Plains Tornado Outbreak 4/14-15

[Texas Snowman]

Will we see the dreaded 60% tornado risk?

I'm betting yes.

EDIT: And given the ramp up to this event, the fact that it is on a Saturday, and the fact that it is in the wide-open Great Plains, I can't help but wonder:

What will be more dangerous today - the tornado potential or the high speed convergence of storm chasers?

[CrazyC83]

13Z: High Risk filled in and expanded slightly southward and significantly eastward

[cycloneye]

13Z: High Risk filled in and expanded slightly southward and eastward

Much bigger now.

[CrazyC83]

SPC AC 141245

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0745 AM CDT SAT APR 14 2012

VALID 141300Z - 151200Z

...THERE IS A HIGH RISK OF SVR TSTMS LATER THIS AFTERNOON INTO
TONIGHT FOR CENTRAL/ERN NEB...CENTRAL/ERN KS...AND CENTRAL/N CENTRAL
OK...

...THERE IS A MDT RISK OF SVR TSTMS SURROUNDING THE HIGH RISK...FROM
SW OK TO FAR NE NEB AND WRN IA...

...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK...FROM
NW TX TO WRN NEB...IA...AND MO...

...TORNADO OUTBREAK EXPECTED LATE THIS AFTERNOON INTO TONIGHT FROM
CENTRAL/ERN NEB SWD ACROSS KS TO CENTRAL OK...WITH THE POTENTIAL FOR
LONG-TRACK/DAMAGING TORNADOES...

...SYNOPSIS...
A CLOSED LOW OVER NW AZ THIS MORNING WILL PROGRESS EWD/ENEWD TO THE
HIGH PLAINS BY THIS EVENING WHILE EVOLVING INTO MORE OF AN OPEN
WAVE...AND THEN CONTINUE INTO THE CENTRAL PLAINS BY THE END OF THE
PERIOD. AN ASSOCIATED SURFACE CYCLONE WILL DEEPEN AND MOVE NEWD
FROM ERN CO THIS AFTERNOON TO NE NEB/SE SD BY 12Z SUNDAY. S OF THE
CYCLONE...A WELL-DEFINED DRYLINE IS EXPECTED TO RESIDE FROM CENTRAL
KS SWD INTO WRN OK AND NW TX BY THIS EVENING...WHILE A WARM FRONT
MOVES NWD FROM KS THIS MORNING TO CENTRAL/ERN NEB BY LATE AFTERNOON.
A MOIST AND UNSTABLE WARM SECTOR WILL COVER NEB/KS/OK/N TX TO THE E
OF THE DRYLINE AND S OF THE WARM FRONT. THE PRIMARY LOCATIONS FOR
SEVERE STORM DEVELOPMENT TODAY WILL BE NEAR THE SURFACE LOW MOVING
INTO NEB...AND THE DRYLINE TRAILING SWD INTO KS/OK.

...CENTRAL PLAINS THROUGH TONIGHT...
THE FORECAST REASONING REMAINS LARGELY UNCHANGED FROM THE PAST FEW
DAYS. IN THE WAKE OF MORNING WAA STORMS ACROSS NE OK/SE KS/SW
MO...LOW-LEVEL MOISTURE WILL SURGE NWD ACROSS KS TO S CENTRAL/SE NEB
BY MID-LATE AFTERNOON. DAYTIME HEATING INVOF THE DRYLINE AND
BOUNDARY LAYER DEWPOINTS RANGING FROM THE LOW 60S IN NEB TO THE
MID-UPPER 60S IN CENTRAL OK WILL CONTRIBUTE TO AFTERNOON MLCAPE
VALUES OF 2000-3500 J/KG. MEANWHILE... DEEP-LAYER VERTICAL SHEAR
WILL BE QUITE SUPPORTIVE OF SUPERCELLS IN THE UNSTABLE WARM
SECTOR...WITH EFFECTIVE BULK SHEAR OF 50-70 KT ACROSS ALMOST THE
ENTIRE WARM SECTOR. THE DEGREE OF LOW-LEVEL MOISTURE AND AN
EXPECTED INCREASE IN LOW-LEVEL SHEAR LATER THIS AFTERNOON INTO EARLY
TONIGHT WILL RESULT IN AN ENVIRONMENT CLEARLY INTO THE PARAMETER
SPACE ASSOCIATED WITH PREVIOUS STRONG-VIOLENT AND LONG-TRACK TORNADO
EPISODES.

