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MAG5035

Central PA - Winter 2020/2021

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3 hours ago, paweather said:

Thanks Blizz! Keep us positive. It will be a month and a half since we saw accumulating snow. I’ll try to remain hopeful. The Januarys seem to be the most boring months around here anymore. 

It’s been 1 month since our top 5 December winter storm that still has everyone in our region above normal in the snow department through today’s date.

Most of our great winters have slow periods.
Some people in other threads have mentioned the great winter of 09-10. That season we also had a great December storm that delivered a similar amount of snow in the Harrisburg area that this year’s storm brought. Then, there was NOTHING in the snow department all of January. Thankfully we were then treated to one of the greatest weeks of winter weather of all time with our 2 February blizzards. After that, we just missed the great storm later in February that retrograded in off of the coast that crushed NJ into upstate New York and New England. We got a few inches of snow from that storm, but it could have been much more with a slightly more west track. March of that year brought Nothing in terms of snow to CTP.

My point is that even our great memorable Winters can have long periods of down time. This year, if we get another good winter storm late this month, another good one in February or March, plus a few small events mixed in, we would remember this winter as a great one and forget about the 5 weeks of down time.

I think that we have much to look forward to in the next few weeks!

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The two periods I have an eye on are D5-6 and D9-10 range. There's also going to be some weak shortwaves in the flow early this coming week but will likely primarily deliver periods of snow showers/light snow to the Laurel's and western PA. For the D5-6 (Thursday-ish) there's been some solutions that amp the northern branch just enough to generate a wave of precip to move across PA, esp on the Euro. This would probably be a light event if it occurred. Something's likely going to come out of this D10 range, but hard to say what at this point obviously. So far today the GFS and Canadian have something notable, but differ in the pattern somewhat. GFS dropped and phased a shortwave out of Canada making the huge storm it has. Canadian doesn't phase and also dumps the trough in the western US raising heights and making a more messy storm that tries to cut. 

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13 minutes ago, paweather said:

I’ll take this

image.thumb.png.fd0f5a1c67022ef9421443c6e0b497b1.png

The storm is far from over at the end of the 12z Euro run at 240 hours. The storm is transferring at a great spot for us near the coast of North Carolina. I wish that we could see the next couple of frames!

 

198C78C6-4520-41A8-A277-2FAD03E95480.png

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The GFS & Euro both have good agreement today with the position of the low for 9 days out. The GFS has the transferred low off of the Virginia coast while deepening as it heads north.

Here is the 12z GFS for comparison.

 

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9F419FCD-A8F7-4B79-8ECB-D31C9D2425C1.png

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The 0z EPS still looked really good for the winter storm chance for early next week. The general low track cluster goes to the Ohio Valley and then transfers to the mid Atlantic coast.

Here are snapshots of one of the 6 hr precip panels early in the storm and then another map with the low clusters later in the storm on Monday night.

 

 

C240A0B2-9283-4AF4-92B3-566AB4B05B29.png

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Here is the 0z EPS snow map for just the 3 days near the time period of this early next week winter storm chance. 
This is a nice snow signal for over one week out. I like that on this map, CTP is right in the middle with some room to spare on all sides for inevitable adjustments.

 

4C61645A-75C2-495B-A501-4761EDAD08A6.png

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One final map for now, which is the 0z EPS overall 15 day snow map.

This is a great snow signal for our region. It is great to see the 6 inch snow line extend to the South of I-95 for the first time in a long time!

This is all mostly for next week, with the early week threat and then another chance later in the week.

 

D80BABF2-BB7F-436F-BAC9-72CF9A792A34.png

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This system in the longer range slated for early next week seems to be solidly in all guidance now in the general sense. All the op guidance last night tried to cut it to some degree, making messy solutions. Todays 12z GFS was more of the same with the Euro and Canadian now having a colder/weaker solution that does slide south and is all snow. GFS's deeper solution has more amplification and some northern stream interaction while Euro/Canadian run a weaker shortwave wave out with no interaction. One would have to worry more about suppression with the latter given the blocking. Either way big differences in the afternoon suite.

I've def been as optimistic as the next person with this upcoming pattern but i've soured a bit the last few days on some aspects. I'm not a fan of the evolution that has come about of retro-ing the pac ridge far enough west that it dumps the main trough into the western US (aka solid -PNA). Yea, with the strong NAO block the storm track will generally try to stay under us but I see limited phasing/amplification opportunity and if you do get it lined up/amped enough to get something like the stronger solutions from last night or today's GFS, they will try to cut. That brings me to the next problem, temps. Now if this potential system does try to cut into the block... it's likely going to weaken and/or transfer, and normally i'd favor a mostly frozen outcome even if the primary did get west of us. Problem is we currently don't have an actual solid cold air connection, and if that main trough dumps into the western US right when we finally see negative anomalies with some teeth building in Canada.. we're not going to be much colder than we are now as a lot of that cold will dump into the trough. So my worry with even the scenario of a stronger system with miller B evolution is we don't have strong enough antecedent cold to stave off a messy wintry mix type event over what normally could be a mainly snow event. Obviously a weaker system like the 12z Euro/Canadian wouldn't have the precip issues as we maintain colder temps, but the weaker system would be more apt to get outmuscled by the -NAO and only give us a lighter event or even a southern or suppressed one. 

