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12z Models 2/11/2014 | Potential Major Coastal Storm


earthlight

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22 hour event from start to finish on the 12z GGEM. Mostly snow NW of NYC. Some mixing issues at the coast for a time.

 

Takes a weird track looks S/E of most guidance off of the Delmarva....but then goes due north (maybe even a hint W of north) to just off the NJ shore, then finally goes N/E. Even so, maybe only a 2-4 hour period of mix/rain from the Parkway West in N NJ though...and probably a lot of snow.

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A partial summary for LGA: using Cobb Method. NAM 17hrs. 1.20" liquid and a whopping 17" Snow.

GFS not avail. @12z prev. runs have been incoherent

showing about .60" liquid and never more than 5"

of snow in an alternating Sn-Rn pattern, or just

no snow at all.

SREF Plume 22hrs. 1.05" liquid but just 5" Snow.

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Takes a weird track looks S/E of most guidance off of the Delmarva....but then goes due north (maybe even a hint W of north) to just off the NJ shore, then finally goes N/E. Even so, maybe only a 2-4 hour period of mix/rain from the Parkway West in N NJ though...and probably a lot of snow.

That due north jog follows the slightly warmer water temps just offshore

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That due north jog follows the slightly warmer water temps just offshore

It has more to do with the synoptics than thermal gradients, which I would think have less pronounced effects on the track of a mature storm than a developing one. With a steeply negative trough and not a ton of confluence, the storm will surge poleward until the infamous 'kicker' starts sending it ENE.

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Nobody is throwing it out, but some are minimizing it because it doesn't give them the most snow. His point is valid.

 

Here is a post I made earlier in the southeast thread:

 

 

This... this is looking more and more like a KU snowstorm. Euro ensembles are in very good agreement on this outcome now.

 

 

 

 

 

I'm going to get on my high horse for a brief moment, but I think the GFS and NAM are doing a horrible job with this event  (wednesday and beyond). When I look at models and try to get an assessment of what is going to happen, the first thing I do is look at the ECMWF and its ensembles.

 

When the ECMWF is showing an overamplified solution relative to the rest of the guidance, I stand back and try to understand if its catching on to something the other models are missing or if its an outlier that should be thrown out. The easiest way to figure this is out is to look at the its ensemble mean. Guess what, the ECMWF ensemble mean is pretty much exactly what the deterministic solution is. The ECMWF Ensemble Prediction System (EPS) is superior to the GFS Ensembles because it contains 50 members and does a more realistic job of depicting the probability PDF of any one particular solution, preventing it from being under dispersive like the GFS ensembles are in most cases.

 

So when there is strong agreement within 72 hours from the ECMWF and the ECMWF ensembles, I place that in the highest regard over all other guidance. Thats what we are seeing currently. The GFS and NAM are completely on the edge of the ECMWF ensemble PDF and therefore should both be considered outliers in this case. Its a little startling to see this must dispersion between the model guidance within 72 hours, but for tricky phasing cases like this, its the norm. While taking a mean might sound like the best course of action, in reality when there is this much spread, you are taking a good forecast and merging with a bad forecast to create a mediocre forecast. I think it would be a better idea to place greater emphasis on the ECMWF solution given the strong support it has by its ensembles. 

 
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That due north jog follows the slightly warmer water temps just offshore

It's a track that doesn't seem to make sense. It appears to be just east of the Delmarva for a time and then tracks due north. To me it should at least be headed somewhat east. GGEM hasn't been that consistent though so I wouldn't be too worried. Yesterday at 12z it was among the eastern solutions.

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Ukie looks fine...much better than last night and good QPF with the 850's just getting into the city for a brief period of time.

 

The GFS, interestingly, is showing mostly snow on the precipitation-type graphics on wxbell. Not sure on accuracy but the soundings aren't as terrible as I figured they would be either.

based on this map i would think we have issues, no?

140211165225.gif

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There's still a lot of model noise that the Euro can hopefully help clean up. The GGEM seems too warm given such explosive dynamics even with the low just offshore, but the low itself is likely way too powerful (most are in the mid 980s) which might explain the northward jog off the Delmarva compared to the other models, when it should realistically track further to the NE. 

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Most of the really big ones for this area have had a period of mixing along the immediate coast. Even PDII which was about as cold as you'll ever see.

very true and wouldn't still be shocked if some places in western LI, Suffolk/nassua border with this storm still do great as the CCB would be hanging over us for a long time with some prolific rates

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The models are going to be too warm with the surface in this storm with this track because they think the winds will be ESE or E...the setup is classic for the ageostrophic flow becoming more NE or NNE with the positioning of that high and the deepening low...this was part of the reason the models busted on 1/22/87.

I had to bump this because this is spot on and agree 150% :popcorn:

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