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Nick F

Chase Day 8 - Big Day in OK, KS, NE

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For a while Saturday has been shaping up to be a Big Day for severe weather hazards across the south/central Plains and as expected SPC have issued a moderate risk across OK, KS and NE - with a 15% probability of tornadoes.

 

http://www.spc.noaa.gov/products/outlook/day1otlk.html

 

So what's making this shaping up to be a biggy? Well, a look at the parameters show:

 

- a very strong SWly 500mb flow towards western OK and KS which will inject dry air and create strong vertical velocity that will enhance instability, also the strong winds aloft will help vent the storms which will mean that they are long-lived.

 

post-1052-0-08889600-1431762991_thumb.gi - 500mb winds 6pm

 

post-1052-0-47395200-1431763047_thumb.gi 500mb RH 6pm

 

post-1052-0-65099600-1431763096_thumb.gi 500mb verical velocity 6pm

 

- a strong southerly low level jet is indicated to develop in the evening, which will inject increased moistureand increase storm relative helicity SREH and increase the risk of evening and even nocturnal strong tornadoes:

 

 

post-1052-0-64161800-1431763726_thumb.gi

 

- rich moisture with Td approaching 70F - which with steep lapse rates and strong surface heating will create upwards 3000 j/kg CAPE - again this combined with with strong low-level shear, will provide the ingredients for strong tornadoes:

 

post-1052-0-39316200-1431763908_thumb.gi - 6pm dew points

post-1052-0-77525400-1431763893_thumb.gi - 6pm CAPE

 

post-1052-0-41167100-1431763998_thumb.gi - 0-1km shear

post-1052-0-13020300-1431763960_thumb.gi - 10m winds and significant tornado

 

There are some caveats though, ongoing overnight/morning line of storms (MCS) over western KS, OK and TX Panhandles near cold front - this convection is modelled to drift E/NE across KS/OK away from the CF but may hamper recovery in the northern most risk areas of Kansas and Nebraska, so I'm thinking Oklahoma central/south may have better period of recovery. Morning MCS to the W and NW likely to push out an outflow boundary (OFB) east into OK too, which may initiate storms early in the afternoon when the sun gets to work - especially as there doesn't look to be too much capping. These are my main concerns - which may may make it less  clear-cut for targeting.

 

post-1052-0-45074100-1431764916_thumb.gi - NAM 4km for 6pm

 

06z 4km NAM initiates some strong precip SW of OK city down the I-44 corridor to Red River, so I'm going to target Lawton, OK, though must admit anywhere from south central OK into central Kansas is looking good, and with the team in Salina, KS, a trek down to south central KS/ north central OK border would be just as good a bet, given low-level shear looks slightly better up here. Though question marks over effects from recovery from morning convection to the west up here.

 

Anyway. live stream to follow the Tour 1 later: http://www.netweather.tv/index.cgi?action=chaselive;sess=

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Yep great assessment Nick. I think that assuming the grunge clears further north, I am going for Medicine Lodge KS. I am off out tonight so will try and looking forward to catching up when I get in after midnight, if I am capable. By then hopefully something to see.

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That's a decent summary Nick, and we're just looking now at  initiation and coverage detail. Here in Pratt, KS the early morning thundery area is now moving over. There is however still much to solve regarding the 'window' that is required from noon to allow recovery. HRRR and RAP maintain ppn and a degree of cloud cover right through the day in the target zones so if this occurs the severe risk is reduced. We also don't have a classic sharp DL - at 22Z it's quite diffuse, except perhaps further south in SW OK.

Not an easy one today. SPC correct in going MDT, but it's not a done deal by any stretch.

 

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A gloomy view from the motel window in Salinas right now, as morning storms clear through.  The news and weather channels here are all on high warning levels with advice about finding shelters, being prepared and perhaps the worst anyone wants to hear - long track night time tornadoes possible.

