April 26th-30th, 2014 Major Tornado Outbreak

[SluggerWx]

Gravity waves in the Gulf on visible this AM? That sounds familiar.

[JoMo]

Baxter Springs, KS tornado

This post has been promoted to an article

 

That's an impressive picture. 100 homes and 12 businesses were damaged. The death in nearby Quapaw, OK was actually a man traveling through town with his wife, the man was from Baxter Springs. They parked in a parking lot and a concrete wall fell on his car, killing him, the wife was taken to a hospital and released.

[Disc]

SluggerWx, on 28 Apr 2014 - 11:36 AM, said:

Gravity waves in the Gulf on visible this AM? That sounds familiar.

 

Looks very familiar.

 

[Disc]

[Chicago Storm]

Gravity waves showing up in W. Illinois.

[UKStormFan]

Forgive my ignorance and lack of knowledge, but what exactly are gravity waves? What do they affect? What do they pre-cursor? 

 

Thanks. 

 

Big learning curve on this thread for me.

[JoMo]

Forgive my ignorance and lack of knowledge, but what exactly are gravity waves? What do they affect? What do they pre-cursor? 

 

Thanks. 

 

Big learning curve on this thread for me.

 

A quick search yielded this result:

http://science1.nasa.gov/science-news/science-at-nasa/2008/19mar_grits/

[Superstorm93]

The fact that we have the gravity wave extending into LA where cells are supposed to initiate is somewhat concerning. 

 

Mentioned the possibility of this occurring last night. 

 

[nrgjeff]

Northern Mississippi will see tornadoes this afternoon. OFB has set up from morning convection. OFB arcs from North Alabama, back through Mississippi, curling up through Memphis into eastern Arkansas. Pac CF / quasi-DL is moving into eastern Arkansas. Upstairs a jet max is departing the Delta region. New jet max is coming in from the OK/TX Red River Valley. LLJ is currently disrupted by central Mississippi rain, but it will push through with authority later this afternoon.

 

Thunderstorms in northeast Arkansas are weakening as morning jet max lift departs. Despite broken clouds Delta region atmosphere will recharge with ample heating. The OK/TX jet max will start to come in by mid-afternoon. It will be somewhat more perpendicular to the Pac CF / quasi-DL but thankfully (for public) still about 45 deg not 90 deg. The said second jet max will enhance the LLJ as well by late afternoon. Expect new thunderstorms to develop close to the Mississippi River. Interaction of the CF/quasi-DL with the OFB will be a focal point for strong/long-track supercells. Except for terrain, this is a chasable day with a somewhat defined target (for the South). Nowcasting the boundary intersection will be vital. Safety is always first in the hazy Southern environment.

[Superstorm93]

[geddyweather]

Might just be me, but is anyone else seeing parallels to what happened yesterday? Lots of crapvection that was out earlier now starting to break up. 1630z SPC outlook should be out shortly....thoughts?

[TheWeatherPimp]

SPC outlook is running way late. Normally there is a good reason for that. 

[Superstorm93]

SPC outlook is pretty late...interested to see whats going on. 

[1900hurricane]

Yep, been a while since they've made us wait 15 or more minutes past the expected outlook release time. Makes me think there might be some changes upcoming.

[geddyweather]

SPC outlook is running way late. Normally there is a good reason for that. 

 

Noticed that, hmmmm....

 

Starting to see some nicer cells pop up on the AR/LA/MS line too.

[tornadoguy11]

I think a high risk is coming

[Superstorm93]

SPC outlook is pretty late...interested to see whats going on. 

 

Virtually no change. 

 

 

 

 

..MS/AL/TN THIS AFTERNOON THROUGH TONIGHT  

 

