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February 15-MOrch possible wintry threats


tombo82685

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12z gfs squashes everything. Kind of a waste of a good trough. Def looks like the coldest shot of air, until next winter. Energy mets going to look great Sunday night, when all of fl has freeze warnings lol

 

Well if it was longer lasting, didnt fall on a weekend, and if they cared about oranges in FL, then it would have certainly mattered more. I know the european guidance failed at this cold shot coming up and all, but this is really not a big deal for energy though.

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Any hope for further interior sections, or is everything going to be suppressed? We've had a few very minor events this year but I'd like one big one before spring.  Apologies to the eastern sections but there aren't any mets that post in the Pittsburgh area thread.  Since the STJ got going I thought we might all get involved ala 2010, '96, PDII, etc.

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System between the 21-23 is the one that's had my attention for a while and I am LOVING the setup (quasi 50/50, ridging near Greenland, ridge off West coast, and big HP at the surface sitting over the Lakes with a mean looking s/w coming across the country). This is likely our last hurrah so let's enjoy tracking this baby!

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System between the 21-23 is the one that's had my attention for a while and I am LOVING the setup (quasi 50/50, ridging near Greenland, ridge off West coast, and big HP at the surface sitting over the Lakes with a mean looking s/w coming across the country). This is likely our last hurrah so let's enjoy tracking this baby!

Agree. The HM last hurrah before morch

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Here's one thing i noticed on the 0z GFS compared to the 18 and 12z runs.. ( prob 6z too, but havent had time to check).

Check out this "player" shortwave dropping into the backside of the trough. It's obviously not fast enough to catch the energy in the base of the trough on the 0z GFS. However, if you put that in the 18z trough , same time frame and shortwave orientation, things would probably get interesting.

0z GFS left, 18z GFS right.

zyga2u3u.jpg

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adam, how far west?

big shift pending soon on op's?

100 miles are so. I wouldn't suggest that we're absolutely going to see a shift to the west... the ensemble means have been farther west with this system all along. Again, I would just reiterate that the chances of this coming back to affect the coast are higher than you would otherwise think from the op models only

 

Adam when you an HM were talking yesterday about the next storm probably won't cut were you talking about the tues event or later in the week one?

I was talking about the Tuesday-Wednesday event, but the same logic holds for the late week event on the models. The deeper any system gets as it goes out to sea, will make it more likely that the following system can ride up the coast.

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100 miles are so. I wouldn't suggest that we're absolutely going to see a shift to the west... the ensemble means have been farther west with this system all along. Again, I would just reiterate that the chances of this coming back to affect the coast are higher than you would otherwise think from the op models only

 

I was talking about the Tuesday-Wednesday event, but the same logic holds for the late week event on the models. The deeper any system gets as it goes out to sea, will make it more likely that the following system can ride up the coast.

Pushes the boundary to the coast or offshore? Or creates a 50/50 low and kind of blocks it from cutting.

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The euro op, its ensembles, and the GFS and its ensembles are show a pretty decent ATL blocking scheme showing up. However, the PNA looks to dip a bit negative, and well as the EPO /AO rise nuetral-postive. Just something to keep an eye on.

The Oz ECM did develop a surface reflection this weekend similar to the 0z canadian ( rip old GGEM), just not as wet as the GGEM. something to watch too.

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I find it interesting that back in late Jan, this was the discussion between Wes and me:

http://www.americanwx.com/bb/index.php/topic/38643-medium-range-long-range-thread/page-27#entry2051101

Basically, he wasn't really feeling the DC area with the first threat but we agreed that things would improve for the Mid Atlantic with time. Interesting how we both were on the fence about something being major in the Mid-Atlantic and it turned out that the storm was generally major north of NYC on 2/8-9.

The analogs once again strongly point to 2/20-2/22 and have for over a month now after the 2/8-10 threat. The in between dates I was always unsure of, going back and forth between snowy and meh. It looks like things will turn out snowier with tonight's light to moderate event and possibly this weekend (I agree with Adam that this isn't a "done deal" with the GFS/EURO ensembles, GGEM and UKMET offering a accumulating snow threat).

