February 4th-6th Overunning & Possible Coastal Threat

[wolfsheepsheadbay]

Not great trends on the models.  The strong upper support moves through the MS valley on Tue, allowing for heavy snow from N MO through IL and IN.  Thereafter, the s/w dampens out as a piece of the PV retrogrades west and then drops into the LW trof.  That leaves us with a relatively flat trof, a far west trof axis, and a big slug of moisture.  As modeled, this is all front side with minimal upper support and weak surface deepening.  This still looks potentially decent, but for a 6 day threat it does not peg the excitement meter.

I disagree. Trends overnight were to have a weaker primary and the coastal transfer occurring earlier. Even crazy amped models like the Navgem have this scenario now. This could easily translate into colder future runs.

[earthlight]

Not great trends on the models.  The strong upper support moves through the MS valley on Tue, allowing for heavy snow from N MO through IL and IN.  Thereafter, the s/w dampens out as a piece of the PV retrogrades west and then drops into the LW trof.  That leaves us with a relatively flat trof, a far west trof axis, and a big slug of moisture.  As modeled, this is all front side with minimal upper support and weak surface deepening.  This still looks potentially decent, but for a 6 day threat it does not peg the excitement meter.

 

As modeled now this is a SWFE. But I think the trends being bad is relatively to how long you've been watching. If you compare the 18z GFS from yesterday to the 06z GFS run from this morning, you can see the PV has trended more consolidated and farther south. The 00z run was right in the middle of this trend. If you keep this idea going, we'll be looking at a significant winter weather event in not much time. 

 

For being 5-6 days out, the set up is not screaming major winter storm to me. But the way the models have essentially thrown their hands up at this range, especially in Canada, I'll be watching carefully considering the amplitude of the southern stream fort. 

[IsentropicLift]

We've all been down this road before. As long as this transfers to the coast before reaching Pennsylvania the majority of us should be fine. For those that live on the south shore of Long Island, you should know the drill by now, but don't fret because you'll be jackpotted by the day ten system. Us inlanders love these strong WAA events. Great over running snows, flipping to ZR late in the game. If the primary makes it to Pennsylvania then we all get screwed, but right now that looks like the least likely scenario next to this cutting to Detroit. Almost all of the 00z GEFS members show the transfer to the coast, albeit some later than others. A couple members showed the primary tracking to our south, that would be fine too.

[user13]

We have to wait for the sunday storm to get out of the way so the models can get a better handle on the split flow. Also by looking at the gfs, that might have a sneaky secondary with that storm

[REDMK6GLI]

As modeled now this is a SWFE. But I think the trends being bad is relatively to how long you've been watching. If you compare the 18z GFS from yesterday to the 06z GFS run from this morning, you can see the PV has trended more consolidated and farther south. The 00z run was right in the middle of this trend. If you keep this idea going, we'll be looking at a significant winter weather event in not much time.

For being 5-6 days out, the set up is not screaming major winter storm to me. But the way the models have essentially thrown their hands up at this range, especially in Canada, I'll be watching carefully considering the amplitude of the southern stream vort.

fixed that for you "vort" not fort haha

But i agree it trended better with the PV and that is what is going to be the determining factor for CAD in a SWFE like this. I personally just hope a snow-rain or plain snow event with no ice threat.

[earthlight]

fixed that for you "vort" not fort haha

But i agree it trended better with the PV and that is what is going to be the determining factor for CAD in a SWFE like this. I personally just hope a snow-rain or plain snow event with no ice threat.

 

As modeled right now, synoptically it still blows chunks. The best lift and forcing goes into Chicago. So while we are getting a secondary development due to the compressed height field north of us, the mid level warm air advection is having no problem pushing northward. We need that PV to continue to trend southward. When that happens we'll start to see the best PVA in the mid levels shift on a more northeasterly direction and then we can really start talking.

 

Also, whenever we have EPO ridges like this and cold air dislodged over Canada and the Northern 1/3 of the US, systems like this will have inherent ice threats away from the coast as the low level cold is more genuine. These are not your 07/08 SWFE systems. There could be significant freezing rain in the NW/interior if the mid level warm air advection does in fact take over. 

[bluewave]

Really could do without that. Hoping for a South shift. This look continues and I'm going generator shopping.

 

I really hope the default position isn't the high to the north is too strong to prevent an outright cut, but the 

storm is too amped to keep the 850 line to our south with a nasty ice storm somewhere in the transition zone.

[earthlight]

Worth noting that the Euro ensembles were farther southeast than the OP and more inline with the GFS. Very strong agreement on the system, but still obvious variation on the track. The OP was on the left/more amplified side of the ensemble mean. 

[Zelocita Weather]

So in summary both the GFS/EURO have a 4-8" snow to mix/cold rain or ice storm similar to the Dec storm earlier in the year....

