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E PA/NJ/DE Winter 2017-18 OBS Thread

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Got a dusting overnight that stuck to mostly cold surfaces like cars. A bit of a surprise because it was progged for a low chance of sideswipe and mostly further N/W of here.  Temp stayed at or above freezing through the night (so far).  Currently 33F and cloudy.

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Most models including the NAM have a quick moving clipper Thursday morning. Not much accumulation coating to inch but temps into the low-mid 20s.
namconus_ref_frzn_neus_45.png

namconus_T2m_neus_46.png

 

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00Z EPS looks ugly in the LR for cold and snow. Still have the pacific cooperating but the -NAO completely breaks down bringing a zonal pattern. Now this is a big change from 12z and models have a tendancy in breaking down patterns too quick but if it is reality, then January looks warm and wet. Could be a good pattern for Central PA up through NNE though. 6z gfs ensembles are a bit similar in the LR as well. Now we may get a chance of a storm before this switch but if the model is right, it'd be cold and dry until we get the shift to inland cutter and rain. Shame as the pacific pattern couldn't look any better in the LR. I was worried about this in my winter outlook. I thought the pattern shift would occur much later into January, and it still may as many times we see a -NAO in the long range continue to be pushed back, but if this is right I think a BN winter for many would be just about a lock.

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In the short term, I think most places should see at least an inch on Thursday morning though. Don't go by the clown maps on this one. There is not a lot of precip but we will get some good ratios with the clipper. I think 20:1 could be possible in places and so 1-3" should be common through the area. 3" more common in the LV. After that though there is nothing really on the horizon. Still most area's should be at or above their average snow for December after Thursday.

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00Z EPS looks ugly in the LR for cold and snow. Still have the pacific cooperating but the -NAO completely breaks down bringing a zonal pattern. Now this is a big change from 12z and models have a tendancy in breaking down patterns too quick but if it is reality, then January looks warm and wet. Could be a good pattern for Central PA up through NNE though. 6z gfs ensembles are a bit similar in the LR as well. Now we may get a chance of a storm before this switch but if the model is right, it'd be cold and dry until we get the shift to inland cutter and rain. Shame as the pacific pattern couldn't look any better in the LR. I was worried about this in my winter outlook. I thought the pattern shift would occur much later into January, and it still may as many times we see a -NAO in the long range continue to be pushed back, but if this is right I think a BN winter for many would be just about a lock.

 

Classic Nina look LR. However, as I mentioned back in my outlook, there would be some wild-card *possible* saving graces as we head into Jan-Feb which would help us avoid an all out torch in deep winter which can be common in some Nina years. Most important are the persistence of the EPO ridge AND the staying power of the -AO. This allows for cold air to filter into the NE. Couple this with the Nina-ish SE Ridge I talked about and you can see this look is reflected nicely in most of the LR data headed into late month and the New Year. This setup has all the markings of a SWFE/gradient pattern with our general area as a battleground. With the balance between the cold side of the gradient (thank you epo/ao) and the warm side (thank you SE Ridge/+NAO) and there will be plenty of threats moving forward. I still dont believe we end up BN snowfall this season. The wrench in all of that would be ice if the epo/ao hold with the N Atl look as progged. Thermal gradient with the deep cold could make things more icy than snowy but that is mere speculation. General Atlantic look is moving toward very progressive as originally thought so I think any wrapped up Noreaster style storm is off the table for a while though we could cash in on overunning gradient decent snows or thump snow to rain events if the pattern aligns in our faver.

 

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In the short term, I think most places should see at least an inch on Thursday morning though. Don't go by the clown maps on this one. There is not a lot of precip but we will get some good ratios with the clipper. I think 20:1 could be possible in places and so 1-3" should be common through the area. 3" more common in the LV. After that though there is nothing really on the horizon. Still most area's should be at or above their average snow for December after Thursday.

