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Pattern Dazzling December

0z Euro at hour 240 and GFS at hour 240
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Although we've seen some changes for the worse on the models in the shorter-term (as I explained earlier yesterday), the overall evolution looks better as we get to the middle of December. Namely, the location of the blocking ridge to our north is a little more favorable for producing a coastal storm for the Carolinas, w/ the center of the +z500a being closer to the north shore of Labrador vs Baffin Island, as it was in earlier model forecasts.

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Loganelliott99 said:
What a premature thing to do by accuweather.
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more likely be right...
ATLwxfan said:
The SER firmly entrenched for the duration of the 06z gfs. This “models don’t know how to handle pattern changes” is harder to believe with each run.


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what pattern change ? Lol
 
Just woke up and skipped last nights runs, they weren’t that bad honestly, in fact seemingly sped up a little on modeling, change trickling back to around day 7-8, we’ve certain delayed the pattern, but even with the +PNA event last winter, it was seemingly rushed on NWP on to be pushed back, just common NWP issues, sucks that we’re not gonna get a major chunk of the TPV under the block initially but models are dialing in on cold seeping in from the Alaskan ridge. Not great runs, but not bad runs from the 00z EPS and 06z GEFS.9FA4C2C3-3EA8-4E90-856D-0220837FC1A0.png3AF51B2E-CAD5-40D7-8818-8135A25DC93F.pngF9A791BD-CE98-4495-9C94-447CF84DD3CD.pngDA7FCEC5-2925-4130-B832-8D2636CDAEC6.png95A3CACB-634F-43D3-A7AC-3007A193ADF0.png
 
Webberweather53 said:
Although we've seen some changes for the worse on the models in the shorter-term (as I explained earlier yesterday), the overall evolution looks better as we get to the middle of December. Namely, the location of the blocking ridge to our north is a little more favorable for producing a coastal storm for the Carolinas, w/ the center of the +z500a being closer to the north shore of Labrador vs Baffin Island, as it was in earlier model forecasts.

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Do you think this is just going to keep getting pushed out? Or is it a matter of not if but when?
 
Myfrotho704_ said:
Just woke up and skipped last nights runs, they weren’t that bad honestly, in fact seemingly sped up a little on modeling, change trickling back to around day 7-8, we’ve certain delayed the pattern, but even with the +PNA event last winter, it was seemingly rushed on NWP on to be pushed back, just common NWP issues, sucks that we’re not gonna get a major chunk of the TPV under the block initially but models are dialing in on cold seeping in from the Alaskan ridge. Not great runs, but not bad runs from the 00z EPS and 06z GEFS.View attachment 124661View attachment 124662View attachment 124663View attachment 124664View attachment 124665
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That’s a typical Niña look
 
Jimmy Hypocracy said:
Siberia already had the good chunk of the cold air. I was ok with my small chunk. But no, they wanted it all, and they got it all.View attachment 124670
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I made a comment about this a few days ago when it looked like all of the cold air was going back upstream instead of downstream under the block. I thought it was just bad model physics. Another nail in the coffin for Bastardi’s bathtub sloshing theory.
 
Looking out to day 10, the latest GFS has lost the (great Lakes - transitioning to Hudson Bay) low. That helps establish the better pattern to pull cold air eastward. Side note: we don't tend to talk anymore about the Hudson Bay low effects on weather. I think it's because it gets set because of a -NAO. But nevertheless, seeing it is a good thing.

6z GFS at day 10:
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0z GFS:
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0z Euro:
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Interested to see if it pops back up at 12z on the GFS and continues on the euro.
 
FallsLake said:
Looking out to day 10, the latest GFS has lost the (great Lakes - transitioning to Hudson Bay) low. That helps establish the better pattern to pull cold air eastward. Side note: we don't tend to talk anymore about the Hudson Bay low effects on weather. I think it's because it gets set because of a -NAO. But nevertheless, seeing it is a good thing.

6z GFS at day 10:
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0z GFS:
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0z Euro:
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Interested to see if it pops back up at 12z on the GFS and continues on the euro.
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I remember that the Hudson Bay low use to be a term you would hear all the time on the Weather Channel back in the 90s, but I honestly haven’t heard in there in years. It does a couple things… first a stronger low can help steer disturbances and pieces of energy around well to the south of it…the deeper the low, the further south it pushes the track. Also it can act as a cold air source as well. It being in place prevents Canada from getting flooded with mild Pacific air and allows for more in the way of homegrown cold air masses… this can be certainly be helpful the deeper we go into the month and closer to peak climo as you don’t necessarily need an airmass of Siberian origin to get winter storms in the south.. especially when there is strong blocking

Edit: for example both the January 1988 and February 2004 storms had a well established Hudson Bay low. Obviously those are two very different set ups, but it goes to show you that there are definitely different ways to get the job done when the Pacific is far from perfect.
 