 

As Nick said on the original post, there is potential for very damaging storms today if everything comes together, and we're in the middle of the risk area right now so will be heading out later this morning and hoping for some central plains chasing away from all the towns and cities.

 

I'll be keeping an eye on the stream once we're up and running so you can follow along, but if it gets hectic and the stream does go down, I might not be able to fix it instantly, so please bear with us.

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Looking at the satellite I am getting the impression the recovery will come into SW Oklahoma a lot sooner than further north.  

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Briefing for today   destination to be determined.  

 

 

 

Tom

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Yep

 

I have seen enough to get me heading south soon, will be heading down to Wichita and then into Oklahoma, can see Western Oklahoma lighting up by 3-4pm with some Intense Supercells getting going. I have no doubt the Kansas Target will verify but much later on from 01-03z near Wichita.

 

Paul S

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MD issued from the SPC.

post-5386-0-06324400-1431792446_thumb.pn

MESOSCALE DISCUSSION 0657  NWS STORM PREDICTION CENTER NORMAN OK  1055 AM CDT SAT MAY 16 2015    AREAS AFFECTED...NWRN/N-CNTRL OK...S-CNTRL KS    CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE     VALID 161555Z - 161730Z    PROBABILITY OF WATCH ISSUANCE...40 PERCENT    SUMMARY...STRONG THUNDERSTORMS MOVING OUT OF THE ERN TX PANHANDLE  ARE MOVING INTO AN INCREASINGLY UNSTABLE AIR MASS ACROSS WRN/NRN OK.  THE POTENTIAL MAY INCREASE FOR A COUPLE TORNADOES...LARGE HAIL...AND  DMGG WIND GUSTS INTO THE EARLY AFTERNOON...BUT THE SHORT-TERM  CONVECTIVE EVOLUTION IS STILL UNCERTAIN. OBSERVATIONAL TRENDS ARE  BEING MONITORED FOR A POSSIBLE WW.    DISCUSSION...A PERSISTENT ELEVATED TSTM CLUSTER OVER THE ERN TX  PANHANDLE IS MOVING NEWD AT AROUND 30 MPH....BUT IT IS STILL  UNCERTAIN WHETHER THIS CLUSTER WILL BE ABLE TO MAINTAIN INTENSITY  OVER THE NEXT COUPLE HRS. HOWEVER...BREAKS IN CLOUDINESS ARE  ALLOWING TEMPERATURES TO WARM INTO THE LOW 70S AMIDST A MOIST  BOUNDARY LAYER ACROSS WRN AND CNTRL OK. THERE IS SOME CONCERN THAT  CONVECTION WILL BECOME SFC-BASED AND MOVE ALONG AN OUTFLOW BOUNDARY  ORIGINATING FROM MORNING CONVECTION...IN WHICH CASE A THREAT FOR A  TORNADO AND LARGE HAIL WILL INCREASE. VWP DATA FROM VNX APPEAR TO  SAMPLE THE VERTICAL WIND PROFILE TO THE NORTH OF THE BOUNDARY...AND  SHOWS AMPLE LOW-LEVEL AND DEEP-LAYER SHEAR FOR A SUPERCELL/TORNADO  THREAT. OBSERVATIONAL TRENDS ARE BEING CLOSELY MONITORED FOR A  POSSIBLE WW IN THE NEXT 1-2 HRS.    A MORE WIDESPREAD SVR THREAT IS STILL LIKELY TO MATERIALIZE THIS  AFTERNOON AHEAD OF A STRONG UPPER TROUGH APPROACHING THE SRN  PLAINS...AND THE POTENTIAL FOR ADDITIONAL WW/S IS LIKELY TO  INCREASE.    ..ROGERS/DIAL.. 05/16/2015 

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Look at recent sfc analysis picks out an outflow boundary NE from eastern TX Panhandle through western OK to north central KS, pushing into juicier air coming up from the SE - maybe a focus for convection this afternoon:

 

post-1052-0-39423100-1431793163_thumb.gi

 

As the post by NL mentions above, the MD map highlighting the area where the OFB is ...