Guidance keeps adjusting the 500mb farther N with each run. We do have the NAVGEM with the energy in a good spot farther S but this could just be its progressive bias in play. Have to watch if it keeps moving N or the trend stops. Thinking LV can cash in, South of there in jeopardy. Need that energy to pass 75 miles or so to the South of mason-dixon line for PA Turnpike South to 40n to cash in with light accums.

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One can't help but notice the pattern resembling the analog of 2005 with early cold and snow, though that year was colder and may have had more snow in December depending on what happens the next 10 days.

 

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4 hours ago, Ralph Wiggum said:
4 hours ago, The Iceman said:
In the short term, I think most places should see at least an inch on Thursday morning though. Don't go by the clown maps on this one. There is not a lot of precip but we will get some good ratios with the clipper. I think 20:1 could be possible in places and so 1-3" should be common through the area. 3" more common in the LV. After that though there is nothing really on the horizon. Still most area's should be at or above their average snow for December after Thursday.
 

Guidance keeps adjusting the 500mb farther N with each run. We do have the NAVGEM with the energy in a good spot farther S but this could just be its progressive bias in play. Have to watch if it keeps moving N or the trend stops. Thinking LV can cash in, South of there in jeopardy. Need that energy to pass 75 miles or so to the South of mason-dixon line for PA Turnpike South to 40n to cash in with light accums.

Yep, after 12z looks like south of 78 is in trouble for anything more than a coating.

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Lost in the fray of the snow and the week tracking it is how much the cold wave has tempered from what was being projected at the start of December. The mild up the last 10 days of the month could skew the colder than normal month back to near average.

 

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4 minutes ago, RedSky said:

Lost in the fray of the snow and the week tracking it is how much the cold wave has tempered from what was being projected at the start of December. The mild up the last 10 days of the month could skew the colder than normal month back to near average.

 

If you look at the EPS it does'nt indicate much of a warming the last 10 days.

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12z euro drops about 0.1 inches precipitation from the Thursday morning clipper. Temps into the low-mid 20s would yield 15:1 ratios, if not slightly higher. Newest NAM runs are concerning putting the bulk of the precip north of I-78, though, and I don't see this being a strong clipper as well. Hopefully someone can cash in on a lucky inch or two to whiten the ground up again.

ecmwf_t_precip_pennsylvania_66.png

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20F Levittown. Temps crashed last night. Was at 46 at 7 PM and was in the mid 20's by midnight. Pretty impressive cold shot.

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Not impressed with tomorrow's Clipper system unless N of 78 into the LV and even there I wouldnt say Im encouraged or impressed. Maybe an inch or two in spots but generally is going to look very snow showery and ragged on radar. South of there to the PA/MD border maybe some flurries or a snow shower or two. Little if any accums.

12z ens yesterday thru 6z today have shown improvement. The 18z GEFS which looked the worst scenario seems to have been a hiccup. Models are still showing a reload of the overall pattern headed into next week. EPO and AO ridges relax before EPO goes back on steroids late in the period. AO will eventually go from neutral back into negative territory. These 2 features are our source of cold thus far so with those ridges relaxing we moderate somewhat next week briefly before cold/mild battleground sets up in the region towards Christmas. NAO still looks meh with any ridging being progressive. SE ridge is showing up but may be pressed South with the Arctic intrusions attempting to infiltrate the NE. We will likely be tracking a couple systems next week with at least one being a cutter in response to the pattern reload.....others are borderline but have sneaky potential....active storm track definitely seems to be ramping up.

Just to throw out a bone, some of the LR ops/ens hint at a borderline wintry event centered around the 25th for anyone hoping for White Christmas miracle this year. Obviously a ways out there and also several systems prior to that but just noting it for kicks and giggles at this point.






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Yeah, we are kind of striking out on the 2 events this week. Too bad.

But things still look interesting going forward. There is certainly potential. We already are beating last year which was the search for anything other than temps where we need to turn on the air conditioner. (I think it was 70 degrees on Xmas day)

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