January 28-30 Severe threat. S Plains to TN valley to SE

[OKpowdah]

And I present... a sounding we'll probably be begging for even in April and May when there is convection. Torture.

 

OUN.gif

 

Seriously. That's incredible

[thewxmann]

Eh, it's an okay sounding. The CAPE profiles are a little thin, and the temps at H5 are a little warm -- there's something left to be desired in the mid-level lapse rates. Nitpicking, I know, but these are details that could affect the severity of the potential outbreak tomorrow.

[OKpowdah]

Eh, it's an okay sounding. The CAPE profiles are a little thin, and the temps at H5 are a little warm -- there's something left to be desired in the mid-level lapse rates. Nitpicking, I know, but these are details that could affect the severity of the potential outbreak tomorrow.

 

It's f*cking January

[brettjrob]

Eh, it's an okay sounding. The CAPE profiles are a little thin, and the temps at H5 are a little warm -- there's something left to be desired in the mid-level lapse rates. Nitpicking, I know, but these are details that could affect the severity of the potential outbreak tomorrow.

 

It immediately reminded me of the 2011-11-07 00z OUN sounding that also had skinny CAPE, but that Vernon-Ft Cobb storm didn't care much. In all seriousness, it's obviously not a top-tier Plains outbreak sounding, but still remarkable for mid-winter and supportive of tornadic supercells if we had initiation. As for tomorrow, I agree that the relative warmth around the H7-H5 layer does not instill confidence that instability will greatly outperform progs.

[OKpowdah]

Eh, it's an okay sounding. The CAPE profiles are a little thin, and the temps at H5 are a little warm -- there's something left to be desired in the mid-level lapse rates. Nitpicking, I know, but these are details that could affect the severity of the potential outbreak tomorrow.

 

ML lapse rates are lacking, but should improve with the approach of the mid level trough and cooling temps aloft.

 

Also, thin CAPE profile outbreaks are a specialty of the Southeast 

[Ground Scouring]

Well, 00Z NAM continues to up the instability over the warm sector tomorrow morning...

The interesting thing is that, though afternoon 700-mb temperatures are a bit warmer than on previous runs (hence, somewhat less instability due to mixing in the afternoon), the dew points by late afternoon are even higher than on the preceding run.

In my view, something has to give here.

[Stebo]

It's f*cking January

 

Thank you lol.

[Buckeye05]

Just looked at a high-res NAM reflectivity that somebody posted on another forum. I am on my phone so I can't enlarge it, but the convective mode looks sloppy. With this among other potential issues that have been previously discussed, I don't think it is wise to cry high risk. I remember similar discussion about a high risk upgrade the night before last years Christmas outbreak, and the moderate ended up being appropriate in the end. I realize a potentially significant event could occur, but I don't want to get to ahead of myself here.

[Chicago Storm]

FWIW...

 

It should be noted that the 1959J/KG of SB CAPE of the OUN sounding is approx 750-1000 J/KG higher than the 12z NAM showed for 0z, and the GFS was off by over 1000J/KG. LZK was also higher, by about 500J/KG. Meso analysis was way off for most of the area too.

 

Obviously just two locations and just talking SB CAPE, but yea.

[JoMo]

Looks like some storms are trying to pop near OKC. 

[Indystorm]

SPC meso discussion out for OK for possible tornado watch with those developing cells.

[Siberian Express]

Elevated T storm moving into SE Mn and I see NE Iowa......it's a rather robust system. Having heaving rain when it's 32 degrees out sucks.

[andyhb]

New D1 has 15 sig hatched tor/45 sig hatched wind, will post momentarily.

[yoda]

New D1 has 15 sig hatched tor/45 sig hatched wind, will post momentarily.

 

 

 

[andyhb]

 

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1201 AM CST TUE JAN 29 2013

VALID 291200Z - 301200Z

...THERE IS A MDT RISK OF SVR TSTMS ACROSS PARTS OF SE MO...FAR WRN
TN...AR...NW MS...NRN LA AND FAR NE TX...

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE SRN
PLAINS...CNTRL PLAINS...MID MS VALLEY....LOWER MS VALLEY...OH VALLEY
AND TN VALLEY...

