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December Medium/Long Range Discussion


yoda
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4 hours ago, psuhoffman said:

 

@CAPE  @losetoa6

It's been quite a few years since I did my nina study, I think it was before 2017, so I wanted to refresh my memory.  I also expanded my snow study to include all 2" or greater storms at BWI in Dec-Feb during Nina's that peaked at -.1 or greater since 1950.  I excluded March because that is kind of a wildcard in a Nina and that is a long way off.  Let's hope we aren't heading into March needing to avoid a disaster.    Even expanding down to 2" I only found one storm out of 23 (and it was a kinda pathetic 3" to rain) during the 11 moderate or stronger Nina seasons that didn't feature a lot of high latitude help.  It is true that a lot of those storms did feature a period of less hostility on the pac side also...but the fact there are almost no examples of even minor snows without blocking to me indicates the break in the pac puke pattern was an effect of the blocking helping to press the TPV out of western Canada or Alaska where it will tend to set up shop and sit otherwise as a response to the central pacific ridge which is a direct effect of the nina.  But get a block somewhere in the AO or NAO domain and you can squeeze that feature out of there just enough...retrograde or squash the pac ridge temporarily, and make it work.  

I agree we need significant HL help, particularly for the first half of winter with a moderate Nina. The ens means have been pretty persistent in advertising a -NAO in recent runs so thats a good sign- all caveats apply about verifying in real time. We are also seeing a western US ridge return on the means beyond day 10, and that would be be big in conjunction with a favorable NA in getting some cold aimed more towards the east. My posts about the EPO are wrt to the back half of winter. Assuming the Nina is going to continue to weaken some moving forward, we may see more of a tendency for ridging over AK at times later in winter. It would be great if the NA remains generally favorable throughout, and maybe it will, but recent history says otherwise. If a SWE does occur, who knows how that may shuffle things in the troposphere down the road, or if it will have any impact at all.

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8 minutes ago, losetoa6 said:

Thanks for taking the time to break that all down . The December 16th 1973 my mom talks about to this day . She was pregnant trying to get to the hospital to have my brother . She called it a blizzard ...said she barely made it :scooter:

Where was she living at the time. Westminster had 11” from that storm. I could see given the circumstances calling that a blizzard!  
 

January 2000 is a fond memory but not for the same reason as most. I was manning the weather station at PSU Hazleton the day before that storm hit. I remember looking at the vapor loop and comparing it to the guidance and it just wasn’t matching up. I Kept running the loop and thinking “why wouldn’t that just come up based on the flow”. I convinced my friend of such.  I can’t remember the guys name, he replaced Jon Neese when he left psu, but me and my friend were driving the meteorologist who came in to check on the station crazy.  He was dismissing it out of hand  “No chance the models are that wrong at such short lead”.  He didn’t even want to look at what we were trying to show him.  Everyone else was focused on the long range progs for what would be the superbowl storm 5 days later.  The next day we didn’t even have to say a word.  We walked in and just looked at him and he said “I know don’t say it”  

 

   

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Maybe it’s the season of energy left behind? New England’s storm over the weekend originated from energy left behind that then rotated and phased. Usually when the euro is by itself for a run or two you usually see other models jump onto the idea, if not they usually cave, but you never know....

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I know the argument over PAC vs ATL can be made almost every year and one bad side can overwhelm the one good side.  But IMO in order to have ANY chances you need the AO/NAO to help be neutral/neg.  I think that graph Wes showed many a time showed that its needed for snow in the MA.  Obvi the PAC matters and both help with KUs but I'll take chances with a crap PAC and good Greenland blocking any day.

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Just now, H2O said:

I know the argument over PAC vs ATL can be made almost every year and one bad side can overwhelm the one good side.  But IMO in order to have ANY chances you need the AO/NAO to help be neutral/neg.  I think that graph Wes showed many a time showed that its needed for snow in the MA.  Obvi the PAC matters and both help with KUs but I'll take chances with a crap PAC and good Greenland blocking any day.

