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


Rtd208

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As I said earlier, with the differences at 24 hours out between the models, we'll know tomorrow morning which one completely out to lunch. I'm guessing it won't be the euro/gfs. Not throwing in the towel until tomorrow and we can see if the precip is similar to the CMC/NAM/UK or GFS/Euro. The cmc camp all have precip further north and west than the gfs/euro tomorrow. If we see a widespread surprise southern snowstorm then that will be a good sign for us. If it is just mood flakes down there outside of higher elevation then the gfs/euro camp is going to be a lock. 

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I will note that it is fairly concerning that the Euro/GFS are both just cold and dry for 10 days with maybe flurries on a day or 2. This is what I was concerned about in my winter forecast. Have the cold air around but have a complete lack of any precipitation. A lot can happen between now and then but the pattern forecasted on both models doesn't exactly scream active. There is multiple clippers in the medium-long range, but they either head to our north or get sheared out before reaching us. If we don't get one of them to produce a WWA event, it is very possible we could strike out in our cold period. The good news is that there are no signs of a warm up anywhere in the LR.

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Progressive and fast-moving NS La Nina type pattern to continue over the next 7-10 days. While the hemispheric pattern and even the mean longwave pattern over N Amer as a whole is far from progressive, the NS flow around the PV situated in SE Canada is ripping and not allowing for much digging/phasing between NS and SS. Embedded with Clipper-like disturbances, any of these could cause a snow shower or a quick burst of snow periodically over the next several days.

In the short term, a few weak areas of slp will ride up along the old cold front off well off the East coast. Coastal-grazing flizzard watch in effect as flurries or even a period of light snow could extend as far West as the Delaware River over the next few days while these waves pass by to the S and E. Little to no accumulation expected in general. Coastal areas may even just be plain rain showers as BL temps are always a concern along the coastal plain this time of the year.

Moving forward, pattern relaxes headed into the 2nd half of next week while the -epo weakens slightly and tries to reload. Not impressed with the Atlantic side look to the pattern. Ensembles are mixed with the NAO signal in the LR with some guidance trying to progress the PV into the Davis Strait region shifting the -NAO to a +NAO with a SE Ridge taking shape. Doesn't equate to warmth here always, just moderation and a battle between BN/AN temp gradient possible. This type of setup could actually provide a better shot at an overunning wintry setup though Im not sure exactly which side of the gradient we might be on at this range.

I've said before that thru Christmas we usually need BOTH Atlantic AND Pacific teleconnections working in tandem if we want early-season snow, though there is the rare anomaly where one side does produce. It was looking promising but not sure if the Atlantic is going to cooperate. As we move into true calendar winter, however, we can get away with one or the other for those hoping for frozen precip. I personally dont see any *major* east coast storms for our immediate area over the next 7-10 days with nothing really allowing for big ticket amplification/phasing in preferred locations (unless you are a fish or live in far NE US and Nova Scotia).

So in general, fast moving NS, BN temps, and generally dry for the next 7 days give or take some renegade flakes from Clipper-like impulses that will be swinging thru.





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06z gfs brings accumulating snow back into s NJ. actually even extreme se pa gets a period of light snow. 6z nam is similar but just a bit further south with the precip. interesting tick at this range. keeps me interested as far as getting the first snowfall of the year. we'll see at 12 z if it was just a tick or a trend but if we get a tick like that throughout the day, SE PA would be back in line to get a light snowfall. I will say the radar looks similar to what the cmc and NAM projected yesterday. If you look at the 6z nam, 6z gfs, and current radar, the precip is already further north than they projected. the 00z euro is way off in LA and Miss with precip as well. a good 50 miles too far south. this could be something to watch.

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12 minutes ago, Ralph Wiggum said:

Progressive and fast-moving NS La Nina type pattern to continue over the next 7-10 days. While the hemispheric pattern and even the mean longwave pattern over N Amer as a whole is far from progressive, the NS flow around the PV situated in SE Canada is ripping and not allowing for much digging/phasing between NS and SS. Embedded with Clipper-like disturbances, any of these could cause a snow shower or a quick burst of snow periodically over the next several days.

In the short term, a few weak areas of slp will ride up along the old cold front off well off the East coast. Coastal-grazing flizzard watch in effect as flurries or even a period of light snow could extend as far West as the Delaware River over the next few days while these waves pass by to the S and E. Little to no accumulation expected in general. Coastal areas may even just be plain rain showers as BL temps are always a concern along the coastal plain this time of the year.

Moving forward, pattern relaxes headed into the 2nd half of next week while the -epo weakens slightly and tries to reload. Not impressed with the Atlantic side look to the pattern. Ensembles are mixed with the NAO signal in the LR with some guidance trying to progress the PV into the Davis Strait region shifting the -NAO to a +NAO with a SE Ridge taking shape. Doesn't equate to warmth here always, just moderation and a battle between BN/AN temp gradient possible. This type of setup could actually provide a better shot at an overunning wintry setup though Im not sure exactly which side of the gradient we might be on at this range.

