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NYC/PHL Jan 17-19 Forecast Discussion


am19psu

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Final map for a tricky forecast. Hard to say whether snow or ice will be the more dominate frozen type of precip for those areas getting frozen precip. Who knows may turn into a sleet fest for much of NNJ north of I78 and west of GSP. N&W of I-80 & I-287 most at risk to significant snow and or ice as temps may struggle to reach freezing in this area.

post-2229-0-35572600-1295312028.jpg

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Final map for a tricky forecast. Hard to say whether snow or ice will be the more dominate frozen type of precip for those areas getting frozen precip. Who knows may turn into a sleet fest for much of NNJ north of I78 and west of GSP. N&W of I-80 & I-287 most at risk to significant snow and or ice as temps may struggle to reach freezing in this area.

Looks good to me. Seriously.

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Final map for a tricky forecast. Hard to say  whether snow or ice will be the more dominate frozen type of precip for those areas getting frozen precip. Who knows may turn into a sleet fest for much of NNJ north of I78 and west of GSP. N&W of I-80 & I-287 most at risk to significant snow and or ice as temps may struggle to reach freezing in this area.

guess you dont like morris county lol

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Final map for a tricky forecast. Hard to say whether snow or ice will be the more dominate frozen type of precip for those areas getting frozen precip. Who knows may turn into a sleet fest for much of NNJ north of I78 and west of GSP. N&W of I-80 & I-287 most at risk to significant snow and or ice as temps may struggle to reach freezing in this area.

If that map were to verify verbatim, folks living in Zone A are in for some serious problems tomorrow.

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So touchy as to when things transition form snow to sleet to ice. I suspect most zones will not be able to max out on both snow and ice amounts. Either stays snow longer but moves quicker thru the ice stage or vice versa. Particularly in zones B & C. Zone A is a serious problem. Could see mid to high range of both snow and ice amounts especially the N&W portion of that area. The other killer to accumulaitons of snow and ice is prolonged sleet. That would cut down on snow and ice accreation from freezing rain. Its probably subject to big bust potiential in many ways. So so difficult to nail to precisely when and where temps will hit that critical 32F from 0-5000Ft. Regardless it will be a messy morning. Just a matter of how long into the day the mess continues and where.

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Some things where pondering here tonight, Temp / dew pt spread is 15 degrees here, so that's a lot of dry air still in place and wet bulbs are in the lower 20s. LAMP numbers don't put newark above freezing until about 17Z on Tuesday, our thinking here is a coating to an inch or so in newark metro then sleet and freezing rain before going over to non freezing rain by 1pm tomorrow afternoon. Things many are trying to warm things up much too fast in the AM.

A lot of times in these setups, the precip arrives faster than forecasted but the column warms faster than forecasted as well. There could still be a few hour thump for the immediate NYC/EWR metros if we luck out, but the warm air will definitely arrive sooner or later given the low track and lack of a high. I like the fact that dewpoints are so low, meaning that we have plenty of time to wetbulb down and use up that cushion. It's still not out of the realm of possibility, especially if the snow comes in heavy, that we have a few inch thump in some areas before flipping over to sleet then rain. Inland near I-287 and especially in some of the elevated areas there could be a substantial ice storm given the 1"+ QPF outputs. The radar also looks quite impressive.

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If that map were to verify verbatim, folks living in Zone A are in for some serious problems tomorrow.

Yeah, and NWS Bing would need to upgrade to an ice storm warning ASAP. but they are adament about downplaying the chances of Frzrn in their forecasts. They had trace to .1 of ice this afternoon for my location.

This is their evening forecast for my town

"Tuesday: Snow, freezing rain, and sleet before 11am, then rain. High near 38. East wind 6 to 8 mph becoming north. Chance of precipitation is 90%. Little or no ice accumulation expected. New snow and sleet accumulation of 1 to 3 inches possible"

are they missing something or are the folks on this board missing something. I am well N&W of the "big cities".

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A lot of times in these setups, the precip arrives faster than forecasted but the column warms faster than forecasted as well. There could still be a few hour thump for the immediate NYC/EWR metros if we luck out, but the warm air will definitely arrive sooner or later given the low track and lack of a high. I like the fact that dewpoints are so low, meaning that we have plenty of time to wetbulb down and use up that cushion. It's still not out of the realm of possibility, especially if the snow comes in heavy, that we have a few inch thump in some areas before flipping over to sleet then rain. Inland near I-287 and especially in some of the elevated areas there could be a substantial ice storm given the 1"+ QPF outputs. The radar also looks quite impressive.

I have to ask this is wet bulb down the same as evaporational cooling?

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A lot of times in these setups, the precip arrives faster than forecasted but the column warms faster than forecasted as well. There could still be a few hour thump for the immediate NYC/EWR metros if we luck out, but the warm air will definitely arrive sooner or later given the low track and lack of a high. I like the fact that dewpoints are so low, meaning that we have plenty of time to wetbulb down and use up that cushion. It's still not out of the realm of possibility, especially if the snow comes in heavy, that we have a few inch thump in some areas before flipping over to sleet then rain. Inland near I-287 and especially in some of the elevated areas there could be a substantial ice storm given the 1"+ QPF outputs. The radar also looks quite impressive.

