March 1-3 -NAO Comeback Coastal Discussion/OBS

[RedSky]

We just got NAM'D biggly 

 

 

[Ralph Wiggum]

12k NAM continues to want to drop 6-10" over most of SE PA Friday afternoon-night. Has been quite consistent. Vort/ULL pass this run much better.

 

Eta: I think much of those totals is probably mixing but cant deny the consistent signal for accumulating snow. Becoming more and more likely at least an advisory level event is headed our way.

[Ralph Wiggum]

3k (which *should* be the better model) ups the ante....wow!

[RedSky]

I hate March except when it's got paste bombs and this is one on the NAM. Back to back smarches could it be?

 

[Ralph Wiggum]

I hate March except when it's got paste bombs and this is one on the NAM. Back to back smarches could it be?
 

3k almost has a capture look and damn near makes a try at pulling it back W at a point. Slows to a crawl in any event and pastes the area.

[RedSky]

6 minutes ago, Ralph Wiggum said:

9 minutes ago, RedSky said:

I hate March except when it's got paste bombs and this is one on the NAM. Back to back smarches could it be?
 

3k almost has a capture look and damn near makes a try at pulling it back W at a point. Slows to a crawl in any event and pastes the area.

Hopefully we get the RGEM on board at 0z and a better ECM run. I don't care what the GFS does after it's Feb 17 performance.

  

[MillvilleWx]

This is a beautiful look for SE PA. Intense H85 Frontogen over the region. This would support some beautiful banding structures with long north-south oriented bands down Eastern PA. If it unfolds anywhere close to that, it would be a fun afternoon in this sub forum. I’ll be visiting my friend in Thorndale on Friday morning. I’ll gonna stay the day if this keeps up.

 

 

 

[Birds~69]

I'm a bit excited...even if it's wet crap snow which will melt quickly.

[Ralph Wiggum]

Hopefully we get the RGEM on board at 0z and a better ECM run. I don't care what the GFS does after it's Feb 17 performance.
  

Didnt see the 12z euro, what happened there? EE rule no longer in effect?

[RedSky]

Just now, Ralph Wiggum said:

5 minutes ago, RedSky said:

Hopefully we get the RGEM on board at 0z and a better ECM run. I don't care what the GFS does after it's Feb 17 performance.
  

Didnt see the 12z euro, what happened there? EE rule no longer in effect?

lol i was busy today and just took a look it was an inch to maybe 2 imby, too far east and not as much retrograde

 

[SnowLover22]

RGEM is on board.


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[KamuSnow]

9 minutes ago, MillvilleWx said:

This is a beautiful look for SE PA. Intense H85 Frontogen over the region. This would support some beautiful banding structures with long north-south oriented bands down Eastern PA. If it unfolds anywhere close to that, it would be a fun afternoon in this sub forum. I’ll be visiting my friend in Thorndale on Friday morning. I’ll gonna stay the day if this keeps up.

It's looking pretty nice at the moment. Hopefully something close to that and you will be staying for the day!

[RedSky]

Getting excited now with the RGEM joining the party. 

 

[Ralph Wiggum]

ICON up for SE PA from c-2" to 2-4" now. This actually seems most reasonable for now. Until the NAM uber high totals gain some support thinking this is another WWA 1-3"/2-4" type which again, fits the seasonal mold.

[Birds~69]

5 hours ago, Ralph Wiggum said:

ICON up for SE PA from c-2" to 2-4" now. This actually seems most reasonable for now. Until the NAM uber high totals gain some support thinking this is another WWA 1-3"/2-4" type which again, fits the seasonal mold.

Accu Weather thinking pretty much the same this morning...

[Ralph Wiggum]

Largest aspect of this storm for our area will *probably* not be any snow impacts irt to travel and road conditions that we see but rather 50mph winds with gusts near 65mph for some. A little concerned with how saturated the ground has become.....I still have standing pools of water in spots in my yard from the recent prolonged rains. Could easily spell increased power outage threat. Add in a possible few hours of pasting and we have the potential for quite an impactful storm inland (and area-wide for that matter).

