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Late April severe weather risk ~Mon-Sun 4/24-30

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This is still a week away, however, the SPC already has this day pinned for a day 8 potential significant severe weather event.

 

 

Edit :Map Update to reflect current date of 4/26/17

 

 

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...Friday/Day 8...
   The ECMWF and GFS are in better agreement in the western U.S.,
   developing a vigorous upper-level trough in the Four Corners region.
   This coincides with strong moisture advection across the Great
   Plains. The synoptic setup which the medium-range models have been
   forecasting for a couple days, could result in a significant severe
   weather event on Friday into Friday night across parts of the
   southern and central Plains with tornadoes, large hail and wind
   damage possible. Due to the potential for a higher-end event on
   Friday, have added a 15 percent contour where model consensus places
   the greatest chance of severe weather.
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Might as well change the title to ~Mon-Sat 4/24-29 or even just "late April" severe threats. Expect multiple opportunities for severe across the central U.S. Knowing how these things can unfold, we could easily get a bigger day prior to next Friday, and/or the outlook for the 28th could end up evolving synoptically different than currently anticipated. 

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2 minutes ago, TheBudMan said:

Heading out to Chicago next week - any chance I can see some good action out there or will all the good action be way south of me ?  

There are multiple chances in Illinois over the next 10 days. As noted in other threads, on going convection could be a problem though 

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I'm tending to like the potential on Wednesday  /Thursday better than Friday, probably Thursday as cyclogenesis occurs farther north and the LLJ is much more impressive... The cap is concerning for Thursday, but that might work in our favor and produce isolated supercells, compared to Friday where we will see heaping loads of storms. On Friday the potential for meridonial flow and VBV is concerning, lots of deleterious storm interactions, but the strength and direction of the low-level flow lends credence to a higher-end tornado threat regardless... 5/24/11 featured a lot of storms and storm interactions if I recall... obviously this is based off of current model depictions, namely the op gfs, and things will evolve. Many of the GEFS ensembles as well as the euro FWIW don't really show meridional flow quite like the GFS does... so that's positive.

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Most likely issued Day 8 as Euro prefers Friday > Thursday. Still time for change, but the stretch late next week, possibly into early May looks active. 

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2 hours ago, jojo762 said:

I'm tending to like the potential on Wednesday  /Thursday better than Friday, probably Thursday as cyclogenesis occurs farther north and the LLJ is much more impressive... The cap is concerning for Thursday, but that might work in our favor and produce isolated supercells, compared to Friday where we will see heaping loads of storms. On Friday the potential for meridonial flow and VBV is concerning, lots of deleterious storm interactions, but the strength and direction of the low-level flow lends credence to a higher-end tornado threat regardless... 5/24/11 featured a lot of storms and storm interactions if I recall... obviously this is based off of current model depictions, namely the op gfs, and things will evolve. Many of the GEFS ensembles as well as the euro FWIW don't really show meridional flow quite like the GFS does... so that's positive.

The GFS operational run is probably developing too quickly, as we've seen often. The GFS' own ensemble seems to support Friday more than Thursday, granted there is considerably spread. ECMWF and especially EPS favor Friday, and as someone else said this is probably why Friday is highlighted on the day 4-8 outlook.

 

The EPS is actually pretty damn impressive in its agreement based on anomaly forecast and graphic posted above. I definitely lean Friday myself.beat.thumb.png.17635a1b85e020af11f216e434d838a1.png

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True... GFS always has those issues it seems, 12Z euro remained steady-state for Friday depicting a major severe threat across the I-35 corridor in OK/KS, as did the 12Z GEM FWIW.  

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It's not unusual for patterns like this to yield multi day outbreaks and at this range it's hard to pinpoint any one particular day as being better than another at least based off of ensembles alone. I don't know how many times I've seen day X jump out me on a deterministic model run at this range only to have day X-1 or X+1 actually be the big boy. So at this point the I'm just keeping my eye on the 27th through 30th though . One thing I imagine we all agree on is that ensembles and deterministic modeling have a very strong signal for an uptick in activity during this time period.

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Heidi ho weather folks!!  This coming week looks interesting. Per SPC focus is obviously Friday. Has anyone looked at recent GFS run at 18Z for 00Z Saturday?

 

im very much an amateur or less than that when reading but it looks like it has shifted way south and east per EHI?  Am I wrong? What else should I look at? 

i know this will change a lot until the event gets closer

 

thanks

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1 hour ago, Misstertwister said:

Heidi ho weather folks!!  This coming week looks interesting. Per SPC focus is obviously Friday. Has anyone looked at recent GFS run at 18Z for 00Z Saturday?

 

im very much an amateur or less than that when reading but it looks like it has shifted way south and east per EHI?  Am I wrong? What else should I look at? 

i know this will change a lot until the event gets closer

 

thanks

The Operational GFS is currently faster than pretty much every other model, and develops the system faster so it moves the front east much faster than the euro or GEM by friday. I wouldn't pay too  much attention to any one run from one model at this point. The GEFS/EPS/Euro/GEM still support friday being a potentially big day further west toward the I-35 corridor. If every model  and the ensembles start to trend toward a faster evolution, then it might be something to pay attention to, and perhaps Thursday could be a bigger day then. 

