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andyhb

May 7th-9th Severe Weather Episodes

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FWIW, all these same Hi-Res models essentially nailed that supercell--at least with its track-- on 4/29 across SW/SC OK.

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12Z RAOBs from CRP and BRO show mid 60s dews and an appreciable low-level moisture profile... Decent/meager moisture advection will bring the 60 DP isotherm into Northern Texas by this evening, with a pool of higher DPs into C/S TX. Intense moisture-advection should start tonight and continue through the day Sunday thanks to a 30-50kt LLJ. By 21-00z (May 8/9) the GFS/NAM/4KNAM all support mid 60's dewpoints being along and east of the dryline... Don't think moisture is going to be an issue now given the intense advection that will occur overnight and during the day. Given that moisture is/was really the only issue, not seeing too much wrong right now, as long as the mid-upper level wind profile holds up as it is current progged, and as long as unforeseen morning convection does not happen... Looking like a dangerous day across Western and possibly Central OK.

 

Definitely a more evident tornado threat even before 00Z than what we saw on 4/26.

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12Z RAOBs from CRP and BRO show mid 60s dews and an appreciable low-level moisture profile... Decent/meager moisture advection will bring the 60 DP isotherm into Northern Texas by this evening, with a pool of higher DPs into C/S TX. Intense moisture-advection should start tonight and continue through the day Sunday thanks to a 30-50kt LLJ. By 21-00z (May 8/9) the GFS/NAM/4KNAM all support mid 60's dewpoints being along and east of the dryline... Don't think moisture is going to be an issue now given the intense advection that will occur overnight and during the day. Given that moisture is/was really the only issue, not seeing too much wrong right now, as long as the mid-upper level wind profile holds up as it is current progged, and as long as unforeseen morning convection does not happen... Looking like a dangerous day across Western and possibly Central OK.

Definitely a more evident tornado threat even before 00Z than what we saw on 4/26.

Agree 100%. Like I said yesterday, the moisture was there, you just had to find it. That's where tracking streamlines on the models to figure out where the moisture originated from. Then the RAP comes in nice and handy to grab those soundings. Don't forget to check AMA and points south and southwest to confirm that an EML is being advected in. Spoiler alert, it is.

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Nam 4km is pretty aggressive with return flow. Will have to monitor.

It's always aggressive, and always wrong.

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Really as should be expected...Forbes upped the Tor:Con to a 5 for W/C OK and W/C KS.

 

Also a 5 now on Monday across Eastern OK/KS.

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06Z GFS has dewpoints ahead of the dryline in the 63-65 degree range with 64-67 closer to the Red River. Still high enough to pose a significant severe weather threat tomorrow. I do agree the 4KM NAM is likely being overzealous with moisture levels but luckily the OK Mesonet will allow for accurate monitoring of that overnight. 

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Guidance showing several higher UH tracks in NE. CO/SW. NE/SE. WY.

With the easterly flow north of the SLP and DP's rising into the low 50's, should be able to kick out one or two of the usual short lived tors for this area.

9a66a41ef01fea31186435c5fda38263.jpg

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OUN

 

 

 

SUNDAY AFTERNOON AND EVENING...ADDITIONAL ISOLATED TO SCATTERED
SEVERE THUNDERSTORMS ARE POSSIBLE WITH HIGHER CHANCES FOR STORMS
COMPARED TO TODAY. KEPT THE HIGHEST STORM CHANCES IN THE 40 TO 50
PERCENT RANGE IN NORTHERN OKLAHOMA WHERE CAPPING SHOULD BE
WEAKEST. NOT SURE HOW MANY STORMS WILL OCCUR DUE TO CAPPING.
FIRST STORM DEVELOPMENT MAY OCCUR IN THE 2 TO 4 PM TIME FRAME
SOMEWHERE POSSIBLY NEAR A ALVA TO CLINTON TO SEYMOUR TEXAS LINE.

