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May 19 threat in chaser land


Ed Lizard

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Tornado watch issued until 11pm for Western/Central Oklahoma.

509

WWUS20 KWNS 182052

SEL6

SPC WW 182052

OKZ000-190400-

URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 306

NWS STORM PREDICTION CENTER NORMAN OK

350 PM CDT WED MAY 18 2011

THE NWS STORM PREDICTION CENTER HAS ISSUED A

TORNADO WATCH FOR PORTIONS OF

WESTERN AND CENTRAL OKLAHOMA

EFFECTIVE THIS WEDNESDAY AFTERNOON AND EVENING FROM 350 PM UNTIL

1100 PM CDT.

TORNADOES...HAIL TO 2.5 INCHES IN DIAMETER...THUNDERSTORM WIND

GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE

AREAS.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 60 STATUTE

MILES EAST AND WEST OF A LINE FROM 45 MILES SOUTHEAST OF FORT

SILL OKLAHOMA TO 15 MILES NORTH NORTHWEST OF ALVA OKLAHOMA. FOR

A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU6).

REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR

TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH

AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR

THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS

AND POSSIBLE WARNINGS.

OTHER WATCH INFORMATION...CONTINUE...WW 305...

DISCUSSION...ISOLATED STORM DEVELOPMENT IS ANTICIPATED WITHIN THE

NEXT ONE TO TWO HOURS ALONG DRYLINE WHICH HAS BECOME STATIONARY OVER

WRN OK. AIR MASS E OF DRYLINE IS CHARACTERIZED BY DEWPOINTS IN THE

LOW/MID 60S...WHICH WHEN COUPLED WITH MIDLEVEL LAPSE RATES OF AROUND

7 C/KM...IS RESULTING IN A MODERATELY UNSTABLE AND WEAKLY CAPPED

ENVIRONMENT WITH MLCAPE AROUND 2000 J/KG. PROFILER DATA ACROSS ERN

NM SUGGEST THAT CIRRUS PLUME SPREADING EWD ACROSS WRN TX INTO WRN OK

IS ASSOCIATED WITH A 50 KT MIDLEVEL JET STREAK WHICH WILL SERVE TO

STRENGTHEN DEEP-LAYER SHEAR THROUGH THIS EVENING. LOW-LEVEL SHEAR

SHOULD ALSO INCREASE AROUND OR SHORTLY AFTER 19/00Z WITH VERTICAL

WIND PROFILES BECOMING QUITE CONDUCIVE FOR SUPERCELL DEVELOPMENT.

VERY LARGE HAIL WILL BE THE PRIMARY HAZARD...THOUGH TORNADOES WILL

BE POSSIBLE WITH ANY MATURE SUPERCELLS THAT CAN PERSIST INTO THIS

EVENING.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL

SURFACE AND ALOFT TO 2.5 INCHES. EXTREME TURBULENCE AND SURFACE

WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO

500. MEAN STORM MOTION VECTOR 24025.

...MEAD

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A little surprised the watch extends so far west with Lawton sitting at about 92/52 at the moment and Medicine Park 93/41, and areas even further on the wrong side of the (slowly retreating) dry line included in the polygon. Chickasha to Norman looks pretty good at mid 80s/mid 60s... Perhaps it's because a weak convergence boundary is located a little west of the better moisture.

Still think large hail is primary threat, given the fairly high LCLs, and the aforementioned spreads, but the good lapse rates, increasing shear and decent CAPE might be able to overcome it all.

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Yes, it could get somewhat interesting in OK this evening.

CENTRAL_RUC236_ATMOS_STP_07HR.gif

Won't mean much if convection doesn't occur. Right now its slowly starting look bustish. I hope not because we're down here and we have to drive back to Kansas for tomorrow... but its looking rather discouraging at the moment. You can have the highest STP in the world, but if there are no storms, it doesn't matter.

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You're under a ridge with rising heights, unfavorable jet positioning, and weakening low-lvl convergence due to backing winds behind the dryline... not much to expect there.

Subsidence was always a concern for today, and yet people seemed to be all gung ho about today, never saw the potential.

I'm not necessarily blaming it on subsidence, but that was a major concern of mine today.

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I really thought something isolated would go today in western OK....guess not. That cirrus that come over the warm sector wasn't associated with a subtle jet streak to kick things off. Looking at the 0z OUN raob sounding...a degree or two more would of done it. That cirrus ruined it today.

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I really thought something isolated would go today in western OK....guess not. That cirrus that come over the warm sector wasn't associated with a subtle jet streak to kick things off. Looking at the 0z OUN raob sounding...a degree or two more would of done it. That cirrus ruined it today.