...SRN PLAINS/ARKLATEX/LOWER TO MID MS VALLEY...
AN UPPER-LEVEL TROUGH OVER THE ROCKIES WILL MOVE EWD INTO THE GREAT
PLAINS TODAY AS A POWERFUL 90 TO 110 KT MID-LEVEL JET OVERSPREADS
THE SRN AND CNTRL PLAINS. AS THE EXIT REGION OF THE MID-LEVEL JET
CORE MOVES ACROSS THE SRN PLAINS THIS MORNING...THUNDERSTORMS APPEAR
LIKELY TO DEVELOP FROM SE KS SWWD ACROSS CNTRL OK INTO NORTH TX.
THIS ACTIVITY SHOULD DEVELOP A SEVERE THREAT AROUND DAYBREAK AS A
BAND OF LARGE-SCALE ASCENT MOVES INTO THE SRN PLAINS AHEAD OF THE
APPROACHING UPPER-LEVEL SYSTEM. CONVECTIVE COVERAGE SHOULD QUICKLY
INCREASE THIS MORNING WITH A SQUALL-LINE DEVELOPING AND MOVING EWD
ACROSS THE OZARKS AND ARKLATEX REGION THIS AFTERNOON. CONDITIONS
WILL BE FAVORABLE FOR SEVERE STORMS ACROSS A LARGE AREA AND A
SIGNIFICANT SEVERE WEATHER EVENT APPEARS LIKELY TO OCCUR LATE THIS
AFTERNOON FROM SERN MO SWWD ACROSS AR INTO NRN LA.

FORECAST SOUNDINGS THIS AFTERNOON FROM NEAR THE BOOTHEEL OF MO SWWD
TO LITTLE ROCK AND SHREVEPORT INCREASE SFC TEMPS INTO THE LOWER 70S
F ALLOWING FOR INSTABILITY TO APPROACH MODERATE LEVELS. IN
ADDITION...DEEP LAYER SHEAR WILL BECOME STRONG AS THE RIGHT SIDE OF
THE MID-LEVEL JET APPROACHES THE REGION FROM THE WEST LATE THIS
AFTERNOON. 0-6 KM SHEAR VALUES OF 60 TO 70 KT ALONG WITH LONG LOOPED
HODOGRAPHS SHOULD SUPPORT SUPERCELL AND TORNADO DEVELOPMENT. THE
GREATEST TORNADO THREAT SHOULD EXIST WITH DISCRETE CELLS THAT
INITIATE AHEAD OF THE SQUALL-LINE FROM SE MO EXTENDING SWD ACROSS
ECNTRL AR WHERE A FEW SIGNIFICANT TORNADOES WILL BE POSSIBLE.
TORNADOES WILL ALSO BE POSSIBLE WITH BOWS AND ROTATING STORMS
EMBEDDED IN THE SQUALL-LINE ITSELF. WINDS JUST ABOVE THE SFC ARE
FORECAST TO BE AROUND 50 KT SUGGESTING THE LINE WILL BE VERY
EFFICIENT AT PRODUCING WIND DAMAGE. SOME DAMAGING WIND GUSTS ABOVE
70 KT MAY OCCUR ACROSS THE SLIGHT AND MODERATE RISK AREA WITH THE
GREATEST THREAT IN ECNTRL AR WHERE THE GFS SUGGESTS THE APEX OF A
LARGE-SCALE BOW COULD DEVELOP. MODEL FORECASTS MOVE THE SQUALL-LINE
EWD ACROSS THE TN VALLEY AND CNTRL GULF COAST STATES AFTER 06Z
SUGGESTING A WIND DAMAGE AND TORNADO THREAT WILL PERSIST THROUGH
MUCH OF THE NIGHT.

...MID MS VALLEY/LOWER OH VALLEY....
AN UPPER-LEVEL TROUGH WILL MOVE INTO THE GREAT PLAINS TODAY AS A 90
TO 110 KT MID-LEVEL JET TRANSLATES EWD INTO THE SRN AND CNTRL
PLAINS. THUNDERSTORMS SHOULD DEVELOP ACROSS ERN KS AND WRN MO THIS
MORNING WITH CONVECTION RAPIDLY EXPANDING NEWD ACROSS THE MID MS
VALLEY AROUND MIDDAY. AS THE EXIT REGION OF THE MID-LEVEL JET
OVERSPREADS THE REGION THIS AFTERNOON...SQUALL-LINE DEVELOPMENT
SHOULD OCCUR ACROSS CNTRL MO WITH A WELL-DEVELOPED LINE-SEGMENT
MOVING EWD ACROSS THE VICINITY OF ST LOUIS EARLY THIS EVENING.
FORECAST SOUNDINGS AT 03Z IN THE VICINITY OF ST LOUIS INCREASE
SBCAPE TO AROUND 1000 J/KG AS 0-6 KM SHEAR REACHES 60 KT. THIS ALONG
WITH VERY STRONG LOW-LEVEL FLOW EXCEEDING 70 KT SHOULD BE FAVORABLE
FOR WIND DAMAGE. A SPLIT MID-LEVEL JET STRUCTURE IMPLIES THAT LIFT
WILL BE VERY STRONG HELPING TO ORGANIZE A WELL-DEVELOP SQUALL-LINE.
THIS LINE IS FORECAST TO MOVE EWD ACROSS THE LOWER OH VALLEY TONIGHT
WHERE THERE WILL BE A POTENTIAL FOR DAMAGING WIND GUSTS AND
TORNADOES EVEN INTO THE OVERNIGHT HOURS.

