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Central PA Late January thread


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I have no clue how to read sounding charts. Anyone have an easy explanation and a link to MDT?

It's not easy to decipher at first, but once you figure out the code, it's like riding a bike. Here is a link to help: http://airsnrt.jpl.nasa.gov/SkewT_info.html

You can create a sounding for any station here: http://www.stormchaser.niu.edu/machine/fcstsound.html

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Someone mentioned we could see a bigger CCB because we have an Atlantic/GOM hookup. Do you think this is true? If so we could see more precip spreading west.

Its def possible but dependent on some factors. To get precip deep into PA from these things you need a strong anomalous easterly 850 windflow from the Atlantic to transport in the moisture. This was very weak for the Boxing Day storm, which was a bigger reason why things didn't expand very far west even given a track which wasn't necessarily unfavorable for the eastern CPA folks. I did say a few days ago that I think the models ultimately converge on a coastal hugging track (not necessarily inland runner), but that issues regarding precip gradient might crop up.

With that said, I look at the 12z Euro and am somewhat surprised really that there just isn't good precip penetration, especially in the hours 54 to 60 range. With a track in inland eastern NC/SC to still inland over Norfolk at 60, you can't really ask for a better central PA track for a low pressure. And yet after 54 has some more moderate precip getting up into the PA southern zones..with the look of sending some good amounts into the eastern half of PA at least, hour 60 has trace amounts over most of of the eastern 2/3s of PA and just the philly region seeing 0.1-0.25". This is a 992ish low over Norfolk, VA.. which is a benchmark for CPA nor' easters. I just think with a track like the euro vs its precip output, its shortchanging the region south of say IPT between AOO and MDT from a more decent event. The 12z GFS with a very similar track to the Euro had a better take on the precip shield IMO. The 12z Canadian.. appeared to me to have some kind of feedback issues with the low. But once again pretty much inline with that more coastal hugging track. I like their take on the track as a whole, but the fact it sort of fades toward the benchmark vs tucking plus forward speed prolly puts a cap on how heavy the snow totals get assuming the idea of a better westward extent ends up valid. And thats not even going over the mixing issues that could occur over the southeast and overall snow ratios in an all snow scenario. This storm has been pushed back a day later than it was just a day or so ago, so I think there's another set of 12z/0z runs yet before we can really lock this one down better with some of these details.

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You gotta love ABC27! :gun_bandana:

"After a quiet and cloudy Tuesday, our focus turns to a developing coastal storm. This storm reminds me of the Christmas weekend storm when the big cities like Philadelphia, NYC and Boston were hit hard and places farther inland missed out. Once again, we are struggling with a sharp cut off of snow along the coast. One difference this time around will be the chance for a mix of rain/sleet and snow along the coast. What we do know is that it is going to be another close call for us. If we do see an icy mix or snow, it will happen during the daylight hours Wednesday and last into Wednesday night. The storm should be gone by rush hour Thursday morning."

How is the coast going to see snow and we will seeing mixing? :lmao: Also, they have the timing off...I am pretty sure most models are showing the storm starting Wednesday evening.:banned:

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Its def possible but dependent on some factors. To get precip deep into PA from these things you need a strong anomalous easterly 850 windflow from the Atlantic to transport in the moisture. This was very weak for the Boxing Day storm, which was a bigger reason why things didn't expand very far west even given a track which wasn't necessarily unfavorable for the eastern CPA folks. I did say a few days ago that I think the models ultimately converge on a coastal hugging track (not necessarily inland runner), but that issues regarding precip gradient might crop up.

With that said, I look at the 12z Euro and am somewhat surprised really that there just isn't good precip penetration, especially in the hours 54 to 60 range. With a track in inland eastern NC/SC to still inland over Norfolk at 60, you can't really ask for a better central PA track for a low pressure. And yet after 54 has some more moderate precip getting up into the PA southern zones..with the look of sending some good amounts into the eastern half of PA at least, hour 60 has trace amounts over most of of the eastern 2/3s of PA and just the philly region seeing 0.1-0.25". This is a 992ish low over Norfolk, VA.. which is a benchmark for CPA nor' easters. I just think with a track like the euro vs its precip output, its shortchanging the region south of say IPT between AOO and MDT from a more decent event. The 12z GFS with a very similar track to the Euro had a better take on the precip shield IMO. The 12z Canadian.. appeared to me to have some kind of feedback issues with the low. But once again pretty much inline with that more coastal hugging track. I like their take on the track as a whole, but the fact it sort of fades toward the benchmark vs tucking plus forward speed prolly puts a cap on how heavy the snow totals get assuming the idea of a better westward extent ends up valid. And thats not even going over the mixing issues that could occur over the southeast and overall snow ratios in an all snow scenario. This storm has been pushed back a day later than it was just a day or so ago, so I think there's another set of 12z/0z runs yet before we can really lock this one down better with some of these details.