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At this point, we just gotta hitch our wagons to the Euro days 8 to 13 based on how it is handling Alaska and the west coast (00z Ens Mean and Control Runs shown). In the old days, we'd be riding high in a nice looking Boomer Schooner...but nowadays, it's a dilapidated wagon hooked to a borrowed mule

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Loganelliott99 said:
And you’re leaving out the most important thing for winter storms. The PNA is not positive.


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But I don’t understand why people are losing hope. It’s looking right on schedule. A flip to a cooler pattern around the 15- 20th. The latest GEFS,CMCE, and EPS all looked decent for mid month. We’ll be okay


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Itryatgolf said:
Until we get more of a -epo and less of a -pna, we are chasing unicorns. Patience is required
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Mid to late month is when the PNA should chill out. That was the idea all along. The models just gave us false hope that it would happen sooner


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Loganelliott99 said:
And you’re leaving out the most important thing for winter storms. The PNA is not positive.


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I actually did a little bit deeper look into this on the ncsu.edu climate page, and for North Carolina at least, the -NAO is the most important teleconnection for winter storms. Months with an observed -NAO have a 25% increase in snow days. Now we’re obviously up against it if the PNA is much higher lower than -1 which is why we’re not going to get much help the next week. Something else interesting I found with regard to the PNA is that a +PNA has more of a positive impact on winter weather chances in El Niño years… this makes sense because often times periods of +PNA in a La Niña often lead to very suppressed storm tracks, fast flow, and very little moisture to work with.
 
It takes time sure. But changes started the 1st week in Dec and we were rolling by the 2nd week of December in 2010. So our top analog year for this -NAO clearly isn't going to follow the same progression. Maybe it finally gets there who knows
 
Chazwin said:
I actually did a little bit deeper look into this on the ncsu.edu climate page, and for North Carolina at least, the -NAO is the most important teleconnection for winter storms. Months with an observed -NAO have a 25% increase in snow days. Now we’re obviously up against it if the PNA is much higher lower than -1 which is why we’re not going to get much help the next week. Something else interesting I found with regard to the PNA is that a +PNA has more of a positive impact on winter weather chances in El Niño years… this makes sense because often times periods of +PNA in a La Niña often lead to very suppressed storm tracks, fast flow, and very little moisture to work with.
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FYI - I believe they defined a snow day as any day where any monitor outside of the mountains in NC recorded 1” or more of snow. FWIW.
 
RainlessSnowless & Grumpy said:
It takes time sure. But changes started the 1st week in Dec and we were rolling by the 2nd week of December in 2010. So our top analog year for this -NAO clearly isn't going to follow the same progression. Maybe it finally gets there who knows
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Something to keep in mind though is that we are looking at timing differences compared to 2010… back then the processes had started about two weeks earlier and if you remember, there was some very mild weather leading into Thanksgiving that year with some severe weather across the Deep South
 
RainlessSnowless & Grumpy said:
It takes time sure. But changes started the 1st week in Dec and we were rolling by the 2nd week of December in 2010. So our top analog year for this -NAO clearly isn't going to follow the same progression. Maybe it finally gets there who knows
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Agree, here in the Midlands I remember some very cold nights the first week of Dec in 2010. I feel like we even hit the upper teens one morning. Just a fantastic month altogether. So many small events that led to & set the tone to the big one.
 
Chazwin said:
Something to keep in mind though is that we are looking at timing differences compared to 2010… back then the processes had started about two weeks earlier and if you remember, there was some very mild weather leading into Thanksgiving that year with some severe weather across the Deep South
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Looking back, the initial block in 2010 moved into Greenland around Nov 20th. This time, it's Dec 5.....so, 15 days later. Of course, no 2 years are alike
 
Looking at the teleconnections this morning, I think Fro might be onto something about his 17th-25th timeframe for storm potential. The MJO stays in COD and basically close to phases 1 and 2. The AO stays solidly negative. By the 15th-17th the PNA is almost right at a neutral, rising to -.3 to -.1, and the NAO while staying solidly negative relaxes somewhat in strength…. this is often times where we see storms develop
 
Chazwin said:
Something to keep in mind though is that we are looking at timing differences compared to 2010… back then the processes had started about two weeks earlier and if you remember, there was some very mild weather leading into Thanksgiving that year with some severe weather across the Deep South
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Good point. Maybe we'll get there and be cold by the 20th and be solidly in a winter storm pattern by months end into the 1st half of January when climo is peaking
 
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