Tornadoes and Flash Flood in Missouri, May 19 to 20, 2013

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPRINGFIELD MO
659 PM CDT SUN MAY 19 2013

...UPDATED MESOSCALE AND AVIATION DISCUSSIONS...

.MESOSCALE DISCUSSION...
ISSUED AT 639 PM CDT SUN MAY 19 2013

THE SOUTHEAST KANSAS AND WESTERN MISSOURI AIRMASS CONTINUES TO
BECOME MORE CONDUCIVE FOR SEVERE THUNDERSTORMS OVER THE NEXT
SEVERAL HOURS.

WARM SECTOR CONVECTION NEAR THE KANSAS AND MISSOURI STATE LINE IS
SHOWING SIGNS OF BECOMING MORE ROOTED WITHIN THE BOUNDARY LAYER.

THIS WILL CAUSE UPDRAFTS TO STRENGTHEN WITH TIME...FACILITATING
THE RISK FOR LARGE HAIL AND DAMAGING WIND GUSTS.

18Z NAM ANALYSIS SUGGESTS AN UPTICK IN LOW LEVEL CAPE OVER THIS
REGION. THIS IN CONJUNCTION WITH AN UPTICK IN LOW LEVEL SHEAR IN
RESPONSE TO A DEVELOPING LOW LEVEL JET...A TORNADO RISK WILL
INCREASE FROM NOW THROUGH ABOUT MIDNIGHT.

THE 00Z RAOB IS JUST IN THROUGH 400MB...AND IT MEASURED IMPRESSIVE
LAPSE RATES ABOVE 800...GIVING THE OVERALL AIRMASS A DECENT
NORMALIZED (FAT) CAPE WITHIN THE HAIL GROWTH ZONE. HAIL LARGER
THAN GOLF BALLS ARE A GOOD BET WITH ANY ORGANIZED UPDRAFTS. ONE
NEGATIVE WITH THE SOUNDING...WAS THE AMOUNT OF MIXED LAYER
INHIBITION MEASURED...WHICH WAS 229 J/KG. THESE VALUES ARE LESS
OUT WEST TOWARD THE KANSAS BORDER...ACCORDING TO SHORT TERM MODEL
GUIDANCE...AND AS SUGGESTED BY DEEPENING CONVECTION.

AND FINALLY...THE 00Z HODOGRAPH IS QUITE CURVED...WITH ESTIMATED
CRITICAL ANGLES OF AROUND 80 TO 90 DEGREES...WHICH IS FAVORABLE FOR
STREAMWISE VORTICITY INGESTION NEEDED FOR TORNADOES.

&&

.SHORT TERM...(TONIGHT THROUGH TUESDAY)
ISSUED AT 345 PM CDT SUN MAY 19 2013

THE POTENTIAL FOR MULTIPLE SEVERE WEATHER EVENTS CONTINUE TO TAKE
SHAPE FOR LATE THIS AFTERNOON THROUGH TUESDAY WITH THE POTENTIAL FOR
SEVERE THUNDERSTORMS PRODUCING LARGE HAIL...DAMAGING
WINDS...ISOLATED TORNADOES...AND FLOODING.

ON MONDAY...THE UPPER TROUGH WILL SHIFT INTO THE NORTHERN PLAINS
WHICH WILL MAINTAIN A BELT OF WESTERLIES ACROSS THE REGION. THE
ASSOCIATED COLD FRONT WILL SAG SOUTHWARD INTO THE REGION AND
BECOME ORIENTED PARALLEL WITH THE FLOW ALOFT. IT APPEARS THAT MORE
THAN AMPLE INSTABILITY AND DEEP LAYER SHEER WILL BE IN PLACE TO
SUPPORT STRONG TO SEVERE STORMS ESPECIALLY MONDAY EVENING AS A JET
STREAK COMES ACROSS EASTERN KANSAS AND WESTERN MISSOURI. THE RISK
FOR SEVERE WILL INCREASE IF SUBSTANTIAL CLEARING AND SUBSEQUENT
DESTABILIZATION OCCURS.

PROGGED SHEAR PROFILES SUGGEST THE POTENTIAL FOR SUPERCELLS AS WELL
AS TRAINING CELLS. THIS COULD LEAD TO A PROLONGED SEVERE WEATHER
EVENT FROM MONDAY AFTERNOON THROUGH MONDAY NIGHT.

ALL MODES OF SEVERE WEATHER WILL BE POSSIBLE MONDAY AFTERNOON INTO
MONDAY NIGHT INCLUDING TORNADOES. THE RISK FOR SEVERE STORMS WILL
BE ENHANCED ALONG AND JUST OF THE SAGGING FRONT FROM SOUTHEASTERN
KANSAS INTO SOUTHWESTERN MISSOURI.