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I've come South to Woodward hoping to catch any early storms latching onto the OFB I saw developing a few hours ago.

There's a likely candidate down near Cheyenne now and I see the hordes moving towards it. To be honest if I loose internet I'll probably be able to follow the masses!
There's a storm ongoing here now (northern end of the line) so I'm going to sit here for 10 minutes and monitor.

 

PS: For any virtual chasers back home I am not with NWx team currently but might be later if and when it gets interesting!

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Being a weekend, I bet it will be busy with chaser convergence.

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guys you need to get some rainex on that windscreen, which will cut down on the wiper usage, it makes it so much easier to drive in rain..

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TVN map really struggling tonight.

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TVN live video page won't even load!

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Its up and running now..not really surprised considering the amount of chasers.. David Drummond has over 3000 watching his stream alone..!! lots going on with tornado watches popping up. 

http://www.spc.noaa.gov/products/watch/

 

post-5386-0-87788500-1431806769_thumb.pn

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Serious lightning in the tornado warned storm. Kelley Williamsons stream is covering this very well.

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Serious lightning in the tornado warned storm. Kelley Williamsons stream is covering this very well.

 

Yep.

 

Nick Drieschman is repositioning pretty close to it.

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Basehunters/Nick Drieschman say possible Tornado on the Shamrock cell..

 

Although, Basehunters have just driven through the RFD on the cell, and not had much.

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Looks like most are heading to Texola.

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Looks a bit outflow dominant with no clear meso the storm engulfing Shamrock, TX, got a classic outflow whalesmouth, did at one point look like it was trying to put down a funnel.

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New Tornado Watch issued.. 

 

http://www.spc.noaa.gov/products/md/md0666.html

 

MESOSCALE DISCUSSION 0666
NWS STORM PREDICTION CENTER NORMAN OK
0341 PM CDT SAT MAY 16 2015

AREAS AFFECTED...CNTRL/ERN TX/OK PANHANDLES...FAR NW AND N
TX...WRN/CNTRL OK

CONCERNING...TORNADO WATCH 175...

VALID 162041Z - 162215Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 175 CONTINUES.

SUMMARY...A BROKEN LINE OF INTENSE TSTMS IS PROGRESSING NEWD ACROSS
THE ERN TX PANHANDLE AND NW TX. THE DOWNSHEAR ENVIRONMENT ACROSS OK
IS BECOMING INCREASINGLY FAVORABLE FOR TORNADO POTENTIAL /POSSIBLY
STRONG/. A NEW TORNADO WILL BE ISSUED SOON FOR WRN/CNTRL OK AND
POSSIBLY PARTS OF NORTH TX.

DISCUSSION...A BROKEN LINE OF INTENSE TSTMS WITH A FEW EMBEDDED
SUPERCELLS CONTINUES TO MOVE NEWD ACROSS THE ERN TX PANHANDLE AND
THE ROLLING PLAINS OF NWRN TX...WITH REPORTS RECEIVED RECENTLY OF
LARGE HAIL AND A COUPLE TORNADOES. ADDITIONAL TSTMS ARE DEVELOPING
FARTHER W WITHIN TORNADO WATCH 175...BUT WITH VEERED LOW-LEVEL WINDS
AND A DRIER BOUNDARY-LAYER...LARGE HAIL AND DMGG WINDS WILL BE THE
PRIMARY THREATS.