 

Down at the shore, some of the surge numbers I am seeing modeled are, well, alarming quite frankly and close to a Sandy-esque look. Im thinking alot will depend on intensity, wind trajectory, movement/speed of lp getting away from the coast......but the biggest question mark now (and a function of how far SW any banding retrogrades for snow here) is the looping/capture attempt of the system near our coastline. That sort of looping trajectory back towards the coast at the right latitude will play a massive role in storm surge potential. Cant even believe we are discussing this with a non-tropical system. Extremely unique and potentially dangerous situation unfolding over the next 36-48 hours for parts of our area. THAT is what blocking from a -NAO can do.

 

As far as snowfall, Im certain some flakes will fly. EPS mean bumped to an inch or 2 of snow. NAM is clearly still on the extreme side and after looking into the why, it seems it is the coldest model irt dynamic cooling and a much more vigorous appearance at 850mb with the closed low. With that said, may be an outlier on the heavy snow amt side but we need to see what other mesos do today. The more reliable RGEM certainly isnt loving it, tho the HDRPS is running colder. BUT it seems also the colder models are also the ones that loop the coastal banding back NE to SW into our region thus allowing for 1) enhanced dynamic cooling and 2) much heavier banding qpf rates. If we can get that banding to push back into E PA Friday evening/night we may see some incredible sights. But whoever IS lucky enough to get into that zone will be greeted with a March lion gift......tropical storm forced winds with heavy pasting snow. Dare I use the term "near blizzard conditions" for some areas?

 

I am really not sure where this banding sets up, if it retrogrades, or how far S and W it will get. This is going to be a wait and see approach with this system. Would think conservative is the way to go for now for SE PA with a couple of pasty inches of snow possible Friday afternoon/night with the potential for upside amounts totally dependent on banding setup and retrograde track of lp.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[The Iceman]

Seems to be a clear line between the meso models and globals. Mesos get us cold enough to changeover while the globals don't. I think 1 to 3" region wide is a fair call right now. That's my best guess but theres bust potential both ways. Wouldn't be surprised if I end up with only wet grass or a surprise 6 inches...

[ChescoWx]

The top CIPS analog for this storm is the March 31/April 1, 1997 storm where we ended up with over 13" of snow in Chester County after 60 degrees the day before. Not saying that will happen but these sort of upper low systems are a bear to forecast.

[Ralph Wiggum]

The top CIPS analog for this storm is the March 31/April 1, 1997 storm where we ended up with over 13" of snow in Chester County after 60 degrees the day before. Not saying that will happen but these sort of upper low systems are a bear to forecast.

Ah, the April Fools Day Storm! A classic from here to New England with many different aspects. I remember watching the ETA qpf maps come out 24 hours prior with 36-60" forecast for Boston to Cape Cod. I never saw the black qpf color contour used before on an ncep prog and dont recall ever seeing it since. I dont think the 5' totals verified but still. Rare storm event for sure.

[Mikeymac5306]

1 hour ago, Ralph Wiggum said:

Largest aspect of this storm for our area will *probably* not be any snow impacts irt to travel and road conditions that we see but rather 50mph winds with gusts near 65mph for some. A little concerned with how saturated the ground has become.....I still have standing pools of water in spots in my yard from the recent prolonged rains. Could easily spell increased power outage threat. Add in a possible few hours of pasting and we have the potential for quite an impactful storm inland (and area-wide for that matter).

 

Down at the shore, some of the surge numbers I am seeing modeled are, well, alarming quite frankly and close to a Sandy-esque look. Im thinking alot will depend on intensity, wind trajectory, movement/speed of lp getting away from the coast......but the biggest question mark now (and a function of how far SW any banding retrogrades for snow here) is the looping/capture attempt of the system near our coastline. That sort of looping trajectory back towards the coast at the right latitude will play a massive role in storm surge potential. Cant even believe we are discussing this with a non-tropical system. Extremely unique and potentially dangerous situation unfolding over the next 36-48 hours for parts of our area. THAT is what blocking from a -NAO can do.