MORNING STORMS HAVE BEEN WEAKENING...LEAVING AN OUTFLOW BOUNDARY  

THAT IS BETTER-DEFINED ACROSS SRN MIDDLE TN...AND MORE DIFFUSE WITH  

SWWD EXTENT ACROSS NW MS TO NE LA. CLEARING OF THE MORNING CLOUD  

DEBRIS IS ALSO ALLOWING STRONGER SURFACE HEATING TO COMMENCE FROM LA  

INTO SW MS...WITH ADDITIONAL CLEARING EXPECTED BY EARLY AFTERNOON  

ACROSS NE MS AND NW AL. BY EARLY AFTERNOON...WEAKENING OF  

CONVECTIVE INHIBITION SHOULD ALLOW RENEWED STORM DEVELOPMENT ALONG  

OR JUST E OF THE RESIDUAL OUTFLOW BOUNDARY FROM NE LA NEWD ACROSS MS  

AND NW AL TO SRN MIDDLE TN BY EARLY-MID AFTERNOON. THE STORM  

ENVIRONMENT WILL BE CHARACTERIZED BY MLCAPE NEAR 2000  

J/KG...EFFECTIVE BULK SHEAR OF 50-60 KT...EFFECTIVE SRH OF 200-300  

MS2/S2...AND A MOIST BOUNDARY LAYER. GIVEN THE SUBTLE FORCING FOR  

ASCENT...A DISCRETE OR CLUSTER SUPERCELL MODE APPEARS LIKELY...WITH  

THE POTENTIAL FOR SEVERAL STRONG AND LONG-TRACK TORNADOES THIS  

AFTERNOON/EVENING FROM CENTRAL MS NEWD TO NW AL. THIS AREA WILL BE  

MONITORED CAREFULLY FOR A HIGH RISK UPGRADE IN A NARROW CORRIDOR BY  

20Z.  

 

BY LATE EVENING AND OVERNIGHT...CONVECTION SHOULD EVOLVE INTO A BAND  

OF STORMS WITH EMBEDDED SUPERCELLS AND BOWING SEGMENTS...WITH A  

CONTINUED RISK FOR A FEW TORNADOES...DAMAGING WINDS...AND LARGE HAIL  

WELL INTO THE OVERNIGHT HOURS ACROSS ERN TN...NW GA...AL AND  

CENTRAL/SRN MS.  

[Thrasher Fan]

SPC AC 281646

DAY 1 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

1146 AM CDT MON APR 28 2014

VALID 281630Z - 291200Z

...THERE IS A MDT RISK OF SVR TSTMS THIS AFTERNOON INTO EARLY

TONIGHT ACROSS PARTS OF MS...AL..TN...

...THERE IS A SLGT RISK OF SVR TSTMS AROSS A LARGE AREA FROM THE

LOWER/MID MS VALLEY EWD TO THE SRN APPALACHIANS AND CAROLINAS...

...SUMMARY...

A SEVERE WEATHER OUTBREAK IS FORECAST TODAY INTO TONIGHT FROM PARTS

OF THE LOWER MISSISSIPPI VALLEY INTO THE TENNESSEE VALLEY AND

CENTRAL GULF COAST STATES. NUMEROUS TORNADOES ARE EXPECTED...SOME OF

WHICH COULD BE INTENSE. VERY LARGE HAIL AND DAMAGING STRAIGHT LINE

WINDS ARE ALSO LIKELY.

...SYNOPSIS...

A CLOSED/OCCLUDED LOW OVER ERN NEB WILL WOBBLE EWD ACROSS IA/NRN MO

AS SERIES OF EMBEDDED SPEED MAXIMA ROTATE AROUND THE SRN AND ERN

PERIPHERY OF THE LOW. AT THE SURFACE...THE WARM SECTOR EXTENDS AS

FAR N/NW AS CENTRAL IL AND SRN IA...THOUGH THE RICHER MOISTURE AND

GREATER BUOYANCY WILL BE CONFINED TO THE LA/MS/AL AREA TODAY. THE

MAIN SEVERE THREATS THIS AFTERNOON WILL BE CONFINED TO TWO CORRIDORS

- A SUPERCELL/TORNADO RISK FROM MS ACROSS NW AL/SRN MIDDLE TN...AND

AN ARC OF STORMS WITHIN THE DRY SLOT FROM SRN IA TO CENTRAL IL.

...MS/AL/TN THIS AFTERNOON THROUGH TONIGHT...

