MAG5035

Transitioning over to snow now. 

Mostly sleet falling currently after a bit of a damp start to this. Had a glaze of ice on the car first thing this morning. Now to see if this gets to snow quick enough so it can do something accumulation wise. 

Still not totally sure what to make of today's system. Looks like two different waves of precipitation. Surface temps have cooled off nicely overnight and most areas near or below freezing. However, temps per mesoanalysis at the 925mb (southern third of the state) and 850mb level (most of the state) still above freezing. This means the initial wave of precip arriving later this morning likely to be a mix, which is the main basis of the advisory for the Sus Valley (for the possibility of a T of ice). The second and probably main wave of precip arrives in the afternoon associated with the upper level low itself. Under this is where we have the cooling at 925 and 850 to support an all snow column. Track of the weak mid level low features seem a tad NW to me, thus I kind of support CTP having the best snows from UNV on to the NE instead of LSV locations like MDT. This could cover more of the central counties depending on how precip develops though. Near term guidance has generally been putting the best QPF from the upper level low from the central counties to NE PA. Dare I say Williamsport appears to be the new snowtown these days haha. 

Was able to get a couple general measurements of the ice. Looks like about 0.2" of ice accrual. Temps still hovering in the 33-34ºF range. 

I upgraded to an iPhone 12 Pro a few weeks ago, it has one heck of a camera system. Really excels at the low light stuff, and also showing we’re still in the thick of the icing phase of this system here.

Have had some sleet occasionally but all freezing rain currently. Starting to be pretty noticeable on the trees. Have a feeling this is gonna end up more towards a warning level ice event.

24 minutes ago, canderson said:

I’m surprised dauphin is in the WWA - but the hills up north might be why. 

You only need a T of freezing rain to verify a WWA, which is fairly likely even in H-burg. 

50 minutes ago, showmethesnow said:

Admittedly my excitement level has increased this last week after each day of runs. But last night's run of the EPS has me over the moon. And the EPS is not on an island as both the GEFS and the CMC are extremely similar.

When I see this, the whole of Canada torching with cold anomalies under riding it through almost the whole of the CONUS...

And please, no references to how this sucks because our source region for cold air is on fire. Doesn't matter here.

 

 

Then I see this... The PAC firehouse which has been blasting the west coast and overwhelming the flow through the CONUS is pulling westward and weakening in the extended. And the southern/subtropical jet, which has been active, is now aligning up and off the east coast and planting around day 10 in a very favorable local, all the while strengthening as we move forward in time. 

 

 

The two maps portend well for what we would actually see at 500 mbs. And they did not disappoint. I think we would be hard pressed to find a better look then what the EPS (and other models) are now throwing out. This is a seven day mean from day 8 to 15. As we can see there is massive blocking now projected over almost all of Canada. This will tend to force the storm track farther south through the CONUS. If you look over Alaska and was hinted at by the PAC jet, we see that the PV has shifted west so subsequently energy/storms revolving around it have shifted west as well. This is a favorable local as it will help to pump up heights in western Canada. In the western CONUS we now have ridging/higher heights from subtropical regions extending all the way up into Canada. The importance of this is twofold. It sets up a delivery of cold air into the central US which will be pushed eastward underneath the blocking through Canada. It also is playing a part in bumping up the southern jet from the Gulf and up the East coast which provides moisture as well as potentially injecting southern stream energy into any potential storm. As you can see, we have lower pressures over the southern states and the Gulf and it is exactly where we want to see them. If you note they are extending eastward trying to connect with lower pressures in the north Atlantic. This is a signature look for storminess in the east. You may say the lower pressures  (pseudo 50/50) in the N-Atlantic are too far to the south and east for our needs. But no, in this case they are exactly where we want to see them when considering the given projected pattern. Now when it comes to snow there is always a degree of luck involved in the East. But really, this is a winning look for our chances. It doesn't get much better then this.

 

 

 

If it wasn't exciting enough to see the above for the day 8 to 15 period, what really should excite you is that this will more then likely be a very stable pattern. This is a pattern that could potentially last for quite an extended period of time. So what would I expect given the above? In my opinion this argues for the axis of heaviest snow being centered around the mid-Atlantic. Somewhere between New York city down to Richmond. This could very well be a case where those in NE are smoking cirrus time and again, especially away from the coast, and those in DC/Balt/Philly are exhausted from shoveling 1-2+ feet of snow time and again. 