[jm1220]

I really hope the default position isn't the high to the north is too strong to prevent an outright cut, but the 

storm is too amped to keep the 850 line to our south with a nasty ice storm somewhere in the transition zone.

There's going to be a lot of cold air at the surface before the storm arrives, so it wouldn't surprise me at all that there's a zone of heavy ice inland where the cold air stays firm.

 

Hopefully the PV keeps strengthening and doesn't split. That would force a redevelopment south enough to have us all or mostly snow. I'd say the odds favor inland and New England for a lot of snow, since this seems to be similar to the pattern we had in December where the coast had slop and rain systems and inland more snow/ice, but we'll see.

[uncle W]

if we get a system like we saw in December with colder temperatures on land and in the Ocean it could turn out to be a big ice problem even in NYC...I'll take 6" of snow and nearly an inch of sleet and freezing rain that ends as drizzle...

[Jersey Shore snow]

Earthlight provides the best synoptic discussions and model interpretation on any of these forums....bar none.  Always look forward to his insight

[REDMK6GLI]

Earthlight provides the best synoptic discussions and model interpretation on any of these forums....bar none. Always look forward to his insight

Agree that he is one of the best. Always informative and honest forecasting whether we like the outcome or not

[bluewave]

There's going to be a lot of cold air at the surface before the storm arrives, so it wouldn't surprise me at all that there's a zone of heavy ice inland where the cold air stays firm.

 

Hopefully the PV keeps strengthening and doesn't split. That would force a redevelopment south enough to have us all or mostly snow. I'd say the odds favor inland and New England for a lot of snow, since this seems to be similar to the pattern we had in December where the coast had slop and rain systems and inland more snow/ice, but we'll see.

 

I also hope the under 72 hrs northward trend we normally see doesn't land the the South Shore on the wrong side of

the gradient. But it's still too early to know how things will play out just yet. It has helped us this year with

systems that looked OTS come closer for good snows here. But seeing the models have the freezing

line so close from days 6-7 makes me a little nervous.

[jm1220]

if we get a system like we saw in December with colder temperatures on land and in the Ocean it could turn out to be a big ice problem even in NYC...I'll take 6" of snow and nearly an inch of sleet and freezing rain that ends as drizzle...

The storm in December flipped winds to easterly and warmed the coastal plain well into the 40s. I remember it warming up 5 degrees in a matter of minutes when that happened. Even though the water's colder now, it's still warm enough to flip the coastal plain over to rain if the winds turn easterly. We would want winds to stay northerly as long as possible. That's what happened in February 2007's ice storm that was very bad right down to the coast.

[eduggs]

As modeled now this is a SWFE. But I think the trends being bad is relatively to how long you've been watching. If you compare the 18z GFS from yesterday to the 06z GFS run from this morning, you can see the PV has trended more consolidated and farther south. The 00z run was right in the middle of this trend. If you keep this idea going, we'll be looking at a significant winter weather event in not much time. 

 

For being 5-6 days out, the set up is not screaming major winter storm to me. But the way the models have essentially thrown their hands up at this range, especially in Canada, I'll be watching carefully considering the amplitude of the southern stream fort. 

I'm not looking for a SWFE.  A few days ago most guidance had a powerful southern stream s/w going under the PV, progressing east, and maintaining mid/upper level structure long enough to enhance SLP along the east coast.  Since then, as you've pointed out, we've trended toward more PV involvement further west.  That obviously opens the door to all the potential negatives that go with the generalized SWFE... shorter duration, warm, less QPF etc.  What I do like is the strong Gulf connection.  And there is obviously lots of time to trend better.

[REDMK6GLI]

I also hope the under 72 hrs northward trend we normally see doesn't land the the South Shore on the wrong side of

the gradient. But it's still too early to know how things will play out just yet. It has helped us this year with

systems that looked OTS come closer for good snows here. But seeing the models have the freezing

line so close from days 6-7 makes me a little nervous.

Im staying stead fast and say this storm will deliver upstate and the weekend storm will deliver for the megalopolis in a big way. Going to be exciting forecasting time starting monday for us. Start stocking up on red bull drinks folks

[earthlight]

I'm not looking for a SWFE.  A few days ago most guidance had a powerful southern stream s/w going under the PV, progressing east, and maintaining mid/upper level structure long enough to enhance SLP along the east coast.  Since then, as you've pointed out, we've trended toward more PV involvement further west.  That obviously opens the door to all the potential negatives that go with the generalized SWFE... shorter duration, warm, less QPF etc.  What I do like is the strong Gulf connection.  And there is obviously lots of time to trend better.