Wes had a great CWG article on the phases/states of the indices wrt to DC snowfall years ago, with some scatter plots to illustrate. -AO has the highest correlation to above avg snow in DC, and when that occurs we almost always have a -NAO too. That being said, there are other ways to get there as we saw with favorable EPO/WPO in back to back winters several years ago, with little to no help from the the AO/NAO. That setup has a high risk of cutters for anything amped though. Ofc we also want ENSO to be warm neutral to moderate Nino in general for big snow in these parts.

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54 minutes ago, WxUSAF said:

Seems likely the AO will be negative on average for December. First winter month with that in awhile.

That's a good plot...even the upper percentiles keep the AO near neutral or ever so slightly positive. I think @tombo82685 or @Rainshadow did some research and found that a -AO in December generally correlates to a -AO for most of the winter.

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1 hour ago, psuhoffman said:

Where was she living at the time. Westminster had 11” from that storm. I could see given the circumstances calling that a blizzard!  
 

January 2000 is a fond memory but not for the same reason as most. I was manning the weather station at PSU Hazleton the day before that storm hit. I remember looking at the vapor loop and comparing it to the guidance and it just wasn’t matching up. I Kept running the loop and thinking “why wouldn’t that just come up based on the flow”. I convinced my friend of such.  I can’t remember the guys name, he replaced Jon Neese when he left psu, but me and my friend were driving the meteorologist who came in to check on the station crazy.  He was dismissing it out of hand  “No chance the models are that wrong at such short lead”.  He didn’t even want to look at what we were trying to show him.  Everyone else was focused on the long range progs for what would be the superbowl storm 5 days later.  The next day we didn’t even have to say a word.  We walked in and just looked at him and he said “I know don’t say it”  

 

   

A friend of mine that worked in the Climate Analysis Center emailed me that morning and said he felt the models were wrong. I watched it for a bit and then called all my plowing buddies by noon and told them to get ready for a surprise snowstorm. Called my parents in Richmond and told them to go to the store well before any forecasts had updated. Was a fun system to watch, but it was in a drier band in Eastern Loudoun so I only had 10 inches when further west had about 6 inches more and, well, it was so awesome up near Baltimore. Was a fun one to watch and enjoy!

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16 minutes ago, usedtobe said:

IF I counted right the 06Z Euro ensembles have 12 of 50 members showing snow in  the 14th/15th time slot. 

It’s a long shot but it’s the best chance we’ve had in a long time. Low bar lol. Doesn’t seem to be a lot of wiggle room. We need perfect spacing between systems.  Ji was complaining we don’t even get fantasy storms to track anymore. At least he had one run to look at. 

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16 minutes ago, WinterWxLuvr said:

Laugh if you want but beware the model that’s in its own. It was one thing when this had support from the Canadian and the ICON but with them moving toward the gfs I’m skeptical.

Ukie was most similar at 500

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40 minutes ago, psuhoffman said:

It’s a long shot but it’s the best chance we’ve had in a long time. Low bar lol. Doesn’t seem to be a lot of wiggle room. We need perfect spacing between systems.  Ji was complaining we don’t even get fantasy storms to track anymore. At least he had one run to look at. 

I started to take it as a really bad sign that climo is super hostile to snow down there now when it seemed like the models couldn't even bring themselves to show digital snow. We were just so far off from what was required to get a good snowstorm that model errors and biases couldn't even get it done. When I look at the GFS and Euro for MD now, it is such a dreadful snoozefest.

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6 hours ago, Ji said:

I wouldn't. I'm going to call it a winter after 7.9 inches lol?

Dont sweat it Ji. You can just come 25 miles west and see 20+.

@psuhoffman Thanks for those setup maps. The thing I find interesting on them are the differences in the PAC. To me it really shows just how important Atlantic blocking is for us.

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