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Discussion in 'Weather' started by wxdavid, Dec 25, 2015.

  1. wxdavid

    wxdavid Junior Member
    Messages: 12

    Over the last several days my main focus with regard to winter weather has been for the impending significant snowstorm likely for portions of the lower and central plains into the upper Mississippi Valley as we come out of the long holiday weekend. But there is a second event which deserves significant attention and focus for the interior portions of New England and the Northern Middle Atlantic states on December 20. Although I have briefly mention the potential for significant winter weather over New England ...I have not given is a lot of attention -- mostly due to other workload considerations. However it is now time to focus on this event because is looking more more significant and the model data is finally settling down.

    The strong area of intense LOW pressure which is going to develop over eastern TX and eastern OK wil drive up towards the Great Lakes DEC 27-28 This Low will bring significant snow to much of the lower Plains into eastern NEB IA and the upper Mississippi Valley (MN WI). At the same time a strong arctic air HIGH will drive out of southwestern Canada and track west to east just north of the U.S. Canada border. This cold air mass will ensure that temperatures will be cold enough for significant snow over large portions of the Plains and the upper Mississippi Valley into the western Great lakes. This large arctic HIGH will also play a key role in setting up a significant snow and possible ice storm for the interior portions of the northeast on December 29.


    This snowfall amounts will be greater than 12 inches across much of eastern NM the TX and OK panhandles... 6 to 12" over central and eastern KS central and eastern NEB and SD. The snow amounts may increase to well over 12 inches across all of IA (except for the far southeast corner ) southeastern MN and the southern half WI.

    Once a strong surface LOW pressure area moves into the Great Lakes it will begin to weaken rapidly. Without getting too technical " the LOW cannot move into the HIGH". In fact what is happening is that the LOW is moving into the confluence zone across the northern Great Lakes and eastern Canada which of course it cannot do... so the LOW begins to break down and tries to find another place to reform.


    This will result in the much weaker surface LOW redeveloping over southern NJ coast by the morning of December 29. To the north the large arctic HIGH which was located to the north of Lake Superior ....is now located over Montreal and southeast Canada. Much colder air will begin to drive rapidly southward across New England into the Middle Atlantic states on December 28. If this was a normal winter pattern with seasonal temps then it is possible the frozen precipitation area might make as far south as Central Virginia. Bu that is not going to happen here. The line showing frozen vs. non frozen precipitation will make as far south as central or Northern Pennsylvania -approximately along interstate 80 - but no further south. The precipitation may begin as snow or sleet over northern NJ eastern PA and coastal CT / NYC but it won't stay frozen.

    get_orig_img (1).jpg

    Let talk the significant difference in the snowfall maps between the operational GFS and the operational European models with regard to the total snowfall accumulations from this event. As you can see they are significantly different. The 0z Friday morning GFS model shows extremely heavy snow developing and accumulating over much of western central and northern PA and moderate to significant snows over much of interior New England. This may be a classic example were the GFS model cold bias plays a significant impact.

    The second image is the European model from 0z FRI run and as you can see it is significantly different with regard to the snowfall. It has almost no significant snow of any kind over any portion of PA and southern NY state or northwest NJ or southern CT. To be certain the model does have huge snow mounts over the interior portions of central and northern NY State and New England so it is not like the European model is not showing ANY snow... Because that certainly is not the case.


    The KEY issue between the various weather models has o do with where will the cold air setups and how long the cold air will lock in place during the the event.

    The problem with the last few runs of operational GFS solutions is that if you look of the low level temperatures the model continues to forecast temperatures well above 32°over southeastern PA most NJ NYC nd coastal CT. Given how warm it has been... is going be hard enough near the coast to get any sort accumulating snow but if the low level temperatures are 35 are 38° it is going to be next to impossible. Of course it is still quite possible that the GFS that may be correct in forecasting over 10 inches of snow in much of central and northern PA and southern NY state but on the coast ...the operational GFS solution simply makes no sense. Yes there may be snow accumulations in NYC and Philly and coastal CT but my concern here is that the GFS model's internal consistency is lacking. If you wish to forecast accumulating snow in Philly Northeast NJ NYC and coastal CT with low level temperatures in the mid 30s and still fairly mild ocean water temperatures near by... well good luck with that

    get_orig_img (5).jpg

    What is also significant is that the last several runs of 0z European model is showing significant ICE buildup across much of central and northern PA into southern interior NY State. This is where the GFS model is showing significant snowfall and not ice accumulations. As I suggested above this may be a case where the colder bias of the GFS is forcing temperatures down just enough so that the model is producing snow instead of sleet.

    I suspect over the next several runs the operational GFS will begin to shift the significant snow northward and move into closer alignment with the vastly superior European model. What this means for much of central and northern PA as well as in northern interior NJ and coastal CT... is that they may be looking at more of ICE situation then snow ... So I am not sure that this is a good thing for those areas.



    get_orig_img (1).jpg


    get_orig_img (5).jpg
  2. wxdavid

    wxdavid Junior Member
    Messages: 12

    ** NEW 12Z FRIDAY operational GFS shows MAJOR shift of the heavy snow to the NORTH -- this is KEY and shows me that the EUROPEAN Model is far more likely to be correct and its solution should be the one to follow


  3. precisioncare

    precisioncare Junior Member
    from NY
    Messages: 24

    Thanks for the info
  4. Mark Oomkes

    Mark Oomkes PlowSite Fanatic
    Messages: 13,257

    I'm not liking that run at all.
  5. JMHConstruction

    JMHConstruction PlowSite.com Addict
    Messages: 1,722

    On behalf of everyone in Kansas City, let's hope your model is correct.

    What are the odds of that dropping a little further south?
  6. jonniesmooth

    jonniesmooth Senior Member
    Messages: 296

    Sounds good for us here in MN. Thanks for sharing!
  7. wxdavid

    wxdavid Junior Member
    Messages: 12

    as forecasted LATEST NWS FORECASTS

    the ORANGE = blizzard


  8. 1982atm

    1982atm Senior Member
    from indy
    Messages: 146

    How prepared are they in the Amarillo area? Is it going to be like southern KY was during the 1st big snow storm early this year.
  9. cbservicesllc

    cbservicesllc PlowSite Fanatic
    Messages: 12,533

    What are your thoughts on what we're looking at in the Twin Cities Metro for Monday Night?
  10. wxdavid

    wxdavid Junior Member
    Messages: 12


    My 1st guess map


  11. iceyman

    iceyman 2000 Club Member
    Messages: 2,926

    Base building snow for the mountains