IN ADDITION A RICH SUPPLY OF MOISTURE WILL INTERACT  WITH THE FRONT
TO SUPPORT TORRENTIAL RATES. GIVEN THE ORIENTATION OF THE FRONT
INTERACTING WITH A LOW LEVEL JET...AND THE POTENTIAL FOR TRAINING
STORMS THE RISK FOR FLOODING WILL INCREASE MONDAY AFTERNOON INTO
MONDAY NIGHT. THE NEED FOR A FLASH FLOOD WATCH WILL BE CLOSELY
MONITORED TONIGHT THROUGH MONDAY.

ON TUESDAY...MODELS DIFFER ON THE TIMING OF THE FRONTAL PASSAGE AS
THE PRIMARY TROUGH AXIS SWINGS EAST BUT IT APPEARS THAT CONVECTION
WILL REDEVELOP ACROSS MUCH OF THE AREA. THE RISK FOR SEVERE STORMS
WILL CONTINUE ESPECIALLY IF ANY CLEARING CAN TAKE PLACE.

.LONG TERM...(WEDNESDAY THROUGH SUNDAY)
ISSUED AT 345 PM CDT SUN MAY 19 2013

FOR THE REMAINDER OF NEXT WEEK...UPPER LEVEL RIDGING WILL
GRADUALLY BUILD INTO THE REGION AS THE TROUGH SHIFTS TO THE EAST.
MODELS CONTINUE SUGGEST PERIODIC CHANCES OF CONVECTION AS MINOR
DISTURBANCES COME OVER THE RIDGE BUT DETAILS ON TIMING AND
COVERAGE ARE UNCERTAIN. OTHERWISE SEASONABLY WARM WEATHER IS
EXPECTED.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING)
ISSUED AT 659 PM CDT SUN MAY 19 2013

PRIMARY FORECAST CHALLENGE WILL CONTINUE TO BE THE POTENTIAL FOR
SEVERE THUNDERSTORMS. SHOWERS AND STORMS CONTINUE TO BLOSSOM
ACROSS WESTERN MISSOURI AND THIS ACTIVITY WILL POSE A RISK OF
LIGHTNING AND A ISOLATED RISK FOR WIND/HAIL. MORE SUBSTANTIAL
THUNDERSTORMS (BOTH LINEAR AND CELLULAR) ARE DEVELOPING ACROSS
KANSAS AND OKLAHOMA RESPECTIVELY. THIS ACTIVITY WILL MOVE INTO
THE REGION BETWEEN 02Z-06Z. THIS WILL POSE A RISK OF LARGE HAIL
AND STRONG WINDS. THE EVOLUTION OF SHOWERS AND STORMS HEADING INTO
THE OVERNIGHT REMAINS IN QUESTION. AT THIS POINT IT APPEARS THAT
SHOWERS AND STORMS MAY LINGER AND PERSIST ACROSS CENTRAL MISSOURI
MUCH OF THE NIGHT...JUST NORTH OF THE AERODROMES. WILL NEED TO
CLOSELY MONITOR JUST EXACTLY WHERE THIS AXIS OF SHOWERS AND STORMS
WILL SET UP AND FURTHER FORECAST REFINEMENTS ARE EXPECTED. IN
ADDITION TO THE RISKS ASSOCIATED WITH THE STORMS...ENVIRONMENTAL
WINDS WILL REMAIN GUSTY AT ALL SITES WITH INCREASING LOW LEVEL
WIND SHEAR THIS EVENING INTO THE OVERNIGHT HOURS.

&&

.SGF WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&

MESOSCALE...CRAMER
SHORT TERM...FOSTER
LONG TERM...FOSTER
AVIATION...GAGAN

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE SPRINGFIELD MO
352 PM CDT SUN MAY 19 2013

KSZ073-097-101-MOZ055>058-066>071-077>083-088>098-101>106-202100-
BOURBON-CRAWFORD-CHEROKEE-BENTON-MORGAN-MILLER-MARIES-VERNON-
ST. CLAIR-HICKORY-CAMDEN-PULASKI-PHELPS-BARTON-CEDAR-POLK-DALLAS-
LACLEDE-TEXAS-DENT-JASPER-DADE-GREENE-WEBSTER-WRIGHT-NEWTON-
LAWRENCE-CHRISTIAN-DOUGLAS-HOWELL-SHANNON-MCDONALD-BARRY-STONE-
TANEY-OZARK-OREGON-
352 PM CDT SUN MAY 19 2013

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF THE MISSOURI
OZARKS AND EXTREME SOUTHEAST KANSAS.

.DAY ONE...THIS AFTERNOON AND TONIGHT.

