Severe Weather - April 26th - Potential Tornado Outbreak

[venture]

Sorry didn't get a chance to get a forecast out this morning. I wanted some sleep before this mess started. Currently on going crapvection through most of western oklahoma. Mainly heavy rain, some wind, and and hail with a couple of these. They could continue to strengthen and organize later this afternoon. One severe storm right now out in the Panhandle by Shamrock (west of Sayre). One thing to keep in mind, things will be evolving rapidly today throughout the day...so what is going on now won't be going on in 15 minutes. Hence why the storm in Harmon/Greer counties is now severe as I am typing this. Oh and another one for Beaver County in the panhandle.

Current mesoanalysis from the SPC shows extremely high significant tornado parameters through out northern and western OK. They are a big lower here, but we'll need to just watch this through the day. Effective helicity in the 0-1km category is crazy today in the same areas. It looks like the highest risk area for extremely large hail (up to 4 inches) is in Northern Oklahoma right now, but this will also change.

Greatest instabilities right now are also north of I-40 and west of I-35. As storms move into this area, they will need to be watched on how they transform.

Pretty much today is a day where things can get out of hand very quickly, and is why we have the high risk issued now and that the watch box is a PDS box (these are fairly rare only a dozen or so a year).

[venture]

Thunder, I can't. No one can. This is a situation that evolves as it goes. Models are handling this morning convection by moving it out quickly into KS early this afternoon. Now the problem comes when one set of models develop absolutely nothing again in SW OK, but develop a massive MCS/Bow in SE Oklahoma later. Then another set is showing convection out west and staying there.

I am watching to see if these low clouds over us can burn off. Areas out west in the high risk area are getting some sun in between storms right now.

[Thunder]

Okay, a waiting game. I like it, Venture!

[Thunder]

Is that a mini hook trying to form for the storm near Hobart? Looks like a possible tornado anytime there.

[Thunder]

It was smaller, now it looks a bit more defined.



Latest...

[Karried]

hmmm, just awhile ago it seemed that the metro was under a watch but it appears to have shifted out west...

Maybe it might miss us all together?

(please say yes)

[Thunder]

It looks like these storms wont affect the metro. We still got a whole day left for more developments. We're not in the clear yet. OKC will definately see something, but what comes of it remains unseen for now.

[Thunder]

Looks like this storm, the back/tail end is more of rooting itself while the rest continue to move NE. Scretching this storm out, as shown in the pix. I still think something's going on there.



Venture?

I was planning to go to Cordell to pick up this cute lil kitty!

[Thunder]

TORNADO WARNING for that same storm posted above.

[venture]

Bulletin - eas activation requested
tornado warning
national weather service norman ok
1236 pm cdt sun apr 26 2009

the national weather service in norman has issued a

* tornado warning for...
Northeastern greer county in southwest oklahoma...
Extreme northwestern kiowa county in southwest oklahoma...
Eastern beckham county in western oklahoma...
Western wa****a county in western oklahoma...

* until 115 pm cdt

* at 1236 pm cdt...national weather service doppler radar indicated a
severe thunderstorm capable of producing a tornado 7 miles
southwest of retrop...moving northeast at 45 mph.

* locations in the warning include bessie...burns flat...canute...
Dill city...elk city and retrop.

[venture]

Just a heads up...storm moving into Roger Mills Co from the panhandle does have signs of rotation now as well.

Update - this storm is located in an area of enhanced potential for a tornado.

[venture]

MESOSCALE DISCUSSION 0582
NWS STORM PREDICTION CENTER NORMAN OK
1258 PM CDT SUN APR 26 2009

AREAS AFFECTED...NW-WCNTRL TX AND EXTREME SWRN OK

CONCERNING...SEVERE POTENTIAL...TORNADO WATCH LIKELY

VALID 261758Z - 261930Z

MID-LVL TROUGH AXIS CONTINUES TO ADVANCE EWD THROUGH ERN NM WITH
STRONGEST PVA LIKELY TO TRANSLATE INTO NWRN-WCNTRL TX THROUGH EARLY
THIS EVENING. BANDS OF ACCAS HAVE BEEN COMMONPLACE OVER W TX SINCE
EARLY MORNING WITH SFC BASED CBS DEVELOPING OVER THE ERN SIDES OF
THE GLASS MOUNTAINS IN PECOS COUNTY RECENTLY.

