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November 11th-12th storm system


Thundersnow12

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Welp, I'm starting to get geeked for this one.  Could be looking at like 18 hours of at least wind advisory criteria with a couple periods of high wind warning criteria possible.  Could have some tree issues scattered about if this comes to pass but I'd be more concerned if it were earlier in the season.  Still about 4 days to go though so the ultimate severity is still in question.  I'd be lying if I said I didn't want it to trend stronger.

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This system is going to put forecasting skills to the test in more ways than one.  Specifically regarding the severe weather potential... weighing the totality of the circumstances, this one looks like it has more going for it than the system that just rolled through.  About the only thing that's worse is low level moisture, which could be a significant factor and certainly something that you don't want to downplay.  But the signals are strong for a forced line that will be looking for any excuse to bring damaging winds to the surface given those strong low level wind fields.  Looking back on past big deep lows like 11/10/1998 and 10/26/2010 does help I do believe, to compare and contrast.

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This system is going to put forecasting skills to the test in more ways than one.  Specifically regarding the severe weather potential... weighing the totality of the circumstances, this one looks like it has more going for it than the system that just rolled through.  About the only thing that's worse is low level moisture, which could be a significant factor and certainly something that you don't want to downplay.  But the signals are strong for a forced line that will be looking for any excuse to bring damaging winds to the surface given those strong low level wind fields.  Looking back on past big deep lows like 11/10/1998 and 10/26/2010 does help I do believe, to compare and contrast.

Actually Halloween 2013 isn't a bad comparison either in a broader sense.  Not quite as deep though...

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Yeah, there's probably a number of events to look back on.  I think Halloween overperformed as well, relative to expectations.

Unless we get an obviously decent amount (or zero) of CAPE, it will be interesting to see how widespread any severe weather is especially with eastward extent in this system when overlaying the best dynamics with any instability.  Seems like there is always so much "potential" with the strong low level winds but some events overperform and others underperform. 

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Might be our first AFD mention of the Edmund Fitzgerald storm

 

 

Louisville

 

 


WELL...SIGNIFICANT SYNOPTIC SCALE LOW COMING OUT OF THE SRN ROCKIES  AND LAND OF ENCHANTMENT WILL BE THE BIG STORY IN THE EXTENDED  PORTION OF THE FORECAST.  THIS SYSTEM WILL GO THROUGH VERY EXPLOSIVE  DEEPENING AND IS SOMEWHAT REMINISCENT OF THE HIGHLY ANOMALOUS SFC  LOW IN NOV 1975 THAT BROUGHT DOWN THE SS EDMUND FITZGERALD IN LAKE  SUPERIOR.  THIS WILL BRING SHOWERS AND STORMS WEDNESDAY EVENING AND  NIGHT. NWS MARQUETTE WILL BE LIVE TWEETING THE FINAL VOYAGE OF THE E  FITZGERALD UNDER #FITZ40 IN CASE YOU ARE INTERESTED.    
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post-13488-0-23065000-1446997581_thumb.gpost-13488-0-69263300-1446997589_thumb.g

NAM continues to deepen the low further west as to be expected with such a rapidly deepening system. What looked like an early afternoon FROPA could be pushed back another 12 hours. Looks like a rather robust line of convective showers along the front. With the amount of shear evident... damaging winds would seem likely.

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Of course it's Broyles. Are mid level lapse rates not a thing now?

 

Until we get out of this coolish-pattern we've been stuck in for the last several years (and back into a warmish 2010-2012 or mid/late 1990s-type pattern), mid-level lapse rates will continue to not remain a thing.

 

Though I'm sure those who hate hot summers and are enjoying the snowy winters of late have no complaints about the rather poor severe weather setups we've had lately (it's a trade-off).

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Cyclone this run of the ECMWF was the strongest in awhile, so its not trending weaker, and the 0Z GFS was stronger/deeper.

 

Incorrect.  Euro bottomed out at 984 with latest 00z, 984mb yesterday's 12z, and 983mb from the previous 00z.  The GFS is what has trended a little weaker, coming more in line with the Euro.  It's last run of sub 980mb was 6z from early yesterday morning.  The new 12z settles down to 983mb, which is very close to what the Euro has been advertising the last several runs.  Anyway, still a very strong storm system.

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I've been keeping quiet until we get into the NAM range which usually tends to do better with the thermo environment over the GFS..

 

New 12z NAM with quite the uptick instability values and also some better mid-level lapse rates it looks like. Also included sig tor values below. All for 18z and 21z on Wednesday. 

 

 

 

 

 

 

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Couldn't find a 21z image for 0-3km CAPE but here is 18z Weds...very impressive bullseye which then translates east looking at a forecasting sounding for the IA/MO border. Impressive fat CAPE and low level lapse rates with great shear.

CONUS_NAM_0-3KM_CAPE_78HR.gif

ia-mo border 21z.gif

would like to see a larger warm sector but I do think the NAM has the right idea with the instability, it did a better job than the GFS did on previous system.
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I'm a little surprised he went 30% already...but we have seen more than a couple fairly widespread events this time of year with weak lapse rates and instability as others have mentioned.

Yeah in defense of the risk it won't take much to get a good wind event, this system is better than the previous system with more dynamics and potentially more instability. The 30% doesn't mean he is calling for a tornado outbreak, a good squall line could very well yield wind reports equivalent to a 30% risk.
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Incorrect.  Euro bottomed out at 984 with latest 00z, 984mb yesterday's 12z, and 983mb from the previous 00z.  The GFS is what has trended a little weaker, coming more in line with the Euro.  It's last run of sub 980mb was 6z from early yesterday morning.  The new 12z settles down to 983mb, which is very close to what the Euro has been advertising the last several runs.  Anyway, still a very strong storm system.

 

 

System won't be fully onshore until 12z Tuesday (or maybe even 00z Wednesday).  Can I pull out the weenie card that we may see changes/a stronger system once land based sampling occurs?  :weenie:  Really though, model solutions have been pretty stable lately all things considered.

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