Monday Discussion: Preliminary Storm Forecast

There is an unofficial meteorological concept known as ‘weather memory’.  It’s the idea that when a seasonal pattern sets up, sometimes the atmosphere develops a “memory” and storm systems tend to repeat the same general track over and over.  This winter, the atmosphere has settled into a pattern that has led to multiple storms of the same variety… this system appears to be another example.

Timing:
– 7am to 11am : Snow develops from SW to NE
– 12pm to 4pm : Snow changes to sleet from SW to NE
– 5pm to 8pm : Sleet changes to freezing rain south of I-84
– 7pm to 11pm : Sleet mixes/changes to freezing rain north of I-84
– 12am to 6am : Sleet, freezing rain & possibly rain tapers off

Impacts:
– Low visibility during burst of moderate snow, up to 1″ per hour
– Snow covered and icy roadways, temps well below freezing
– Extended period of sleet expected, ice pellet accumulation over 1″ possible
– Icing of up to 1/4″ on top of snow and sleet possible
– Tuesday PM travel heavily impacted, possibly affect Wed AM commute

Accumulations:
– Catskills (Zone 1,2,5,6) : 3 to 7 inches of snow (with 1″ to 2″ of sleet)
– Mid & Upper HV (Zone 3,4,7): 2 to 5 inches of snow (1″+ of sleet & 0.2″ frz rain)
– Lower HV (Zone 8,9): Coating to 3 inches of snow (up to 1″ of sleet & 0.25″ frz rain)

Discussion :

Another complicated system that will bring multiple types of precipitation to the Hudson Valley.  This has been the story of the winter so far, with each significant winter storm tracking inland, and pulling warm air up into the region.  The result will be a period of snow, transitioning to an extended period of sleet, then a period of freezing rain, and in some places ending as a period of rain.  The timing of each transition, and intensity of precipitation… will determine how much snow falls, how much sleet falls, and how much ice we see.

A cold high pressure in SE Canada will circulate cold, dry air down into the Hudson Valley from the Northeast.  That could delay the start of the snow through the AM commute in many areas, we’ll have to see how the timing develops.  But once the snow breaks through the dry air, it should begin to fall rather steadily to heavily at times.  Snowfall rates could reach 1″ per hour in some spots for a time.  Because of the quick progression of the mild air at the mid levels… we will only see an average of 2 to 3 inches of snow before the changeover (based on this scenario).  Should the cold be more resilient, that could change… we’ll have to stay focused on this.

But as we near mid day, the snow/sleet line is already advancing toward our area…

The culprit is a thin wedge of warm air between the 700mb and 850mb level… right at the cloud level.  So the transition to sleet is expected to occur rather quickly, and that will put a halt on the potential for big snow totals.  However, what is interesting, is that the warm air isn’t expected to flood downward in the atmosphere.  So enough cold air will stay locked in at the lower parts of the atmosphere and surface… that an extended period of sleet is possible.

Notice how after sunset… sleet is still projected to be falling under this scenario.  This will result in a moderate accumulation of sleet pellets, which are like little icy grains of sand.  These won’t accumulate as quickly as snow does… but a half inch to an inch of sleet can’t be ruled out, and the further north you go, 1 to 2 inches of sleet can’t be ruled out.  Then, on top of the heavy grains of sleet pellet sand… we should see a period of freezing rain across the southern half of the Hudson Valley… which will put an icy glaze on top of the whole wintry mess.

As we get closer Monday night, we should have a better handle on the timing of transition from snow, to sleet, to freezing rain.  That said, the setup as it appears now, will mean an extended period of frozen precipitation in the form of sleet.  This will mean lots of early closures on Tuesday, and could possibly extend it’s problems into the Wednesday AM commute… especially if the sleet and freezing rain persists until the pre-dawn hours on Wednesday.

More details as we get closer.  Thanks for all the continued support!