THE PRIMARY QUESTION THIS OUTLOOK WILL BE STORM COVERAGE ALONG THE
DRYLINE THIS EVENING IN KS/OK. THE CONVECTIVE SCHEMES IN THE
OPERATIONAL MODELS VARY WITH STORM INITIATION SIGNALS...WHILE
SEVERAL OF THE CONVECTION-ALLOWING MODELS GENERATE WIDELY SCATTERED
DRYLINE SUPERCELLS IN THE 22-01Z TIME FRAME. FORECAST
SOUNDINGS...MODIFIED FOR EXPECTED AFTERNOON TEMPERATURES ALONG THE
DRYLINE...SHOW DEEP MIXED LAYER AND LITTLE OR NO CONVECTIVE
INHIBITION. PLUS...A WELL-DEFINED BAND OF LOW-LEVEL ASCENT IS
EXPECTED ALONG THE DRYLINE...WHICH SUGGESTS AT LEAST
WIDELY-SCATTERED THUNDERSTORM DEVELOPMENT ACROSS THE KS/OK PORTION
OF THE DRYLINE IS ENTIRELY PLAUSIBLE. FARTHER N...POTENTIALLY MORE
CONCENTRATED STORM DEVELOPMENT IS EXPECTED NEAR THE SURFACE LOW AND
NW EDGE OF THE UNSTABLE WARM SECTOR IN NEB /WITHIN THE LEFT EXIT
REGION OF THE JET ALOFT/. ALL FACTORS FAVOR DISCRETE CONVECTIVE
MODES THROUGH EARLY TONIGHT...AND THOUGH STORMS COULD BE WIDELY
SPACED...THEY WILL BE CAPABLE OF PRODUCING LONG PATHS OF VERY LARGE
HAIL AND DAMAGING TORNADOES THROUGH AT LEAST 06Z.

LATE TONIGHT...THE MIDLEVEL TROUGH WILL FULLY EMERGE OVER THE PLAINS
AND THE PACIFIC COLD FRONT WILL OVERTAKE THE DRYLINE...POTENTIALLY
SUPPORTING MORE EXTENSIVE SQUALL LINE DEVELOPMENT NEAR OR AFTER 06Z.
DAMAGING WINDS WILL BE MORE OF A THREAT WITH THE MORE LINEAR AND
WIDESPREAD CONVECTION LATE TONIGHT...GIVEN A CONTINUATION OF
SURFACE-BASED INSTABILITY AND 60-70 KT FLOW IN THE LOWEST FEW
THOUSAND FEET AGL.

..THOMPSON/MOSIER.. 04/14/2012

CLICK TO GET WUUS01 PTSDY1 PRODUCT

NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z
CURRENT UTC TIME: 1251Z (8:51AM), RELOAD THIS PAGE TO UPDATE THE TIME

[Texas Snowman]

13Z: High Risk filled in and expanded slightly southward and eastward

Much bigger now.

Wow. Wow, wow, wow. Cue the "Jaws" soundtrack with that map.

Moderate risk edging closer to my area in the Red River Valley.

[apocalypt-flyer]

I'm struggling to remember a high risk area that large. Massive.

[Cyclenall]

Tornado Hatched Area:



In regards to the expanded High Risk area, my mind exploded X 40. That is by far the largest I've ever seen and dwarfs even April 27, 2011...must be the largest ever since the SPC began. The floodgates of hell are opening today. Was wondering if 60% hatched for the first time before the actual tornadoes start would be issued but not yet. There is a good chance to see the 2nd only 60% tornado hatched area ever given today.

Southern area has some potential for busting indeed. However, it does appear that the atmosphere is clearing out with the storms well to the east now.

If you have time, you should go back and see what was happening overnight. Hook echoes were popping out of the line blobs out of nowhere and they weren't TOR warned.

Probably a little wishful thinking on my part - who needs an outbreak of strong, long-tracked tornadoes - but I keep hearing from various sources an idea that supercell coverage on the southern end of the high risk may be somewhat limited.

With the worked over atmosphere from last night's storms in portions of Oklahoma, can't help but wonder if there's any potential for a "bust" of sorts today - i.e. lots of storm chasers looking at radars that aren't lit up as expected.

On your first point, that could actually be better for the intense supercells that do form because less interaction leaves more for what's there. The problem of too many cells in a confined space would be a total non-issue. It's very unclear in general.

