Oklahoma Severe Weather Discussion - April 2011

[venture]

Working on an update forecast map. Not really all that different from what I had last night, except for moving boundaries around a little. 12Z NAM indicating storms firing along cold front in NE OK and also near the triple point in South Central OK. I have an outline area of "enhanced risk" for large hail in this areas. Tornado threat looks lower than it did yesterday, so pulling the moderate off my outlook. Still expect a tornado or two in the state, but that is about it...which could of course change. NAM has also moved to back build storms north of the frontal boundary (and even start moving the front north a bit over night). These will be mostly elevated hail storms as instability in the mid levels begins to increase towards early evening. HRRR model seems to agree with this thinking and will post outlook graphic once the new run completes.

[cameron_405]

...a sad Texan once prayed, "Lord, I wish you would make it rain - not so much for me, I've seen it - but for my 7-year-old."

[venture]

Okay new HRRR is done and here is the updated thinking.

[ou48A]

Would cloud seeding help us?

[Thunder]

Why is it that the cold front been moving on thru so fast the past few months?!

[venture]

LOL so the minute I second guess myself and pull the moderate risk off, SPC goes ahead and puts one up.



DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1104 AM CDT FRI APR 22 2011

VALID 221630Z - 231200Z

...THERE IS A MDT RISK OF SVR TSTMS LATE THIS AFTERNOON AND EVENING
OVER PORTIONS OF EASTERN OK...NORTHWEST AR...AND SOUTHERN MO...

...THERE IS A SLGT RISK OF SVR TSTMS FROM CENTRAL TX INTO THE MID MS
AND MUCH OF THE OH VALLEY...

A FAST-MOVING UPPER TROUGH OVER THE CENTRAL PLAINS WILL TRACK
EAST-NORTHEASTWARD DURING THIS FORECAST PERIOD INTO THE UPPER
MIDWEST. AS THIS OCCURS...STRONG SOUTH-SOUTHWESTERLY LOW LEVEL
WINDS ACROSS THE PLAINS AND MS VALLEY WILL TRANSPORT GULF MOISTURE
RAPIDLY NORTHWARD AND RESULT IN A RATHER LARGE AREA OF THUNDERSTORM
POTENTIAL. THE GREATEST CONCENTRATION OF SEVERE WEATHER WILL LIKELY
EXTEND FROM OK INTO SOUTHERN MO.

...MO/IL INTO OH VALLEY...
A CLUSTER OF INTENSE THUNDERSTORMS IS ONGOING THIS MORNING NEAR THE
STL AREA. THESE STORMS APPEAR TO BE ASSOCIATED WITH WARM ADVECTION
NEAR THE NOSE OF THE LOW LEVEL JET...AND IN REGION OF MODERATE
ELEVATED INSTABILITY. THIS ACTIVITY APPEARS TO BE SUFFICIENTLY
ORGANIZED TO MAINTAIN INTENSITY AND TRACK EASTWARD INTO THE OH
VALLEY DURING THE AFTERNOON AND EVENING. A RETREATING SURFACE WARM
FRONT OVER THE OH VALLEY WILL LIKELY HELP FOCUS THE CONVECTION.
DAMAGING WINDS AND LARGE HAIL ARE THE MAIN THREATS.

...MO/AR/OK/TX...
A SURFACE COLD FRONT IS SURGING SOUTHEASTWARD ACROSS NORTHWEST
OK...AND SHOULD EXTEND FROM SOUTHEAST KS INTO CENTRAL OK BY LATE
AFTERNOON. AHEAD OF THE FRONT...SOUTHERLY WINDS HELPING TO ADVECT
MOISTURE NORTHWARD WITH MID 60S DEWPOINTS LIKELY ACROSS THE REGION
LATER TODAY. CONSIDERABLE DAYTIME HEATING WILL WEAKEN THE CAPPING
INVERSION AND HELP THE DEVELOPMENT OF SCATTERED THUNDERSTORMS ALONG
THE FRONT...AND POTENTIALLY MORE DISCRETELY IN THE WARM SECTOR.
FORECAST SOUNDINGS SHOW RATHER LARGE HODOGRAPHS AND STEEP MID LEVEL
LAPSE RATES. THIS SUGGESTS SUPERCELL STORMS ARE LIKELY WITH VERY
LARGE HAIL AND DAMAGING WINDS POSSIBLE. TORNADOES APPEAR OF
GREATEST CONCERN OVER SOUTHERN MO...FAR NORTHERN AR...AND EVENTUALLY
INTO SOUTHERN IL WHERE ENHANCED LOW LEVEL SHEAR NEAR THE RETREATING
WARM FRONT WILL BE PRESENT. STORMS MAY PERSIST THROUGH MUCH OF THE
NIGHT WITH ACTIVITY SPREADING ACROSS THE MID MS AND INTO THE OH
VALLEY.

[venture]

Going to bring the chat room up at chatokc.com for the rest of the afternoon/evening. Feel free to email me at info@chatokc.com to request an invite to the room that will allow you to be unmoderated.

