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NYC/PHL Potential Jan 11-14 Event Discussion


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Check that...I just got them now. The Euro ensembles are a huge hit. 998mb surface low is southeast of Montauk. Cold enough for everybody and a good amount of precipitation too.

john,how are you feeling about this event?looking fairly good for a safe call of 6-12" in the area next week if most of these hits are correct.

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Earthlight.. would you mind giving me a quick look at how we do down in the MA? TIA

They look pretty good for you guys. I can't really see the precipitation on the ensembles..it's pretty muted as the Euro has like 50 ensemble members. But the surface low tracks from OBX to just off Ocean City, MD. At 96 hours it has precipitation for most of the area with H85 temperatures below zero..the 850 line runs basically directly over OC MD and then off the coast. 32 F line runs through DC or maybe a hair east.

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They look pretty good for you guys. I can't really see the precipitation on the ensembles..it's pretty muted as the Euro has like 50 ensemble members. But the surface low tracks from OBX to just off Ocean City, MD. At 96 hours it has precipitation for most of the area with H85 temperatures below zero..the 850 line runs basically directly over OC MD and then off the coast. 32 F line runs through DC or maybe a hair east.

Thanks Earthlight. Appreciate it :) BTW, whats the SLP at 96?

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Lol ! I wouldn't be too worried. They aren't bad for you either. The cooling is already underway as evidenced by the H85 temperature loops between 72-84 hours. Here are the 2m temps.

http://www.nco.ncep....ef_b2m_087s.gif

It's hard to worry about or be excited about anything 72 hours out this winter (just look at today and tomorrow's combined event which the NAM is yanking away viciously this 6z run and the mesoscale band that produced 12" and less than 3" 50 miles apart), but this storm looks like one that could go either way (hit vs possible rain/mix on the coast, OTS isn't very likely right now). The low will be deepening and cooling as it gets here, and the coastal should be in charge but these redeveloping systems are always tough to nail down and can change at the last minute, and drastically alter impacts for a wide swath of territory. Also, if the confluence is moving out too fast the low could easily hug the coast and be a lot less fun than people think on the immediate shore. It's also a Nina when anything will try to cut as NW as possible when given the chance.

Not trying to be a debbie downer or overly negative, but I think the possibility is still there. Hopefully the close to the Benchmark tracks verify and the overrunning over interior sections verify and we all enjoy a moderate to possibly major storm.

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It's hard to worry about or be excited about anything 72 hours out this winter (just look at today and tomorrow's combined event which the NAM is yanking away viciously this 6z run and the mesoscale band that produced 12" and less than 3" 50 miles apart), but this storm looks like one that could go either way (hit vs possible rain/mix on the coast, OTS isn't very likely right now). The low will be deepening and cooling as it gets here, and the coastal should be in charge but these redeveloping systems are always tough to nail down and can change at the last minute, and drastically alter impacts for a wide swath of territory. Also, if the confluence is moving out too fast the low could easily hug the coast and be a lot less fun than people think on the immediate shore. It's also a Nina when anything will try to cut as NW as possible when given the chance.

Not trying to be a debbie downer or overly negative, but I think the possibility is still there. Hopefully the close to the Benchmark tracks verify and the overrunning over interior sections verify and we all enjoy a moderate to possibly major storm.

Lol no use worrying like Ace-- if youll notice, one thing we have going for us is history of the past two winters with very strong blocks.... if this were the early 90s, Id be more worried.

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snippet from the blog discussion

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Potential for a coastal storm system with wintry weather in this period. Shortwave trough ejects out of the southern stream by early Monday. Models struggling with the degree of ridging which will build into the area at that time. Much depends on the strength of the southern stream system; but just as much depends on the eventual track of the upper level low to our east and associated confluent flow over our area. Northern stream pacific energy digs southeast from the Pac NW towards the Plains states.

Models in good agreement on the fact that the initial energy will dampen out a bit..but still set the baroclinic zone and the stage for a developing coastal low. Shortwave energy expected to traverse the country from west to east through the Plains..TN Valley..and eventually to the Mid-Atlantic. Primary surface low may cut into the OH Valley, but bending H5 heights should allow for coastal development to keep most areas cold enough for snow. There are some concerns along the immediate shores of mixed precipitation..but we didn't reflect those in the package yet.

GFS OP remains further southeast of all models..including it's own ensembles. ECMWF OP has trended towards a more coastal surface low track--while it's ensembles are even a hair northwest still. The GFS Ensembles are also northwest of it's operational run as noted above. What becomes problematic is the development of precipitation in relation to the cold conveyor belt--which may be delayed by the primary low, as well as the relatively broad H5 trough depiction. The GFS is keying in on this depiction..as it has trended further northwest but is not quite there with the dynamics to produce precipitation just yet.

We like a blend of the ECMWF and GFS ensemble means for this forecast..which takes the surface low from just off OBX to southeast of Montauk and then over the 40/70 Benchmark. Not enough confidence to raise to likely pops..so stuck with the last package 40 pops in the grids. Should this track verify..likely a moderate snowstorm with potential for higher amounts in banding. As mentioned..track..details..etc..still uncertain, so stay tuned.

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Nam is way west

Yeah..the GFS is quickly becoming the de-amplified outlier. That being said, we have seen some major shifts inside this time frame. We shouldn't be ready to lock anything up at this point. Things look good for a moderate snowfall right now, though. Which I am sure everybody will take.

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Yeah..the GFS is quickly becoming the de-amplified outlier. That being said, we have seen some major shifts inside this time frame. We shouldn't be ready to lock anything up at this point. Things look good for a moderate snowfall right now, though. Which I am sure everybody will take.

You'd think with that kind of track, we'd have loads of qpf.... what's going on? Is it the speed of the storm plus the fact that the primary zaps some of the moisture that is making it less of a hit than it might otherwise be, John?

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You'd think with that kind of track, we'd have loads of qpf.... what's going on? Is it the speed of the storm plus the fact that the primary zaps some of the moisture that is making it less of a hit than it might otherwise be, John?

Hit on the point in the discussion on the blog tonight. :thumbsup:

GFS OP remains further southeast of all models..including it's own ensembles. ECMWF OP has trended towards a more coastal surface low track--while it's ensembles are even a hair northwest still. The GFS Ensembles are also northwest of it's operational run as noted above. What becomes problematic is the development of precipitation in relation to the cold conveyor belt--which may be delayed by the primary low, as well as the relatively broad H5 trough depiction. The GFS is keying in on this depiction..as it has trended further northwest but is not quite there with the dynamics to produce precipitation just yet.

---

We have a diffluent flow aloft which is good for the surface low development in the area models are showing now..but we need it to occur a bit faster and the dynamics to get here for the CCB to really develop. The Euro is nice--hopefully we see the NCEP models go that way too.

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You can see the mid level dry punch developing at 84 hours on the NAM RH charts..which is indicative of it trying to develop the cold conveyor belt within 12 hours or so. The shortwave is still back over the OH Valley..but the height lines are backing pretty good towards the Plains so there's definitely enough forcing to get this going. Will the DGEX do it? Who knows...but it certainly doesn't look anything like the under developed GFS OP.

http://www.meteo.psu.edu/~gadomski/WRFEAST_6z/f84.gif

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