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December Med/Long Range Disco


WinterWxLuvr

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Euro ensembles are mixed but actually support a chance of snow more than 12z.

Typically when our area is depending on a key transient feature to make things work it's best to always take the under. Especially at 5+ day leads.

Interesting.  How do they support it more?  From the MSLP track, it looks like the ensembles are following the Op's big bag of WTF.  

 

I'm liking the european ens mean after xmas.   If I were doing a long range forecast for the week between Christmas and New Years, I'd put our snow chances above normal, not  the measly slightly above for the prior week. 

I dig it, Wes.  I'm feeling optimistic that we all get some decent snow before January.  

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Interesting. How do they support it more? From the MSLP track, it looks like the ensembles are following the Op's big bag of WTF.

Probably a byproduct of spread more than support. There were very few snowy memebers with the 12z run yesterday. More are popping up.

Ensembles are definitely quicker than the op with precip and storm track. I suppose it's possible to get snow on the front of a storm pushing towards the Ohio valley if it moves fast enough because the airmass is half decent.

I'm honestly not expecting much. Fluke in an overall hostile pattern with marginal temps. I'll only get excited when all guidance is showing the same thing. Would be nice to luck into a 1-3" event for the cities even if it's messy.

I like seeing what Wes is posting. Ensemble guidance is starting to converge on a -ao/nao/epo setup right after Xmas.

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Probably a byproduct of spread more than support. There were very few snowy memebers with the 12z run yesterday. More are popping up.

Ensembles are definitely quicker than the op with precip and storm track. I suppose it's possible to get snow on the front of a storm pushing towards the Ohio valley if it moves fast enough because the airmass is half decent.

I'm honestly not expecting much. Fluke in an overall hostile pattern with marginal temps. I'll only get excited when all guidance is showing the same thing. Would be nice to luck into a 1-3" event for the cities even if it's messy.

I like seeing what Wes is posting. Ensemble guidance is starting to converge on a -ao/nao/epo setup right after Xmas.

Ah ok, a couple big members in the group.  I'd wager those members are the coastals?  Based on the MSLP anomalies, it still looked like a cluster was along the coast.  

 

I'm still going to stick with my original idea that the storm right around Xmas is the best chance of the 3 to get widespread snow out of, but I think post-Xmas the chances will improve even more.  

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Ah ok, a couple big members in the group. I'd wager those members are the coastals? Based on the MSLP anomalies, it still looked like a cluster was along the coast.

I'm still going to stick with my original idea that the storm right around Xmas is the best chance of the 3 to get widespread snow out of, but I think post-Xmas the chances will improve even more.

About half the members show some snow during the period. Only 9 or so have 2"+ but that's including the bad math.

There's a fairly big disagreement in speed. The majority of ensemble members have precip starting between hour 204-216 and not 228 like the euro op. What a faster solution means is anyone's guess.

GEM has a straight up coastal. GFS has west track. Euro is right in between.

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    MORE ON THE COMING PATTERN   CHANGE ...    

 

glad to see   WES is  on  board....

i have been talking about the  dec 22-26  change  for   over a week now  so the  TREND IS MY FRIEND

 

One of the reasons why   I am not particularly bullish about the event /threat for December 21  is that the overall pattern on a hemispheric scale ...is not very favorable.   Yes the models  DO show   what appears to be cold  HIGH  in a pretty good set up ...at least for   the beginning of the event.   The  problem is that the flow  at 500 mb  across Canada is Pacific  and  ZONAL ....and has no arctic connection.  

Thus the HIGH is NOT  very cold and has to be the perfect ideal position when the  coastal  Low begins in order  to keep some  the precip snow.     The only reason why this is potential threat to begin with is the development of the big ocean Low over southeastern Canada    (the   50/50 LOW)

The    NAO is strongly positive which along with the Pacific pattern strongly  interdicts   the supply of cold air into the Northeast US.  

 
 
But beyond the December 21 event...  If we use the overall hemispheric pattern as a starting point we can truly see some significant changes taking place across the hemisphere by  DEC 25. 
 

  Here is the   324  hrs    EURO  EPS MEAN....   It shows several important tihngs...    many of which are  self  explanatory 

 
post-9415-0-59113000-1418398846_thumb.pn
 
 
 The   5  days  CFS  from  from the website tropicaltidbits  web site has been showing this for while....  and increasingly amplified +PNA and  -EPO  pattern . Now the  euro  ensembles  are showing  this as well.  see   image
 
The one thing that should be noted is that we do not on this map yet see a  -NAO  and the    PV is still very far to the north over Baffin island.
 
 here is the  week 3 and 4     500 mb on anomaly  maps from  CPC.  I have drawn in some key features for ease of comprehension.     The cfs   clearly indicates that the pattern amplification is going to really picked up speed  In week 3 and  week 4 .    The  -EPO goes absolutely ballistic in week4 and strongly resembles what we saw last January 
 
 
post-9415-0-49596400-1418398855_thumb.jp
But again ...even though there IS a  -AO    we do not   have   -NAO..   Yet  Here is why.  

Next week  as the zonal flow  across Canada  begins to amplify   it will  take on the    WIDE   and BROAD    shape.    We can all see that.  Because of this  ...the   PV is   forced to  over   to Baffin Island   in far Northeast Canada . This in turn  means any    RIDGE is    forced over  iceland  or the uK or Norway ...and the  NAO is   either positive or neutral. 
 
