February 17-18 Threat Discussion

[The Iceman]

Well with the potential event being inside 5 days now and the Euro making a big shift at 12z towards the CMC, this storm is officially a threat. Euro snow totals were this BTW.

 

I'm copying my thoughts from the OBS thread that remain pretty unchanged even with the new 12z Euro burying us. I am still very worried about this becoming too amped and trending north as we approach the event meaning we will change to rain or become majority rain. We don't have a high locked in so the airmass in place doesn't have much depth but the timing is very very good on this event. This may just be our fluke storm make up from not cashing in on a big one from earlier in the winter when we had a much more favorable pattern.

From earlier:

12z CMC shows basically the perfect track for us on the Saturday night storm. Would be 6-10" region wide. GFS is flatter and squashes it south. But in this range, that may be where we want it to be seeing as the last few events saw a big north trend as we got closer to the event and with the SE ridge building in, I have a hard time seeing this one slide south and OTS. I am worried more about temps than an event at this stage. With the +NAO, I don't really think it is a question of if we see a north trend but how far north is it going to end up. If the GFS had us in the jackpot right now, I would say this is almost certainly a rain event. It has a few things going for it like timing which will be overnight saturday so no sun angle worries and no lakes low to scour out the cold air ahead of the storm but we are still in this progressive pattern so changes with the key players are going to have impacts on the track. I don't expect any kind of consensus for another 48 hours at least and possibly not until all of the players are on the field. Overall, my feeling is that this has a fairly decent shot at being a 6" storm for the region despite being in a hostile pattern for winter weather. Like I said in an earlier post, I still am favoring north and west areas at this time as having the best chance for this storm.

 

One more thing that I just noticed. The 06z NAVGEM is actually a decent hit for us and not squashed/suppressed when it is typically the furthest S and E of the models on storms. Another "Wiggum rule" tells me that when the NAVGEM isn't the S and E outlier, the storm is likely going to trend back north. I haven't seen the 12z NAVGEM yet though to see if this is still the case but it is a good sign for us that the 06z was not suppressed south.

[anthonyweather]

Well with the potential event being inside 5 days now and the Euro making a big shift at 12z towards the CMC, this storm is officially a threat. Euro snow totals were this BTW.

 

I'm copying my thoughts from the OBS thread that remain pretty unchanged even with the new 12z Euro burying us. I am still very worried about this becoming too amped and trending north as we approach the event meaning we will change to rain or become majority rain. We don't have a high locked in so the airmass in place doesn't have much depth but the timing is very very good on this event. This may just be our fluke storm make up from not cashing in on a big one from earlier in the winter when we had a much more favorable pattern.

From earlier:

12z CMC shows basically the perfect track for us on the Saturday night storm. Would be 6-10" region wide. GFS is flatter and squashes it south. But in this range, that may be where we want it to be seeing as the last few events saw a big north trend as we got closer to the event and with the SE ridge building in, I have a hard time seeing this one slide south and OTS. I am worried more about temps than an event at this stage. With the +NAO, I don't really think it is a question of if we see a north trend but how far north is it going to end up. If the GFS had us in the jackpot right now, I would say this is almost certainly a rain event. It has a few things going for it like timing which will be overnight saturday so no sun angle worries and no lakes low to scour out the cold air ahead of the storm but we are still in this progressive pattern so changes with the key players are going to have impacts on the track. I don't expect any kind of consensus for another 48 hours at least and possibly not until all of the players are on the field. Overall, my feeling is that this has a fairly decent shot at being a 6" storm for the region despite being in a hostile pattern for winter weather. Like I said in an earlier post, I still am favoring north and west areas at this time as having the best chance for this storm.

 

One more thing that I just noticed. The 06z NAVGEM is actually a decent hit for us and not squashed/suppressed when it is typically the furthest S and E of the models on storms. Another "Wiggum rule" tells me that when the NAVGEM isn't the S and E outlier, the storm is likely going to trend back north. I haven't seen the 12z NAVGEM yet though to see if this is still the case but it is a good sign for us that the 06z was not suppressed south.