MORNING STORMS HAVE BEEN WEAKENING...LEAVING AN OUTFLOW BOUNDARY

THAT IS BETTER-DEFINED ACROSS SRN MIDDLE TN...AND MORE DIFFUSE WITH

SWWD EXTENT ACROSS NW MS TO NE LA. CLEARING OF THE MORNING CLOUD

DEBRIS IS ALSO ALLOWING STRONGER SURFACE HEATING TO COMMENCE FROM LA

INTO SW MS...WITH ADDITIONAL CLEARING EXPECTED BY EARLY AFTERNOON

ACROSS NE MS AND NW AL. BY EARLY AFTERNOON...WEAKENING OF

CONVECTIVE INHIBITION SHOULD ALLOW RENEWED STORM DEVELOPMENT ALONG

OR JUST E OF THE RESIDUAL OUTFLOW BOUNDARY FROM NE LA NEWD ACROSS MS

AND NW AL TO SRN MIDDLE TN BY EARLY-MID AFTERNOON. THE STORM

ENVIRONMENT WILL BE CHARACTERIZED BY MLCAPE NEAR 2000

J/KG...EFFECTIVE BULK SHEAR OF 50-60 KT...EFFECTIVE SRH OF 200-300

MS2/S2...AND A MOIST BOUNDARY LAYER. GIVEN THE SUBTLE FORCING FOR

ASCENT...A DISCRETE OR CLUSTER SUPERCELL MODE APPEARS LIKELY...WITH

THE POTENTIAL FOR SEVERAL STRONG AND LONG-TRACK TORNADOES THIS

AFTERNOON/EVENING FROM CENTRAL MS NEWD TO NW AL. THIS AREA WILL BE

MONITORED CAREFULLY FOR A HIGH RISK UPGRADE IN A NARROW CORRIDOR BY

20Z.

BY LATE EVENING AND OVERNIGHT...CONVECTION SHOULD EVOLVE INTO A BAND

OF STORMS WITH EMBEDDED SUPERCELLS AND BOWING SEGMENTS...WITH A

CONTINUED RISK FOR A FEW TORNADOES...DAMAGING WINDS...AND LARGE HAIL

WELL INTO THE OVERNIGHT HOURS ACROSS ERN TN...NW GA...AL AND

CENTRAL/SRN MS.

...ERN MO/WRN IL INTO SRN IA THIS AFTERNOON...

A BROKEN ARC OF THUNDERSTORMS WILL FORM THIS AFTERNOON ALONG THE

SURFACE FRONT FROM ERN MO NWD AND NWWD INTO SRN IA...WITH STORMS

EXPECTED TO SPREAD INTO W CENTRAL IL DURING THE LATE

AFTERNOON/EVENING. SOME LOW-TOPPED SUPERCELLS WILL BE POSSIBLE IN

AN ENVIRONMENT WITH VERY STEEP LAPSE RATES AND MARGINALLY FAVORABLE

SHEAR...WHICH WILL SUPPORT A RISK FOR LARGE HAIL/DAMAGING WINDS AND

A COUPLE TORNADOES.

...SRN NC/NRN SC THIS AFTERNOON...

ISOLATED STRONG/SEVERE STORM DEVELOPMENT WILL BE POSSIBLE ALONG THE

STALLED FRONT THIS AFTERNOON...WHERE LOW-MIDLEVEL VERTICAL SHEAR

WILL BE SUFFICIENT FOR ORGANIZED CLUSTERS. MODERATE INSTABILITY

ALONG THE FRONT AND SEA BREEZE WILL SUPPORT A RISK FOR LARGE

HAIL/DAMAGING WINDS.

..THOMPSON/EDWARDS.. 04/28/2014

[Hoosier]

Gravity waves showing up in W. Illinois.

 

 

ILX is going to be doing an 18z sounding.

[Stebo]

Judging by the mention of a potential high later in the day and the fact that it took 15 extra mins, I am thinking they almost pulled the trigger with this outlook.

[natecast]

No change from moderate, but very strong wording tells me an upgrade to high this afternoon is very possible.

 

"A DISCRETE OR CLUSTER SUPERCELL MODE APPEARS LIKELY...WITH THE POTENTIAL FOR SEVERAL STRONG AND LONG-TRACK TORNADOES THIS AFTERNOON/EVENING FROM CENTRAL MS NEWD TO NW AL."

[Chinook]

i saw this on TWCBreaking twitter feed

 

Malden, Missouri had 8.5" of rain recently

 

Water rescue in Hohenwald, Tennessee

 

 

PAH radar estimates 13.0" of rain next to Malden.

[Superstorm93]

[Quincy]

Once they can pin down exactly where a line of tornadic supercells/possibly long-lived tornadoes will be, then we could see the high risk upgrade.