Second thing, worked over? It wasn't worked over at all but what it may have done is cleared the way for no morning convection so that could end up making storms later on worse. Last nights storms can also lay down boundaries.

[Ntxw]

HRRR and HRW both initiate numerous supercells along the Kansas/Nebraska border, looks very bad up there indeed. Sluggish with storms in Oklahoma as they are closer to capping later this afternoon but I think the high risk there is warranted due to the fact that the few that do form will become very intense quickly especially northern Oklahoma. SE Nebraska is dead on bullseye.

[Tireman4]

Tor Con Numbers...

Saturday April 14
IA west night - 8
IA central - 5
IA central, northeast night - 4 to 5
KS central - 8
KS east night - 8
MN southwest - 4
MN south, east-central night - 5
MO northwest night - 6
NE central, east - 8
OK west, north-central (except panhandle) - 7
OK central, northeast night - 5
SD southeast night - 6
TX northwest near Wichita Falls - 7
TX central night, west of I-35 - 4
WI west-central night - 4
Other areas - less than 2


Sunday April 15
AR - 3
IL north - 4
IL central, south - 3
IN northwest - 2 to 3
LA northwest - 3
MI upper - 3
MI west - 3
MN southeast - 4
MO east-central, south - 3
OK southeast - 3
TX southeast - 4
TX rest of area east of I-35 - 3
WI central - 5
WI north - 3 to 4
WI south - 4
Other areas - less than 2

http://www.weather.com/outlook/weather- ... 2011-07-11

[Bunkertor]

Tiny watch

SEL4

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 164
NWS STORM PREDICTION CENTER NORMAN OK
340 AM CDT SAT APR 14 2012

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

EXTREME SOUTHEAST KANSAS
NORTHEAST OKLAHOMA

EFFECTIVE THIS SATURDAY MORNING FROM 340 AM UNTIL 900 AM CDT.

TORNADOES...HAIL TO 2 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 40 STATUTE
MILES NORTH AND SOUTH OF A LINE FROM 35 MILES SOUTHWEST OF PONCA
CITY OKLAHOMA TO 10 MILES NORTHEAST OF GROVE OKLAHOMA. FOR A
COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE
UPDATE (WOUS64 KWNS WOU4).

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...THIS TORNADO WATCH REPLACES TORNADO
WATCH NUMBER 163. WATCH NUMBER 163 WILL NOT BE IN EFFECT AFTER
340 AM CDT.

DISCUSSION...CLUSTER OF STORMS WITH EMBEDDED SUPERCELLS WILL LIKELY
PERSIST THROUGH THE EARLY MORNING HOURS IN CONJUNCTION WITH
LOW-LEVEL WAA AND A FEED OF MOISTURE AND MODERATE INSTABILITY FROM
THE S/SW. STRONG LOW-LEVEL SHEAR AND INSTABILITY ROOTED AT OR VERY
NEAR THE SURFACE WILL SUPPORT THE RISK FOR A COUPLE OF
TORNADOES...AS WELL AS LARGE HAIL AND ISOLATED DAMAGING WINDS.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 2 INCHES. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
500. MEAN STORM MOTION VECTOR 25025.


...THOMPSON

[Dave]

TORNADO WATCH NUMBER 164 has expired. At this time no watches in effect. Stay tuned I'm sure that will change today.

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

[cycloneye]

Latest Mesoscale Discussion

MESOSCALE DISCUSSION 0521
NWS STORM PREDICTION CENTER NORMAN OK
0942 AM CDT SAT APR 14 2012

AREAS AFFECTED...TX/OK PANHANDLES...WRN OK...SWRN KS

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

VALID 141442Z - 141615Z

CONVECTIVE INITIATION MAY BE UNDERWAY ACROSS PARTS OF THE SRN/CNTRL
HIGH PLAINS. TRENDS WILL BE MONITORED DURING THE NEXT FEW
HOURS...AND A TORNADO WATCH WILL LIKELY BE ISSUED FOR THE TX/OK
PANHANDLES...WRN OK...AND SWRN KS IF THE THREAT FOR DEEPENING
CONVECTION ACTUALLY MATERIALIZES.

