Tornado and Flash Flooding in Missouri, April 27 to 30, 2012

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPRINGFIELD MO
627 AM CDT FRI APR 27 2012

...UPDATE TO AVIATION...

.DISCUSSION...

MAIN CONCERNS FOR THE FORECAST PACKAGE FOCUS ON THE POTENTIAL FOR
SEVERE THUNDERSTORMS THIS AFTERNOON INTO THIS EVENING.

EARLY MORNING CONDITIONS ACROSS THE OZARKS AND SOUTHEASTERN
KANSAS HAVE DEWPOINTS IN THE 50S WITH TEMPERATURES IN THE 60S
NORTH OF A FRONT LAID OUT ACROSS CENTRAL ARKANSAS. THIS IS THE
COLD FRONT THAT MOVED THROUGH THE OZARKS YESTERDAY MORNING AND IT
WILL BEGIN TO MOVE ITS WAY NORTH AS A WARM FRONT TODAY AND BRING A
RETURN OF SOUTHERLY WINDS AND ADDITIONAL MOISTURE TO THE REGION.
THIS WILL BRING THE POTENTIAL FOR SEVERE WEATHER TO THE REGION
THIS AFTERNOON AND EVENING.

CURRENT SHORT TERM MODELS HAVE THE WARM FRONT LIFTING THROUGH THE
OZARKS THROUGH THE DAY TODAY AS SURFACE LOW PRESSURE NOW OVER
EASTERN COLORADO AND WESTERN KANSAS TRACKS EAST ACROSS THE PLAINS.
THIS WILL OCCUR IN RESPONSE TO THE UPPER LEVEL SHORT WAVE/CLOSED
LOW MOVING EAST. THE LEFT EXIT REGION OF A 250MB/500MB JET MAX WILL
BEGIN TO ROUND THE BEND OF THE UPPER TROUGH AND PROVIDE GOOD
DIFFLUENCE ALOFT. THIS WILL BE OCCURRING OVER A REGION OF
INCREASING INSTABILITY WITH MLCAPE VALUES VIA THE NAM UP TO AROUND
2000 J/KG...WITH 150 J/KG IN THE 0-3 KM LAYER. WHILE THE MODELS DO
TEND TO OVER DO THE LOW LEVEL CAPE...EVEN TAKING HALF OF THE
MODEL OUTPUT WOULD BE ENOUGH FOR SEVERE STORMS TO DEVELOP. THIS
WILL OCCUR IN CONJUNCTION WITH 0-3 KM BULK SHEAR AROUND 50-60
KTS AND 0-1 KM STORM RELATIVE HELICITY VALUES OVER 400M2/S2.
WOULD EXPECT THAT AREAS WEST OF HIGHWAY 65 IN GENERAL WILL HAVE
THE BEST CHANCES FOR SEVERE STORMS...WITH LARGE HAIL...DAMAGING
WINDS AND TORNADOES ALL POSSIBLE. WILL NEED TO MONITOR THE
PROGRESS OF THE WARM FRONT AND HOW CLOSE TO THE REGION THE DRY
LINE GETS TODAY.

AS THE UPPER LEVEL TROUGH LIFTS OUT OF THE REGION FRIDAY NIGHT A
SECONDARY SLOW MOVING CUTOFF LOW OVER THE NORTHERN PLAINS WILL AID
IN DEVELOPING A SLIGHTLY SOUTHWESTERLY UPPER LEVEL FLOW OVER THE
WESTERN CONUS THROUGH THE WEEKEND. THIS WILL NOT ONLY HELP TO KEEP
THE FRONT WANDERING ACROSS MISSOURI BEFORE THE UPPER LOW LIFTS
NORTH SUNDAY NIGHT...IT WILL CONTINUE TO BRING UPPER LEVEL
MOISTURE INTO THE REGION THROUGH EARLY NEXT WEEK. THIS WILL KEEP
CHANCES FOR SHOWERS AND THUNDERSTORMS IN THE FORECAST FOR THE
WEEKEND AND INTO TUESDAY OF NEXT WEEK.

THE REGION MAY SEE A BRIEF RESPITE FOR THE MIDDLE OF NEXT WEEK
BEFORE ANOTHER FRONT ATTEMPTS TO PUSH THROUGH THE OZARKS. THE
FRONT THEN LOOKS TO GET HUNG UP ACROSS MISSOURI AS UPPER LEVEL
RIDGING ATTEMPTS TO BUILD ACROSS THE SOUTHWESTERN CONUS FOR LATE
NEXT WEEK...RETURNING NORTHWEST UPPER FLOW OVER THE OZARKS.

