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Front-End Potentials 2/22-2/23 and 2/26-27


HM

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I don't know what to make of tomorrow, myself. I think the data is suggesting that there will be leftover bands that will be capable of moistening the entire layer to adequately make snowflakes / wetbulb down. In between these, any lighter precip will probably be sleet, freezing rain/drizzle and light rain/drizzle (hard to get freezing rain during daylight hours near big cities in late-Feb). So, it is quite possible the meso models are too focused on the bands and the GFS isn't focused enough.

Tomorrow is kind of cool because there is high uncertainty. Between what's going on now in the Plains and the 9z SREF h7 MPV anomalies showing up, I could buy the idea of a compromise with "convective-like" banding. In between, you won't be making snowflakes and temps will have an easier time warming aloft.

This threat seems best for N VA/WV, MD, S PA and DE tomorrow and even SW NJ / southwestern areas of the PHL region (Like Chester Co). Then it will shift into our NW suburbs overnight into Sat AM. Looking forward to the euro!

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12z euro, notta.

some precip moves in 12z saturday, warm

 

Well, the best models we have say "nope" so it is looking like this is a fail.

And the ECMWF is already drastically different in the West at day 4-5. lol

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This euro run is, well, WTF... seriously bizarre happenings with this pattern in the 6-10 day and beyond

 

In many ways you can see why there are 3 top cpc analog dates from feb 2010 

 

Using the best analogs for early March that had this kind of setup may be the best way to go here for evolution, along with ensemble means. But yeah, that was definitely some good entertainment on the euro.

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I'll continue to keep my eye on this for the TTN area (in case something happens that ends up being archive-worthy) but right now I'm not enthusiastic.  But I've been wrong before.

 

Agreed. The initial shot to our Southwest should miss (whatever is left of it) and the coastal should be rain. It seems like it will be the outskirts of our general region that have the most potential over the next couple of days...meh.

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Agreed. The initial shot to our Southwest should miss (whatever is left of it) and the coastal should be rain. It seems like it will be the outskirts of our general region that have the most potential over the next couple of days...meh.

 

Not so sure the NAM is b/s on this one... clearly all of the models NOT showing the front end snow are speeding up the convection across the SE... resulting in a faster moving boundary that chokes off moisture supply to the front end convergence.  Given that the NAM and WRF are better convection models and are both slower with the boundary, and hence more advection and convergence on the front end makes this a not so totally absurd idea in my mind despite limited support.

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Not so sure the NAM is b/s on this one... clearly all of the models NOT showing the front end snow are speeding up the convection across the SE... resulting in a faster moving boundary that chokes off moisture supply to the front end convergence.  Given that the NAM and WRF are better convection models and are both slower with the boundary, and hence more advection and convergence on the front end makes this a not so totally absurd idea in my mind despite limited support.

I did not look into that and I hope you're right. I did note, however, the HPC favoring a non-NAM solution overall. But, I didn't think that was exactly pertaining to this localized event either.

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I did not look into that and I hope you're right. I did note, however, the HPC favoring a non-NAM solution overall. But, I didn't think that was exactly pertaining to this localized event either.

 

Definitely not forecasting that yet, but not eliminating the possibility just yet either.  I don't want you to think I am trying to weenie something out of nothing, just saying I am not ready to dismiss it yet.  Gut says no.... or maybe very very brief.

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Well, the best models we have say "nope" so it is looking like this is a fail.

And the ECMWF is already drastically different in the West at day 4-5. lol

He is looking at stormvista and it doesn't show precip that is under .05 during a 6 hr period. By saturday morning before 850s warm its 05-.1 for the region

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Not so sure the NAM is b/s on this one... clearly all of the models NOT showing the front end snow are speeding up the convection across the SE... resulting in a faster moving boundary that chokes off moisture supply to the front end convergence.  Given that the NAM and WRF are better convection models and are both slower with the boundary, and hence more advection and convergence on the front end makes this a not so totally absurd idea in my mind despite limited support.

