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May 17th - 21st Severe Weather Thread


andyhb

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It looks to me like the gfs has won out over the euro in moving the precip out of MSP by late afternoon Sunday instead of early evening. So way did I post that? The GFS has shown a consistent signal for the Western OK area the last few days and it still has it. If it was right up here, could it be right with the trailing cold front? 0-6km shear values show a narrow band of 30-60 knots tomorrow night around 7pm over western OK, its not up on Earls site yet, so I can't show it, but if a tornado or two shows up down there, it would be a big win for the GFS, IMO

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I'm interested to see what happens farther east, but that's for a different thread...

thurs? i think we're going to try to hit it if there is something left.

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It looks to me like the gfs has won out over the euro in moving the precip out of MSP by late afternoon Sunday instead of early evening. So way did I post that? The GFS has shown a consistent signal for the Western OK area the last few days and it still has it. If it was right up here, could it be right with the trailing cold front? 0-6km shear values show a narrow band of 30-60 knots tomorrow night around 7pm over western OK, its not up on Earls site yet, so I can't show it, but if a tornado or two shows up down there, it would be a big win for the GFS, IMO

LCLs look prohibitively high for the southern Plains tomorrow, excepting the GFS, which has consistently shown a 5-10 F high bias in dew points even inside 24 hr. this season. Still hoping for some decent supercells, though.

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If this pattern holds into June (the strong ridge over the east) we could see some problems here because of Evapotranspiration, leading to a very active pattern here in MN, and the rest of the Northern Plains to the Western Great Lakes. Way to early to say for sure, but it does look interesting IMO

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thurs? i think we're going to try to hit it if there is something left.

Yes. I haven't honestly looked at much other than the 12z, 18z, and 00z GFS runs, but boy oh boy, you do not see hodos like that in a warm sector with >65°F very often, especially in this area. Serious turning and kinematics...forcing and exact level of instability remain to be seen...

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Yes. I haven't honestly looked at much other than the 12z, 18z, and 00z GFS runs, but boy oh boy, you do not see hodos like that in a warm sector with >65°F very often, especially in this area. Serious turning and kinematics...forcing and exact level of instability remain to be seen...

Yeah the 18z GFS had some nasty nasty hodographs in western IL on Weds.

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A bit surprised the slight risk is not further north into central MN. There's no reason for it not too....

Up here in Minnesota there is almost a complete lack of shear. Having said that, isolated severe is not out of the question, the greatest risk I would think would be winds > 58mph, shear values IMO don't really support strong updrafts over a wide enough area to support a slight risk area up here.

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Yes. I haven't honestly looked at much other than the 12z, 18z, and 00z GFS runs, but boy oh boy, you do not see hodos like that in a warm sector with >65°F very often, especially in this area. Serious turning and kinematics...forcing and exact level of instability remain to be seen...

18z gfs looked better in that area than the plains at least at 500 in the evolution. in some ways it would be optimal as it's a bit closer to the EC.. gfs has liked the midwest/lakes a good bit of runs tho the euro builds the ridge in where nothing really even happens that far east on the 0z run. wonder if the euro is going too big on it.. seems a bit odd the evolution... but it's there run after run now. lots of time in wyoming and montana ahead.. ;)

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Up here in Minnesota there is almost a complete lack of shear. Having said that, isolated severe is not out of the question, the greatest risk I would think would be winds > 58mph, shear values IMO don't really support strong updrafts over a wide enough area to support a slight risk area up here.

Moisture will be lacking as well. Operational NAM/GFS have been overly moist lately, especially the GFS...almost crippling it in some cases. Dews will likely remain in the mid to upper 50s...maybe a few 60s along the front. MLCAPE will range from 750 -1250 j/kg, but shear profiles are junk at best.

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00z ECMWF was rather uninspiring overall. I couldn't pick out any distinct waves/perturbations ejecting i that SW flow sufficient to support any type of organized DMC across much of the plains.

models suck

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I think the point is to stay in the shallow end for a while. You may know 'technical' terms, but I have learned that this isn't a place for rabid wish casting.

Just from reading posts from here has taught me a ton, and shown me just how little I know even though I have spent hundreds of hours studying severe weather. Sometimes being so enthusiastic about something can blind you to important facts, and these guys are very good at pointing those out. It's not being pessimistic, it's being a professional and seeing past what you want to see and what is reality.

Sitting back and reading the evolution of events around here is fascinating sometimes.

Thank You. That was the explanation I was looking for...

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Does anybody have any idea why the RAP lowers the DP's in the Eastern 1/4 of KS to 30/40? Obviously there is nearly no chance storms could survive in that environment...

RAP_255_2012051913_F12_DPTF_2_M_ABOVE_GROUND.png

This is the 13Z RAP at 01Z this evening...

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Does anybody have any idea why the RAP lowers the DP's in the Eastern 1/4 of KS to 30/40? Obviously there is nearly no chance storms could survive in that environment...

RAP_255_2012051913_F12_DPTF_2_M_ABOVE_GROUND.png

This is the 13Z RAP at 01Z this evening...

It means the moisture is shallow. When mixing commences it's bringing down drier air from aloft and lowering the dewpoints. You'll see the term the dewpoints mixed out being used. The RAP has been doing a better job lately of accounting for afternoon mixing out of a shallow surface moist layer than the NAM and GFS though I haven't looked at anything today so I wouldn't know if it's overdone or not in how dry it makes things this evening. Baro did a comparison of the 3 on an earlier post and also believed the RAP was more realistic in it's dewpoint depiction today.

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It means the moisture is shallow. When mixing commences it's bringing down drier air from aloft and lowering the dewpoints. You'll see the term the dewpoints mixed out being used. The RAP has been doing a better job lately of accounting for afternoon mixing out of a shallow surface moist layer than the NAM and GFS though I haven't looked at anything today so I wouldn't know if it's overdone or not in how dry it makes things this evening. Baro did a comparison of the 3 on an earlier post and also believed the RAP was more realistic in it's dewpoint depiction today.

I figured it had to do with them Mixing out... But just wanted to make sure...

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14z HRRR popping storms on the KS/NE state line early this evening.

Today looks marginally interesting across eastern KS/NE. Effective bulk shear is marginal, but MLCAPE should range around 1250-2000 j/kg with nearly dry adiabatic lapse rates through the troposphere above the cap. That front is sufficiently deep that it should erode the EML late afternoon. Bases are too high for tors most likely...but there will be supercells for the chaser crowd looking to salvage chase trips. It should be quite active later this afternoon.

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Lots of elevated severe storms in western Kansas and south central Nebraska today. Mainly hail, ranging from quarters to golf balls.

If I were on a chasecation, I'd probably consider gambling on the postfrontal upslope activity now developing across SE CO. The HRRR and WRF-NNM show these to be persistent through early evening, with high values of updraft helicity, as they move SE toward GUY-LBL. Imagine they have a good shot at being more photogenic than any of the warm sector storms today.

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Today looks marginally interesting across eastern KS/NE. Effective bulk shear is marginal, but MLCAPE should range around 1250-2000 j/kg with nearly dry adiabatic lapse rates through the troposphere above the cap. That front is sufficiently deep that it should erode the EML late afternoon. Bases are too high for tors most likely...but there will be supercells for the chaser crowd looking to salvage chase trips. It should be quite active later this afternoon.

We are currently in Pratt. Deciding where to go from here. Liking south more into Oklahoma. Things should go quickly linear in KS/NE given flow parallel to front.Possible meso/theramlly induced low near west of CDS to possibly back winds in western OK along I-40 and increased convergenges to pop off supercell or two near or after 23z

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