This is a good post. I agree that the QPF shield should be larger, but I can't come up with a good reason dynamically why the models are wrong. Usually they overdo warm advection in the low/mid levels, but that doesn't appear to be the case here. The best DCVA is going to be closer to the coast, so I'd think Central PA will have to rely on the low/mid level WAA, unless there is some mesoscale feature I am forgetting about.

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Just got home from work...

Just read the latest discussion

"

OPERATIONAL ECMWF/GFS BASICALLY IN LINE NOW WITH LOW TRACKING

NORTHEASTWARD ACROSS THE CAROLINAS AND OFF THE MD/DE/NJ COAST

WHICH LOOKS TO KEEP EVENT FAIRLY MINOR FOR MUCH OF CENTRAL PA.

BIGGEST THREAT CONTINUES TO BE ACROSS SE HALF OF CWA...WITH AREA

EAST OF SUSQ RIVER AT HIGHEST RISK. AS STORM APPROACHES

WED LIGHT SNOW SHOULD SLIDE IN FROM THE SOUTH. SOME WARMER AIR

WILL WORK INTO THE LOWER SUSQ...WHICH COULD BRING A WINTRY MIX OR

A RAIN/SNOW MIX DURING THE DAY...LIMITING ACCUMS. BUT CURRENT

TRACK AND LACK OF EXPLOSIVE DEEPENING OF LOW SHOULD KEEP ACCUMS ON

LIGHTER SIDE. PRECIP TURNS OVER TO SNOW WED NIGHT AS SYSTEM LIFTS

TO THE NE...BUT COULD PICK UP A COUPLE INCHES OF SNOW AS IT

EXITS...ESPECIALLY ACROSS SE COUNTIES.

ONE ISSUE OF CONCERN IS THE ORIENTATION OF LLJ ON THE NORTH SIDE

OF THE STORM LATER WED INTO THU...THOUGH THIS APPEARS TO HAVE SLID

FURTHER TO THE EAST WITH NEWEST RUNS. QPF FIELDS REMAIN

VARIABLE...BUT EXPECT A SHARP EDGE TO PRECIP FOR THE EVENT. A

NOTE...THE NAM CONTINUES TO KEEP CENTRAL PA DRY."

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Yeah, the one model that was completely OTS is the solution being grabbed onto right now (In the philly thread of course who benefits the most from the eastern track). If I'm not mistaken the Euro hasnt had a run with less than 1" qpf yet. In fact CTPs grid forecast for me is below almost every model including the GFS ensembles??? I'm sort of stumped. Or Maybe I'm just getting emotionally attached...

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Talked this over with SnowGoose in the PHL/NYC thread -- we probably should hope for a weaker low...a stronger low wraps more precip up towards the center, thus you get the tight gradients and of course general miss in the NW.

Yeah that would tend to result in it being closer to the low center...the 12/26 event was a good example...if that low was 10-12mb weakeer NW NJ sees more snow likely but the combination of a stronger storm pulling everything more in and the mesoband screwed NW areas...thats another reason inland areas can get shafted in a deep low center, meso bands are more likely to their east.

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Yeah, the one model that was completely OTS is the solution being grabbed onto right now (In the philly thread of course who benefits the most from the eastern track). If I'm not mistaken the Euro hasnt had a run with less than 1" qpf yet. In fact CTPs grid forecast for me is below almost every model including the GFS ensembles??? I'm sort of stumped. Or Maybe I'm just getting emotionally attached...

yeah :lol: I'm sticking with the euro...if gfs wins so be it but the euro has been ridiculously consistent with this storm.

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