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Central PA & the fringes - January 2015 Part II


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I'm a little confused. The latest GFS has MDT seeing 6-8 but I can't tell if that's the clipper early Monday or the wraparound Tuesday.

 

This due to the clipper actually. The GFS has a more robust look to the clipper and dumps more precip on the southern PA area than the NAM had and even previous runs of the GFS. The system is a pretty potent piece, so the idea is there for a good period of steady snow for I80 to the MD line. Lancaster county gets scraped by the coastal per GFS and that's the furthest western extent on this particular run.

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The 0Z Nam gives me close to 0.80" of liquid while the 0Z GFS gives me 0.40". Regarding the "bomb" there's a pretty big difference between these two models on this run. NAM seems insistent that the heaviest precip stays just offshore until it reaches New England. GFS brings heavy precip inland to most of NJ with majority over 1" of liquid.

Who would like to explain these differences? I'm sure it must have something to do with exactly where the phase completes and the low then slows down and bombs out.

BTW, GFS only out to day 10 but man, there's two more systems with fairly significant precip (snow) after the Mon/Tue storm and then we have the -20's at 850 paying us a visit again. With a pretty decent snowpack by that time I suspect many of us will visit the 0-degree mark or even go negative. So it would seem there's plenty of excitement to go around for all of us over the next 2 weeks.

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The 0Z Nam gives me close to 0.80" of liquid while the 0Z GFS gives me 0.40". Regarding the "bomb" there's a pretty big difference between these two models on this run. NAM seems insistent that the heaviest precip stays just offshore until it reaches New England. GFS brings heavy precip inland to most of NJ with majority over 1" of liquid.Who would like to explain these differences? I'm sure it must have something to do with exactly where the phase completes and the low then slows down and bombs out.BTW, GFS only out to day 10 but man, there's two more systems with fairly significant precip (snow) after the Mon/Tue storm and then we have the -20's at 850 paying us a visit again. With a pretty decent snowpack by that time I suspect many of us will visit the 0-degree mark or even go negative. So it would seem there's plenty of excitement to go around for all of us over the next 2 weeks.

The difference is the nam is a joke this far out.
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How is it a joke? The storm begins in less than 24 hours and a significant amount of the total precip for the event takes place between hours 24 and 48.

Maybe one of the mets can chime in and show us if the NAM is to be believed or not?

The nam initialized way east of any other model. It can't handje the gulf moisture it seems and imo it is out of its wheelhouse.

The clipper is our biggest threat, we're prob 75-100 miles too west for the coastal bomb that'll bury the 95 corridor. Generally belief is under 36 is best for nam.

Preface that with I'm no met, just extrapolate info from reading others' thoughts.

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I would be thrilled with a 4-6 in snowfall in the Harrisburg area at this point. I guess a wild card is the idea of an inverted trough. I saw what that did out in the Pittsburgh area in 2010 where they were calling for 2-6" and got 12"+. I saw it mentioned on the AFD and on the NAM and GFS. What signs would there be if one was setting up?

Sent from my iPhone using Tapatalk

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From reading: Euro very similar to 12z. 984mb still just inside BM. Slower evolution than GFS. Most of CPA appears to not really be in the game post clipper. PHL is close to sharp gradi

It then stalls at hr 66 and obliterates NYC/BOS/SNE. More than 2.25" qpf in NYC and NJ. Wow. 30"+ or many out that way.

Looks like 4-6" total or MDT, nearly all from the clipper.

Edit: Found this from the euro

image.jpg

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Hazelton your right on the edge of the coastal's primary deform shield on the Euro. It would only take a slight shift to get you into the thick of it, but I think Scranton/WB had at least some measureable as is. Seems like the Lower Sus Valley is in the tough spot on the Euro, where clipper precip dives under and fades and the coastal storm precip passes just barely east. Inverted trough precip looked best for western PA.

 

PHL-BOS, northern NJ SE NY western Mass, etc... wow. Measured by the foot for sure, maps will probably be ridiculous. NYC area had two frames of being under or near 0.75-1.00 bookended by .25-.50. And with 850 temps at or below -8C during those two major frames.

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Hazelton your right on the edge of the coastal's primary deform shield on the Euro. It would only take a slight shift to get you into the thick of it, but I think Scranton/WB had at least some measureable as is. Seems like the Lower Sus Valley is in the tough spot on the Euro, where clipper precip dives under and fades and the coastal storm precip passes just barely east. Inverted trough precip looked best for western PA.

 

PHL-BOS, northern NJ SE NY western Mass, etc... wow. Measured by the foot for sure, maps will probably be ridiculous. NYC area had two frames of being under or near 0.75-1.00 bookended by .25-.50. And with 850 temps at or below -8C during those two major frames.

 

Mag, what did the Euro show for western PA since the map posted only shows the central part of the state?

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Hazelton your right on the edge of the coastal's primary deform shield on the Euro. It would only take a slight shift to get you into the thick of it, but I think Scranton/WB had at least some measureable as is.

 

EuroWx.com Kuchera maps had about 9"...but again, it just doesn't feel as spectacular when you're missing 30"+ by 100 miles.

 

phil882 mentioned in the NYC forum (Before I took shelter from yet another celebration there) something about the energy just coming ashore in British Columbia...do you think there's any chance we do get a slight left shift? It did happen to some extent with the event last night...desperation is setting in isn't it :(

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EuroWx.com Kuchera maps had about 9"...but again, it just doesn't feel as spectacular when you're missing 30"+ by 100 miles.