EXPECT THAT CLEAN INITIATION ALONG THE DRYLINE /NEARING THE CAPROCK
EARLY THIS AFTN/ WILL BE MUDDLED BY GRADUAL UPSCALE GROWTH/
DEEPENING OF THE ACCAS STREETS INTO TSTMS AS THE DEEP LAYERED UVV
APCHS. INITIAL STORMS WILL PRODUCE LARGE HAIL GIVEN STEEP LAPSE
RATES ATOP THE BOUNDARY LAYER. BUT...AS HEATING CONTINUES AND ACCAS
BOOTSTRAPS INTO THE MOIST BOUNDARY LAYER -AND- ADDITIONAL SFC-BASED
STORMS DVLP ALONG THE DRYLINE...ALL FACETS OF SVR WEATHER ARE LIKELY
AS STORMS EVOLVE INTO SUPERCELLS.

HIGHEST TORNADO POTENTIAL WILL EXIST ACROSS NWRN TX/ERN S PLNS WHERE
STRONGEST SELY LLVL FLOW WILL REMAIN THROUGH EVENING. FARTHER
S...THOUGH TORNADOES WILL BE A THREAT...THE LLVL FLOW/LARGE SCALE
SUPPORT WILL BE COMPARATIVELY WEAKER.

A TORNADO WATCH WILL BE REQUIRED FOR PARTS OF THE REGION LATER THIS
AFTN.

[venture]

This will include the entire Metro area...it is a PDS Tornado.



URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 192
NWS STORM PREDICTION CENTER NORMAN OK
140 PM CDT SUN APR 26 2009

THE NWS STORM PREDICTION CENTER HAS ISSUED A TORNADO WATCH FOR PORTIONS OF

LARGE PART OF CENTRAL AND SOUTHWEST OKLAHOMA
PARTS OF NORTHWEST TEXAS

EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM 140 PM UNTIL 1000 PM CDT.

...THIS IS A PARTICULARLY DANGEROUS SITUATION...

DESTRUCTIVE TORNADOES...LARGE HAIL TO 3 INCHES IN DIAMETER...
THUNDERSTORM WIND GUSTS TO 80 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 70 STATUTE MILES NORTH AND SOUTH OF A LINE FROM 90 MILES SOUTHWEST OF CHILDRESS TEXAS TO 25 MILES SOUTH SOUTHEAST OF CHANDLER OKLAHOMA.
FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU2).

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 189...WW 190...WW 191...

DISCUSSION...WITH STRONG SHEAR AND A VERY UNSTABLE ENVIRONMENT IN PLACE...THUNDERSTORMS WILL RAPIDLY INTENSITY ALONG AND E OF DRY LINE NWRN TX. SUPERCELLS WITH THE POTENTIAL FOR ISOLATED STRONG TORNADOES ALONG WITH VERY LARGE HAIL WILL BECOME AN INCREASING THREAT THROUGH THE AFTERNOON AS STORMS DEVELOP NEWD ACROSS THE WATCH AREA.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT TO 3 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 70 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 550. MEAN STORM MOTION VECTOR 24030.



Ww 192 tornado ok tx 261840z - 270300z
axis..70 statute miles north and south of line..
90sw cds/childress tx/ - 25sse cqb/chandler ok/ ..aviation coords.. 60nm n/s /29ese lbb - 47e okc/ hail surface and aloft..3 inches. Wind gusts..70 knots.
Max tops to 550. Mean storm motion vector 24030.

Lat...lon 34520137 36409665 34369665 32490137

this is an approximation to the watch area. For a complete depiction of the watch see wous64 kwns for wou2.