Now some people throw out comparisons to glorious previous winters at the drop of the hat. I don't. I believe that each winter is unique in its own way. So though there may be similarities there are also differences. Differences that can have a big say on the final outcome. That said, the similarities we are now seeing are striking to a previous winter. Dare I say 09/10? 

Below we have the mean for the month of Feb 2010. I want you to compare this to the above 7 day mean from the EPS. They are eerily similar. Now some may look at the lower pressure anomalies on the 7 day mean above and say it doesn't quite match up to Feb 2010. Let me just say, if we were to run that 7 day mean forward for another 2 1/2 weeks (to give us a full month) I would put good money that this is the look (lower pressures in the east and off the coast) we would end up with as the storminess kicked in.  

 

 

 

Now there is always a degree of luck involved when it comes to snow. But if the above projected pattern is in fact what we see, I very much like our chances as we are rolling with the equivalent of loaded dice that come up 7's almost every time. 

Generally in agreement here. While not completely flipping the EPO, ensembles have been at least neutralizing it some as it's gotten out past next week. It's a key thing to happen, because we do have an issue of source region of cold initially which likely manifests in the coastal later this week probably not getting cold enough at the low levels for much snow in PA (more likely toward interior NY/New England) and probably the next system of note that comes about later next week. But you can see it on the models.. once they build any semblance of higher heights on/just off the west coast, it's enough to get the eastern US right where we want it. With that block over the top, we don't really need a raging -EPO ridge to succeed (though an EPO ridge would be nice). We just need to tone down the Pac jet enough as to not flood the CONUS with Pacific air under this awesome block we have materializing in the NAO/AO realm. I'm pretty confident were going to get there.. it just might be around week 2 of Jan or so where we really start seeing this. 

The 09/10 comparison is relevant here.. simply because we haven't seen that kind of a strong and stable NAO/AO blocking regime since 09/10 and the early part of the 10/11 winter. What I'm curious to see is where the obvious differences between this winter and that winter take us. Of course the big difference is we're working a solid La Nina vs 09/10's solid Nino. The other thing is the SST anomalies in the north Pacific. I was going to post about this earlier in the month, but then the big snowstorm showed up and that was the big topic. But pretty much when comparing past Nina's of the last 25 years+, you won't find one with the + anomalies in the N Pacific that this one has. Most of them are quite cold there. The most recent Nina in 2017-18 is about the closest comparison but still had more colder water.

My big worry initially when seeing anomalies like this going into the winter was the assumption of not much help from the NAO/AO and seeing hostile teleconnections from the Pac side materialize. One could see the potential torch in the making. The blocking is a game changer, and now suddenly one can see the potential from an active pattern and suppressed storm track from the blocking. Back to 09-10, here's what that looked like at this point.

The Atlantic and the Gulf of Mexico got even colder with respect to average when February rolled around. But yea, huge difference in SST makeup. I tend to suspect that the much warmer N Atlantic this year might help keep a tighter storm track to the coast and you might not see quite the suppression you saw in the 09-10 winter, which was certainly less memorable in New England.. or Williamsport for that matter if we're talking about this particular subforum haha. There were some folks in here that got next to nothing from Feb 5-6, 2010. It's going to be interesting to see how all this shakes out going through January. If we hang onto the -NAO/AO regime we're definitely going to have chances.  

Currently getting a brief period of steady snow early this morning, ahead of what's looking like a really icy New Year's Day later on tomorrow around here.  

5 minutes ago, CarlislePaWx said:

Quick review from 12Z GFS & NAM.  GFS has total qpf for the late Thursday through Friday evening of 0.85".  Of that, it shows almost a perfect 50/50 split with 0.39" of freezing rain falling between Fri 12Z and 18Z and a temp of 30 to 31 degrees.  Then in the next six hours it shows 0.46" of rain with early temp of 33, rising to 36 by 0Z Sat.

NAM has total qpf of about 0.5" through 0Z Sat and is 3 to 6 hours slower with the whole event.  It gives 0.2" of freezing rain mainly between 18Z and 21Z Friday and a temp of 31 to 32, followed by 0.3" of rain with a temp of 33 degrees at the end of the run 0Z Sat.  It looks like there might be another period of rain between 0Z Sat and 6Z Sat, but probably no more than an additional 0.1".