HATCH

&&

.AVIATION...

LOW LEVEL WIND SHEAR WILL PERSIST THIS MORNING AS A STRONG LOW
LEVEL JET STREAM SHIFTS OVER THE REGION. MEANWHILE...A WARM FRONT
WILL SHIFT NORTH TOWARDS THE AREA STARTING THIS MORNING. MVFR
CEILINGS ARE EXPECTED TO DEVELOP AHEAD OF THE FRONT...AS WELL AS
SCATTERED SHOWERS AND THUNDERSTORMS. STRONG AND GUSTY SOUTHEAST
WINDS WILL ALSO DEVELOP...WITH GUSTS OVER 30 KNOTS LIKELY INTO
THIS AFTERNOON. WE WILL THEN GET A BREAK IN THE PRECIPITATION AND
MVFR CEILINGS LATER THIS AFTERNOON. SCATTERED STRONG TO SEVERE
THUNDERSTORMS ARE THEN EXPECTED TO DEVELOP ACROSS SOUTHEASTERN
KANSAS AND WESTERN MISSOURI FROM LATE THIS AFTERNOON INTO THIS
EVENING. WITH TIMING SOMEWHAT IN QUESTION...WENT WITH A PREVAILING
VCTS GROUP FOR NOW AT KJLN AND KSGF. MOST IF NOT ALL ACTIVITY IS
EXPECTED TO REMAIN NORTH OF KBBG.

SCHAUMANN

&&

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

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE SPRINGFIELD MO
1006 AM CDT FRI APR 27 2012

KSZ073-097-101-MOZ055>058-066>071-077>083-088>098-101>106-281515-
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-
1006 AM CDT FRI APR 27 2012

...SEVERE THUNDERSTORMS EXPECTED LATE THIS AFTERNOON AND
EVENING...

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

.DAY ONE...TODAY AND TONIGHT.

WEATHER HAZARDS EXPECTED...

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

DISCUSSION...

A FEW THUNDERSTORMS ARE EXPECTED FROM THIS MORNING INTO EARLY
THIS AFTERNOON AS A WARM FRONT BEGINS TO MOVE NORTHEAST INTO THE
OUTLOOK AREA. THE MAIN RISKS WITH THESE STORMS WILL BE OCCASIONAL
CLOUD TO GROUND LIGHTNING AND HAIL TO THE SIZE OF PENNIES.

STRONG TO SEVERE THUNDERSTORMS ARE THEN EXPECTED TO FORM DURING
THE MID AND LATE AFTERNOON HOURS OVER EASTERN KANSAS...WITH STORMS
THEN MOVING INTO FAR SOUTHEASTERN KANSAS AND WESTERN MISSOURI
BETWEEN 4 AND 6 PM. STORMS WILL THEN CONTINUE TO DEVELOP AND PUSH
EAST INTO MISSOURI THIS EVENING.

VERY LARGE HAIL TO THE SIZE OF BASEBALLS...DAMAGING WIND GUSTS
OVER 60 MPH...AND A FEW TORNADOES WILL ALL BE POSSIBLE. THE
GREATEST RISK FOR SEVERE STORMS WILL BE ALONG AND NORTHWEST OF A
LINE FROM ANDERSON...TO SPRINGFIELD...TO LAKE OF THE OZARKS.

EAST TO SOUTHEAST WINDS GUSTING TO 40 MPH WILL ALSO OCCUR IN SOME
AREAS TODAY. BOATERS ON AREA LAKES ARE URGED TO USE EXTRA
CAUTION.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY.

UNSETTLED WEATHER WILL CONTINUE AT TIMES IN THE FORM OF ISOLATED
TO SCATTERED THUNDERSTORMS OVER THE WEEKEND AND EARLY NEXT WEEK.

A FEW STRONG TO MARGINALLY SEVERE STORMS WILL BE POSSIBLE ON
SATURDAY ACROSS MAINLY SOUTHERN MISSOURI.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED LATER TODAY OR TONIGHT FOR AREAS
ALONG AND NORTHWEST OF A LINE FROM ANDERSON...TO SPRINGFIELD...TO
LAKE OF THE OZARKS.

&&

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)

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