 

As far as snowfall, Im certain some flakes will fly. EPS mean bumped to an inch or 2 of snow. NAM is clearly still on the extreme side and after looking into the why, it seems it is the coldest model irt dynamic cooling and a much more vigorous appearance at 850mb with the closed low. With that said, may be an outlier on the heavy snow amt side but we need to see what other mesos do today. The more reliable RGEM certainly isnt loving it, tho the HDRPS is running colder. BUT it seems also the colder models are also the ones that loop the coastal banding back NE to SW into our region thus allowing for 1) enhanced dynamic cooling and 2) much heavier banding qpf rates. If we can get that banding to push back into E PA Friday evening/night we may see some incredible sights. But whoever IS lucky enough to get into that zone will be greeted with a March lion gift......tropical storm forced winds with heavy pasting snow. Dare I use the term "near blizzard conditions" for some areas?

 

I am really not sure where this banding sets up, if it retrogrades, or how far S and W it will get. This is going to be a wait and see approach with this system. Would think conservative is the way to go for now for SE PA with a couple of pasty inches of snow possible Friday afternoon/night with the potential for upside amounts totally dependent on banding setup and retrograde track of lp.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

I am glad you are finally bringing this up. Seems like everyone is more concerned with how much snow (or lack of ) snow IMBY is going to happen. We are looking at some serious winds this area has  not had since Sandy. Not to mention the weeks of substantial rain that has fallen and more on the way. If the snow does fall and gives a paste job of an inch + on Friday which will stick to the trees, there is more insult to injury with regards to power outages.  

Local crews in this area (PECO, Delmarva) are a little light right now as they currently have crews in Puerto Rico. It's not many but if this is widespread, it could delay a few places from getting power back on in a timely manner.

 

[The Iceman]

If anyone wants a great snow experience and not have to travel up to NE, Mt Pocono area I think is going to get slammed. They have the elevation plus should be right in the CCB. They may see tremendous snow rates with wind...best chance at blizz conditions would be there imo Wouldn't be surprised at all if they got a foot+

[MillvilleWx]

Largest aspect of this storm for our area will *probably* not be any snow impacts irt to travel and road conditions that we see but rather 50mph winds with gusts near 65mph for some. A little concerned with how saturated the ground has become.....I still have standing pools of water in spots in my yard from the recent prolonged rains. Could easily spell increased power outage threat. Add in a possible few hours of pasting and we have the potential for quite an impactful storm inland (and area-wide for that matter).
 
Down at the shore, some of the surge numbers I am seeing modeled are, well, alarming quite frankly and close to a Sandy-esque look. Im thinking alot will depend on intensity, wind trajectory, movement/speed of lp getting away from the coast......but the biggest question mark now (and a function of how far SW any banding retrogrades for snow here) is the looping/capture attempt of the system near our coastline. That sort of looping trajectory back towards the coast at the right latitude will play a massive role in storm surge potential. Cant even believe we are discussing this with a non-tropical system. Extremely unique and potentially dangerous situation unfolding over the next 36-48 hours for parts of our area. THAT is what blocking from a -NAO can do.
 
As far as snowfall, Im certain some flakes will fly. EPS mean bumped to an inch or 2 of snow. NAM is clearly still on the extreme side and after looking into the why, it seems it is the coldest model irt dynamic cooling and a much more vigorous appearance at 850mb with the closed low. With that said, may be an outlier on the heavy snow amt side but we need to see what other mesos do today. The more reliable RGEM certainly isnt loving it, tho the HDRPS is running colder. BUT it seems also the colder models are also the ones that loop the coastal banding back NE to SW into our region thus allowing for 1) enhanced dynamic cooling and 2) much heavier banding qpf rates. If we can get that banding to push back into E PA Friday evening/night we may see some incredible sights. But whoever IS lucky enough to get into that zone will be greeted with a March lion gift......tropical storm forced winds with heavy pasting snow. Dare I use the term "near blizzard conditions" for some areas?
 