[SkyWestOKC]

Here is a shot of the cold front from 30,000 feet near the West-Texas/Oklahoma border at about 935am central time. This was shot looking back behind the wing from my cellphone, so it's blurry and grainy. It was pretty bumpy running through it. I will try and get a better shot here in a few hours on my return leg.

http://img809.imageshack.us/i/img2011042200070.jpg/

Bright spot is a reflection of a personal reading light off of the window, not a UFO or the sun.

[venture]

Cold front appears to be running roughly from Stillwater to Edmond to just west of Chickasha right now. HRRR run is hinting that initial activity could develop in the next 2-3 hours over South Central Oklahoma.

[SkyWestOKC]

Must not have been the cold front, sure looked like one from how I saw it. a huge line that stretched as far as I could see. Might have been just something else.

Hopefully these storms will wait for me to get back Been stressing it all week, I would love to say I was stressing for no reason.

[venture]

Here is a shot of the cold front from 30,000 feet near the West-Texas/Oklahoma border at about 935am central time. This was shot looking back behind the wing from my cellphone, so it's blurry and grainy. It was pretty bumpy running through it. I will try and get a better shot here in a few hours on my return leg.

http://img809.imageshack.us/i/img2011042200070.jpg/

Bright spot is a reflection of a personal reading light off of the window, not a UFO or the sun.

Very nice. M80 I'm guessing by the wing? lol

[venture]

Update to last week's tornadoes...

[BG918]

Looks like a repeat of 4/14 with storms this time forming slightly further to the west but basically along the 35 corridor.

[Thunder]

Here is a shot of the cold front from 30,000 feet near the West-Texas/Oklahoma border at about 935am central time. This was shot looking back behind the wing from my cellphone, so it's blurry and grainy. It was pretty bumpy running through it. I will try and get a better shot here in a few hours on my return leg.

http://img809.imageshack.us/i/img2011042200070.jpg/

Bright spot is a reflection of a personal reading light off of the window, not a UFO or the sun.

My first thought was that its UFO. It was a good thing you mentioned that it was not.

[SkyWestOKC]

You would be correct....MD80.

[venture]

http://rapidrefresh.noaa.gov/hrrrcon...main=t5&wjet=1

That is the latest HRRR run. Initial storms developing in South Central OK in the next 2-3 hours. Additional storms then fire up along the front from Central OK up through NE OK. If this run is taken literally, it does keep everything north and west of I-44 dry through midnight.

CU field is developing fairly nicely now from Stephens County back to the northeast.

[venture]

Here is a small glimmer of hope for rain in the metro area.

[SkyWestOKC]

I do not want to see that blob near DFW!!!! Hopefully I'll leave DFW before that part hits.

[venture]

Possible new Tornado Watch coming out in the next hour or two.



MESOSCALE DISCUSSION 0518
NWS STORM PREDICTION CENTER NORMAN OK
0123 PM CDT FRI APR 22 2011

AREAS AFFECTED...CNTRL/ERN OK...FAR WRN AR...N-CNTRL/NERN TX

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY

VALID 221823Z - 222000Z

PORTIONS OF CNTRL/ERN OK...FAR WRN AR...AND N-CNTRL/NERN TX ARE
BEING MONITORED FOR THUNDERSTORM DEVELOPMENT AND INCREASING SVR
WEATHER THREAT. TORNADO WATCH WILL LIKELY BE NEEDED DURING THE NEXT
FEW HOURS.

EARLY AFTERNOON SURFACE ANALYSIS SHOWS AN AREA OF LOW PRESSURE
MOVING E-NEWD ACROSS SERN KS...WITH A COLD FRONT TRAILING SWWD INTO
SWRN OK...AND A DRYLINE EXTENDING S-SW FROM CNTRL OK INTO N-CNTRL
TX. STRONG SURFACE HEATING AND STEEPENING LOW-LEVEL LAPSE RATES ARE
DEVELOPING NEWD ALONG THE COLD FRONT/DRYLINE...AIDING IN BOUNDARY
LAYER DESTABILIZATION. MEANWHILE...EXPANSIVE AREA OF MID 60S F
DEWPOINTS RESIDE ACROSS THE WARM SECTOR BENEATH A PLUME OF STEEP
MIDLEVEL LAPSE RATES...RESULTING IN STRONG INSTABILITY /MLCAPE
VALUES AOA 2500 J PER KG/ ALONG/AHEAD OF THE SURFACE BOUNDARIES.

