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Central PA - December 2013


PennMan

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Jamie

Looks like your not looking to bad just looking at this.

http://www.meteor.iastate.edu/~ckarsten/bufkit/image_loader.phtml?site=unv

 

Kipt

http://www.meteor.iastate.edu/~ckarsten/bufkit/image_loader.phtml?site=kipt

 

Again would like to thank all the red taggers for their input!!

i need to study that, so i can understand it. cool web site

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Jamie

Looks like your not looking to bad just looking at this.

http://www.meteor.iastate.edu/~ckarsten/bufkit/image_loader.phtml?site=unv

 

Kipt

http://www.meteor.iastate.edu/~ckarsten/bufkit/image_loader.phtml?site=kipt

 

Again would like to thank all the red taggers for their input!!

Oops! Google Chrome could not connect to www.meteor.iastate.edu

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The 06z NAM, 00z Euro and 10z RAP all now have UNV changing over to mostly snow by 00z Saturday. The GFS is now by itself still having a bit of a warm layer and putting out most of the precip as rain and sleet.

 

And that's probably just a resolution thing. Per the 06z GFS, the closest grid point to State College (to the NW) is all snow by 00z just like the other models--you'll note that the temperature on the sounding does remain above 0C at 800mb, but the wet bulb is at 0C (in reality if it's snowing, that layer would be saturated and the temperature would be at 0C anyway). So, at least at that grid point, the GFS is likely putting out most of the precipitation (>0.6") as snow.

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13z Surface temperatures along with 12z upper air temperatures.

 

white line = 925mb freezing

Blue line  = 850mb freezing

black line = 700mb freezing

red line    = surface freezing

 

Just a note, these are supposed to be the actual upper air data, but it looks like our most important ob (PIT) may not have completed its sounding.

 

post-1406-0-21870200-1386335824_thumb.pn

 

I figure this kind of map would be useful in these borderline events for the winter. If anyone wants to learn how to get this themselves, let me know. It's a very useful tool that I learned from these boards a few years ago.

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And that's probably just a resolution thing. Per the 06z GFS, the closest grid point to State College (to the NW) is all snow by 00z just like the other models--you'll note that the temperature on the sounding does remain above 0C at 800mb, but the wet bulb is at 0C (in reality if it's snowing, that layer would be saturated and the temperature would be at 0C anyway). So, at least at that grid point, the GFS is likely putting out most of the precipitation (>0.6") as snow.

 

I'm looking at the UNV profile in bufkit so it is at the actually station coordinates, though it is still interpolated using the surrounding grid points. That is a good point about the wet bulb temperature; the wet bulb gets close to freezing by 00z Saturday in the 06z run. Still a bit warmer than the other guidance but an outlier now.

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NAM looks messy on sunday for the LSV. 0.4" zr, 0.14" pellets, 0.1" snow. GFS looks a little cleaner, more snow, less ice.

 

SREF has 76% chance of snow at 21z on the 8th for LNS, 50% chance for frozen at 03z on the 9th.

did the timing change or am i looking crosseyed at the nam? looks like for timing it doesn't start til late Sunday with the frzn in the overnight hours? I thought it started early afternoon Sunday, no?

 

edit- Moderate to heavy at times rain in Harrisburg, 45. why can't it be 25...i picked December 5th for 1st measurable snowfall in our work pool

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NWS should expand the advisories SE at perhaps I-81 for at least some sleet/freezing rain. Definitely looking better for more snow along I-99/Rt. 220. Hopefully some of the higher totals, 5 or 6" work out. It's always extremely tricky timing these changeovers when warm mid-level air is involved. The changeover happening 3 hours too late at my location this Feb 8th cost me almost a foot of snow, lol.

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At this point, yeah its definitely looking like that. I think even a 4-8" event is feasible if whatever falls after 00z is snow, but we will have to wait for the raw numbers to know for sure.

 

EDIT: They're available from the link Jamie posted earlier: http://68.226.77.253/text/NAM80km/NAM_kunv.txt

 

Looks like still a shallow warm layer around 800 to 700 mb at 00z so whatever falls before then is sleet, but looks like we should have around 0.5" of precip falling as snow. QPF is 0.74" at UNV from 00z to 06z, and 0.73" at IPT.

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How's the NAM looking I'm stuck at work lol.

from a quick look at the text output of just 12z NAM... has nearly 1" qpf for IPT with 850 temps below freezing... about .25" of that has the warm layer between 700 and 800mb but then all drops below 0C sometime between 0 and 6z tonight (7pm-1am)... just a matter of when during that time period does the transition occur and how much of the .75" is sleet vs snow

 

UNV in similar boat - same with AOO but a little more precip

 

MDT/LNS rain to sleet to dusting - 1" snow at best

 

AVP/MPO - similar situation as IPT/UNV/AOO but less precip and will depend on how quickly and how far east the colder air aloft moves

 

main thing I am going to try and keep an eye on is the upper level analyses to see if they are determining the temperatures from 700 to 850 to be colder than the models faster or not

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The ECMWF has been showing this for days now. Looks like a 5-8 inch snowstorm from Altoona to Williamsport. The SREF members continue to show more snow each run.

It always worries me that the warm layer at mid levels is often more tenacious and expansive than models show. Hopefully it works out but I'd hedge towards the safer side, maybe 3-5". The best shot at 6"+ would be perhaps Clearfield up towards Coudersport. If it's snowing in the JST-IPT corridor shortly after 0z, then you can have the higher totals. If sleet lingers much beyond that, you're running a limited opportunity for much accumulation because the precip is moving fast.

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