..BROYLES/MOSIER.. 01/29/2013

[southmdwatcher]

Can't say that I have seen the hatched shading for possible significant tornadoes extend into the 5% area before.

[andyhb]

This loop suggests an active warm sector out ahead of the front with discrete development along confluence bands.

 

http://www.emc.ncep.noaa.gov/mmb/mmbpll/firewx/firewx_00z_refc_animate_1h.html

[Stebo]

Time sensative:

 

Still in the upper 60s in AR and low 70s in Eastern TX, with dewpoints in the low to mid 60s, temps should not drop much tonight.

[JoMo]

Storms popping in E KS and W MO, may need a watch. 60% chance.

[andyhb]

DAY 2 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   1246 AM CST TUE JAN 29 2013
  
   VALID 301200Z - 311200Z
  
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM ERN KY AND PORTIONS OF WV
   AND VA SWD TO THE CENTRAL AND ERN GULF COAST...
  
   ...SYNOPSIS...
   A LARGE/HIGH-AMPLITUDE TROUGH OVER THE CENTRAL U.S. IS FORECAST TO
   SHIFT NEWD WITH TIME...REACHING THE NERN U.S. AND MID-ATLANTIC
   REGION BY THE END OF THE PERIOD.  MEANWHILE...SHORT-WAVE TROUGHING
   DIGGING SWD OUT OF CANADA ON THE WRN SIDE OF THE INITIAL TROUGH WILL
   REINFORCE TROUGHING OVER THE CENTRAL U.S. -- SUCH THAT CYCLONIC FLOW
   SHOULD COVER MOST OF THE COUNTRY BY THE END OF THE PERIOD.
  
   AT THE SURFACE...A STRONG COLD FRONT IS PROGGED TO EXTEND FROM LOWER
   MI SSWWD TO THE MOUTH OF THE MS RIVER AT THE START OF THE PERIOD.
   THIS FRONT WILL MAKE STEADY EWD PROGRESS...CROSSING THE APPALACHIANS
   THROUGH LATE AFTERNOON/EARLY EVENING AND THEN MOVING OFF THE ERN
   SEABOARD AFTER MIDNIGHT.  UNTIL VACATING THE COAST...THIS FRONT WILL
   FOCUS BANDS OF SHOWERS AND EMBEDDED THUNDERSTORMS ACROSS THE ERN
   THIRD OF THE CONUS.
  
   ...ERN KY/WV/VA SWD TO THE CENTRAL AND ERN GULF COAST AREA...
   SHOWERS AND EMBEDDED THUNDERSTORMS WILL BE ONGOING AT THE START OF
   THE PERIOD ALONG AND AHEAD OF THE COLD FRONT FROM THE LOWER GREAT
   LAKES AREA SSWWD TO MS/SERN LA.  WHILE MEAGER INSTABILITY SUGGESTS
   LOW-TOPPED CONVECTION AND ONLY LIMITED LIGHTNING ACROSS MUCH OF THE
   AREA...VERY STRONG FLOW ALOFT AND VEERING WINDS WITH HEIGHT THROUGH
   THE LOWER TROPOSPHERE WILL RESULT IN PRONOUNCED SHEAR ACROSS THE
   WARM SECTOR.  
  
   GIVEN THE WEAK CAPE BUT VERY STRONG SHEAR...EVOLUTION AND SEVERITY
   OF THE CONVECTION REMAINS DIFFICULT TO DISCERN ATTM.  SHEAR IS
   EXPECTED TO BE MORE THAN FAVORABLE FOR TORNADOES...BUT EXPECT MOST
   CONVECTION TO BE LINEAR AND TIED TO THE FRONTAL ZONE.  GIVEN
   THIS...PRIMARY SEVERE POTENTIAL WILL LIKELY BE DAMAGING WINDS --
   EVEN WITHIN CONVECTION PRODUCING LITTLE OR NO LIGHTNING.  ISOLATED
   TORNADOES WILL ALSO BE POSSIBLE -- WITH POTENTIAL FOR A HIGHER-END
   TORNADO OR TWO EVIDENT GIVEN THE HIGHLY-SUPPORTIVE LOW-LEVEL FLOW
   FIELD.  
  