VIS SATELLITE IMAGERY AT 18Z SHOWS ENHANCED CUMULUS GROWTH OVER
S-CNTRL OK...WHICH IS COINCIDENT WITH THE LOCATION OF RAPID
THUNDERSTORM DEVELOPMENT IN 3KM HRRR OCCURRING BY 19-20Z. GIVEN
THESE TRENDS...CONFIDENCE IS INCREASING THAT CONVECTIVE INITIATION
WILL TAKE PLACE OVER PORTIONS OF CNTRL/ERN OK AND PERHAPS N-CNTRL TX
DURING THE NEXT FEW HOURS. THOUGH DEEP LAYER SHEAR IS SOMEWHAT
MARGINAL /EFFECTIVE BULK SHEAR FROM 35-45 KT/...THE STRONG
INSTABILITY/STEEP MIDLEVEL LAPSE RATES SHOULD LEAD TO RAPID
THUNDERSTORM INTENSIFICATION AND POSSIBLE SUPERCELL DEVELOPMENT
POSING A THREAT FOR VERY LARGE HAIL. IN ADDITION...THE DEGREE OF
INSTABILITY COMBINED WITH SUFFICIENT LOW-LEVEL SHEAR PROFILES /0-1
KM SRH IN EXCESS OF 150 M2 S-2/ SUGGESTS THAT A TORNADO WATCH WILL
NEED TO BE CONSIDERED.

..GARNER.. 04/22/2011

[SkyWestOKC]

Also, I'm unable to post a picture of the cold front. I had to trade seats (window to an aisle). So, I can't see anything right now. We had a bumpy ride so far though.

[Thunder]

Did the cold front actually moved backward already? That picture just above have the front northwest of the metro now.

Earlier, I did feel the northerly wind, but now I feel the southerly wind. Can you confirm? Its all sunshine and moisty here.

SkyWestOKC, have no fear! I don't think a tornado will be on your plane's tail.

[venture]

Visible satellite shows where the front is very well.

[JLin78]

When do you see the tornado watch being issued?

[venture]

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 180
NWS STORM PREDICTION CENTER NORMAN OK
350 PM CDT FRI APR 22 2011

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

NORTHWEST ARKANSAS
EASTERN OKLAHOMA

EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 350 PM UNTIL
1000 PM CDT.

ISOLATED TORNADOES
SCATTERED DAMAGING WINDS
ISOLATED WIND GUSTS TO 70 MPH POSSIBLE
WIDESPREAD LARGE HAIL
ISOLATED HAIL TO 4.0 INCHES IN DIAMETER POSSIBLE

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 75 STATUTE
MILES EAST AND WEST OF A LINE FROM 25 MILES SOUTH OF ARDMORE
OKLAHOMA TO 40 MILES NORTH NORTHWEST OF FAYETTEVILLE ARKANSAS.
FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU0).

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 178...WW 179...

DISCUSSION...THUNDERSTORMS ARE EXPECTED TO RAPIDLY FORM ALONG COLD
FRONT ADVANCING SOUTHEASTWARD INTO EASTERN OK THIS EVENING. OTHER
MORE ISOLATED STORMS ARE POSSIBLE SOUTHWARD ALONG THE DRYLINE NEAR
THE RED RIVER. VERY UNSTABLE CONDITIONS /MLCAPE OVER 3500 J/KG/
ALONG WITH SUFFICIENT VERTICAL SHEAR WILL POSE A THREAT OF
SUPERCELLS CAPABLE OF VERY LARGE HAIL AND DAMAGING WINDS. LOW LEVEL
VERTICAL SHEAR IS NOT PARTICULARLY STRONG...BUT SUFFICIENT GIVEN THE
DEGREE OF INSTABILITY TO WARRANT A THREAT OF ISOLATED TORNADOES.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 4 INCHES. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
550. MEAN STORM MOTION VECTOR 27030.

Spc aww 222043
ww 180 tornado ar ok 222050z - 230300z
axis..75 statute miles east and west of line..
25s adm/ardmore ok/ - 40nnw fyv/fayetteville ar/ ..aviation coords.. 65nm e/w /18sse adm - 23nw rzc/ hail surface and aloft..4 inches. Wind gusts..60 knots.
Max tops to 550. Mean storm motion vector 27030.


TORNADO WATCH PROBABILITIES FOR WT 0180
NWS STORM PREDICTION CENTER NORMAN OK
0346 PM CDT FRI APR 22 2011

WT 0180
PROBABILITY TABLE:
PROB OF 2 OR MORE TORNADOES : 30%
PROB OF 1 OR MORE STRONG /F2-F5/ TORNADOES : 20%
PROB OF 10 OR MORE SEVERE WIND EVENTS : 70%
PROB OF 1 OR MORE WIND EVENTS >= 65 KNOTS : 30%
PROB OF 10 OR MORE SEVERE HAIL EVENTS : >95%
PROB OF 1 OR MORE HAIL EVENTS >= 2 INCHES : 50%
PROB OF 6 OR MORE COMBINED SEVERE HAIL/WIND EVENTS : >95%

&&
ATTRIBUTE TABLE:
MAX HAIL /INCHES/ : 4.0
MAX WIND GUSTS SURFACE /KNOTS/ : 60
MAX TOPS /X 100 FEET/ : 550
MEAN STORM MOTION VECTOR /DEGREES AND KNOTS/ : 27030
PARTICULARLY DANGEROUS SITUATION : NO

[BG918]

T-storms beginning to form over Tulsa and points to the northeast.