TORNADO WATCH PROBABILITIES FOR WT 0192
NWS STORM PREDICTION CENTER NORMAN OK
0139 PM CDT SUN APR 26 2009

WT 0192 PDS
PROBABILITY TABLE:
PROB OF 2 OR MORE TORNADOES : 90%
PROB OF 1 OR MORE STRONG /F2-F5/ TORNADOES : 60%
PROB OF 10 OR MORE SEVERE WIND EVENTS : 50%
PROB OF 1 OR MORE WIND EVENTS >= 65 KNOTS : 40%
PROB OF 10 OR MORE SEVERE HAIL EVENTS : 80%
PROB OF 1 OR MORE HAIL EVENTS >= 2 INCHES : 60%
PROB OF 6 OR MORE COMBINED SEVERE HAIL/WIND EVENTS : >95%

&&
ATTRIBUTE TABLE:
MAX HAIL /INCHES/ : 3.0
MAX WIND GUSTS SURFACE /KNOTS/ : 70
MAX TOPS /X 100 FEET/ : 550
MEAN STORM MOTION VECTOR /DEGREES AND KNOTS/ : 24030
PARTICULARLY DANGEROUS SITUATION : YES

[Luke]

Yuck.

[Thunder]

I notice major lack of blog posts for KOCO. I wonder where that Internet guy that does the LIVEBLOGGING!

[venture]

Current update...

Ongoing activity north of I-40 remains strong to severe. Hail size with storms has generally been around an inch. There have been indications that the storms are trying to rotate, but haven't got anything established. South of I-40 is mostly quiet. There is a severe storm in Western North Texas that will move into Southern Oklahoma in the next 1-2 hours.

Current environment analysis shows the most unstable area to be in the SE TX Panhandle. Over OKC proper, the atmosphere is somewhat unstable but still have some inhibition that will hold development off in this area for a bit longer. LCL heights are dropping in nearly all over the Western half of Oklahoma. Best shear right now is in the area around Roger Mills, Ellis, Woodward, and Dewey counties and somewhat down through SW Oklahoma. Shear is increasing from NW Oklahoma into Central sections. SPC Composite parameters show the best supercell environment right now is over West Central to Southwest Oklahoma, where the environment is mostly void of storms right now. This area also has a heightened risk of tornadoes. As far as hail, the largest hail should be with the storms that form in SW Oklahoma or SE TX Panhandle.

Short term models are handling the ongoing storms well for the next 2-3 hours, but then struggle to maintain any precipitation in western oklahoma after 6-8PM. Just going to do a wait and see since the event is ongoing.

[venture]

SPC's Update:

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0259 PM CDT SUN APR 26 2009

VALID 262000Z - 271200Z

...THERE IS A HIGH RISK OF SVR TSTMS ACROSS PARTS OF WRN OK AND SRN KS...

...THERE IS A MDT RISK OF SVR TSTMS ACROSS PARTS OF KS...OK...AND TX...

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE SRN AND CNTRL PLAINS...UPPER MIDWEST AND LOWER OH VALLEY...

...CURRENT THINKING ACROSS THE MODERATE AND HIGH RISK AREAS...
THE LARGE MCS FROM NW OK EXTENDING NNEWD ACROSS KS INTO NEB AND IA IS ORGANIZING INTO A LINEAR MCS AND WILL CONTINUE TO HAVE A WIDESPREAD SEVERE THREAT LATE THIS AFTERNOON INTO THE MID-EVENING.
RUC ANALYZED INSTABILITY AND VERTICAL SHEAR FIELDS APPEAR FAVORABLE FOR AN EXTENSIVE SEVERE THREAT COVERAGE. LARGE HAIL AND WIND DAMAGE SHOULD ACCOMPANY THE STRONGER CELLS IN THE SQUALL-LINE EWD ACROSS THE REMAINDER OF KS INTO NW MO AND SRN IA. A FEW TORNADOES SHOULD OCCUR WITH SUPERCELLS EMBEDDED IN THE LINE OR AHEAD OF THE LINE THROUGH EARLY TO MID-EVENING.

