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Potential 12/8 Event Discussion Part I


earthlight

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Well I think the thing that has me (and you) most concerned about this set up is how small the window is to get any accumulations. It's not about meaningful snow, it's about snow at all. If the shortwave changes orientation or timing just slightly, this storm could bring much warmer air in to the low levels very easily.

The other side of it is that we have a frontal boundary offshore, so you have to wonder about positioning, model QPF along the front (sometimes overdone), and the interaction with the shortwave itself.

The airmass entering behind the front is definitely fresh and cold. So that helps. I just think we are walking a serious tightrope here.

I agree, we are still walking on very tight rope here. Still plenty of time for things to trend the wrong way. However, the Euro on our side, has gotent me a tiny bit hopeful.

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The RSM members are all monster hits, while the NMM and ARW members are south and east. Leads me to believe the NAM may tick south and east as well. There aren't any ARW or NMM members which have precip into our area.

At least none of them show rain. Which, given the state of the atlantic, should be our biggest fear.

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The RSM members are all monster hits, while the NMM and ARW members are south and east. Leads me to believe the NAM may tick south and east as well. There aren't any ARW or NMM members which have precip into our area.

Just going to post this, RSM's doing this when the more reliable members are blanking says a lot.

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A 2-4" event before Dec 15th is a good deal in any winter, regardless of the pattern. Many years we're snowless until the 3rd week of December, sometimes the last week or later.

I'm hoping it verifies so it finally shuts up all the "no blocking no snow!" people, who seem to think we can't get even minor snows in this pattern (no one in particular, just seems to be the popular catch phrase these days). Transient +PNA/-EPO periods can do it for minor/mdt snows at this time of year.

Yup yup good stuff here. I said in a post either yesterday or Saturday that there is no reason why this Pacific pattern cant produce some minor snow event or a mixed precip event, despite the raging +NAM. It's a small window here through around mid-month before another warm period, but it looks like we can get a little something out of it this Thursday! It still has plenty of room to go wrong especially the closer to the coast, but I'm feeling good now at least for our friends with any elevation just to the northwest.

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Euro ensemble mean snow swath is NW of the op. 2" isohyet right on I-95 from DCA to TTN, then all of N NJ/NYC/SNE get 2-4. Back into PA, 2" isohyet goes JST-AOO-MDT-SEG-IPT-NW of AVP... still like my idea of flurries on the backside for I-95 with heaviest snow swath from LNS-ABE for our area.

From the Philly thread.

2"-4" for NYC on the euro ensembles.

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Seeing the gefs mean so amped up and so wet, is usually a sign of increased qpf coming.

Strange seeing the operational gfs with almost nothing and the usually less amped up ensembles with nearly 1.50" of precip.

http://raleighwx.ame...emblep72096.gif

The GEFS mean has been too wet in the past. This is also a relatively fast moving system. Pretty much over in probably in after 12hrs. Unless it's more amped up, I doubt we see qpf totals much higher than .75" from this event. Especially, if it's colder and flat.

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Just a side note on this...the SREF uses the old WRFV2.2 core with the NMM and ARW. The new nam is using the new WRF core (3.3) which may not have any trend related to the NMM and ARW from the SREFs.

The RSM members are all monster hits, while the NMM and ARW members are south and east. Leads me to believe the NAM may tick south and east as well. There aren't any ARW or NMM members which have precip into our area.

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I've just been gone for less than a day and now this shows up - I guess that's what happens when a snow potential falls under an overall unfavorable pattern... yesterday it seemed most were saying that this storm wouldn't produce snow, has this changed since last night or are the models showing a snowstorm still considered outliers?

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I've just been gone for less than a day and now this shows up - I guess that's what happens when a snow potential falls under an overall unfavorable pattern... yesterday it seemed most were saying that this storm wouldn't produce snow, has this changed since last night or are the models showing a snowstorm still considered outliers?

The SREF mean came NW from 9z, the 12z NAM gives a moderate snow event, the 12z GFS came NW from 0z, the GEFS are really amped with a few :weenie: solutions, the GGEM now gives us a light snow event, the Euro and Euro ENS give a moderate snow event. It looks like as if it is more likely that I-95 will see at least some flakes, and possibly accumulations on the roadways, since this event looks like it is occuring at night.

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The SREF mean came NW from 9z, the 12z NAM gives a moderate snow event, the 12z GFS came NW from 0z, the GEFS are really amped with a few :weenie: solutions, the GGEM now gives us a light snow event, the Euro and Euro ENS give a moderate snow event. It looks like as if it is more likely that I-95 will see at least some flakes, and possibly accumulations on the roadways, since this event looks like it is occuring at night.

Thanks, all I had to do was to step away from the computer for just 1 day and all of this unfolds... The 12z NAM is almost certainly overdone IMO, so far this fall it seems to have frequently overdone the extent of QPF into the cold sector and the intensity of the QPF, but it does seem to have potential to bring a light snowstorm. We've seen many cases where snowstorms happened in overall unfavorable patterns, such as 3/21/11 and the late October storm as well.

Is the 12/5/09 storm a potential analog to this storm? That storm didn't have a strong Canadian PV, although it was also a rain to snow situation for I-95 with a quick moving weak coastal.

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