As discussed for the last few weeks, the 2/20-22 threat was contingent upon the general decline in the NAO due to the final stratospheric response and a leftover southern stream. If the NAO seemed real, this could borderline a KU for our area. Both the NAO and southern stream are being modeled at this time on most NWP. The only issue is the tropical forcing which may or may not trend towards a more unfavorable regime by this point, possibly limiting amplification and cold air availability. I'm currently leaning towards a significant storm on this date just under KU status for our region.

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I find it interesting that back in late Jan, this was the discussion between Wes and me:

http://www.americanwx.com/bb/index.php/topic/38643-medium-range-long-range-thread/page-27#entry2051101

Basically, he wasn't really feeling the DC area with the first threat but we agreed that things would improve for the Mid Atlantic with time. Interesting how we both were on the fence about something being major in the Mid-Atlantic and it turned out that the storm was generally major north of NYC on 2/8-9.

The analogs once again strongly point to 2/20-2/22 and have for over a month now after the 2/8-10 threat. The in between dates I was always unsure of, going back and forth between snowy and meh. It looks like things will turn out snowier with tonight's light to moderate event and possibly this weekend (I agree with Adam that this isn't a "done deal" with the GFS/EURO ensembles, GGEM and UKMET offering a accumulating snow threat).

As discussed for the last few weeks, the 2/20-22 threat was contingent upon the general decline in the NAO due to the final stratospheric response and a leftover southern stream. If the NAO seemed real, this could borderline a KU for our area. Both the NAO and southern stream are being modeled at this time on most NWP. The only issue is the tropical forcing which may or may not trend towards a more unfavorable regime by this point, possibly limiting amplification and cold air availability. I'm currently leaning towards a significant storm on this date just under KU status for our region.

I remember you posting that comment. Both you and Wes were rock solid on that call. For the weekend storm. It seems like the models are keying on a different s/w than they were 48 hrs ago. If i recall the gfs was keying on the disturbance dropping down on the backside of the trof and ampilfying and forming a low on the carolinas and coming north. These later runs seems to be keying on a s/w associated with the polar jet dipping down just below our latitude that tries to fire somewhat of a miller b setup.

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100 miles are so. I wouldn't suggest that we're absolutely going to see a shift to the west... the ensemble means have been farther west with this system all along. Again, I would just reiterate that the chances of this coming back to affect the coast are higher than you would otherwise think from the op models only

 

I was talking about the Tuesday-Wednesday event, but the same logic holds for the late week event on the models. The deeper any system gets as it goes out to sea, will make it more likely that the following system can ride up the coast.

This has been a great period of time to see the lag effects from the Tropical Forcing end of things and stratospheric end of things on the NAO (which is why predicting the NAO is tough since it relies on lag effects of multiple variables). Both factors have promoted cyclonic wave breaking off the North American Coast now for the last week or so and that should continue through next week. Overtime, these CWB anomalies push the jet toward the equator and enhance easterly anomalies across the North Atlantic (all of which is tied into the AAM propagation too). This has been correlated to lead to a -NAO period during the winter season and it is interesting to see this show up on the data.

Why trust it now?

1. The stratospheric setup in the lowest layers continues to remain favorable, not a deterrent.

2. The AAM state is also favorable

3. A 2 week period of CWB off the N.A. coast

4. Favorable MJO propagation but will it speed off into unfavorable territory?

5. Already a positive anomaly up there, just displaced too far east

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I remember you posting that comment. Both you and Wes were rock solid on that call. For the weekend storm. It seems like the models are keying on a different s/w than they were 48 hrs ago. If i recall the gfs was keying on the disturbance dropping down on the backside of the trof and ampilfying and forming a low on the carolinas and coming north. These later runs seems to be keying on a s/w associated with the polar jet dipping down just below our latitude that tries to fire somewhat of a miller b setup.

 

As for this weekend, yes the GFS and ECMWF are focuing on a lead northern stream s/w to initiate cyclogenesis on the cold front that pushes out into the Atlantic. Regardless of the actual low track, snow may be able to break out with the trough itself along with the potential for snow shower/squalls with the Arctic Air.

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