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NYC/PHL Jan 25-27 Potential Bomb Part 5


earthlight

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I posted earlier the UKMET was a smidge warm at 850 for all the local stations around NYC AT 60 hours 7PM Wednesday but what I didn't realize was that the precip was just starting. Here is the ukmet at 60 hours. At 72 hours the soundings are still saturated enough to give snow which means its slower than the GFS and thus what falls after 60 hours for the next 12 hours is probably all snow. What I am driving at is IMHO the UKMET is a colder version of the GFS.

It probably would end up a hair warmer if you were to just take the general GFS thermal profile idea--but maybe the UKMET would pick up on something, who knows. That being said..it's further northwest with the surface low than the GFS ever brings it. The GFS is already east-northeast of Ocean City, MD at 60 hours whereas the UKMET is backed further south but also further northwest..the GFS never tucks it in to that location. So that can be noted, for whatever it's worth.

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It probably would end up a hair warmer if you were to just take the general GFS thermal profile idea--but maybe the UKMET would pick up on something, who knows. That being said..it's further northwest with the surface low than the GFS ever brings it. The GFS is already east-northeast of Ocean City, MD at 60 hours whereas the UKMET is backed further south but also further northwest..the GFS never tucks it in to that location. So that can be noted, for whatever it's worth.

But I think the UKMET holds the cold positioning longer and based on the surface map at 72 hours I think it would be very nice in between. The only warm layer on the ukmet at 60 hours is 850 so as it bombs and cools :snowman:

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It is, but with couple days to go yet, I wonder where it will ultimately set up.

Yeah, pinpointing the exact banding can be a real pain. Usually this is the range when most models (both globals and mesoscale models) will begin to hone in on the general area of the banding. Where the actual areas of banding and subsidence set up will be much more of a mesoscale forecasting deal.

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I think many on this board if current model overall ideas/outputs are correct (especially the EUR0) GFS is close (but it still is splitting the energy a little too much) will be VERY HAPPY with the CCB on this storm. Yes, some rain/mix at the start and the middle (depending on exact location) but the EURO advertises and the GFS is almost there, a significant snowstorm for most. Hate to put a number yet but right now Im expecting 5-10" for NYC & N/C NJ within 15 miles of I-95. More NW...

Not bad...

Pretty much my thinking as well and has been the last two days.

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RGEM and GGEM at 48 hours are twins. GGEM gets an F---- if the trends verfiy.

i put the GGEm post 48 hrs in the same mix as the NOGAPS and UKMET....there isnt even a trend benefit like there could be with the extended times on the NAM and GFS....

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I imagine this is one of those forecasts where the spreads for snow totals have to be significantly wider. I mean, if you're forecasting for the NYC metro, you'd almost have to put the low end at around 2" and the high end at 10", which is obviously way too wide, But if you call for 5-10", it's highly possible the low end won't verify. With that in mnd, I'm thinking 3-6" or 4-8" is the call for the immediate NYC metro area at this time, with a good chance that could change in either direction.:arrowhead:

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GFS 60 hour sounding- mixed sleet/snow/snow pellets?

Edit to Add- not quite saturated at -10ºC- more sleet than snow?

Hard to form snowfalkes with that sounding. Looks like light rain or freezing drizzle off sounding. But based on the 6hr panels it looks suspicious. With deeper lift I'd expect sleet or rain changing to large aggregated snowflakes as intensity increases and mid-levels cool slightly.

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Probably. Should change to snow in the next hour or two as those east winds shift northeast and north.

Greg, the winds are actually northeast the whole time with this storm in our neck of the woods. Surface winds tilt across surface isobars towards the low pressure center rather than exactly parallel to the isobars. It has to do with friction. When you go further up in the atmosphere and friction becomes less of an issue, winds will blow parallel to pressure contours, except in jet entrance/exit regions where our weather happens.

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Wow, this is going to be a tough forecast for Mt. Holly, and the TV meteorologists. I do not envy the spot that Glenn Hurricane Schwartz is probably going to be in when he gives his forecast tonight!

They have time with this aiming for Wed. night-Thurs morning now. Hopefully things become a little more clearcut, or at least consistent on the guidance. I doubt this transitioning situation will be perfectly forecasted just because it's the nature of this type of an event, but it would be nice to see at least good model clustering to interpret.

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Its experimental but the ggem precip maps are not as snowy as the gfs. This is 66 hours when the GFS is clearly all snow for NYC, western LI and back through Jersey.

We'll just have to deal with the blurry improvements it made from 0z. Fortunately, most of us didn't see this kind of map last night.

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Wow, this is going to be a tough forecast for Mt. Holly, and the TV meteorologists. I do not envy the spot that Glenn Hurricane Schwartz is probably going to be in when he gives his forecast tonight!

Agreed. This is really REALLY dicey for our metro area.

I think DT's map a few pages back is a pretty good place to start. Mainly a rain/mix event for south Jersey, and a mix to snow event for Philly and the immediate counties north/west, with about 3-6 of wet snow total.

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I think the issue with this is clearly displayed on the JFK soundings on the 12z GFS....it appears 2/3 of the precip falls with both the boundary and 850mb above 0c....this is not a big snowstorm for coastal areas....you will need to be inland and/or with good elevation to carry the day.

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Greg, the winds are actually northeast the whole time with this storm in our neck of the woods. Surface winds tilt across surface isobars towards the low pressure center rather than exactly parallel to the isobars. It has to do with friction. When you go further up in the atmosphere and friction becomes less of an issue, winds will blow parallel to pressure contours, except in jet entrance/exit regions where our weather happens.

Sounds like youre starting to change your mind about this being predominantly a rain system even half and half would be just fine :)

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Agreed. This is really REALLY dicey for our metro area.

I think DT's map a few pages back is a pretty good place to start. Mainly a rain/mix event for south Jersey, and a mix to snow event for Philly and the immediate counties north/west, with about 3-6 of wet snow total.

Sounds like a moderate event.

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I think the issue with this is clearly displayed on the JFK soundings on the 12z GFS....it appears 2/3 of the precip falls with both the boundary and 850mb above 0c....this is not a big snowstorm for coastal areas....you will need to be inland and/or with good elevation to carry the day.

JFK is not a good reflection of what would transpire in NYC, EWR, TEB or even LGA in this setup.

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