I've said before that thru Christmas we usually need BOTH Atlantic AND Pacific teleconnections working in tandem if we want early-season snow, though there is the rare anomaly where one side does produce. It was looking promising but not sure if the Atlantic is going to cooperate. As we move into true calendar winter, however, we can get away with one or the other for those hoping for frozen precip. I personally dont see any *major* east coast storms for our immediate area over the next 7-10 days with nothing really allowing for big ticket amplification/phasing in preferred locations (unless you are a fish or live in far NE US and Nova Scotia).

So in general, fast moving NS, BN temps, and generally dry for the next 7 days give or take some renegade flakes from Clipper-like impulses that will be swinging thru.

 

 

 

 

 

 

 

good post, i think it is likely most of the area sees at least a period of snow by either a shower, flurries, or light snow this weekend. Nothing major really on the horizon because of what you mentioned. I am slightly worried that all of our big precip events this year are going to be during these slightly above normal times giving us rain and in our cold periods we are just bone dry. There were a few of my analogs that grew more and more dry especially as winter went on and by the time it broke, we had an above normal temp pattern giving us only rain.

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good post, i think it is likely most of the area sees at least a period of snow by either a shower, flurries, or light snow this weekend. Nothing major really on the horizon because of what you mentioned. I am slightly worried that all of our big precip events this year are going to be during these slightly above normal times giving us rain and in our cold periods we are just bone dry. There were a few of my analogs that grew more and more dry especially as winter went on and by the time it broke, we had an above normal temp pattern giving us only rain.

 

I agree with this thoroughly. Fate is bringing us to a cold/dry, warm/wet pattern long term.....I can feel it brewing. Some flakes would be nice tho this weekend. But yeah, nothing major on the horizon it appears.

 

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Unlike most on here I am very optimistic for an overall colder and snowier winter than average. I am pulling together my latest weather article for my Township and will be also putting forth my fearless forecast. I will upload the article later in case there is any interest to see it.

The most important ingredient needed for snow is cold....that we will have much of over the next 4 weeks. An interesting factoid is this December will be the first below normal December in Chester County since way back in 2010. I am not surprisingly forecasting a below normal December (which means it will average quite a bit below normal) after the 1st 6 day positive departures. With a higher than average chance of a White Christmas (over average is a 24% or a bit more than 1 in every 4 years) our last such Christmas was back in 2012. After a cold start to January we should see a sharp warm up by mid-month before a return to colder than normal for the end of Jan into Mid February. After that a return to slightly above normal temps before an early start to spring with above normal temps in March.

Of course take this with a grain of salt....Leave the true forecasting to the Professionals METs

Paul

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wow @ new 12z NAM. it ticked even further west than 6z and brings accumulating snow into extreme SE PA...possibly 2-4 inches if it is correct. inch mark goes up to berks/bucks line. Lehigh valley would even likely gets a period of light snow. Looks like it corrected the precip in the south right now further north.  This could trend into a surpise WWA event for much of SE PA and south/east. Extreme SNJ and the coast even a bit inland will likely have BL issues though.  You have to like the small ticks right now though. Hopefully GFS follows suite and continues it's tick from 6z after correcting the precip down south.. This one is going to be close either way. I do think chances for our first snowfall are very high with this event even if it is only a trace.

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I will wait for the GFS and of course the KING before buying a NAM solution....caution is advised

GFS took a decent jump W. Slower NS energy allows heights to build more along coast which allows flow to back a little more. Definitely closer to the NAM. Maybe a C-2" along river and very immediate burbs, 1-3" S Central NJ with shore points on the line. Maybe an isolated 4" lolli on the GFS.
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If the gfs continues ticking NW, this will soon be a 2-3" line will be into extreme SE PA. The trends thus far are our friend. Both GFS and NAM shifted the precip down south correctly north from their 6z runs. 00z euro was even further south than the 6z gfs and nam with that precip. We'll see if it corrects itself at 12z and if that has any effect in bringing our precip further NW. This still has time to give extreme SE PA a solid advisory snow 2-4", but also has time to shift back to where we were at 00z. 

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Interesting


National Weather Service Taunton MA
719 PM EST Wed Dec 6 2017.

As previous forecaster mention it will come down to trough
amplification entering the Great Lakes late Sat/Sat night. Tracing
back the jet energy that will carve out this mid level trough was
coming onshore to Alaska this morning. Unfortunately 12z upper air
soundings are no longer available across the state of Alaska. This
may result in a different model trend beginning with tonight`s 00z
guidance as this jet energy becomes better sampled by more 00z upper
air soundings along with increased aircraft data at 00z vs 12z

Sent from my LG-H871 using Tapatalk

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36-48 hours til potential onset of precip and what we saw over the last 12 hours irt to model trends are precisely what one wants to see if hoping for a last minute miracle. Still alot of time to shift better or to do a windshield wiper back to the SE. Admittedly, I did not see near-unanimous shifting NW of guidance today.....at least not to the degree of which they did. 18z will be big.....0z is huge.

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