12z nav is quite a bit more north then 6z was

 

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Edit 12z is tucked on the coast line. So yes if it were to play out like that and with the Navgem bias rain would be an issue I-95

[The Iceman]

2 minutes ago, anthonyweather said:

12z nav is quite a bit more north then 6z was

 

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Edit 12z is tucked on the coast line. So yes if it were to play out like that and with the Navgem bias rain would be an issue I-95

That to me is very very concerning. Means we will likely see further amplification. Good news for Lehigh Valley as you guys would likely get slammed if that is the case but precip issues for the metro area would be certain. We would still see a solid thump though and with nothing ahead of the storm scouring out the cold, it would have a good chance of overperforming before changing over. I wouldn't lean on the NAVGEM but with the Euro shifting pretty big at 12z that tells me that this thing is likely going to amplify even further. The GFS has been great in the medium range this year though so who knows at this rate. I think most importantly is that we can say with some certainty there will be a storm this weekend originating down south and progressing off the east coast. How amplified it gets and other details like precip type and amount are still up in the air. At this range though and in this pattern, we really couldn't get a better look...

[anthonyweather]

That to me is very very concerning. Means we will likely see further amplification. Good news for Lehigh Valley as you guys would likely get slammed if that is the case but precip issues for the metro area would be certain. We would still see a solid thump though and with nothing ahead of the storm scouring out the cold, it would have a good chance of overperforming before changing over. I wouldn't lean on the NAVGEM but with the Euro shifting pretty big at 12z that tells me that this thing is likely going to amplify even further. The GFS has been great in the medium range this year though so who knows at this rate. I think most importantly is that we can say with some certainty there will be a storm this weekend originating down south and progressing off the east coast. How amplified it gets and other details like precip type and amount are still up in the air. At this range though and in this pattern, we really couldn't get a better look...

Yup. Still way to early. Thanks for starting a thread because otherwise this would be buried in the banter thread until Saturday morning

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[anthonyweather]

Gefs is Similar to the other models..

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[The Iceman]

The GEFS mean is south of the Euro/CMC. The individual ensembles are about a 50/50 split between amplification or flat and OTS. The one fairly encouraging thing is that even the most amplified members would still be a good amount of snow even if the metro area changes over. I read over in another forum that we really don't have to worry about this being too amped due to how fast the flow is. The cold front comes through friday night and saturday night the storm is here. Not a whole lot of time to amp up and scour out the fresh airmass. There were still a good amount of misses though on the GEFS which shows that this is far from a lock. Between the GFS' tendency to flatten storms in this time frame and the Euro's tendency this year to over amplify in the mid range, a split down the middle may be a good call for where this ends up at this range... Solid 3-6" storm but not as far north as the Euro/Cmc and not as much precip due to it being less amplified. 

[The Iceman]

I havent seen the EPS mean but the individuals look like a good split of same as OP with some more amped and some less amped. In the more amped solutions, most of the area would still see a solid 2-4" before a changeover. We are only totally skunked in maybe one or two members and both of those are like the GFS. Overall pretty encouraging for accumulating snow chances this weekend.

[RedSky]

If the best EPS solutions have 2-4" to rain that is not saying much for the fantasy OP

* Just saw the members it looks like buckshot lol, I have no confidence with the OP run 

 

[The Iceman]

7 minutes ago, RedSky said:

If the best EPS solutions have 2-4" to rain that is not saying much for the fantasy OP

* Just saw the members it looks like buckshot lol, I have no confidence with the OP run 

 

More amped doesn't equal best. In the best members it's 12+". And just the fact all but like 3  or 4 have a storm is a step up from the op gfs and even some of the gefs.

[KamuSnow]

4 hours ago, The Iceman said:

More amped doesn't equal best. In the best members it's 12+". And just the fact all but like 3  or 4 have a storm is a step up from the op gfs and even some of the gefs.

18z GFS is better, 0z runs should be interesting. If they're somewhat consistent we might even see Ralph in here tomorrow morning!

[Ralph Wiggum]

This is a tightrope walk event right now but I venture that will change as lead time shrinks. All season these waves have gotten dampened out in the progressive NS flow. I dont see this squashing completely but it is fitting the pattern.....good look with pressing high pressure to the N at 7 days lead time.......high pressure begins to appear more progressive and starts moving out before or right as precip moves in at 5-6 day lead time with some models luring us in with some reasonable hits.....4-5 day lead a few models show even more progressively and dominant ns and start signaling a fropa look......3 day lead time most guidance locks into fropa. This one does have the amped up NAVGEM as a red flag so there is that going for us, otherwise I would say this has the look of every other minor event and fropa this season. Again, the NAVGEM has me raising an eyebrow though so Im not sold that this fits the seasonal pattern completely.