   GREATEST SEVERE THREAT SHOULD RESIDE FROM ERN KY/SRN WV/SRN VA SWD
   ACROSS THE SRN APPALACHIANS...WHERE SLIGHTLY GREATER INSTABILITY IS
   EXPECTED.  THE THREAT SHOULD PEAK DURING THE AFTERNOON...WITH SOME
   DECREASE IN INTENSITY LIKELY TO OCCUR THROUGH THE EVENING BEFORE THE
   CONVECTIVE BAND MOVES INTO THE WRN ATLANTIC.
  
   ..GOSS.. 01/29/2013

[SluggerWx]

Significant rotation north of Childress, TX about to cross into OK.

This thing needs at least a SVR at this point, and its strengthening.

[SmokeEater]

Tornado watch out for C OK until noon, here we go.

[SquatchinNY]

What time will the discrete cells be firing? After, or before 3pm?

[Indystorm]

Current RUC focusing upon ne AR and se MO for sig tor values in 4-6 range for this evening.

[SquatchinNY]

SPC is impressed.

[Ground Scouring]

STRENGTHENING DEEP LAYER WIND FIELDS WITH EFFECTIVE BULK SHEAR EXCEEDING 50 KT AS FAR N AS THE LOWER MO TO LOWER OH VALLEYS AND SHEAR VECTORS ORIENTED NEARLY PARALLEL TO THE POLAR FRONT AND DRY LINE SUGGEST PRIMARILY A LINEAR STORM MODE. HOWEVER...GIVEN THE STRENGTH OF THE BULK SHEAR AND INCREASING LOW LEVEL HODOGRAPH CURVATURE...TORNADOES WILL BE POSSIBLE IN ADDITION TO DAMAGING WINDS. MODELS CONTINUE TO INDICATE A STRONG INCREASE IN DEEP LAYER WINDS AS THE UPSTREAM PACIFIC NW/GREAT BASIN JET ADVANCES INTO THE SRN EXTENT OF THE OUTLOOK AREA INCLUDING THE MODERATE RISK. THIS WILL FURTHER INCREASE LOW LEVEL SHEAR/HODOGRAPH CURVATURE FOR AN ENHANCED THREAT FOR STRONGER TORNADOES INCLUDING THE METRO AREAS OF LITTLE ROCK AND MEMPHIS AFTER DARK THIS EVENING/TONIGHT. GIVEN THE STRENGTHENING DEEP LAYER SSWLY WINDS TONIGHT ACROSS A MODESTLY UNSTABLE WARM SECTOR...MODELS CONTINUE TO ADVERTISE THE DEVELOPMENT OF A WELL DEFINED QLCS ADVANCING E OF THE MID-LOWER MS RIVER. THIS SCENARIO IS ALSO SUPPORTED BY THE 00Z 4KM WRF-NSSL SUGGESTING THE QLCS WITH A THREAT FOR DAMAGING WINDS AND A FEW TORNADOES REACHES PARTS OF THE LOWER OH VALLEY TO CENTRAL GULF COAST STATES. THUS...THE SLIGHT RISK AND SEVERE WIND AND TORNADO PROBABILITIES HAVE BEEN EXTENDED EWD SOME WITH THIS OUTLOOK ISSUANCE.

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

5% hatched area has been greatly expanded with no other changes since SWODY1 at 06Z.

[Ground Scouring]

PROBABILITY OF WATCH ISSUANCE...95 PERCENT SUMMARY...STORMS SHOULD CONTINUE TO INCREASE IN COVERAGE ACROSS NERN TX...SERN OK...AND WRN AR...WITH A THREAT OF TORNADOES AND DAMAGING WINDS. DISCUSSION...A MOIST AIR MASS IS IN PLACE ACROSS THE REGION WITH DEWPOINTS RISING INTO THE MID 60S F. ALTHOUGH HEATING WILL REMAIN LIMITED...FORCING FOR ASCENT WILL BE ON THE INCREASE THROUGH THE DAY. ASIDE FROM THE COLD FRONT WHICH CURRENTLY EXTENDS FROM OKC TO SPS...CONFLUENCE FLOW WITHIN THE MOIST AXIS AND BENEATH A 65 KT LOW LEVEL JET SHOULD RESULT IN ADDITIONAL CONVECTION ACROSS THE WARM SECTOR. WIND PROFILES ARE VERY STRONG WITH VWP AND PROFILER DATA INDICATING 0-1 SRH IN EXCESS OF 400 M2/S2. FURTHER....THE 12Z FWD SOUNDING SHOWED STEEP MIDLEVEL LAPSE RATES IN PLACE. WHILE INITIAL ATTEMPTS AT NEW STORMS MAY BE SLOW DUE TO MARGINAL CAPPING...SUPERCELLS ARE EXPECTED TO MATERIALIZE ONCE DEEP CONVECTION IS REALIZED AND TORNADOES AS WELL AS DAMAGING WINDS WITH BOWS ARE LIKELY.