STRONG 0-6 KM BULK SHEAR AND MID/UPPER LEVEL WINDS DURING SUNDAY
AFTERNOON AND EVENING SUGGEST FAST MOVING SUPERCELLS WITH VERY
LARGE HAIL...POSSIBLY TENNIS BALL OR LARGER...AS THE MAIN HAZARD
WITH ANY SEVERE STORM. TORNADOES WILL BE POSSIBLE WITH SEVERE
STORMS AS 0-1 BULK SHEAR INCREASES RAPIDLY TO 20-40 KT BETWEEN 4
AND 10 PM ON SUNDAY. NOT SURE IF SIGNFICANT TORNADOES WILL OCCUR
WHICH WILL BE DEPENDENT ON THE QUALITY OF LOW LEVEL MOISTURE AS
SURFACE DEWPOINTS MAY ONLY BE IN THE LOWER 60S. IF SURFACE
DEWPOINTS GET INTO THE UPPER 60S...STRONG TORNADO POTENTIAL WOULD
INCREASE CONSIDERABLY.
STORMS MAY TRY TO ORGANIZE INTO CLUSTERS
AND LINES DURING THE EVENING WHICH WOULD ALLOW FOR DAMAGING WINDS
AS WELL...THOUGH NOT SURE THIS WILL HAPPEN.

 

 

 

 

 

 

 

 

image_full3.jpg

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Monday is starting to look very interesting for Monday I35 and to the east.  Moisture quality will be significantly better than Sunday and the GFS has a fairly sharp dry line in place.  Tomorrow is also starting to look more impressive.

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If the generous moisture return depicted on 12z guidance largely comes to fruition, then this could be shaping up as a serious situation between US-183 and I-35 in OK tomorrow evening. The unstable, (relatively) uncapped warm sector is depicted as increasingly wide, and CAMs are signaling dryline initiation fairly early (around 20-21z). This would be a recipe for storms to mature over W OK and perhaps produce a few tornadoes in the afternoon, then enter a more serious environment around places like Lawton/Weatherford/Watonga at 23z-00z, before decoupling begins. With strong 0-1 km shear and relatively fast easterly storm motions to help maximize SRH, the only notable weaknesses in this environment will be contingent on the degree of S-shaped hodos (mainly above 4-5 km AGL) and, of course, moisture return. Otherwise, the sigtor threat would be real.

Assuming moisture return is modestly overdone right now, and ultimately 64-65 F dew points are the rule along the moisture axis, then it will probably be a close call as to whether storm intensity continues unabated all the way to I-35. But even with that moisture, there will probably be a legit window for tornadoes somewhere in W OK a couple counties off the dryline.

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In this situation I feel like it is dumb to focus on the fact that Broyles issued it. Just a quick glance at any of the models shows an obviously significant environment across that MDT risk and ENH risk area tomorrow afternoon and evening into the night even. Lots of collaboration goes into these... But it is the forecasters' final decision.

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The moderate risk is probably a bit too far north. I would have it positioned across W. OK, where the highest threat will likely be. Across KS/TX the threat will likely be slightly lower.

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MD up for NE CO/W KS, doesn't sound like they're too confident about tornado potential. Wonder if they'll issue a severe thunderstorm or tornado watch based on that wording.

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It's Broyles so might want to take this one with a little bit of salt, but SPC did go MDT for tomorrow afternoon for parts of NW OK and SW KS. 

 

I think he is spot on with his wording for tomorrow and his reasoning seems to be logical as well. He did a good job on this one. 

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It's amazing how many times in history a potential severe weather outbreak/tornadic event is set to occur on Mother's Day.

 

Well it is in May so that's kind of a given.

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It's amazing how many times in history a potential severe weather outbreak/tornadic event is set to occur on Mother's Day.

 

 

Law of Averages; Mother's Day is no more likely to have a significant event than any other day during the peak of tornado season. The events just stick out more in your mind due to it being a holiday. 

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Law of Averages; Mother's Day is no more likely to have a significant event than any other day during the heart of tornado season. The events just stick out more in your mind due to it being a holiday. 

 

That is not true, as that assumes all severe weather season has equal probabilities which isn't the case.  The probabilities peak in central May for the areas in central Oklahoma so these days are actually more likely than others to have outbreaks.  Mothers day is going to be statically more likely to have tornadoes than 90% of other days throughout the year and greater than the majority of those within sever season.

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That is not true, as that assumes all severe weather season has equal probabilities which isn't the case.  The probabilities peak in central May for the areas in central Oklahoma so these days are actually more likely than others to have outbreaks.  Mothers day is going to be statically more likely to have tornadoes than 90% of other days throughout the year and greater than the majority of those within sever season.

 

 

Well I did say the heart/peak of tornado season... There isn't an issue with what I said, there's an issue with your comprehension of what I said.

 

Edit: Duly noted, OKP. Didn't see that before I posted this. -

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Unexplainably the tornado potential on OUN's severe storms graphic still is "low."

I wonder if they forgot to update the graphic. It disagrees with their AFD by just a little. Lol

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