FURTHER SOUTHWEST ACROSS THE HIGH RISK AREA...THE LATEST SHORT-TERM THUNDERSTORM GUIDANCE SUGGESTS A SHORT LULL IN CONVECTIVE DEVELOPMENT SHOULD OCCUR LATE THIS AFTERNOON AS THE SRN EDGE OF A LARGE MCS EXITS TO THE NORTHEAST. THEN THE NEW RUC AND NAM FORECASTS SUGGEST REPEAT INITIATION WILL OCCUR NORTH TO SOUTH ALONG MOST OF THE DRYLINE IN THE 23Z TO 01Z TIMEFRAME. THE RUC ALSO SUGGESTS THE STRONGER VERTICAL SHEAR PROFILES OF 50 TO 60 KT STILL LOCATED JUST WEST OF THE HIGH RISK AREA WILL MOVE EWD INTO WRN OK BY EARLY EVENING. THIS WILL STRENGTHEN VERTICAL SHEAR PROFILES WITH THE LOW-LEVEL JET ALSO INCREASING ATTM HELPING STORMS THAT INITIATE TO RAPIDLY OBTAIN SUPERCELL STRUCTURES CAPABLE OF PRODUCING LARGE HAIL AND TORNADOES. THE THREAT FOR STRONG TORNADOES AND VERY LARGE HAIL APPEARS TO BE THE GREATEST FROM AROUND WOODWARD OK SWD TO ABOUT WICHITA FALLS TX WHERE AN AXIS OF LOW LCL HEIGHTS CURRENTLY EXISTS.
CONFIDENCE IS STILL HIGH THAT A CLUSTER OF TORNADIC SUPERCELLS SHOULD ORGANIZE ALONG THIS CORRIDOR THIS EVENING.

OUN's Update:
SHORT TERM FORECAST
NATIONAL WEATHER SERVICE NORMAN OK
301 PM CDT SUN APR 26 2009

.NOW...
...REGIONAL WEATHER DISCUSSION...

THIS AFTERNOON...NUMEROUS SEVERE THUNDERSTORMS WILL AFFECT THE AREA
WEST OF INTERSTATE 35 IN OKLAHOMA AND NORTH TEXAS. THE PRIMARY
CONCERNS WILL BE VERY LARGE HAIL WITH SUPERCELL THUNDERSTORMS IN
THAT REGION...BUT ALSO FLOODING IN NORTHERN OKLAHOMA...WHERE BETWEEN
6 AND 10 INCHES OF RAIN FELL LAST NIGHT JUST WEST AND NORTH OF ENID.

AT 3 PM...SEVERE THUNDERSTORMS WERE ALREADY IN PROGRESS IN NORTHWEST
OKLAHOMA NEAR FAIRVIEW...FORT SUPPLY...AND AMORITA. ANOTHER SEVERE
STORM WAS LOCATED IN KNOX COUNTY TEXAS...NEAR TRUSCOTT. ALL STORMS
WERE MOVING NORTHEAST AT 30 TO 40 MPH.

LOW PRESSURE STRETCHED FROM SOUTHEAST COLORADO TO THE NORTHERN TEXAS
PANHANDLE. THE LOW WAS INTENSIFYING...AS A STRONG JET STREAM AND
UPPER LEVEL TROUGH APPROACHED FROM SOUTHERN NEW MEXICO. A DRYLINE
WILL REMAIN IN THE EASTERN TEXAS PANHANDLE...WHILE NUMEROUS
THUNDERSTORMS DEVELOP IN A ZONE FROM THE DRYLINE TOWARD WESTERN
OKLAHOMA AND WESTERN NORTH TEXAS. INCREASING UPPER LEVEL WIND SPEEDS
AND MAXIMUM AFTERNOON HEATING WILL YIELD STORMS WITH INCREASING
SUPERCELL CHARACTER...AND A PRIMARY THREAT OF DESTRUCTIVE HAIL. THE
TORNADO THREAT WILL DEPEND SOMEWHAT ON THE NUMBER OF STORMS AND
THEIR INTERACTIONS. PEOPLE ARE URGED TO STAY CLOSE TO A SOURCE OF
WEATHER INFORMATION.