BUT as the   western  Canada ridge amplifies  ...   it will get pulled WEST     because of the --EPO    development.   This  will   cause   western Canada ridge   to shaprens up  ....which    in turn  will allow  he PV  to shift  SW   into  Hudson's  bay    And  THAT that in turn   will allow the   NAO to  go  Negative  in January
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Rain.

Verbatim, yes it is rain, but Im just talking about the overall setup, if you want snow with this potential threat (and yes the airmass isnt the best) this was a step in the right direction. My personal opinion is if the confluence over NE is correctly depicted the shortwave wouldnt track into the Ohio Valley.

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Only two of the today's ten CPC superensemble  mean D+11 analogs had snow within 3 days of the centered mean.  That's pretty close to the average for the time of year.  One of the analogs was Dec 1969 which was a big storm so there is some hope though it's important to point out that 80% of the analogs did not have snow.  For those wondering, DC got almost 5 inches from the 1969 storm but IAD got 12. If I remember correctly DCA had mix issues but maybe howard can correct me if I'm wrong.

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Verbatim, yes it is rain, but Im just talking about the overall setup, if you want snow with this potential threat (and yes the airmass isnt the best) this was a step in the right direction. My personal opinion is if the confluence over NE is correctly depicted the shortwave wouldnt track into the Ohio Valley.

It could easily track west of us. There might be some confluence over the NE but it's not really that impressive. What we need is a 12z euro solution from yesterday.

Any track into the OH valley (even if it jumps fairly quick) is going to be pretty banged up in the midlevels.

Return of the PV after Xmas on the run. Looks cold.

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It could easily track west of us. There might be some confluence over the NE but it's not really that impressive. What we need is a 12z euro solution from yesterday.

Any track into the OH valley (even if it jumps fairly quick) is going to be pretty banged up in the midlevels.

Return of the PV after Xmas on the run. Looks cold.

Yea its not the best confluence in the workd we dont see a strong high build in behind it either which is probably why it tracks inland.

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It could easily track west of us. There might be some confluence over the NE but it's not really that impressive. What we need is a 12z euro solution from yesterday.

Any track into the OH valley (even if it jumps fairly quick) is going to be pretty banged up in the midlevels.

Return of the PV after Xmas on the run. Looks cold.

 

 

The Euro has also consistently been much stronger with any 50/50 low that develops. While the GFS does show a decent setup, I don't think its 50/50 low and confluence are necessarily strong enough to lock in cold air. The Euro had a classic NW flow at 500mb leading up to the event -- that can definitely be enough to maintain a cold event. The GFS doesn't really show that, but it took a step in the right direction.  

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poor wes, being a board sounds awful. 

 

thanks, dt!

 

 I think DT is right about the storm around the 21st.  It is unlikely to be snow as the NAO still is pretty positive.  I have no real inclination about any later storm around xmas but worry that we still could end up with a low over the great lakes even if the low tracks to our south but that is a wag.  It's way too early to think about details at that time range.  The analogs do offer some hope.  Beyond xmas as the PNA goes strongly positive that's when we might garner a negative NAO.   That's the period I'd say right now has above normal chances of snow if the progs are right which is always a big if. 

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The Euro has also consistently been much stronger with any 50/50 low that develops. While the GFS does show a decent setup, I don't think its 50/50 low and confluence are necessarily strong enough to lock in cold air. The Euro had a classic NW flow at 500mb leading up to the event -- that can definitely be enough to maintain a cold event. The GFS doesn't really show that, but it took a step in the right direction.

Absolutely. It's a tough one for us down here either way. GFS shifted better but it's parallel runs it right up the OH into w ny.

The euro ens are divided into whether the storm tracks into the oh vly or underneath us. We pretty much have to have an underneath track to have any shot at larger event. The hp is pretty shallow and not particularly cold. The oh vly track jumping to the coast may work for you guys but it would pollute the midlevels pretty bad down here. Would be tough to recover from as the storm tracks the coast.

We can sometimes score a front thump with an oh vly track at times. So there's that chance as well. Usually ends up being a n-w of the cities/burbs deal though.

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One of the reasons why   I am not particularly bullish about the event /threat for December 21  is that the overall pattern on a hemispheric scale ...is not very favorable.   Yes the models  DO show   what appears to be cold  HIGH  in a pretty good set up ...at least for   the beginning of the event.   The  problem is that the flow  at 500 mb  across Canada is Pacific  and  ZONAL ....and has no arctic connection.  

Thus the HIGH is NOT  very cold and has to be the perfect ideal position when the  coastal  Low begins in order  to keep some  the precip snow.     The only reason why this is potential threat to begin with is the development of the big ocean Low over southeastern Canada    (the   50/50 LOW)

 

These are excellent points, could not agree more. If you can predict the high, you can predict where it snows.

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 12Z  EuRO    has  the   DEC 21  low  going up the appalachians  because  the  50/50 Low   over se canada leaves   too soon.   THis  may be correct  maybe ot... but the   overall pattern   is NOT   set  by dec 21   so  ... like I  said  the dec 21  might bw  snow to ice to rain...      more  bullish about dec  24/25

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 12Z  EuRO    has  the   DEC 21  low  going up the appalachians  because  the  50/50 Low   over se canada leaves   too soon.   THis  may be correct  maybe ot... but the   overall pattern   is NOT   set  by dec 21   som   like I  said  the dec 21  might bw  snow to ice to rain...

 

welcome back man. I look forward to a new and improved relationship as we have both gotten a bit older and more mature!

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