http://www.spc.noaa.gov/products/md/md0068.html

The greater-than-expected early (albeit weak) initiation in the confluence bands--see weak radar echoes--ahead of the main QLCS appears to be reducing the potential for mixing and might help to keep deeper lapse rates in place across the warm sector until bigger activity arrives in the late afternoon. This might in my view lead to a High Risk at 12Z both for tornadoes and wind.

[Ground Scouring]

By the way, latest extrapolated RAP-SPC forecasts as of 16Z give much less CINH and higher SBCAPE (over 1,000 j/kg) over NE LA /SE AR / NW MS/ SW TN by 20Z this afternoon--even more widespread SBCAPE than shown on the latest NAM and GFS. I think all these trends make a more significant tornado outbreak much more probable, especially with deeper-than-expected mid-level lapse rates to be in place over the area.

[Srain]

Storm initiation is developing W of Sonora along the dry line.

[Ground Scouring]

WIDESPREAD CONVECTION IS ONGOING ALONG AND JUST AHEAD OF THE SURFACE COLD FRONT FROM CENTRAL OK TO NRN MO. THOUGH EXTENSIVE CLOUDS ARE PRESENT THROUGH MUCH OF THE WARM SECTOR...CONTINUED MOISTURE ADVECTION FROM THE S AND MODEST SURFACE HEATING IN CLOUD BREAKS WILL BOOST MLCAPE VALUES TO THE 1000-2000 J/KG RANGE ACROSS E TX AND SE OK THIS AFTERNOON...WITH LESSER BUOYANCY FARTHER TO THE E AND NE. THERE ARE ALREADY INDICATIONS THAT ADDITIONAL PRE-FRONTAL CONVECTION WILL DEVELOP FROM NE TX INTO SE OK/WRN AR AND EVENTUALLY SRN MO THIS AFTERNOON ALONG THE MOIST AXIS. VERTICAL SHEAR PROFILES WILL BE FAVORABLE FOR SUPERCELLS WITH AN ATTENDANT RISK FOR TORNADOES AND DAMAGING WINDS ACROSS THIS CORRIDOR. FARTHER N...CONVECTION WILL GRADUALLY EVOLVE INTO A WELL-DEVELOPED QLCS WITH AN INCREASING RISK FOR DAMAGING WINDS LATER THIS AFTERNOON INTO EARLY TONIGHT...WITH A RISK OF EMBEDDED MESOVORTICES AND TORNADOES. THE GREATEST SEVERE RISK IS EXPECTED THIS EVENING THROUGH TONIGHT...BEGINNING AS THE PRE-FRONTAL CONVECTION NEAR AND NW OF THE ARKLATEX...AND CONTINUING OVERNIGHT AS ADDITIONAL PRE-FRONTAL CONVECTION FORMS WITHIN ONE OR MORE WARM SECTOR CONFLUENCE BANDS NEAR THE MS RIVER. VERTICAL SHEAR WILL BE EXTREMELY STRONG WITHIN A MOIST ENVIRONMENT WITH AT LEAST WEAK SURFACE-BASED INSTABILITY. THOUGH MLCAPE MAY ONLY REACH 500-750 J/KG...EFFECTIVE SRH OF 500-700 M2/S2 IN ASSOCIATION WITH A 70-80 KT LLJ WILL SUPPORT THE POTENTIAL FOR A FEW STRONG TORNADOES WITH FAST-MOVING PRE-FRONTAL SUPERCELLS...AS WELL AS CIRCULATIONS EMBEDDED WITHIN WHAT WILL BECOME A WELL-FORMED SQUALL LINE. WIDESPREAD AND SIGNIFICANT DAMAGING WINDS WILL ALSO BE POSSIBLE AS FAR NE AS THE LOWER OH VALLEY...WHERE 80+ KT FLOW JUST ABOVE THE SURFACE WILL COINCIDE WITH AT LEAST WEAK SURFACE-BASED BUOYANCY THROUGH MOST OF THE NIGHT.

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

SWODY1 at 12Z greatly expands the MDT Risk to include S IN, W KY, most of SE MO, SE OK, NE TX, and N LA--with a very large 15% hatched TOR covering most of this area.

I am thinking that this is a borderline-High Risk case.