hPa 60°N zonal-mean zonal wind, has been used as a diagnostic for the behaviour in the ‘coupling layer’ between the stratosphere and troposphere.

 https://simonleewx.com/polar-vortex-forecasts/

I was looking at that this morning. Not familiar with it so I didn't want to comment. But you can see the temp spike of the AO as we have the pv crossing the pole. I am guessing the period afterwards may be reflective of warming considering winds slow during a warming phase?

[frd]

21 minutes ago, poolz1 said:

yeah...would love to see what is predicted below 50 also.  As it is, 50mb is on fire over the pole.....

The way things are going right now with the vortex is probably the best outcome, more or less. Speculating that we don't have a major SSW in December,    ( at least that is what the current modeling shows and echoed by some strat experts )  

Sometimes the rare very early season SSW can interfere with things and many times the vortex recovers. 

Having any type of  major SWWE later versus early can possibly extend our winter weather potential. Of course, we would have to be lucky in that respect and be the area of focus.  

And, I know you know this poolz1 ,  but we have already experienced a minor warming and it appears yet another minor warming is anticipated in the first half of December. 

So things are looking good a bit down the line.  

Oh, and for the record,  I feel robust blocking returns and coincides with a split flow pattern, leading to a memorable period of winter storms in January and beyond.

 

 

 

[cbmclean]

28 minutes ago, psuhoffman said:

I am pretty sure we are going to "warm up" by around Dec 7th-10th as we briefly lose the pacific and the TPV is moving across the pole creating a brief but extremely positive AO.  What I am looking at is whether we can flip back cold again sometimes mid December in time for the holidays.  

I have a very bitter memory of one point last year when the mid-December warm-up was looking like it was going to be very brief.  Cut to 11 pm New Years Eve and it was 67 F outside my parent's house.  A nearly perfect storm track went over you guys a few days later and produced only rain.  I think it made Bob Chill physically sick.  Hopefully we don;t get a repeat this year.

[frd]

And yeah, steady as she goes .....

 

[C.A.P.E.]

25 minutes ago, showmethesnow said:

I was looking at that this morning. Not familiar with it so I didn't want to comment. But you can see the temp spike of the AO as we have the pv crossing the pole. I am guessing the period afterwards may be reflective of warming considering winds slow during a warming phase?

That's my general takeaway yes. I was looking for some updated QBO data but this would seem to correlate with whats happening at 10-30 mb level, re- weaker zonal wind propagating downward.