Heading to central MS to get into place now.

[Chicago Storm]

ILX is going to be doing an 18z sounding.

Good, good.

[1900hurricane]

Getting cloud cover breaks across Mississippi now. With dewpoints into the 70s, that'll help things quickly destabilize.

 

 

[yoda]

PDS watch or regular tor watch?

MESOSCALE DISCUSSION 0451   NWS STORM PREDICTION CENTER NORMAN OK   1205 PM CDT MON APR 28 2014   AREAS AFFECTED...PORTIONS NERN LA...WRN/NRN MS...NWRN AL...SRN   MIDDLE TN.   CONCERNING...SEVERE POTENTIAL...TORNADO WATCH LIKELY    VALID 281705Z - 281900Z   PROBABILITY OF WATCH ISSUANCE...95 PERCENT   SUMMARY...TORNADO WATCH IS HIGHLY PROBABLE WITHIN NEXT HOUR ACROSS   DISCUSSION AREA.  SUPERCELLS ARE EXPECTED TO DEVELOP IN BKN/SW-NE   BAND AND INTENSIFY THROUGH AFTN WITH A FEW SIGNIFICANT/LONG-TRACK   TORNADOES POSSIBLE.   DISCUSSION...EARLIER CONVECTION HAS LEFT   OUTFLOW/DIFFERENTIAL-HEATING BOUNDARY ALIGNED SW-NE ACROSS   DISCUSSION AREA...BECOMING MORE DIFFUSE WITH SWWD EXTENT AT SFC.    MEANWHILE VIS IMAGERY SHOWS EXPANDING POCKETS OF RELATIVELY   CLOUD-FREE AREAS THAT WILL FOSTER SUSTAINED PERIOD OF INSOLATION AND   QUICK SBCINH REMOVAL.  MODIFIED RAOBS AND FCST SOUNDINGS OVER THIS   CORRIDOR SUGGEST 1500-2500 J/KG MLCAPE WILL BUILD NEWD.  IN THIS   ENVIRONMENT...TSTMS ALREADY ARE DEVELOPING OVER NERN LA INVOF   MLU...AND IF NOT ALREADY SFC-BASED...MAY BECOME SO SHORTLY.    ADDITIONAL CONVECTION IS LIKELY TO FORM NEWD ACROSS MS INTO SRN MID   TN AND NWRN AL AS AIR MASS THERE DESTABILIZES IN NEXT 2-3 HOURS.    DEEP-LAYER AND LOW-LEVEL SHEAR EACH ARE FAVORABLE AND WILL REMAIN   SO...WITH 50-70 KT EFFECTIVE SHEAR MAGNITUDES.  EFFECTIVE SRH SHOULD   INCREASE THROUGH AFTN TO AROUND 300 J/KG...AND VWP ALREADY SHOW   300-500 J/KG OF 0-3 KM SRH OVER NERN MS.   ..EDWARDS/THOMPSON.. 04/28/2014   ATTN...WFO...OHX...BMX...HUN...MEG...JAN...SHV...

http://www.spc.noaa.gov/products/md/md0451.html

[OceanStWx]

Judging by the mention of a potential high later in the day and the fact that it took 15 extra mins, I am thinking they almost pulled the trigger with this outlook.

 

There was some internal discussion (I can only see SPC's chats not the local WFOs responses), but I think the focus was mostly on getting the probabilities right and how to handle the current developing convection over LA. Close, but honestly public awareness should be pretty high given the events of yesterday. They don't necessarily need to go high risk to highlight the threat unless the probabilities are there.

 

[geddyweather]

Here we go...

[OceanStWx]

PDS watch or regular tor watch?

MESOSCALE DISCUSSION 0451   NWS STORM PREDICTION CENTER NORMAN OK   1205 PM CDT MON APR 28 2014   1500-2500 J/KG MLCAPE   50-70 KT EFFECTIVE SHEAR MAGNITUDES.    VWP ALREADY SHOW 300-500 J/KG OF 0-3 KM SRH OVER NERN MS.   ..EDWARDS/THOMPSON.. 04/28/2014   ATTN...WFO...OHX...BMX...HUN...MEG...JAN...SHV...

http://www.spc.noaa.gov/products/md/md0451.html

 

I think it's looking that way.