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2 hours ago, jojo762 said:

The Operational GFS is currently faster than pretty much every other model, and develops the system faster so it moves the front east much faster than the euro or GEM by friday. I wouldn't pay too  much attention to any one run from one model at this point. The GEFS/EPS/Euro/GEM still support friday being a potentially big day further west toward the I-35 corridor. If every model  and the ensembles start to trend toward a faster evolution, then it might be something to pay attention to, and perhaps Thursday could be a bigger day then. 

Another thing to point out that GFS didn't handle today too well and overdid it some.

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11 minutes ago, MattPetrulli said:

00z GFS is quite the setup Thursday evening in OK.....

hr144 from the 00Z GFS for thursday has a eerily similar look to what the 12z euro had for hr180 on friday...  DL and WF location and orientation, H5 trough/flow orientation, along with the explosive CAPE and ridiculous low-level hodos. Only the Euro had more CAPE. Believe the 12Z Euro verbatim had ~600m2/s2 ESRH at OKC at 7pm next friday. Not like details like this are relevant at all right now, just interesting and crazy what models are putting out right now... 

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2 minutes ago, jojo762 said:

hr144 from the 00Z GFS for thursday has a eerily similar look to what the 12z euro had for hr180 on friday...  DL and WF location and orientation, H5 trough/flow orientation, along with the explosive CAPE and ridiculous low-level hodos. Only the Euro had more CAPE and slightly more impressive SRH. Believe the 12Z Euro verbatim had ~600m2/s2 ESRH at OKC at 7pm next friday. Not like details like this are relevant at all right now, just interesting and crazy what models are putting out right now... 

Yeah either one of these days or both could really go up and be big.  All depends on smaller features though, still a week out.

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Just for the sake of the lolz, and for posterity for what the 00z GFS looks like for thursday across NC OK... Bullseye hunting. lol. :P Save this, as its probably one the most "weather porn" soundings you'll ever see.2017042200_GFS_144_36.44,-97.42_severe_m

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4 minutes ago, jojo762 said:

Just for the sake of the lolz, and for posterity for what the 00z GFS looks like for thursday across NC OK... Bullseye hunting. lol. :P Save this, as its probably one the most "weather porn" soundings you'll ever see.2017042200_GFS_144_36.44,-97.42_severe_m

Yep. Found that one in my backyard literally. lol. See what Euro shows. GFS even had trouble today just 36hrs ago..

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17 hours ago, Quincy said:

Might as well change the title to ~Mon-Sat 4/24-29 or even just "late April" severe threats. Expect multiple opportunities for severe across the central U.S. Knowing how these things can unfold, we could easily get a bigger day prior to next Friday, and/or the outlook for the 28th could end up evolving synoptically different than currently anticipated. 

 

Done

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41 minutes ago, jojo762 said:

Just for the sake of the lolz, and for posterity for what the 00z GFS looks like for thursday across NC OK... Bullseye hunting. lol. :P Save this, as its probably one the most "weather porn" soundings you'll ever see.2017042200_GFS_144_36.44,-97.42_severe_m

Meh... the speed shear sucks between 850-400 mb. :guitar:

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00z Euro shows Friday as more of an in between day now (between shortwaves) with more apparent threats on Thursday and Saturday. 

Expect more fluctuations with time. Bottom line: Multiple days of severe weather remain probable this upcoming week across the sub-forum. 

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   ...Thursday/Day 6...
   As with previous runs, the ECMWF ejects a lead shortwave trough
   across the central Plains on Thursday/Day 6 while the GFS maintains
   an upper-level trough further west in the Four Corners region. Both
   solutions surge a moist high-quality airmass northward into the
   southern Plains and develop a well-formed dryline by late afternoon.
   In spite of the differences at 500 mb, both solutions move a
   mid-level jet over the moist sector as a low-level jet strengthens
   during the early evening. This setup suggests a higher-end severe
   weather event will be possible in the southern and central Plains
   during the late afternoon and evening with a potential for
   tornadoes, large hail and wind damage.

   ...Friday/Day 7...
   The ECMWF and GFS solutions continue to develop an upper-level
   trough in the Four Corners region on Friday/Day 7 as a mid-level jet
   ejects out of the base of the trough into the southern and central
   Plains. The GFS maintains a high-quality moist sector over the
   southern Plains Friday afternoon and evening while the ECMWF waits
   until the overnight period to surge moisture northward across the
   Southern Plains. Both of these solutions would be favorable for a
   severe weather event in parts of the southern and central Plains
   Friday or Friday night. A higher-end severe weather event will be
   possible with supercells and a potential for tornadoes, large hail
   and wind damage.

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10 hours ago, jojo762 said:

Just for the sake of the lolz, and for posterity for what the 00z GFS looks like for thursday across NC OK... Bullseye hunting. lol. :P Save this, as its probably one the most "weather porn" soundings you'll ever see.2017042200_GFS_144_36.44,-97.42_severe_m

giphy.gif

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43 minutes ago, andyhb said:

06z GFS suppressing everything after that lead wave passes through on Tuesday/Wednesday. That would be quite the mitigation of the threat.

12Z GFS is similar.. but not quite as bad as 06Z. Bleh. Guess we'll see what the euro has to say. 

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