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December 9-10, 2018 Wintry Weather Threat


Ralph Wiggum

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1 hour ago, Ralph Wiggum said:

Not going to post the individual maps but the EPS have many members that are huge hits for our region...several I95 hits as well as several big ticket NW crushers. This is obviously in response to the Euro phasing that we saw overnight. CMC is a phase, Icon was a phase, and the ukmet was looking to go phased as well. There are still timing issues irt to confluence up north and just how far the slp can crawl North but those differences are very much expected at this range. Some minor diffs at 500mb are making for big diffs at the surface. Almost reminds me of a storm we had in Jan 2000 where models missed a final small sw and were showing slp headed off the SE coast but that energy which didnt seem like it would have a large impact caused a phase off of SC and allowed the system to phase and pull almost due N. No I'm not calling for a repeat just noting how at this range without sampling all sw's we are going to see 2 camps between a southern slider and a coastal crawler. Wouldn't let my guard down on this threat especially given the overnight runs. GFS family is in it's own camp for now.

We tend to score on these kind of threats in mid-winter, not sure about this early in December though. With a dynamic setup the vorticity will weaken the high pressure. I think our biggest problem will be temperatures. The ground is so saturated it adds additional heat capacitance to the ground, using more work to heat it up and cool it down. Of course the cold blast helped us in November, we will need something similar to score here. 

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GFS and Euro along with their ensembles all signaling southern squash right now. But hey we have the CMC holding firm... however the SE ridge on the CMC is modeled stronger than every other model squashing this south. And quite frankly that is not really a stretch to occur imo. It also has stronger ridging in the west as well. While the threat looks bleak right now, we are not far off at 500 mb to seeing this come back.

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14 minutes ago, The Iceman said:

GFS and Euro along with their ensembles all signaling southern squash right now. But hey we have the CMC holding firm... however the SE ridge on the CMC is modeled stronger than every other model squashing this south. And quite frankly that is not really a stretch to occur imo. It also has stronger ridging in the west as well. While the threat looks bleak right now, we are not far off at 500 mb to seeing this come back.

Surely worth its own thread. The internet is abuzz with talk of this storm. Like I said early our key will be temperature and the strength of the high pressures. The latest Euro hinted at a sheared out precip field getting squished between to strong highs, reminded me of the of that thread the needle bust we had in late February a few years back (Feb '13 or '14 can't remember). Sometimes those shear scenarios make for interesting ice storms (...shutters in fear) 

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No model analysis here, just a thought on our overall weather since spring: It wants to precipitate.

Sure, this event may very well end up squashed/squished/slide off the coast. But jeez, it seems we can't go more than a few days w/o something falling from the sky. I'm not expecting a HECS or MECS, (heck, it might just be a cold rain). But given the pattern since spring, it's hard to believe we'll end up high & dry.

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37 minutes ago, JTA66 said:

No model analysis here, just a thought on our overall weather since spring: It wants to precipitate.

Sure, this event may very well end up squashed/squished/slide off the coast. But jeez, it seems we can't go more than a few days w/o something falling from the sky. I'm not expecting a HECS or MECS, (heck, it might just be a cold rain). But given the pattern since spring, it's hard to believe we'll end up high & dry.

You took the words right outta my mouth.

I can't get as technical as many but I see patterns/setups etc and for longest time (or so it seems) mother nature wants to drop some kind of precip on us. Let's just hope we get the precip and cold(er) air to connect so snow/wintry precip will occur...

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5 hours ago, The Iceman said:

While the threat looks bleak right now, we are not far off at 500 mb to seeing this come back.

Not sure I agree that this looks "bleak" at this time with 6 days lead time.....that is an eternity with enough hits on the ens and a potent cyclone literally right on our doorstep on several ops.

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Keep that northern confluent energy far enough north or blast it through quicker and it'll allow the heights up the east coast to respond quicker and allow this storm to come further north. If we don't see positive trends with the overall NW confluent flow in the NE and SE Canada then I don't see this storm coming too far north. The flow will just squash the system to the south. Good thing we've seen positive trends today with that regard. You don't want to be in the bullseye of a Miller A six days out. How many of our big Miller A's in the past 20 years have trended back north? These juiced up storms naturally want to pump heights with the latent heat release. Don't get me wrong, the bullseye will likely not be SE PA. Somewhere in VA will get the bullseye, but this storm is not far off from giving DC Philly and NYC a SECS or maybe even a MECS. There's just too much time left to call absolutes.    