Btw, sun angle concerns in mid-February? If this were mid-March I would say yes to that notion, but it honestly isnt a major factor for another 2 weeks or so. Compared to early January, sure. However, WAA and SERing are absolutely more of a concern as we enter mid-February based on climo.

Fingers crossed we can get to avg snowfall for the season this weekend.

[The Iceman]

35 minutes ago, Ralph Wiggum said:

This is a tightrope walk event right now but I venture that will change as lead time shrinks. All season these waves have gotten dampened out in the progressive NS flow. I dont see this squashing completely but it is fitting the pattern.....good look with pressing high pressure to the N at 7 days lead time.......high pressure begins to appear more progressive and starts moving out before or right as precip moves in at 5-6 day lead time with some models luring us in with some reasonable hits.....4-5 day lead a few models show even more progressively and dominant ns and start signaling a fropa look......3 day lead time most guidance locks into fropa. This one does have the amped up NAVGEM as a red flag so there is that going for us, otherwise I would say this has the look of every other minor event and fropa this season. Again, the NAVGEM has me raising an eyebrow though so Im not sold that this fits the seasonal pattern completely.

Btw, sun angle concerns in mid-February? If this were mid-March I would say yes to that notion, but it honestly isnt a major factor for another 2 weeks or so. Compared to early January, sure. However, WAA and SERing are absolutely more of a concern as we enter mid-February based on climo.

Fingers crossed we can get to avg snowfall for the season this weekend.

Fwiw sun angle will be the same as early November so not a major factor but a factor nonetheless. But with the projected timing this discussion is mute point since most precip falls overnight. So youre thinking this has a better shot at flat and squashed over amped further north? I agree it was the seasonal trend up to February but the last few storms have seen a north and further amped trend from about day 4-5 up until the event. The flat and weak trend really hasn't been the trend of late hence why I believe the bigger miss threat is more amped and precip issues. Always appreciate your input though Steve. Hopefully we ll have a bit better idea which way this is trending after 00z though I wouldn't count on it

[Ralph Wiggum]

Fwiw sun angle will be the same as early November so not a major factor but a factor nonetheless. But with the projected timing this discussion is mute point since most precip falls overnight. So youre thinking this has a better shot at flat and squashed over amped further north? I agree it was the seasonal trend up to February but the last few storms have seen a north and further amped trend from about day 4-5 up until the event. The flat and weak trend really hasn't been the trend of late hence why I believe the bigger miss threat is more amped and precip issues. Always appreciate your input though Steve. Hopefully we ll have a bit better idea which way this is trending after 00z though I wouldn't count on it

Nah, I was saying whenever we had a threat on guidance at 5-6 day leads in Dec and most of Jan they had trended more progressive (fropa) and/or minor for the most part (save for the big bombogenesis event in Jan that was off the coast but trended W from Bermuda lol). I agree the pattern is different and I noted as you did the NAVGEM is a red flag being farther N and W so Im not 100% sold that this system follows earlier progressive system looks, but it is certainly in the back of my mind in this Nina.

[Ralph Wiggum]

Hmmm, GFS gets all amped up after the squashed look it had at 12z, GGEM is a hit but ticked South (colder but when isnt it), and UKIE, NAVGEM, and Euro started what I mentioned earlier trending South and much weaker. NAVGEM lost the red flag amped look and is more of a fropa with a very distinguishable LP passing just N of the GL. At least we trended away from the big thump->rain looks we had yesterday for now. Not sure I 'love' (Valentine's Day pun intended) the look for this one right now but at least we are tracking a threat again. Too much can still go wrong very quickly.

 

 

 

 

 

 

 

 

[Ralph Wiggum]

6z didnt exactly go where snow-lovers had hoped. The trends this season just cannot be denied it seems. ICON is weak sauce and now starting to get squashed in the progressive flow, GFS headed that way even though verbatim it still shows some snow here.....much weaker (but colder with the ns pressing), NAVGEM has a fropa.

We are shortening lead time here and could use some help at 12z to buck the trend.