NAM isn't much different from the GFS/EC as far as sensible weather as far as I can see in the LV down to TTN with the front-end...  its the difference between a coating and an inch or so.  Difference is a bit more marked in PHL where the NAM gets them closer to 2" before the changeover.  As always... we'll know better tomorrow ;)

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hell, even the gfs has -6 to -12 vv's entering DC at 18z tomorrow... So I'm certainly still very intrigued on what happens down there, and I think the situation has been properly diagnosed as having surprise potential. Its been an impressive to watch out in the midwest today that's for sure.

I have the morning of 1/26/11 in the back of my mind with this one... but still think its not likely to be a big deal as far north as TTN, for sure.  New NAM seems to have backed off on the northward extent and it looks like the SREF is drier than the NAM, which is usually a red flag.  Not that either of them have been doing well lately. 

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I have the morning of 1/26/11 in the back of my mind with this one... but still think its not likely to be a big deal as far north as TTN, for sure.  New NAM seems to have backed off on the northward extent and it looks like the SREF is drier than the NAM, which is usually a red flag.  Not that either of them have been doing well lately. 

 

That was a very hectic morning for me! Seem to recall you flew back for that storm. i occasionally forget what forum I'm in, but my comments were mainly DC-centric. i guess I couldd see it surprise further north up to philly too, but much more of a long shot. The 18z nam is quite juicy heading into DC tmrw aftn, and I think I'm kinda liking that scenario for them over the globals  :yikes: 

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That was a very hectic morning for me! Seem to recall you flew back for that storm. i occasionally forget what forum I'm in, but my comments were mainly DC-centric. i guess I couldd see it surprise further north up to philly too, but much more of a long shot. The 18z nam is quite juicy heading into DC tmrw aftn, and I think I'm kinda liking that scenario for them over the globals  :yikes: 

Ah, yeah that makes more sense.  :lol:  I WISH I had flown back for that one, but work prevented it...  The best storms at TTN over the last 6 years have been when I was on midnight shifts and had no realistic way of getting off work (2/10/10 and 1/26/11), so if that trend holds you can expect the next potential big one to be sometime between March 5th and March 12th :axe:

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hell, even the gfs has -6 to -12 vv's entering DC at 18z tomorrow... So I'm certainly still very intrigued on what happens down there, and I think the situation has been properly diagnosed as having surprise potential. Its been an impressive to watch out in the midwest today that's for sure.

I'm liking your optimism for the Mid Atlantic (NC to MD). The soundings are going to look funny with this one because if you don't have ample lift, it will appear to be an icy sounding or even rain down there. But, snow will be made, I think, properly with a shot of decent VVs...especially during the first half of the event. In between bands or convective showers, yeah snowflakes won't be made properly or temps will warm aloft and precip type changes.

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As I recall the 2007 analog wasn't forecast very well at all with little snow expected in DC

Yes but for different reasons. More of a wave came eastward from the Midwest low in that one that increased the vertical motion. In this case, we have isentropic lift, moisture, warm air advection and a touch of mid level frontogen but none of it is strong. 2007 had more help from cyclonic vorticity advection too.

Still, a surprise element possibly does exist for the N VA-SW NJ corridor tomorrow.

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Yes but for different reasons. More of a wave came eastward from the Midwest low in that one that increased the vertical motion. In this case, we have isentropic lift, moisture, warm air advection and a touch of mid level frontogen but none of it is strong. 2007 had more help from cyclonic vorticity advection too.

Still, a surprise element possibly does exist for the N VA-SW NJ corridor tomorrow.

Dew point at TTN is 13 degrees F. Will take some major WAA is scour this out. NWS predicting 20F tonite but it may go lower with the winds calming. 

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The other element on the soundings that no one has mentioned yet is the "seeder feeder" possibility, esp. for folks to our south who benefit from the 700mb s/w. The moist layer way up there in cirrus land could help produce snowflakes.

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