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18z GEFS honking...big changes. 50/50 low....check. NAO ridging....check. Potent sw in Miss river valley undercutting confluence as it pulls out....check. Flow backing ahead of sw.....check. Developing PNA ridge.....check. Closed ull in Gulf of Alaska pumping a -epo...check. Nice signal for a deep storm.

gfs-ens_z500_vort_namer_24.png

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31 minutes ago, Ralph Wiggum said:

Looks identical to several of the phased EPS members fwiw

gem_asnow_neus_26.png

This map is similar to the Euro several days ago. The Euro has reputable and repetitive natural history of being pretty much spot on ten days prior to the winter storm event in the past several years. To further expound, the weather pattern for precip this summer and fall has also been very similar to this snowfall map. It appears that just when the current weather pattern for precip this fall  relaxes for a few days, the new lp bombs out  somewhere along the coast. If you look at recent heavy rain events locations, the projected snowfall amounts line up pretty well with this map. The cold air will be here this time, its matter of where the LP begins to strengthen, TN Valley or gulf coast.  If it is in the TN Valley, we stand a good chance in the LV and eastern PA of being wacked if the LP parks its ass at the sweet spot (Chesapeake Bay area.)  My past 30 plus years doing this as a hobby- a folklore has been established for an WSW event for us, If there is an accumulating  snows in either Memphis or Nashville,  the cities along the piedmont and the I-81 corridor get nailed with heavy snow. How far up the piedmont with heavy snow will be the question for this storm event and whether confluence will hold the southern LP at bay especially if strengthens further south and strictly rides underneath the Canadian High out to sea. This a good storm to watch as it evolves and if I was betting man , last minute weather forecast changes  maybe in order for this event for us in eastern pa. as more sampled data is ingested into  the models once the pacific lp gets on shore

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1 hour ago, Ralph Wiggum said:

Looks identical to several of the phased EPS members fwiw

gem_asnow_neus_26.png

haha the weeniees on that other forum site are all in the panic room already. If it isnt modeled at least as strong as a 1996 miller a, they all jump. GEFS outputs really don't look like real life storms. CMC looks like a more classical storm. Its nice to see the higher level features coming around. I think the mesoscales will be important for figuring out the temperatures and precip field rot. I'll take a secs/mecs in december. I can understand why DT loathes the gfs, its good at sniffing them out, just not at figuring out the details. 

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6z gfs had some changes at 500mb irt confluence lifting out faster. The fv3 did the same. This is starting to gain that look of a classic track TN to off Carolinas to inside Hatteras then NE/NNE. More support gained. Note the differences over the Northeast with the overall relaxing of confluent flow allowing for more of a N track. 

fv3p_z500_vort_us_fh132_trend.gif

Flow is backing along coast and trof trying to go negative.

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20 minutes ago, Ralph Wiggum said:

6z gfs had some changes at 500mb irt confluence lifting out faster. The fv3 did the same. This is starting to gain that look of a classic track TN to off Carolinas to inside Hatteras then NE/NNE. More support gained. Note the differences over the Northeast with the overall relaxing of confluent flow allowing for more of a N track. 

fv3p_z500_vort_us_fh132_trend.gif

Flow is backing along coast and trof trying to go negative.

Yep that's what I touched on yesterday. Without the confluent flow lifting out, there's no way really for the storm to reach our regions. Also, a healthier phase would be welcomed.

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1 minute ago, Newman said:

Yep that's what I touched on yesterday. Without the confluent flow lifting out, there's no way really for the storm to reach our regions. Also, a healthier phase would be welcomed.

Positive changes overnight. Not all surface maps are on board yet but not too concerned. I saw what I wanted to and needed to see at 500mb with the overnight runs.

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Was looking at individual GEFS members....there are now a few that stall the low off of NC/SC then crawl it North off S NJ coast over a 2 day+ period. Most of those members are also N of the mean. Needless to say that scenario wouldn't be an all snow event but would be a mess for coastal areas irt tidal flooding. Lots of options still on the table with this one.

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12 ops are still meh with fv3 and cmc still right there. Ironically the Euro is extremely close to making the second wave a beast but who knows. I do know they say a storm delayed is a storm denied. Going to come down to the confluence and timing of NS waves ripping thru the Northeast.

GEFS still has a equal split of suppressed, hits, and full phases. Interestingly the full phases are more snowfall this run than last few. Some HECS in there. If we get to 96 hours and start moving away then time for concern but attm still several options on the table. Conventional wisdom says around 84 hours the mesos start picking up and sampling energy better and draw us all in with some solid solutions. Then the globals follow them. Curious to see if that happens this time.

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The spread on the EPS and GEFS is unreal..there's everything from southern squash to MECS to driving rain storm and everything in between...like steve said above, i don't think we are going to see any kind of consensus until the 84 hour mark. Expect lots of bouncing around until then between hits and non hits between all of the globals. I am concerned of this storm being pushed back though and hope those solutions do not come to pass.

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6 hours ago, Ralph Wiggum said:

EPS are much better looking than the euro op. More later....back to work.

 

5 hours ago, Ralph Wiggum said:

Starting to see more solutions showing up on ens members with LP running the coast thru S NE. If these ideas at least stick I am willing to bet once we get within 84 hours give or take some op spit out insane solutions. 

You mean it will be time for the inaugural Namming? Nam is pretty good at discerning surface temperature/precip sheild issues. OP's are not to be trusted (except the King of course). If we get a fully locked, early-phase showing up consistently on the modeling, I'll go out to get my milk and eggs early.  How have we seen any shortwave interaction with these recent rain systems- I haven't been paying enough attention?  

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