Climo's on our side this time of the year with seasonable or marginal temps but we're going to get bit if we don't get some legit arctic air involved in the pattern. That goes double for the Mid-Atlantic region and the southern fringes of our region that can pretty much be an extension of the northern Mid-Atlantic climo. Current case in point... despite passage of a pretty deep trough where at 12z tomorrow morning there's sub 528 heights and sub 522 thicknesses across most of the state in mid-January, we're still going to be above average temp wise. That's something that normally could equate to a day that has highs in the teens to 20s-30ish NW to SE across the state with a run of the mill cold airmass. Harrisburg is forecast to still hit 41 tomorrow.  

ecmwf-deterministic-conus-z500_anom_1day-1014400.thumb.png.1c4ac8314a84e6ae541a7e5615fee388.pngecmwf-deterministic-conus-t2m_c_anom_1day-1014400.thumb.png.a452fecba819cb29095ea01d0084dc7e.png

 

 

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The 12z EPS offered a wide range of solutions from big hits to events similar to the Op run, to whiffs to everything in between. 
Here is the 12z EPS for the 3 day window around this storm chance early next week.

I like where we are sitting at this time.

 

D6A37B9B-9058-48FD-9E34-E9474C3AC8EC.png

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4 hours ago, Blizzard of 93 said:

The 12z EPS offered a wide range of solutions from big hits to events similar to the Op run, to whiffs to everything in between. 
Here is the 12z EPS for the 3 day window around this storm chance early next week.

I like where we are sitting at this time.

 

D6A37B9B-9058-48FD-9E34-E9474C3AC8EC.png

The 18z GEFS looks similar to the EPS for the early next week threat.

73E875BD-EFCD-4E99-9C30-3BEE1D43507C.png

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Had 0.8" overnight, mainly between 10-2am or so. I'm sure that'll be gone by lunchtime like Sat night's measured 0.9" snowfall was yesterday. 

Overnight guidance was meh on our potential longer range event. All the ops have the deeper system now which cuts. 0 and 6z GFS and 0z Euro have primary lakes cutters while Canadian tried to cut but forced a secondary (still a mix event). Ensemble guidance seems to look like it does something similar to the Canadian where front part of the storm cuts but secondary low takes over under PA. These are all mix event scenarios right now. This could trend colder to a more frozen event as it gets closer even if guidance still cuts the low, but I'm pessimistic on holding deep enough cold air for long for the reasons I discussed yesterday unless we force a secondary early enough. 

Longer range pattern just has not looked good on guidance to me. Moving the Pac ridge all the way to the Aleutians or even west of that and dumping a trough into the western US (also gone in the progs is the more sustained -EPO/-WPO) is going to screw up what was looking like a really good period if it comes to fruition..especially so if the -NAO relaxes but it's going to affect it either way when it comes to the storm track and cold air. Of course the longer range is highly changeable, but I am somewhat concerned this change in things may be right. MJO has quietly tracked into a low amplitude phase 4, looking like it may be arcing for a 4-5 run instead of being in the null phase. It's notable because model guidance is completely whiffing on it right now. The MJO site updates once a day with 0z guidance, and today's isn't in yet, but look at yesterday. You can see the big separation between the plotted point and where the ensemble guidance starts it's spaghetti plot. This is like this on NCEP guidance too. Models could be starting to adjust to where the MJO actually is, which would actually support what guidance has the Pac eventually doing. I hate to be pessimistic after being really confident on a very good winter period coming up last part of the month, but just don't like how things have evolved the last few days.   

ECMF_phase_MANOM_51m_small.gif.11686481be4b3c615a34c84fd2ae21c2.gif

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The 0z EPS still looks good for the early next week winter storm chance. The mean still has the general idea of a low track to the Ohio Valley and then transferring off of the coast. There is still over a week to go until the event, so there is  lots of time for changes for the Op runs to lock in over the next few days.

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875DC480-0295-4A4C-BA4F-074B84E3C445.png

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@MAG5035 Thank you for the honest, straightforward assessment. 

It just isn't cold )anything noteworthy) ANYWHERE in the country. Right now, we can get by with an acceptable storm track and enough dynamics to cool thermals. As we start getting later in the season, the lack of cold is going to kill us. 

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So far 12z guidance looks better today for the system, GFS is more of a classic coast to coast out the latitude it came in type system.. which would generally keep it just underneath PA. Canadian actually squashed it under us completely with another shortwave trying to approach at 240. It had much stronger blocking above us (too strong in this instance). Gonna be quite changeable given the range yet and models trying to handle the block. I should clarify that I do think this system is going to be a winter event for us, but whether we can get a mostly snow event is the challenge as this has so far shown a pretty icy look. Whatever comes out is going to get deflected by that block, how much it cuts before it does so is the question. 

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Just now, MAG5035 said:

So far 12z guidance looks better today for the system, GFS is more of a classic coast to coast out the latitude it came in type system.. which would generally keep it just underneath PA. Canadian actually squashed it under us completely with another shortwave trying to approach at 240. It had much stronger blocking above us (too strong in this instance). Gonna be quite changeable given the range yet and models trying to handle the block. I should clarify that I do think this system is going to be a winter event for us, but whether we can get a mostly snow event is the challenge as this has so far shown a pretty icy look. Whatever comes out is going to get deflected by that block, how much it cuts before it does so is the question. 

Thanks Mag!

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