 

Lol, I don't think anybody in their right mind that lives in this area is hoping for a SWFE. But that may very well be what we have to deal with at least initially. The warm air advection is going to drive the initial precipitation. As you mentioned, and I think we agree, we want to see the models trend more consolidated and farther east with the Polar Vortex. As it stands now it is just too far west to allow for a retrogression and lobe southward into the mean trough over the Central United States. This really compounds the problem and helps amplify the Southeast Ridge. 

 

The trends from 18z to 06z on the GFS and the other ensembles were somewhat encouraging. So I will mostly be interested in seeing if that continues today. The inconsistency of the models with the handling of several features over Canada for the better part of the past few weeks should at least stop the panic at this range. We have a long time to go with this threat and all of the ones following it as well. 

[Zir0b]

The storm in December flipped winds to easterly and warmed the coastal plain well into the 40s. I remember it warming up 5 degrees in a matter of minutes when that happened. Even though the water's colder now, it's still warm enough to flip the coastal plain over to rain if the winds turn easterly. We would want winds to stay northerly as long as possible. That's what happened in February 2007's ice storm that was very bad right down to the coast.

I could see a prolonged period of ice JUST inland. Here in New Brunswick we only got to 34 in December, and this was after the majority of precip had fallen. I think we also had to be upgraded to a WSW. I expect the models to be keying in on the low level cold in a few more days if this storm is more of a coastal hugger instead of a bonafide inland runner. 

[SnoSki14]

I could see a prolonged period of ice JUST inland. Here in New Brunswick we only got to 34 in December, and this was after the majority of precip had fallen. I think we also had to be upgraded to a WSW. I expect the models to be keying in on the low level cold in a few more days if this storm is more of a coastal hugger instead of a bonafide inland runner. 

Yeah the low level cold can be incredibly stubborn even when the mid and upper levels are warming like crazy. The ocean is much colder now than in December (like mid to upper 30s I believe) and SWFE can be notorious for dangerous icing/sleet. The problem is that often the models don't see the low level cold until the event begins to unfold, which is why we frequently see last minute upgrades to WSW or ice storm warnings because forecasters realize the cold isn't going anywhere. 

[MJO812]

The storm from 2/22/08 looks pretty similiar to the one coming up.

 

http://www.meteo.psu.edu/~fxg1/NARR/2008/us0222.php

[IsentropicLift]

The 06z GEFS probabilities for significant icing favor the northern tier of PA and into the Philly area. The 06z GFS text output had 0.47" of ice at KMMU falling in about a 9-12 hour period.

 

What I find interesting is that none of the 120hr analogs over the east have significant ice or snow for the area. Almost all rain.

[IsentropicLift]

Lol, I don't think anybody in their right mind that lives in this area is hoping for a SWFE. But that may very well be what we have to deal with at least initially. The warm air advection is going to drive the initial precipitation. As you mentioned, and I think we agree, we want to see the models trend more consolidated and farther east with the Polar Vortex. As it stands now it is just too far west to allow for a retrogression and lobe southward into the mean trough over the Central United States. This really compounds the problem and helps amplify the Southeast Ridge.

The trends from 18z to 06z on the GFS and the other ensembles were somewhat encouraging. So I will mostly be interested in seeing if that continues today. The inconsistency of the models with the handling of several features over Canada for the better part of the past few weeks should at least stop the panic at this range. We have a long time to go with this threat and all of the ones following it as well.

NW folks cash in the best with WAA. Coastals usually only brush us. Exceptions of course.

[donsutherland1]

PLease mention the Monday possible threat in your analysis if possible.

 

QPF for that event from the 0z ECMWF:

 

ACY: 0.36"

BLM: 0.13"

NYC: 0.04"

[IsentropicLift]

Monday's non-event is pretty far south on the 12z GFS. Precip only makes it up to about DC.

[PB GFI]

Monday's non-event is pretty far south on the 12z GFS. Precip only makes it up to about DC.

Good , maybe it helps pressing the cold for WED . 

[IsentropicLift]

The Polar Vortex looks more consolidated this run and perhaps further east through hr 96. Looks like it's going to elongate more north to south instead of splitting like it was doing yesterday.

[96blizz]

The Polar Vortex looks more consolidated this run and perhaps further east through hr 96. Looks like it's going to elongate more north to south instead of splitting like it was doing yesterday.

And the cold is continuing to squash that first disturbance.  Hopefully that helps downstream on this run as well...

[earthlight]

The GFS has again trended farther south and more compressed with the height field north of New England through 102 hours. It is hard to say if this will have a huge effect on the eventual outcome, but this is a noticeable trend now over 4 straight runs. 

[IsentropicLift]

The trend over the past day has been for stronger northern stream energy dropping into the trough, but today the Polar Vortex looks to be much better oriented. At least through hr 108.