RECENT VISIBLE SATELLITE LOOP INDICATES A ZONE OF TOWERING CUMULUS
EVOLVING FROM FAR SWRN KS SSWWD INTO THE CNTRL TX PANHANDLE. THIS
ZONE ALIGNS WITH A RIBBON OF INFERRED ASCENT PER RECENT WATER VAPOR
IMAGERY. THE 12Z AMARILLO RAOB MODIFIED FOR CURRENT SFC OBS
INDICATES THAT INHIBITION FOR A SURFACE-BASED PARCEL HAS ALMOST
COMPLETELY ERODED OVER THE TX/OK PANHANDLES...PARTICULARLY IN
POCKETS OF INSOLATION. FARTHER NORTH INTO SWRN KS -- I.E. NORTH OF
THE TRACK OF ASCENT ATTENDANT TO A PRIOR SUBTLE IMPULSE -- THE CAP
IS MUCH MORE STOUT PER DODGE CITY 12Z RAOB. REGARDLESS...CONTINUED
SFC HEATING WILL LIKELY RESULT IN STRONG DESTABILIZATION AND
DECREASING INHIBITION THROUGH THE LATE MORNING INTO THE EARLY
AFTERNOON EAST OF A SHARPENING DRYLINE/FRONT...AND CONVECTIVE
INITIATION MAY BE IMMINENT. ALSO OF NOTE...DETERMINISTIC MODEL QPF
FIELDS HAVE STRUGGLED GREATLY WITH REGARDS TO REPRESENTING THE
CURRENT SCENARIO...AND LIKELY ARE NOT RESOLVING SUBTLE FORCING FOR
ASCENT THAT WILL PLAY A KEY ROLE IN SUPPORTING THE INITIATION.
STRONG LOW-LEVEL SHEAR YIELDING EFFECTIVE SRH IN EXCESS OF 300
M2/S2...MAINTAINED BY BACKED SFC WINDS...WILL SUPPORT A THREAT FOR
TORNADOES...WHILE VERY LARGE HAIL AND DMGG WINDS ARE ALSO EXPECTED
WITH SUPERCELL STRUCTURES.

..COHEN.. 04/14/2012

[mcallum177]

Wow initiation so early in the morning????

I know DFW is not really included but what are the chances that anything initiates and moves into our area?

[snoopj]

I'm struggling to remember a high risk area that large. Massive.

Last time I remember a high risk area being that large? 05/04/2003

http://www.spc.noaa.gov/products/outloo ... _1630.html



And it looks smaller than this one.

[Bunkertor]

By the latest multimedia-briefing SPC has disarmed wording significantly

[Dave]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORMAN OK
955 AM CDT SAT APR 14 2012

.UPDATE...
ASIDE FROM INCREASING POPS LATE THIS AFTERNOON THROUGH THIS
EVENING...THE FORECAST IS LARGELY UNCHANGED. WILL CONTINUE TO SEE
STRONG SURFACE WINDS ACROSS MUCH OF THE FA THIS AFTERNOON AND WILL
KEEP WIND ADVISORY INTACT. THE THREAT FOR SEVERE THUNDERSTORMS
WILL INCREASE THROUGH THE AFTERNOON AS A DRYLINE EMERGES ACROSS
THE FAR EASTERN TX PANHANDLE AND WESTERN OKLAHOMA. SUPERCELLS ARE
EXPECTED INITIALLY WITH A TORNADO...LARGE HAIL AND DAMAGING WIND
THREAT. STRONG TORNADOES WILL ALSO BE POSSIBLE ACROSS PARTS OF
NORTHERN AND WESTERN OKLAHOMA...MOVING INTO CENTRAL OKLAHOMA THIS
EVENING. STORMS WILL EVENTUALLY EVOLVE INTO AN EASTWARD MOVING
SQUALL LINE THROUGH THIS EVENING...POSING A RISK FOR MAINLY
DAMAGING WINDS AND HAIL.

&&

[cycloneye]

FYI= The graphic updating as the reports go up is posted at the 2012 U.S Severe Weather Season (Stats / Videos / Forecasts) Sticky thread as is better there than in this thread as for sure,it will be very active and will be lost in the pages.

viewtopic.php?f=24&t=112438&p=2219444#p2219444

[CrazyC83]

Look for a PDS Tornado Watch there by midday then, and several more into the afternoon and evening.

[CrazyC83]

http://www.crh.noaa.gov/gid/?n=briefing

NWS Hastings, which looks to be near the epicenter today.

[Dave]

PDS tornado watch being issued. Will include two tiers of counties in northern OK, including Woodward and Enid....Outlines will be coming in a few minutes...