Jump to content
  • Member Statistics

    17,586
    Total Members
    7,904
    Most Online
    LopezElliana
    Newest Member
    LopezElliana
    Joined

Countdown to Winter 2017-2018 Thread


eyewall

Recommended Posts

  • Replies 1.7k
  • Created
  • Last Reply
7 minutes ago, 8611Blizz said:

While the forecast result is entirely plausible, its content adds about as much value as the epilogue to the Dawn Awakening.

Link to comment
Share on other sites

Just now, 40/70 Benchmark said:

Pretty vague post.

Care to elaborate?

Well it's one of those leading indicators.  High October SLP in the region west of California and south of Alaska correlates significantly with a positive January NAO.  I feel like in general there's a lot of mixed signals for the winter NAO.  You got good impressive snow cover, low sea ice, and the Kara sea ridging there too, all good signs for a negative NAO.  Then on the other hand, the october SAI was low and the PV itself remains pretty strong and cold. 

current october.gif

october 500mb heights vs. jan ao.gif

Link to comment
Share on other sites

2 minutes ago, OSUmetstud said:

Well it's one of those leading indicators.  High October SLP in the region west of California and south of Alaska correlates significantly with a positive January NAO.  I feel like in general there's a lot of mixed signals for the winter NAO.  You got good impressive snow cover, low sea ice, and the Kara sea ridging there too, all good signs for a negative NAO.  Then on the other hand, the october SAI was low and the PV itself remains pretty strong and cold. 

current october.gif

october 500mb heights vs. jan ao.gif

That makes sense becuase I'm going for a mild January.

Link to comment
Share on other sites

Ray's December composite def doesn't look like a typical Niña with the solidly positive PNA....low heights south of Aleutians and higher heights over BC. 

We did see that type of pattern in some previous weak ninas though like December '05, Dec '00, and Dec '85. The 1985 analog has been good in November so far too. 

Link to comment
Share on other sites

50 minutes ago, CoastalWx said:

Bascially a Nino pattern helps correlate to a -NAO. That's kind of what the SLP indicator shows more or less.  Nick, how's St John during blocking episodes? I have to imagine even you guys do well with those with the PV lobe nearby.

Temperatures are colder with a positive NAO.  But nao overall doesn't really matter too much to our snowfall.  I have to imagine either too positive or too negative are bad. Our large snowstorms do still like a bit of a weak -0.5 to -1 block over greenland. 

Link to comment
Share on other sites

Ray's December composite def doesn't look like a typical Niña with the solidly positive PNA....low heights south of Aleutians and higher heights over BC. 

We did see that type of pattern in some previous weak ninas though like December '05, Dec '00, and Dec '85. The 1985 analog has been good in November so far too. 

Link to comment
Share on other sites

4 hours ago, CoastalWx said:

My own thoughts here, but I am noticing what seems to be strong ULL ridging in nrn Siberia, leading to a strong area of HP in Siberia. I have seen work done on Siberian Highs in November and -AO tendencies. I have to think that is a good sign. 

Should be blocking early and late....neg. aggregate NAO/AO for season.

Link to comment
Share on other sites

I just completed my ideas for my St. John's city forecast.  I'm using 4 lead indicators from the late summer-fall, the PDO, the northern oscillation index, the QBO, and Nino 1+2 SST anomaly.  Those are the only larger type indices in the summer-fall that have borderline statistical significance (r=0.2 to 0.25) with winter weather here.  The best 10 matches on all 4 values of those variables were 1956-1957, 1958-1959, 1960-1961, 1968-1969, 1974-1975, 1977-1978, 1984-1985, 1986-1987, 1989-1990, and 2000-2001.

 

Mean snowfall was 428.5 cm here (+93.5 cm above normal) with a standard deviation of 123.3 cm 

7 of 10 were above normal. 

While it might translate for other areas, this was specifically done only using forecast parameters that were useful to the weather here and no other leading indicators. 

 

 

 

 

 

 

leading analogs.png

leading analogs temperature.png

Link to comment
Share on other sites

That's interesting how we have such a huge black hole south of Greenland, yet the heights in the Davis Straits do not have nearly the magnitude in the opposite direction. I wonder if the vortex was a stable feature, but the blocking was either transient..or perhaps located in slightly different areas from month to month...thus giving that appearance of weak + anomalies. 

Link to comment
Share on other sites

On 10/30/2017 at 10:24 PM, ORH_wxman said:

Right...the geography/topography of New England is unique in multiple ways that can often "favor" colder outcomes within an overall warmer regime. The gulf stream bends off to the south of us...in addition to the fact that we are just a big land mass sticking out to the east into the Atlantic ocean like a big chin. Both of these features are hugely favorable for a good baroclinic zone just to our south. Add in the 3rd really important feature...topography. We lie mostly to the east of the Appalachian mountains....so the cold air damming is very strong...and it tends to be enhanced up at our latitude due to the penchant for high pressure to form in Quebec due to the PJ interacting with the natural train car pile-ups that occur in the North Atlantic. Mix that in with the baroclinic zone to our south and you have a lot of synoptically "ugly" storms at 20,000 feet start to look a lot prettier at 5,000 feet and below.

 

It's funny how badly we scoff at certain aspects of our lack of winter. As if there are so may other great places for big snowstorms and retaining snow pack. But when you start looking at the rest of the CONUS, you realize how ugly it is everywhere else to get consistent double digit synoptic snowfalls and also keep their snow around. The snow retention is terrible until either get way north like the Arrowhead of Minnesota and UP of Michigan and N Wisconsin...or up into major mountain towns out west. There's some lake effect belts a bit further south that also do well, but they are definitely more localized. The former don't provide much in the way of big synoptic snowfalls...you pretty much just have to go into the mountains out west to get better on a consistent basis.

 

I suppose the south coast brethren and places like the Cape/adjacent areas have some room to complain a lot more than we do. But interesting how sometimes we obsess over the KU textbook patterns for mid-atlantic snow even here...I will sometimes point that out, but despite that, I will still fall into that tunnel vision at times.

Fantastic post Will

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

  • Recently Browsing   0 members

    • No registered users viewing this page.

×
×
  • Create New...