Interesting that just a few very minor differences could have totally changed everything in Oklahoma this evening. The difference between destructive supercells and a completely quiet evening on the Plains is amazing. When I looked at the RUC earlier, the mid-level jet did seem a bit too far west. 20-30kts in the H5 range is pretty anemic.

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**** this year, **** it hard.

I can't even get the least bit excited about tomorrow right now because for months, it's simply been the case that anytime something can go wrong, it does.

Very nearly puked up the Pizza Hut I had after busting today when I saw the 00z OUN sounding.

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Tomorrow looks MUCH better than today IMO. MUCH better mid-level support over the moderate instability axis. I'd play the KS/OK border just ahead of the dryline. Surface cape forecast to be around 2000j/kg there in a narrow axis, but I think that will end up being a bit too low. 50-65kts at H5 over that area. I'd like to see the low-level wind fields a bit stronger, but it will be enough to get the job done. The GFS has been forecasting slightly higher winds in the 925-850mb range than the NAM as well.

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**** this year, **** it hard.

I can't even get the least bit excited about tomorrow right now because for months, it's simply been the case that anytime something can go wrong, it does.

Very nearly puked up the Pizza Hut I had after busting today when I saw the 00z OUN sounding.

Yeah 0Z OUN sounding was a huge debby downer. Today was about as close to CI you can get without actually getting it, if only we had any upper-air support. Tomorrow though Brett. I'm pulling for you and all the Plains chasers out there!

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**** this year, **** it hard.

I can't even get the least bit excited about tomorrow right now because for months, it's simply been the case that anytime something can go wrong, it does.

Very nearly puked up the Pizza Hut I had after busting today when I saw the 00z OUN sounding.

This time tomorrow night you will have long forgotten today lol. :guitar:

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I really thought something isolated would go today in western OK....guess not. That cirrus that come over the warm sector wasn't associated with a subtle jet streak to kick things off. Looking at the 0z OUN raob sounding...a degree or two more would of done it. That cirrus ruined it today.

I would disagree.

I believe the factors previously mentioned by 'thewxmann' were the bigger issue. The cirrus really didn't overtake the whole dryline risk area until 4PM or after.

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At this juncture I would respectfully disagree. The wind profiles in KS are looking to be excellent. If there are any breaks in the clouds and more instability is able to take hold, KS could get lit up as instability and mid level lapse rates are the only question marks. The NAM is notorious for underestimating instability. The NAM also still had the triple point in north/central Kansas last I checked which would make the northern target you spoke of crap. GFS is the outlier and I wouldn't look much at its more northern track at this point. The euro and the NAM are fairly close. I'm cautiously optimistic as even conservative forecasters are jumping on board. If there isn't much crap vection and the clouds fall away in places in the morning, we could be looking at a very active day. The favorable shear will possibly spawn a handful of tornadoes even without extreme instability, they just may not be as strong or long lived. Just my two cents.

I respectfully hope you are right, and SPC still offers hope.

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It's almost like they copied last weeks outlook for today, before it fell apart at least.

I wouldn't be worried about a last week repeat, though. The morning convection was out of the area before the sun even started rising this morning and now VIS satellite showing the stratus deck slowly moving out from the southwest of Kansas. Last week, we still had crapvection as late as 11 AM if I recall. With storm initiation not likely until around 4-6 pm, we should get some nice diabatic heating to increase CAPE and lapse rates. This setup is already looking worlds better than last week. I think we will see some strong tornadoes today.

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I wouldn't be worried about a last week repeat, though. The morning convection was out of the area before the sun even started rising this morning and now VIS satellite showing the stratus deck slowly moving out from the southwest of Kansas. Last week, we still had crapvection as late as 11 AM if I recall. With storm initiation not likely until around 4-6 pm, we should get some nice diabatic heating to increase CAPE and lapse rates. This setup is already looking worlds better than last week. I think we will see some strong tornadoes today.

Right, the lack of convection robbing moisture return is a plus for sure. The large scale setup is not all that different though--not really a classic outbreak one per se. Certainly more interest this go around, partly with colleges out I assume. I was rooting for a bust but I'll hope for the best. ;)

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Right, the lack of convection robbing moisture return is a plus for sure. The large scale setup is not all that different though--not really a classic outbreak one per se. Certainly more interest this go around, partly with colleges out I assume. I was rooting for a bust but I'll hope for the best. ;)

post-22-0-85944800-1305816870.jpg

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With clearing skies across SW KS - it is beginning to look much better. Anywhere ENE of KDDC looks to get it today, then dry line to the south should get active. But I would still put my money around to the ENE of DDC.

I agree, the combination of rapid destabilization and residual moisture from morning stratus keeping LCLs low have me keying on that area.

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