I am really not sure where this banding sets up, if it retrogrades, or how far S and W it will get. This is going to be a wait and see approach with this system. Would think conservative is the way to go for now for SE PA with a couple of pasty inches of snow possible Friday afternoon/night with the potential for upside amounts totally dependent on banding setup and retrograde track of lp.
 

Great post Ralph. Pretty much hit it home. The winds will undoubtedly be the main show, but Chester Co on east better keep an eye on the upper level progression closely. That April Fools storm was no joke and this one is very similar in the H5 progression and where the closed low sets up shop. The combo of saturated ground leading in, high winds and potentially for a heavy, paste like snow will create a dangerous setup for power outage potential. Given the boundary layer mixing on models, high grounds of Chester Co may see gusts reach 60 mph, which would be ugly no matter how you slice it. This is not being talked about enough in public setting. A lot of people will be caught off guard me thinks.


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[ChescoWx]

2 minutes ago, The Iceman said:

If anyone wants a great snow experience and not have to travel up to NE, Mt Pocono area I think is going to get slammed. They have the elevation plus should be right in the CCB. They may see tremendous snow rates with wind...best chance at blizz conditions would be there imo Wouldn't be surprised at all if they got a foot+

Agreed!! also the Southern Tier in NYS 

[The Iceman]

Man Mt hollys disco is good stuff again

 

Quote

...High-impact coastal storm will affect the region Friday and
Saturday...

Busy night. All focus with the long term was squarely with the
coastal storm affecting the area Friday and Saturday. Models are
closing in on a solution, but several big question marks
remain, primarily associated with the geographical extent and
timing of changeover to snow.

Will attempt to keep the model/scientific discussion short, as
the potential impacts need to be addressed at length. Models are
generally closing in on a solution in which the southern-stream
low progressing off the Mid-Atlantic coast tonight curves
northward and stalls near/south of the southern New England
coast Friday and Friday night before progressing east-southeast
well offshore this weekend. The 00Z NAM is on the western fringe
of guidance with the track and was deemed a lower-probability
solution in general, particularly given its continued very cold
low-level thermal profiles (with the GFS much warmer and the
ECMWF in between). The ECMWF was on the south/east side of the
model clustering but has been persistent with this. However, the
GFS and ECMWF were exhibiting increasing consensus, and the CMC
had a reasonably similar solution.

As a result, the forecast used a blend of the
GFS/ECMWF/CMC/WPC/GEFS for precipitation (including type and
QPF). However, higher-resolution guidance (including the NAM
Nest, the WRF-ARW/NMM, and NamDNG) were weighted highly
regarding the winds on Friday and Friday night, as the coarser
models simply looked too weak with winds/gusts given the
proximity/intensity of the low, the very strong pressure
gradient that will develop, and the favorable steepness of low-
level lapse rates on the west/south side of the low.

However, confidence on the thermal profiles and the resultant
extent of snow and total accumulations is very low outside of
the winter storm watch. Large changes to the forecast Friday and
Friday night are possible in the next 24 hours as a result.

Forecast weather/impacts:

Winds will be one of the biggest impacts of this storm. Have
expanded the high wind watch to include all areas not in winter-
weather headlines (that is, everyone except Carbon/Monroe/Sussex
Counties) Friday and Friday night. This will very likely require
upgrade to a warning by this afternoon. Widespread gusts 50-60
mph should be expected during the height of the winds (late
Friday morning to Friday evening), with gusts above 60 mph
likely near the coast and in portions of Delmarva. Considerable
coverage of power outages is possible as well as a large number
of downed trees.