So, both models are showing an ice storm to ring in the new year during the morning into the afternoon Friday.  I'm sure it will change, of course, but I thought I'd throw in my 2 cents of analysis since I had nothing better to do...lol.

Models have been pretty solid on this threat for the last couple days once they started sticking that high pressure to our north. The high itself has gotten stronger on the progs too as we've gotten closer. It's a pretty good setup for a straight-up ice event, especially in the interior counties. Mid-levels are easily shot already lacking much cold aloft and the system cutting well west. The fairly strong high solidly anchors the sufficient cold we do have in the low levels. The cutting low pressure is weakening as if lifts northward, so it may draw out the ice longer in the central counties. I'd say this is probably an area-wide advisory event in the making, and potentially a WSW worthy one in interior central/north central PA, dependent on QPF and if sleet is a more predominant p-type during the first part of the event.

Canadian joined the Euro today having that kicker system right behind this potential ice event. Both were very marginal in their cold air availability for snow (Canadian somewhat better). 

4 hours ago, Blizzard of 93 said:

The end of the 12z EPS, GEFS & Canadian ensembles today all had a similar look with a great blocking pattern with a more west based -NAO and the trough in the east.

Good winter storm tracking days are ahead if this look verifies!

 

With the EPO/WPO forecast to go way positive during at least the opening week of January, I don't think we're going to live up to this high latitude blocking pattern's potential initially. An active Pac jet (+EPO/WPO) is going to ensure trouble in getting access to any decent cold into our part of the CONUS in a pattern that had already been kind of lacking it since our big snow event with the exception of the couple days in the aftermath of the X-mas eve system. If we break this down, or better yet get a -EPO ridge to build.. then you force a better alignment from a colder source region (such as NW Canada). That coupled with the high latitude blocking in the NAO/AO realm.. ideally shifting westward a bit in time would provide a much colder pattern and a suppressed storm track that is less apt to try to cut in the east. We're just not fully there yet. 

Personally, I'm eyeing up the second half of Jan more than the first half and considering anything we do score in the next two weeks a bit of a bonus. We have a pretty decent strat-warm event seemingly in the cards in the first part of January and it usually takes a couple weeks to start realizing whatever the results are in terms of cold air outbreaks in the mid latitudes. The -NAO/AO regime is looking like more of an overall theme rather than just a passing fad and pretty much couldn't get a more opposite look from what was just getting warmed up this time last winter up in that realm. This significant of a NAO/AO blocking regime was not something I was expecting to see out of this winter. Barring a major change up there or the MJO suddenly busting out into a strong 4-5-6 pulse (currently not looking very likely attm), i'm fairly confident in saying that we're going to eventually see a really good period of winter weather set up at some point.

Might not want to sleep on this New Year's event potentially becoming some kind of a wintry mix event in C-PA.  Models have been toying around with sending the first piece up into the lakes, pulling a front across and holding back a good bit of energy for another wave to roll up. While the southern wave builds, models have been getting some high pressure in place over us/just to our north. Positioning of the mid-level features (850 & 700 lows well west) definitely aren't looking ideal for an extended snow event, but get that high over us for at least a bit and we probably are going to be dealing with some kind of messy mix event on at least the front end. 

10 hours ago, Ahoff said:

Officially we have 23.6" for the month.  That's the 3rd snowmelt December ever!  Chances don't look great for getting to #2, but we'll see.

Also tied for second snowiest Christmas day ever and snowmelt since 1935!

You guys definitely killed it this month over there in western PA. 

If we can speed up by about 12hrs what appears to be a really similar situation to yesterday shaping up on New Year's Eve/Day, maybe there can be some snow added to December's total haha. 

Merry Christmas everyone, it did somehow manage to be a white one here.

Straight-up moderate to heavy wind driven sleet at the moment, maybe a couple flakes. Starting to accumulate and deck's starting to freeze. 

There's two boundaries that are noticeable on velocity images. One associated with the thin line of intense rainfall in the warm sector (impacting H-burg and LSV) and a secondary boundary further west, which i've noted with the blue dash.. that is the actual cold front boundary.

32 minutes ago, Blizzard of 93 said:

@MAG5035

How is the cold front doing in your Area now?

What are your thoughts on the prospects of seeing some snow from your area over to the Susquehanna Valley tomorrow?