11 thoughts on “Monday Discussion: Preliminary Storm Forecast

  1. ‘Weather memory’. If you recall a meteorologist Norm Sebastian from channel 10 in Albany, he said the same thing about the storm tracks. He wasn’t one to just use the computer models either.

  2. Thank you for your very informative reports. My husband, Wilton, and I have learned so much about the weather reading your information. Thank you for taking the time and effort to explain weather patterns in a way that we can understand.

  3. Every storm, every year it’s the same scenario. Storm track, cold air, warm air, seasonal patterns, etc. etc. etc. you can’t pin down Mother Nature, she does what she wants and we just have to sit, wait and deal.

  4. When you evaluate this winter pattern look at the North Atlantic Oscillation it hasn’t set up properly for several winters now. The NAO is a low pressure area that sets up in the fall in Western Southern Canada it is why they receive snow in the Rockies much earlier than we get snow. Its not uncommon for them with their elevation to see snow early to mid October. As it traverses across Canada the Midwest gets their winter as it continues in a normal pattern we get our snows normally in January through Mid March. If there is any blocking pattern that prevents its movement storms like hurricanes follow the path of least resistance like this one and the past couple of years they cut through the Great Lakes.

    Snow lovers who are as ancient as I am remember the classic storm path for snow in our area. Lows formed in the Four corner states dove to the Panhandle of TX reformed along the Gulf Coast and hooked up the Eastern Seaboard deepening as they did so. See pattern 1960’s, especially winter 1962, 1967 and 1969, Blizzard of 1978, Blizzard Feb 1983, Winter 1993 Winter 1996 and 2010. That pattern has been missing. When reviewing the “Possibility for snow” the Models know well in advance if secondary low formation along the coast will blossom and be the primary storm system. If they haven’t latched on to that idea three days out its a dead issue. Three to six inches of snow is nothing in the NE, ice is a problem. But snow lovers hate any changeover. When you forecast weather you can’t do it as a snow lover you have a tendency to wait and eventually make excuses for why a forecast bombed out but if you really dig deep you know why it bombed out “Hope against Hope” equals egg on your face. There is nothing wrong with an incorrect forecast you can call it “Pattern Memory” if you want to but dig deeper and you will see that that pattern was established way before the winter began check the position of the NAO its ability to traverse its path any deviation and the winter is over before it begins.

  5. The Hudson Valley Weather and the volunteer staff do more that predict the weather. They weave a community together especially during inclement winter weather and this support us in feeling like a community. A long needed attribute to this area. So, I don’t know about NAO’s but it is larger than predicting weather. They have become a fabric of this community and make us all feel this way as well.

  6. The reason I trust you guys is exactly the reason your here, I have little faith in the NWS the main reason being they treat the mid hiudson valley as an afterthought, their area is way to broad and our tiny area is by far their hardest to forecast so they devote a few sentences to our area and concentrate on whats easy. You offer us at least the college try and your detail is good. Just don’t accept “weather memory”, the memory is because the winter pattern did not set up yet again. The track I personally remember growing up was the sweet spot. The NAO establishes the winter pattern across NA. If it fails to establish itself then blown forecasts will occur. If you want to just look at the jet stream flow on the models, I can’t remember the last time there was a blocking pattern, see the Feb 1983 Blizzard for blocking that storm had all the true attributes of a blizzard temperatures below 20 degrees, winds in excess of 35 miles an hour well over three consecutive hours and blowing snow.. the forecast was for it to remain off the coast and we were forecasted to get two inches many places received over two feet. It looped but was still a short duration event snow rates were in excess of 4 inches an hour for over three hours it was a very strong storm the stuff snow lovers dream of. Your site is worth the entire effort you put into it. You show why the NWS treats us the way they do, we are the hard part of forecasting we need people who care as you guys do.

    Just understand once the pattern is established and wd get deep into winter that pattern is hard to break. Look for the orospect of phading in your winter outlook without it we get blown forecasts or the garbage wd have seen for almost three years running.

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