[Ralph Wiggum]

EPS for the weekend doesnt look terrible. Farther N than Euro OP.

[The Iceman]

Not sure I agree that the trend looks all that bad. The only models that look like a weak front and give us nada are the crappy icon which has been wrong on just about every event this year and navgem that was the most amped up until 00z. The GEFS and EPS both showed much more good hits than weak misses and both means increased from 12z here. GFS at 00z was way too amped and 06z corrected itself imo. It shows a solid hit now. Even the euro at 00z was still a solid 2-4" event here. In this pattern the trend of amplification being stopped is very likely a good thing.

[The Iceman]

6z gefs has a vast majority of good hits and only 4 members showing a squash. Mean again on the ensembles increased from 00z. The trends on the ensembles have been incredibly positive. Not as fast on exiting the high pressure and more and more members showing hits where now it is a big majority up from about 50-50 at 12z.

[Ralph Wiggum]

Not sure I agree that the trend looks all that bad. The only models that look like a weak front and give us nada are the crappy icon which has been wrong on just about every event this year and navgem that was the most amped up until 00z. The GEFS and EPS both showed much more good hits than weak misses and both means increased from 12z here. GFS at 00z was way too amped and 06z corrected itself imo. It shows a solid hit now. Even the euro at 00z was still a solid 2-4" event here. In this pattern the trend of amplification being stopped is very likely a good thing.

The fact the 6z ops began moving away from the amped up low with warm city concerns is definitely a plus but we seem to have been moving slowly away from the feel for a snow lover's 6"+ system you were feeling yesterday, thus my chatter about how 6z wasnt a great suite for those folks hoping for a warning type event. Can we score another 1-3"/2-4" event? Absolutely.....and the trends to squash the over amped low runs from yesterday more towards the lower end event seem to be taking place as I expected given the pattern. The ens means dont look putrid, I agree with that, but its that time we need to start weighing on the ops more beginning 12z. Fingers crossed.

PS I saw the CMC and it is up to its seasonal Lucy thing of over amplifying lows given the pattern while also running too cold

[Ralph Wiggum]

6z gefs has a vast majority of good hits and only 4 members showing a squash. Mean again on the ensembles increased from 00z. The trends on the ensembles have been incredibly positive. Not as fast on exiting the high pressure and more and more members showing hits where now it is a big majority up from about 50-50 at 12z.

I hope you are onto something, but the ens qpf means have not been very useful this season, especially at 4-5 day leads for whatever reason. They both have repeatedly pulled the old SREF head fake bumping up qpf only to see the ops starts taking the lead and pulling back as we get closer. Hopefully this time is different. Would enjoy at least one warning criteria event this season. Right now Im leaning towards the lower end type of thing we've seen several times earlier this winter. Of course if a solid trend on guidance begins to go gung ho I will adjust my thoughts accordingly, but for right now thats my feel for this one.

 

[The Iceman]

1 hour ago, Ralph Wiggum said:

The fact the 6z ops began moving away from the amped up low with warm city concerns is definitely a plus but we seem to have been moving slowly away from the feel for a snow lover's 6"+ system you were feeling yesterday, thus my chatter about how 6z wasnt a great suite for those folks hoping for a warning type event. Can we score another 1-3"/2-4" event? Absolutely.....and the trends to squash the over amped low runs from yesterday more towards the lower end event seem to be taking place as I expected given the pattern. The ens means dont look putrid, I agree with that, but its that time we need to start weighing on the ops more beginning 12z. Fingers crossed.

PS I saw the CMC and it is up to its seasonal Lucy thing of over amplifying lows given the pattern while also running too cold

I agree with ya there, a warning event is still very much in the air since the amplification trend has seemed to reverse a bit. There are still a good amount of Ensembles that support a warning event along with the CMC but I still am not sold this will be the case until we see another OP model follow suite with the CMC. But I think if we want all snow, we should root for an over performing advisory event at this stage. I really only want 2.3" from this system to get me to normal on the year so my baseline for successful event is pretty low  

[The Iceman]

58 minutes ago, Ralph Wiggum said:

I hope you are onto something, but the ens qpf means have not been very useful this season, especially at 4-5 day leads for whatever reason. They both have repeatedly pulled the old SREF head fake bumping up qpf only to see the ops starts taking the lead and pulling back as we get closer. Hopefully this time is different. Would enjoy at least one warning criteria event this season. Right now Im leaning towards the lower end type of thing we've seen several times earlier this winter. Of course if a solid trend on guidance begins to go gung ho I will adjust my thoughts accordingly, but for right now thats my feel for this one.