[venture]

For those who are around that want to have a more flowing discussion, I have this live chat setup that I'll be in and out of throughout the evening.

Live Severe Weather Coverage Dis

[Karried]

Honestly, it's hard for me to figure some of this out.

I'm giving you my address, just call me if it's coming this way okay?

Seriously, what do we know about the Metro today and tonight?

Specifically Edmond? I'm very nervous today.

[venture]

Mesoscale discussion 0585
nws storm prediction center norman ok
0334 pm cdt sun apr 26 2009

areas affected...ok...nwrn tx...ern pnhdl tx

concerning...tornado watch 190...192...

Valid 262034z - 262230z

the severe weather threat for tornado watch 190...192...continues.

Severe potential will increase...particularly with respect to
tornadoes...through this evening for a large part of cntrl/wrn ok
and nwrn tx. Potential for long-lived supercells with strong
tornadoes and giant hail will exist.

Rapid initiation appears to be taking place now along the ern tx
pnhdl/ok border along the dryline where the air mass heated in wake
of early day storms. Tstms will likely build swwd into the sern tx
pnhdl through late aftn...with activity moving off the dryline and
progressing newd into wcntrl/nwrn ok. Meanwhile... Tstms have been
developing out of pre-existing mid-lvl cloud streets over nwrn
tx...effectively rooting into the very unstable boundary layer.

Ahead of the storms...persistent influx of rich boundary layer
moisture and sfc heating have contributed to mlcapes of 3000 j/kg
across nwrn tx into wrn/cntrl ok. Thus...tstms should have no
trouble intensifying through early evening.

Vertical shear continues to improve per area profilers as the upr
lvl trough over nm begins to swing ene. 45-50 kts of bulk shear
will support supercells with very large hail and dmgg wind gusts.

Primary concern is for the potential for strong tornadoes.
Significant tornado ingredients appear in place from nwrn tx nwd
into cntrl/wrn ok where low-level environment will remain relatively
moist and where storms are apt to stay discrete the longest. 0-1km
srh values will be in excess of 300 m2/s2.

[Thunder]

I know how it feels, Karrie. I gotta go to work and as a good employee, I'll have to let the customers be in the freezers, more room for them, and I'll probably go ahead clock out if somehow a tornado is coming our way, take off in the car.

Venture, I've been trying to use the chat, but no luck with IE7. Altho, it is working for me, finally, on FireFox.

[Thunder]

Everyone, try this Live Severe Weather Coverage Dis on IE or FireFox. Venture will have to promote ya'all to panelist or something, so your posts can go thru unmoderated, then should be working fine for ya.

[Thunder]

Bulletin - eas activation requested
tornado warning
national weather service norman ok
404 pm cdt sun apr 26 2009

the national weather service in norman has issued a

* tornado warning for...
Southeastern ellis county in northwest oklahoma...
Northwestern roger mills county in western oklahoma...

* until 500 pm cdt

* at 404 pm cdt...national weather service doppler radar indicated a
severe thunderstorm capable of producing a tornado near reydon...
Moving northeast at 45 mph.

* locations in the warning include crawford...durham...harmon...
Reydon and roll.

Precautionary/preparedness actions...

Take cover now. Leave mobile homes and vehicles. If possible...move
to a basement or storm shelter. Otherwise move to an interior room or
hallway on the lowest floor. Stay away from windows and outside
walls.

[Thunder]

Andy Gabrielson Live Chase Cam

Posted by Venture in the chat. You'll need Microsoft Silverlight to view the streaming video of the possible tornado near Cheyenne, out west.

http://www.severestudios.com/cgi-bin...rk.hill&uid=82

Posted by Venture in the chat. You'll need Microsoft Silverlight to view the streaming video of the possible tornado coming out of Texas into SW OK.

Sometime the connection on these streaming videos can be lost, but keep checking.

[Thunder]

Possible tornado crossing the border, SW OK. South/SW of Altus.