Yeah, its amazing when you get one of these events thats more a WSW-ENE mover and you check obs in the Midwest you see places seeing PL/ZR that were not even expected to come close to changing over...its harder to see the WAA underestimation when its moving more south to north like this is but it is noticeable a bit already near DC as someone posted in the other thread....sometimes though as you said the significant snow cover that can develop due to an earlier start time as well as a big drop in the surface temperatures can make it very hard to get the lower level cold air pushed out later on.

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Yeah, and NWS Bing would need to upgrade to an ice storm warning ASAP. but they are adament about downplaying the chances of Frzrn in their forecasts. They had trace to .1 of ice this afternoon for my location.

This is their evening forecast for my town

"Tuesday: Snow, freezing rain, and sleet before 11am, then rain. High near 38. East wind 6 to 8 mph becoming north. Chance of precipitation is 90%. Little or no ice accumulation expected. New snow and sleet accumulation of 1 to 3 inches possible"

are they missing something or are the folks on this board missing something. I am well N&W of the "big cities".

Perhaps they think most of the non-snow precip is going to be sleet, which would obviously cut down on any ice accumulations. I can't remember the exact storm, except that it was a couple winters ago where all the talk was of severe icing. What happened was we flipped from snow to a mix of ip/zr for a few hours, and then straight to plain rain which kept the ice accumulations to a minimum.

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ooz NAM just went warm in a hurry ...from slightly colder at the 850s at 6 hrs to shooting well north at 12 hrs...

Looks alittle to warm for me for areas north and west of the cities. On the coast, def. possible but I don't think it warms up that quickly in northeast PA, just my opinion tho.

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ooz NAM just went warm in a hurry ...from slightly colder at the 850s at 6 hrs to shooting well north at 12 hrs...

That high sliding out past Newfoundland ain't doing us any favors. Too bad it couldn't be in a better position to keep the cold air in place aloft. The surface is a much different story however and I doubt many fron I-287 west ever see rain (plain).

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Nate any thoughts for the HPN area?

I'm thinking 2-4 on the front end than .1 to .25 of ice before WAA takes over the surface and we go to rain

You might get a bit more snow than I do up by HPN, although I do live at 350' elevation which may increase the icing here relative to other parts of Southern Westchester. I think 2-4" is a solid forecast as well as the .1-.25" ice; the radar looks fairly juicy and is moving quickly towards our area. This is a good sign, as we need the precipitation to march northward quickly before the mid-levels warm too much and we are stuck with IP/ZR. We're definitely guaranteed to start with some decent snows and then flip to ice for a bit. We'll see how it plays out, I'm staying up for a while to follow it.

23.5/13 here...

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You might get a bit more snow than I do up by HPN, although I do live at 350' elevation which may increase the icing here relative to other parts of Southern Westchester. I think 2-4" is a solid forecast as well as the .1-.25" ice; the radar looks fairly juicy and is moving quickly towards our area. This is a good sign, as we need the precipitation to march northward quickly before the mid-levels warm too much and we are stuck with IP/ZR. We're definitely guaranteed to start with some decent snows and then flip to ice for a bit. We'll see how it plays out, I'm staying up for a while to follow it.

23.5/13 here...

yeah i think its a given we go sn to zr to plain rain. The big question is how long does the lower level cold stick around before it goes above 0c and we go over to rain.

Either way temps wont get past the mid 30's an easterly win wont torch us like a southerly wind does

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2 M temps are warmer as well

Not just the 850s

Verbatim of the 0z NAM I hope the surface temps also fly north like the 850s. 24hr total precip as 1-1.25" precip for NW NJ & eastern PA. Much of that is after 850 0C line has moved well north thus its ice or hopefully rain.

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yeah i think its a given we go sn to zr to plain rain. The big question is how long does the lower level cold stick around before it goes above 0c and we go over to rain.

Either way temps wont get past the mid 30's an easterly win wont torch us like a southerly wind does

I doubt we'll see a major torch with big-time snowpack destruction; that's not in the cards with the coastal keeping winds more E/NE. It's pretty much a given that we go over to plain rain tomorrow afternoon, but not before the damage has been done in terms of widespread school closings and traffic problems. I think this event will actually help our snowpack by adding some liquid and ice to it, making it more resistant to any warm-up that comes down the road (not that there appears to be one). Then we can work on adding another 6-12" snow Thursday night/Friday with the overrunning event.

What's your temp at the ranch?

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I doubt we'll see a major torch with big-time snowpack destruction; that's not in the cards with the coastal keeping winds more E/NE. It's pretty much a given that we go over to plain rain tomorrow afternoon, but not before the damage has been done in terms of widespread school closings and traffic problems. I think this event will actually help our snowpack by adding some liquid and ice to it, making it more resistant to any warm-up that comes down the road (not that there appears to be one). Then we can work on adding another 6-12" snow Thursday night/Friday with the overrunning event.

What's your temp at the ranch?

24.1 but its been running high all day HPN is at 23

RH of 61

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