WEATHER HAZARDS EXPECTED...

  ELEVATED TORNADO RISK.
  SIGNIFICANT HAIL RISK.
  SIGNIFICANT THUNDERSTORM WIND DAMAGE RISK.
  LIMITED FLOODING RISK.
  SIGNIFICANT LIGHTNING RISK.
  LIMITED NON THUNDERSTORM WIND RISK.

DISCUSSION...

  SOUTHERLY WINDS OF 20 TO 25 MPH WITH GUSTS OVER 30 MPH CAN BE
  EXPECTED THROUGH LATE THIS AFTERNOON ACROSS WESTERN MISSOURI AND
  SOUTHEASTERN KANSAS.

  THE RISK OF STRONG TO SEVERE THUNDERSTORMS WILL OCCUR ACROSS THE
  OUTLOOK AREA THIS EVENING THEN EXTEND INTO THE OVERNIGHT HOURS
  AS A STRONG STORM SYSTEM TRACKS INTO THE CENTRAL U.S.

  STORMS HAVE DEVELOPED AS SUPERCELLS ACROSS CENTRAL KANSAS INTO
  CENTRAL OKLAHOMA THIS AFTERNOON ALONG AND AHEAD OF A DRY LINE.
  THESE STORMS WILL MOVE TO THE  NORTHEAST. THESE SUPERCELLS WILL
  DEVELOP INTO A LINE NEAR OR ACROSS PORTIONS OF THE OUTLOOK AREA.

  STORMS ARE EXPECTED TO MOVE INTO EXTREME SOUTHEASTERN KANSAS
  AND FAR SOUTHWESTERN MISSOURI TO THE INTERSTATE 49 CORRIDOR
  BETWEEN 6 AND 9 PM...AND INTO THE MISSOURI OZARKS TO THE HIGHWAY
  65 CORRIDOR BETWEEN 9 PM AND MIDNIGHT AS A SQUALL LINE. THE
  STORMS WILL SPREAD EAST INTO THE REMAINDER OF THE MISSOURI
  OZARKS OVERNIGHT AND GRADUALLY WEAKEN.

  ANY SUPERCELLS WILL HAVE THE POTENTIAL TO PRODUCE HAIL TO THE
  SIZE OF TENNIS BALLS...TORNADOES...AND DAMAGING STRAIGHT LINE
  WINDS. AS THE STORMS CONGEAL INTO A LINE...DAMAGING STRAIGHT
  LINE WIND GUSTS UP TO 70 MPH WILL BECOME INCREASINGLY LIKELY.
  ISOLATED TORNADOES WOULD ALSO REMAIN POSSIBLE EMBEDDED WITHIN
  THE LINE OF STORMS.

  ADDITIONALLY...A VERY MOIST AIRMASS OVER THE REGION MAY LEAD TO
  HEAVY RAINFALL AND FLOODING.

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY.

  THE RISK OF SEVERE WEATHER AND FLOODING WILL AGAIN OCCUR FROM
  MONDAY AFTERNOON INTO EARLY TUESDAY MORNING...AND IMPACT THE
  ENTIRE OUTLOOK AREA. THUNDERSTORMS AND THE POTENTIAL FOR SEVERE
  WEATHER MAY PERSIST THROUGH THE DAY TUESDAY AS WELL.

  ALL MODES OF SEVERE WEATHER WILL BE POSSIBLE LATER MONDAY INTO
  EARLY TUESDAY INCLUDING LARGE HAIL TO THE SIZE OF GOLF
  BALLS...DAMAGING WINDS IN EXCESS OF 60 MPH...AND TORNADOES.

  IN ADDITION...MULTIPLE ROUNDS OF THUNDERSTORMS MAY RESULT IN
  HEAVY RAINFALL AND FLOODING.

  A FEW THUNDERSTORMS WILL BE POSSIBLE THURSDAY AND FRIDAY BUT
  SEVERE WEATHER IS NOT EXPECTED.

.SPOTTER INFORMATION STATEMENT...

  SPOTTER ACTIVATION WILL LIKELY BE NEEDED ACROSS EXTREME
  SOUTHEASTERN KANSAS AND FAR SOUTHWESTERN MISSOURI EARLY THIS
  EVENING...THEN MAY BE NEEDED ACROSS THE REST OF THE MISSOURI
  OZARKS LATE THIS EVENING INTO THE OVERNIGHT HOURS.

&&

THIS PRODUCT IS NOW AVAILABLE IN GRAPHICAL FORMAT...ALONG WITH
OTHER WEATHER...HYDROLOGICAL AND CLIMATE INFORMATION...AT
HTTP://WWW.CRH.NOAA.GOV/SGF(ALL LOWERCASE)

FOSTER