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Severe Weather 2021 (5 Viewers)

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Messages
12
Location
Northern Europe
Next week is showing potential for maybe a more widespread and robust event.
The EPS has definitely trended toward a broader warm sector on Saturday/Sunday. However, the mid-level trough looks to be more positively tilted and “pinched-off” in orientation and appearance. The big takeaway is that these successive shortwaves open the door to the “reloading” in the long range and could thus set the stage for a much bigger event come the first few weeks of March. If one is looking for a singular event, one should probably focus on that timeframe, rather than the last week of February.
 

Fred Gossage

Member
Meteorologist
PerryW Project Supporter
Messages
223
Location
Florence, AL
The EPS has definitely trended toward a broader warm sector on Saturday/Sunday. However, the mid-level trough looks to be more positively tilted and “pinched-off” in orientation and appearance. The big takeaway is that these successive shortwaves open the door to the “reloading” in the long range and could thus set the stage for a much bigger event come the first few weeks of March. If one is looking for a singular event, one should probably focus on that timeframe, rather than the last week of February.
While this one has trended cutoff with time, be careful instantly turning your head away from positive tilt troughs, especially in Dixie. Trough amplitude is a lot more important than trough tilt. Many of Alabama's big tornado days (including April 8, 1998; February 5, 2008; May 18, 1995; April 4, 1977; April 3, 1974; and even March 21, 1932 if we believe the reanalysis data is close enough to correct to be accepted) were all positive tilt troughs. They were all also events with F4-F5 tornadoes in Alabama. April 3, 1974's trough started out negative tilt that morning but evolved into a positive tilt prior to any of the violent tornadoes in Alabama. Lower amplitude troughs are dangerous here, regardless of tilt. There are a whole lot of tornado deaths in this state's history to prove the idea as true.
 

andyhb

Member
Messages
261
Location
Norman, OK
Mid-range guidance seems to be shifting more towards split flow and less severe potential to enter March.
 

Peter Griffin

Member
Messages
69
Location
Newport, NC
Posted this elsewhere, but I wanted to repost here to highlight a feature that I've noticed tonight upon analyzing some of the SSTA patterns with previous La Nina events.

image.thumb.png.e406ec788bb1a6ae94bcd37fdb044207.png

Did some skimming of SSTA data tonight and I'm intrigued by that warm pool centered at ~150˚W and 30˚S to the south of the cold SSTAs with the Nina. Based on looking into some previous analogs around this time, it seems like that strong meridional dipole is not present in years such as 2006, 2009, 2012, 2017, and 2018 (generally quieter severe seasons especially late season). It is more prevalent in several big Nina springs though, including 1974, 1976, and 2011.

It's probably to some degree why this CDAS-derived SSTA analog product from Tropical Tidbits is essentially grouping a who's who of Nina springs with a lot of tornadoes/severe weather, including some with very large outbreaks.

image.png.c5ce00b04be0e1951ca1df3b8f7669a2.png


You can see the SSTA dipole present in the Southern Hemisphere in the mean here.
All of those analog years each had at least 1 F5/EF5. 1974 and 2011 featured super outbreaks. 1999 featured possibly the strongest tornado of all time (Moore), 2008 had Parkersburg which did extremely violent damage and had the Super Tuesday Outbreak. 1976 had 3 F5s. I am not as familiar with the 1976 season as I am the rest but definitely a concerning look.
 

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