As for the rain, the heaviest should occur in northern portions
of the area Friday morning, but a surge southward as the
wraparound cranks up during the afternoon is likely. Models show
tremendous frontogenetical lift in the 850-700 mb layer over the
area during the afternoon/evening, which is one reason the
colder NAM solution cannot be discounted (combination of strong
lift and precipitation-cooling effects will be at work here).

Regarding snow, warning criteria will likely be met in the
southern Poconos, at least in the higher elevations, where 4-7
inches are possible (locally up to a foot in the highest
elevations). There is more uncertainty in Sussex County, NJ,
but given the overall eastward trend of the colder air and
deformation band(s) likely to develop on the northwest side of
the low, the watch was expanded to include it. Very strong winds
are probable Friday afternoon and evening, and local whiteout
conditions are possible. There is some concern blizzard criteria
will be met here.

Farther southeast, changeover to snow is expected gradually
during the day Friday in the Lehigh Valley and adjacent portions
of northern New Jersey. However, temperatures are quite
marginal, and considerable melting of any snow that falls is
expected. Furthermore, it is not clear how soon this changeover
will be. Nevertheless, winds will be strong, so occasional
whiteout conditions are possible anywhere changeover occurs.
Confidence in blizzard conditions (3+ hours of quarter-mile or
less visibilities) is too low for a watch here, so kept these
areas in a high wind watch instead. However, the combined threat
of wind and snow is very worrisome, and a switchover to winter
headlines is quite possible in later forecasts, especially if
the colder solutions are closer to reality.

Storm total liquid-equivalent precipitation will likely be from
1 to 2+ inches north of the Mason-Dixon Line, and around a third
of an inch to a little more than an inch to the south.

 

So they are leaning towards any wraparound snow being minimal outside of the poconos but note that it won't take much for more of the area to see snow and if they see snow it could potential fall fast and furious. I do not envy mt holly's position today as if they go with the NAM and temps don't make it, we bust but if the nam is right, a large part of the area may be caught off guard during the afternoon commute in potential blizzard conditions. Not an easy decision...will be interesting if we see any consensus at 12z between the mesos and globals.

[Jsdphilly]

I would love to see a true surprise storm! I have been loving the spring weather, but we need at least 1 good storm this winter!

 

[Ralph Wiggum]

If anyone wants a great snow experience and not have to travel up to NE, Mt Pocono area I think is going to get slammed. They have the elevation plus should be right in the CCB. They may see tremendous snow rates with wind...best chance at blizz conditions would be there imo Wouldn't be surprised at all if they got a foot+

Agreed. Models have been consistent in hammering these areas all week. Looks to verify for sure now.

[Ralph Wiggum]

Man Mt hollys disco is good stuff again

 

