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Significant Ocean Storm March 5-7 2013 Discussion Part II


earthlight

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Nonsensical. The always inaccurate thermal profile on the GFS combined with hideous convective feedback makes it clear to me that this is way off. Hate the clown maps even when it shows 2 feet. They are awful.

Going by soundings, JFK should be snow sometime after 0z on the GFS, and it could still be a little too warm. There would definitely be more accums on at least the west-central portions of Long Island than the clown map shows.

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Nonsensical. The always inaccurate thermal profile on the GFS combined with hideous convective feedback makes it clear to me that this is way off. Hate the clown maps even when it shows 2 feet. They are awful.

 

i agree...just posted it cuz someone asked.

 

on the other hand, once we are inside the RAPs range...it did extremely well with the feb SNE event....its going to be a good tool to use imo.

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West of Long Island and Manhattan the clown maps are even more silly. You cannot trust the GFS thermal profile in these type of storms, soundings output included. The convective feedback also total messes with the qpf. The GEFS shows very clearly that the GFS indeed has massive convective feedback problems.

 

Going by soundings, JFK should be snow sometime after 0z on the GFS, and it could still be a little too warm. There would definitely be more accums on at least the west-central portions of Long Island than the clown map shows.

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WINTER_GFS0P5_SFC_ACCUM-SNOW_96HR.gif

Thanks.  By the way some were talking, I assumed the GFS was showing 4-8" for NYC and the immediate suburbs, not 2-4" (and maybe only 1-2" south of I-78 in Central Jersey).  With the 1" of liquid equivalent discussed, this means most of the precip is falling as rain.  Huge departure from the NAM in terms of output.  I can see how this is going to be a difficult forecast and why people like Lee Goldberg on Channel 7 are putting up 2-5" or 3-6" amounts.  Kind of hard to say 2-16", lol. 

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West of Long Island and Manhattan the clown maps are even more silly. You cannot trust the GFS thermal profile in these type of storms, soundings output included. The convective feedback also total messes with the qpf. The GEFS shows very clearly that the GFS indeed has massive convective feedback problems.

Look at the QPF max it generates southeast of where the comma head precip would be. The individual members may be having the same issues with feedback. That would shear out and diminish the comma head related precip too much most likely.

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Look at the QPF max it generates southeast of where the comma head precip would be. The individual members may be having the same issues with feedback. That would shear out and diminish the comma head related precip too much most likely.

I noticed that as well but it still not blatantly as bad as the Op. End of the day, between you and me, I want the Euro on board and to maintain up until event time (as well as all the other models) before I feel at ease. It has been a crazy 12 hours waiting for this Euro run considering all the trends we saw at 12z and 18z and now again at 0z, let's hope we all see what we want in an hour or so. At 200 hours I predicted 12-18 for NYC metro, I am sticking by that even if I have to go down in flames while doing it lol.

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That's pretty reasonable...I could see Westchester doing a lot better because they might start off as snow during the day Wednesday while parts of NYC mix, and then stay snow longer if the low wraps up too much when it occludes and brings in warm air. I could see 12-18" for Dobbs Ferry if everything goes well, although that's asking a lot. If I had to make a forecast right now it'd be:

 

NYC: 4-8" (lowest amounts in eastern Queens)

Westchester, Rockland, NNJ, North Shore LI: 8-12"

Eastern LI and central NJ: 3-6"

 

Eastern areas may see more QPF, but may also waste more, so it could be a wash if they get the really big precip totals. This happened in the 2/8 blizzard: LI and CT had some sleet mix in, and rainfall during the day, but they ended up with the jackpot totals because the huge liquid/QPF made up for it. 

 

In the 2/8-9 storm, we blew 0.20" out of 3.87" liquid eqivalent on rain/mix.  No complaints here. 

 

NAM to me looks like mostly a wet snow bomb with taint on the backend as it warms the mid levels.  I didn't look at soundings, but I inferred from the partial thicknesses that there would be a sizeable sub freezing layer remaining below 850, so I wouldn't rule out sleet reaching the surface on the backend if the boundary isn't too warm.

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So far total model qpf for the event, pending on rates 30 - 50% lost to rain or poor rates

 

00z (NYC/NE-NJ)

 

SREF : 1.50 - 1.75

NAM : 1.75 - 2.00

GFS:  0.80 - 1.10

RGEM : 0.25 - 0.50 (thru 48 hours)

UKMET: 0.35 - 0.50

GGEM : took the night off

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So far total model qpf for the event, pending on rates 30 - 50% lost to rain or poor rates

 

00z (NYC/NE-NJ)

 

SREF : 1.50 - 1.75

NAM : 1.75 - 2.00

GFS:  0.80 - 1.10

RGEM : 0.25 - 0.50 (thru 48 hours)

UKMET: 0.35 - 0.50

GGEM : took the night off

 

 

Well if Bulk is at night and it comes down heavy majority should be snow IMO.

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30-50% loss to rain? Where do you speak of? I think for most of C and N NJ along with area just outside of the city, it goes from nothing to moderate snow quite quickly. 700 mb RH and VV's align right at the cusp of 90%. Hence, it looks to be one of these events where the snow comes in like a wall.

 

So far total model qpf for the event, pending on rates 30 - 50% lost to rain or poor rates

 

00z (NYC/NE-NJ)

 

SREF : 1.50 - 1.75

NAM : 1.75 - 2.00

GFS:  0.80 - 1.10

RGEM : 0.25 - 0.50 (thru 48 hours)

UKMET: 0.35 - 0.50

GGEM : took the night off

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30-50% loss to rain? Where do you speak of? I think for most of C and N NJ along with area just outside of the city, it goes from nothing to moderate snow quite quickly. 700 mb RH and VV's align right at the cusp of 90%. Hence, it looks to be one of these events where the snow comes in like a wall.

 

Pending on guidance... some rain , some lighter snowfall rates with lack or minimal accumulations.  Perhaps 25% to as much as half.

That was a quick estimate.  

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