 

phil882 mentioned in the NYC forum (Before I took shelter from yet another celebration there) something about the energy just coming ashore in British Columbia...do you think there's any chance we do get a slight left shift? It did happen to some extent with the event last night...desperation is setting in isn't it :(

 

For you your def in the game with a slight left shift to at least get into a more significant, say 10+ snowfall (probably not the ridiculous stuff). For the C-PA region in general the pattern positioning is just a hair east of my liking with the 500 ridge axis out west running more through CO/WY/MT instead of the favored Boise, ID teleconnection (although axis bends back toward Idaho a bit in a kind of negatively tilted orientation. Def workable for you, and perhaps the Sus Valley if the high up north strengthens a bit quicker and forces the storm to stall or retro more. It's going to come down to the wire to get things positioned confidently with this. I mean wow, what a turn of developments in the last 24 hours that has seen this run of the mill re-developer suddenly opt for the nuclear option.

 

The clipper precip seems as is with a general focus of heaviest amounts on the western half of PA or so. Should be pretty high ratio stuff too, hence the elevated amounts. Development of an inverted trough will help to hang precip somewhere across the state while the coastal gets rolling. Somewhere in our region (and/or Mid-Atl) region is going to get a minimum of precip with the miller B evolution of this system. This is another thing that'll be hard to resolve until we get near go time.

 

 

 

 

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Thanks MAG...a thought did come to mind about how UNV was kind of borderline in the 2/5-6/10 event on the models, and they wind up lucking out with over a foot. Maybe we'll luck out in that respect here as well. We'll see at 12z tomorrow...not confident though as we've rarely won in these marginal setups.

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Thanks MAG...a thought did come to mind about how UNV was kind of borderline in the 2/5-6/10 event on the models, and they wind up lucking out with over a foot. Maybe we'll luck out in that respect here as well. We'll see at 12z tomorrow...not confident though as we've rarely won in these marginal setups.

 

In that case though the primary was MUCH stronger. The models for Pittsburgh were showing 1-1.5 QPF for a lot of the area, even though the locals were putting out 3-6 forecasts. It ticked north at the end, but the amount of snow folks were going to get with the primary was still huge...not the case here.

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In that case though the primary was MUCH stronger. The models for Pittsburgh were showing 1-1.5 QPF for a lot of the area, even though the locals were putting out 3-6 forecasts. It ticked north at the end, but the amount of snow folks were going to get with the primary was still huge...not the case here.

Couldn't have let me  head to sleep with just a little hope. :lol:

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Thanks MAG...a thought did come to mind about how UNV was kind of borderline in the 2/5-6/10 event on the models, and they wind up lucking out with over a foot. Maybe we'll luck out in that respect here as well. We'll see at 12z tomorrow...not confident though as we've rarely won in these marginal setups.

 

Yea 2-5/6-2010 was a straight up juiced southern stream system that was fairly well advertised and places like Pit and UNV eventually reeled it back in north in the short range to turn a fringe event into getting hammered. Kinda thought about 2-10-10 as well, but pattern was way different (---NAO).

 

A good example of this kind of storm is the Jan 21-24, 2005 New England blizzard. Featured same kind of general setup, except the 500 western ridge was in the good C-PA spot and the coastal low developed and ran much closer to the coastline, thus it at least kept pretty much all of PA except for the far SW in the 4-10 range. Also a PHL-BOS storm and still scored a cat 4 on the NESIS (#7 overall).

 

This is the kinda stuff where you see why the folks down in the Mid-Atl are more reliant on an established true negative NAO to get into these big coastals. 

 

http://www1.ncdc.noaa.gov/pub/data/cmb/images/snow/nesis/20050121-20050124-6.80.jpg

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For you your def in the game with a slight left shift to at least get into a more significant, say 10+ snowfall (probably not the ridiculous stuff). For the C-PA region in general the pattern positioning is just a hair east of my liking with the 500 ridge axis out west running more through CO/WY/MT instead of the favored Boise, ID teleconnection (although axis bends back toward Idaho a bit in a kind of negatively tilted orientation. Def workable for you, and perhaps the Sus Valley if the high up north strengthens a bit quicker and forces the storm to stall or retro more. It's going to come down to the wire to get things positioned confidently with this. I mean wow, what a turn of developments in the last 24 hours that has seen this run of the mill re-developer suddenly opt for the nuclear option.

 

The clipper precip seems as is with a general focus of heaviest amounts on the western half of PA or so. Should be pretty high ratio stuff too, hence the elevated amounts. Development of an inverted trough will help to hang precip somewhere across the state while the coastal gets rolling. Somewhere in our region (and/or Mid-Atl) region is going to get a minimum of precip with the miller B evolution of this system. This is another thing that'll be hard to resolve until we get near go time.

 

Yeah the Euro/GFS/(NAM...) have light snow from Sunday night into Tuesday morning. The heaviest precip looks to be 6-12z Monday as the 850 low/trough approaches SW of us. That should induce some deformation on the temperature gradient and provide mesoscale lift through frontogonesis in central PA.

 

As the upper and lower level PV anomalies become in phase and the surface low rapidly intensifies over the Gulf stream (to the delight of the SNE/NYC weenies), it does seem like we must rely on the remnant surface trough from the northern stream disturbance to produce any further pity accumulations. The 06z NAM (perhaps not even worth mentioning?) maintains a localized gradient in the 850 mb temperature field over central PA which enhances the forcing and increases the total QPF. This feature is not nearly as well defined on the other guidance.

 

The eastern third of the state (depending on how far offshore this system develops) may receive another round of snow as the intense surface low off the coast begins to occlude, retrograde slightly and graze that region with the weakening cold conveyer belt.

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