...High-impact coastal storm will affect the region Friday andSaturday...Busy night. All focus with the long term was squarely with thecoastal storm affecting the area Friday and Saturday. Models areclosing in on a solution, but several big question marksremain, primarily associated with the geographical extent andtiming of changeover to snow.Will attempt to keep the model/scientific discussion short, asthe potential impacts need to be addressed at length. Models aregenerally closing in on a solution in which the southern-streamlow progressing off the Mid-Atlantic coast tonight curvesnorthward and stalls near/south of the southern New Englandcoast Friday and Friday night before progressing east-southeastwell offshore this weekend. The 00Z NAM is on the western fringeof guidance with the track and was deemed a lower-probabilitysolution in general, particularly given its continued very coldlow-level thermal profiles (with the GFS much warmer and theECMWF in between). The ECMWF was on the south/east side of themodel clustering but has been persistent with this. However, theGFS and ECMWF were exhibiting increasing consensus, and the CMChad a reasonably similar solution.As a result, the forecast used a blend of theGFS/ECMWF/CMC/WPC/GEFS for precipitation (including type andQPF). However, higher-resolution guidance (including the NAMNest, the WRF-ARW/NMM, and NamDNG) were weighted highlyregarding the winds on Friday and Friday night, as the coarsermodels simply looked too weak with winds/gusts given theproximity/intensity of the low, the very strong pressuregradient that will develop, and the favorable steepness of low-level lapse rates on the west/south side of the low.However, confidence on the thermal profiles and the resultantextent of snow and total accumulations is very low outside ofthe winter storm watch. Large changes to the forecast Friday andFriday night are possible in the next 24 hours as a result.Forecast weather/impacts:Winds will be one of the biggest impacts of this storm. Haveexpanded the high wind watch to include all areas not in winter-weather headlines (that is, everyone except Carbon/Monroe/SussexCounties) Friday and Friday night. This will very likely requireupgrade to a warning by this afternoon. Widespread gusts 50-60mph should be expected during the height of the winds (lateFriday morning to Friday evening), with gusts above 60 mphlikely near the coast and in portions of Delmarva. Considerablecoverage of power outages is possible as well as a large numberof downed trees.As for the rain, the heaviest should occur in northern portionsof the area Friday morning, but a surge southward as thewraparound cranks up during the afternoon is likely. Models showtremendous frontogenetical lift in the 850-700 mb layer over thearea during the afternoon/evening, which is one reason thecolder NAM solution cannot be discounted (combination of stronglift and precipitation-cooling effects will be at work here).Regarding snow, warning criteria will likely be met in thesouthern Poconos, at least in the higher elevations, where 4-7inches are possible (locally up to a foot in the highestelevations). There is more uncertainty in Sussex County, NJ,but given the overall eastward trend of the colder air anddeformation band(s) likely to develop on the northwest side ofthe low, the watch was expanded to include it. Very strong windsare probable Friday afternoon and evening, and local whiteoutconditions are possible. There is some concern blizzard criteriawill be met here.Farther southeast, changeover to snow is expected graduallyduring the day Friday in the Lehigh Valley and adjacent portionsof northern New Jersey. However, temperatures are quitemarginal, and considerable melting of any snow that falls isexpected. Furthermore, it is not clear how soon this changeoverwill be. Nevertheless, winds will be strong, so occasionalwhiteout conditions are possible anywhere changeover occurs.Confidence in blizzard conditions (3+ hours of quarter-mile orless visibilities) is too low for a watch here, so kept theseareas in a high wind watch instead. However, the combined threatof wind and snow is very worrisome, and a switchover to winterheadlines is quite possible in later forecasts, especially ifthe colder solutions are closer to reality.Storm total liquid-equivalent precipitation will likely be from1 to 2+ inches north of the Mason-Dixon Line, and around a thirdof an inch to a little more than an inch to the south.

 

 

The guys at Mt Holly are the best and as always are on top of things and doing a stellar job that the public should be grateful for. We essentially seem to agree as well which I am comfortable being in their company irt this storm. Thanks for all you do Mt Holly.....I see a few of ya's lurking ;-)

 

[Ralph Wiggum]

I would love to see a true surprise storm! I have been loving the spring weather, but we need at least 1 good storm this winter!
 

Odds are usually against a surprise snow event in general, especially this day and age BUT almost every system this winter has overperformed in one way or another so we have that aspect going for us snow hounds anyway. Here's hoping :cheers:

[The Iceman]

12z 12k NAM continues to rock extreme se pa into NJ with heavy snow from 18z-0z. Would definitely see more than 1-3" if that verifies. Has been very consistent the last 24 hours. here's the clown map and obviously won't get 10:1 but I don't think we have trouble sticking if the rates the nam shows are correct. also coming into focus is the sharp gradient.

 

[ChescoWx]

Great briefing write up from NWS Mount Holly on pending storm. Clearly some uncertainty regarding the SE extent of the snow threat as highlighted (see attached) by them down into NW Chester County etc. Although clearly wind will be the greatest impact and any potential power outages.