I still don't think much makes it over to the Sus Valley but we'll have to see how much precip hangs on behind the cold front. Short range guidance like the HRRR and NAM haven't had much lingering by the time it's cold enough. There could perhaps be enough to witness a changeover period and perhaps a coating in spots in the region east of I-99 over to the Sus Valley. The big thing to watch first thing tomorrow morning is for untreated stuff to freeze up. 

Changeover is starting to occur. Sleet, rain, maybe some wet flakes. Temp back to 35ºF.

Frontal passage has occurred here, pretty decent gusty winds. Temp only got to about 41 or so during this whole thing today (about an hour or so ago) and it's back down to 38 already. Frozen precip shouldn't be too far off. 

It seems like the most significant flood potential focuses on the Susquehanna main-stem (and NE PA tributaries), especially in the Upper Sus Valley on into NE PA where that particular region has the trifecta of significant rainfall, the most significant existing snowpack, and a several hour period where warm temps via southerly flow punch up into eastern PA to further enhance a more rapid snow melt. Short range models like the NAM have been downright excessive with rain totals, and the next several hours this evening will reveal if that comes fully to fruition as radar trends look to be starting to focus the heavier rainfall rates into eastern PA along the Susquehanna. 

The other major tributaries coming from the central counties (West Branch and Juniata watersheds) look to have a significant rise but most point forecasts appear to stay below flood stage along those rivers. Temps in this part of C-PA are locked into the upper 30s-low 40s and as mentioned, heavier rainfall is starting to focus towards eastern PA. Appears that any surge in temps in the central probably comes close to/with the frontal passage as the stable b-layer gets mixed out. Lack of big time flooding coming from those two tributaries probably prevents the main stem from going full blown '96 repeat in lieu of a more minor-moderate flood event coming primarily from upstream in NE PA/southern NY. Definitely not ideal anyway you slice it, what an ugly Christmas Eve weather-wise. 

This lead up to the Christmas holiday is definitely looking like it's going to deliver a hard lesson about most of this region when it comes to December snow. Something to the tune of the only guaranteed White Christmas is one where it's snowing on X-mas Day haha. I'm not sure that the portions of north-central PA that got the tremendous totals are going to see a complete pack loss but it's going to get a pretty big dent in it from the Christmas Eve system while the rest of us probably lose the majority of it. Just was hoping to avoid that long drawn out event with the strong cold front but we're going to get a pretty good dumping. Still a bit uncertain about any changeover, that seems the favor from the Laurels west in PA currently and it might be even further west than that with the possible snow swath. Models drawing that secondary low pressure wave that rides up the front through the middle of PA is a pretty good recipe for a slot and shutoff of most precip by the time the cold air's all the way in. 

At least this storm system will be a one day affair and send some pretty decent cold in for Christmas Day. Then heading towards New Year's we have a good pattern setting up with the nice -NAO block and overall high heights near the pole. So good chance we'll have one or two shots at an event between Christmas and New Years. Here's the possible problem I see, and we got a dose of this problem the last couple days. I'm kinda worried about the amount of cold air we might have in this said favorable pattern. A look at temp departures of our source region in Canada on the models shows a fair amount of above normal temps and not really any bouts of big time cold building with respect to average. Obviously, above normal in Canada is still "cold", but that air mass modifies as it gets to our neck of the woods. I'm hoping we don't waste a couple serviceable storms on account of not having good surface temps to work with (see the last day or so).

7 hours ago, anotherman said:

Never went below freezing last night, and that had an impact.

Same, it leveled up at about 34ºF most of the night last night and it hasn't been below since. Def shrinking the pack some here (which has no sleet in it). The active northern branch on the heels of the big storm has kept temps moderate at night with the exception of the one clear night Saturday Morning.  

1.5" this morning and still snowing lightly. 

10 minutes ago, Blizzard of 93 said:

Congrats! 
Do you think that the Clipper on Monday night will produce much of anything outside of the mountains for the Susquehanna Valley?

4 minutes ago, Blizzard of 93 said:

Also, today, do you think any of your snow might survive the trip over the mountains to the Susquehanna Valley?

Might get a period of light snow this morning over there but probably little to no accumulation off the mountains as best precip hasn't been progged to get much further over than western PA (although this is def overachieving here). It appears the clipper might have a better chance of delivering lighter accums (up to an inch or so maybe) out to at least some of the Sus Valley, despite clipper low track going a bit to the north. 

Snowy start to the day here, working on an inch and a pretty good burst of heavier snow currently.