 

That is kind of where I am at right now but maybe a little more bullish. High end advisory I think is a fair forecast at this stage with the potential for this to get better or be a low end advisory depending on how today goes. I hope the trend of the high not being as progressive off the coast that the ensembles/cmc/and even euro to an extent show continues today.  Really though in these 'perfect timing' events, we should be happy to see any accumulating snow because literally so much has to go right to get this threat sandwiched in between 2 awful winter patterns.

[Ralph Wiggum]

I agree with ya there, a warning event is still very much in the air since the amplification trend has seemed to reverse a bit. There are still a good amount of Ensembles that support a warning event along with the CMC but I still am not sold this will be the case until we see another OP model follow suite with the CMC. But I think if we want all snow, we should root for an over performing advisory event at this stage. I really only want 2.3" from this system to get me to normal on the year so my baseline for successful event is pretty low  

Ditto....hoping for a 2-4" type....get me near avg for the season then roll the dice for some early March gravy :-)

[Ralph Wiggum]

NAM finally decided to show up with a good thumping thru 84 hours. Perhaps just what the doctor ordered to get things rolling at 12z!

[The Iceman]

yeah it's the long range NAM but it is encouraging to see that it is similar to other guidance and honestly looks very similar to the CMC just warmer which is to be expected. The nam tends to be overamped in the LR so the fact it isn't really amped up/warm and actually has a storm(never a given with the LR Nam :lol:) is another positive. With the high pressure sliding off the coast though, I am worried still about the inevitable N trend as we get closer to the event. Hopefully other guidance is similar to the NAM because that is right about where we want to be at this stage. With the R/S line south of DC, we'd still have some wiggle room for that trend and still remain frozen save for maybe extreme SNJ/Delaware and coastal areas. I would much rather be rooting for a bit more amplification at the last minute to give us more precip than rooting for it to come in weaker at the last minute to stay frozen.

[anthonyweather]

6z didnt exactly go where snow-lovers had hoped. The trends this season just cannot be denied it seems. ICON is weak sauce and now starting to get squashed in the progressive flow, GFS headed that way even though verbatim it still shows some snow here.....much weaker (but colder with the ns pressing), NAVGEM has a fropa.

We are shortening lead time here and could use some help at 12z to buck the trend.

Your icon at 12z

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[The Iceman]

The ICON is still complete trash. It's basically waffled back and forth every run between nice hit, too amped, too flat, back to nice hit. zero consistency... I have found this model completely to be completely useless this winter in the medium and short range. Really wish tropical tidbits would just get rid of it and add the UKmet..

[anthonyweather]

The ICON is still complete trash. It's basically waffled back and forth every run between nice hit, too amped, too flat, back to nice hit. zero consistency... I have found this model completely to be completely useless this winter in the medium and short range. Really wish tropical tidbits would just get rid of it and add the UKmet..

It sure is. But for some reason as soon as it hit tropical tidbits it is the new Talk of the Town and everybody's seemingly go to model. Got me, we were better off without it

 

 

" well the icons a miss, regardless if every other model in the world shows a hit, we just can't discount what the icon is showing" lmao

 

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[The Iceman]

GFS is a solid hit and has another positive trend. 2-5" region wide. Stays weak and flat as the low slides south of us off the S VA coast but amplifies upon hitting the water leading to heavier rates. Also it is far enough south that a N tick as we get closer would actually be beneficial and give us more snow. The chances of this coming in flat and south are majorly decreasing and the chances of a warning event have increased though the most likely outcome remains high end WWA for much of the area. 

[anthonyweather]

GFS is a solid hit and has another positive trend. 2-5" region wide. Stays weak and flat as the low slides south of us off the S VA coast but amplifies upon hitting the water leading to heavier rates. Also it is far enough south that a N tick as we get closer would actually be beneficial and give us more snow. The chances of this coming in flat and south are majorly decreasing and the chances of a warning event have increased though the most likely outcome remains high end WWA for much of the area. 

Cmc is a rain to snow for PHL. 1-2" m


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