THE ENVIRONMENT ACROSS WRN/CNTRL OK IS ONLY MARGINALLY TO MODERATELY
UNSTABLE /PER 18Z OUN AND LMN SOUNDINGS/...AND STILL CAPPED WITH A
WARM LAYER NOTED NEAR 1.5 KM AGL. EXTENSIVE CLOUD COVER HAS ALSO
LIMITED DIABATIC HEATING ACROSS CNTRL OK...WITH TEMPERATURES
REMAINING IN THE LOW-MID 70S. DESPITE THESE POTENTIAL LIMITING
FACTORS...LOW-LEVEL SHEAR WILL CONTINUE TO INCREASE INTO THE
EVENING...AND WILL FAVOR THE RISK FOR TORNADOES /SOME POTENTIALLY
STRONG/ ACCOMPANYING DISCRETE SUPERCELLS ACROSS WRN/CNTRL OK AND
POSSIBLY INTO PORTIONS OF N TX. AS A RESULT...A NEW TORNADO WATCH
WILL BE ISSUED SOON.

..ROGERS/DIAL.. 05/16/2015

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New MD

 

 

MESOSCALE DISCUSSION 0666
NWS STORM PREDICTION CENTER NORMAN OK
0341 PM CDT SAT MAY 16 2015

AREAS AFFECTED...CNTRL/ERN TX/OK PANHANDLES...FAR NW AND N
TX...WRN/CNTRL OK

CONCERNING...TORNADO WATCH 175...

VALID 162041Z - 162215Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 175 CONTINUES.

SUMMARY...A BROKEN LINE OF INTENSE TSTMS IS PROGRESSING NEWD ACROSS
THE ERN TX PANHANDLE AND NW TX. THE DOWNSHEAR ENVIRONMENT ACROSS OK
IS BECOMING INCREASINGLY FAVORABLE FOR TORNADO POTENTIAL /POSSIBLY
STRONG/. A NEW TORNADO WILL BE ISSUED SOON FOR WRN/CNTRL OK AND
POSSIBLY PARTS OF NORTH TX.

DISCUSSION...A BROKEN LINE OF INTENSE TSTMS WITH A FEW EMBEDDED
SUPERCELLS CONTINUES TO MOVE NEWD ACROSS THE ERN TX PANHANDLE AND
THE ROLLING PLAINS OF NWRN TX...WITH REPORTS RECEIVED RECENTLY OF
LARGE HAIL AND A COUPLE TORNADOES. ADDITIONAL TSTMS ARE DEVELOPING
FARTHER W WITHIN TORNADO WATCH 175...BUT WITH VEERED LOW-LEVEL WINDS
AND A DRIER BOUNDARY-LAYER...LARGE HAIL AND DMGG WINDS WILL BE THE
PRIMARY THREATS.

THE ENVIRONMENT ACROSS WRN/CNTRL OK IS ONLY MARGINALLY TO MODERATELY
UNSTABLE /PER 18Z OUN AND LMN SOUNDINGS/...AND STILL CAPPED WITH A
WARM LAYER NOTED NEAR 1.5 KM AGL. EXTENSIVE CLOUD COVER HAS ALSO
LIMITED DIABATIC HEATING ACROSS CNTRL OK...WITH TEMPERATURES
REMAINING IN THE LOW-MID 70S. DESPITE THESE POTENTIAL LIMITING
FACTORS...LOW-LEVEL SHEAR WILL CONTINUE TO INCREASE INTO THE
EVENING...AND WILL FAVOR THE RISK FOR TORNADOES /SOME POTENTIALLY
STRONG/ ACCOMPANYING DISCRETE SUPERCELLS ACROSS WRN/CNTRL OK AND
POSSIBLY INTO PORTIONS OF N TX. AS A RESULT...A NEW TORNADO WATCH
WILL BE ISSUED SOON.
 

post-7292-0-51371400-1431809138_thumb.gi

post-7292-0-30910500-1431809337_thumb.jp

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Yeah Nick, nice shelf on Kelley's stream atm.  Looking messy on rad... though should be some nice SLWs if nothing else. Guess eyes to the south for the more discrete storms.

Yep, I would step down on those cells further south that are still discrete - one near Wellington or if that merges, further south to Childress.

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