Severe Thunderstorm Warning 227, NWS Springfield, MO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPRINGFIELD MO
619 PM CDT TUE MAY 13 2008

...UPDATE TO AVIATION...

.DISCUSSION...

SHORT TERM (LATE THIS AFTERNOON THROUGH THURSDAY NIGHT)...

MAIN FOCUS FOR THE NEXT 15 HOURS OR SO WILL BE ON SEVERE
THUNDERSTORM POTENTIAL. MOISTURE CONTINUES TO INCREASE THIS
AFTERNOON AHEAD OF A SLOWLY ADVANCING COLD FRONT. AT 2PM...THE
COLD FRONT EXTENDED FROM NEAR TOPEKA TO WICHITA TO OKLAHOMA CITY.
MID TO UPPER 60 DEW POINTS HAD MADE IT INTO NORTHEAST OKLAHOMA
AHEAD OF THIS FRONT.

THE 18Z RAOB FROM KSGF CONTINUED TO REVEAL QUITE THE CAP. THE 19Z
KOUN SOUNDING STILL INDICATED A CAP...BUT IT HAD SIGNIFICANTLY
ERODED SINCE 12Z. RECENT ECHOES ON RADAR ACROSS NORTHEAST OKLAHOMA
HAVE STRUGGLED TO GET ESTABLISHED...LIKELY DUE TO THE CAP.
REGARDLESS...WILL NEED TO WATCH THIS ACTIVITY OVER THE NEXT COUPLE
OF HOURS IN CASE ONE CAN PUNCH THROUGH.

BY EARLY THIS EVENING...SYNOPTIC SCALE LIFT WILL BEGIN TO INCREASE
WITH THE APPROACH OF A WEAK SHORT WAVE TROUGH AND UPPER LEVEL JET
STREAK. THIS COMBINED WITH THE APPROACHING FRONT WILL LIKELY BE
ENOUGH FOR ISOLATED TO WIDELY SCATTERED THUNDERSTORM DEVELOPMENT
ALONG THE FRONT ACROSS EASTERN KANSAS AND WESTERN MISSOURI. THE
INCREASE IN BOUNDARY LAYER MOISTURE AND STEEP MID LAPSE RATES
WILL RESULT IN MODERATE INSTABILITY. WIND SHEAR IN THE HAIL GROWTH
LAYER WILL SUPPORT VERY LARGE HAIL WITH WHAT SHOULD INITIALLY BE
SUPERCELLS. MODIFIED RAOBS AND FORECAST SOUNDINGS WOULD ALSO
YIELD A DAMAGING STRAIGHT LINE WIND THREAT. VEERED WINDS AT THE
SURFACE MAY LIMIT THE TORNADO THREAT SOMEWHAT...BUT LOW LEVEL
SHEAR WILL REMAIN SUFFICIENT FOR AN ISOLATED TORNADO THREAT.

CONFIDENCE DECREASES SOMEWHAT DURING THE LATER EVENING AND
OVERNIGHT HOURS WITH REGARD TO THE STORM MODE AND COVERAGE.
CURRENT THINKING IS THAT WE WILL LIKELY SEE A BROKEN LINE OF
STORMS GET GOING ALONG THE FRONT AND PUSH ACROSS MUCH OF THE
MISSOURI OZARKS. THE PRIMARY SEVERE THREAT WITH THIS BROKEN LINE
WILL BE DAMAGING STRAIGHT LINE WINDS AND LARGE HAIL. THE LATEST
RUC MODEL IS SOMEWHAT CONCERNING ALONG AND SOUTH OF HIGHWAY 60 AS
IT INCREASES LOW LEVEL WIND SHEAR TO A POINT WHERE SPIN UPS ALONG
THE LINE WOULD BE POSSIBLE. THIS MAKES SENSE GIVEN WHAT SHOULD BE
A STRENGTHENING LOW LEVEL JET. WITH LCLS ALSO LOWERING DURING THIS
TIME FRAME...WILL BE UPDATING THE HAZARDOUS WEATHER OUTLOOK BY 4
PM TO INCLUDE PORTIONS OF SOUTH CENTRAL MISSOURI IN THE ISOLATED
TORNADO RISK.

SCHAUMANN

WEDNESDAY...THE REGION WILL BE BETWEEN SYSTEMS. A LINGERING CHANCE
FOR SHRA/TSRA EXISTS OVER THE SOUTHERNMOST CWA AS THE WEAKENING
FRONT BEGINS TO SHIFT TO THE SOUTH AND FURTHER LOSE IDENTITY. MOST
OF WEDNESDAY WILL LIKELY BE DRY. PRECIP WILL ONCE AGAIN GET GOING
TO OUR SOUTH AND SOUTHWEST LATE IN THE DAY.

WEDNESDAY NIGHT AND THURSDAY...STILL HAVE DIFFERENCES WITH THE
SHORT RANGE MODELS DURING THIS TIME FRAME. A WEAK SFC WAVE IS
PROGGED TO DEVELOP TO OUR SOUTHWEST. MODELS AGREE THAT THE CURRENT
CUT OFF LOW OVER THE SOUTHWEST WILL SLOWLY APPROACH AND
WEAKEN...BUT PLACING OF KEY FEATURES IS STILL IN QUESTION. THE GFS
IS THE MODEL SOLUTION FARTHEST TO THE NORTH...AND STRONGEST WITH
SFC LOW PRESSURE. MEANWHILE THE NAM/ECMWF/UKMET ALL AGREE ON
WEAKER SFC LOW DEVELOPMENT AND A SLIGHTLY FARTHER SOUTH SFC
FRONTAL BOUNDARY. HAVE SIDED WITH THE AGREEMENT OF THE
NAM/ECMWF/UKMET GIVEN ECMWF CONTINUITY AS OF LATE.

WILL BASICALLY SEE RAIN DEVELOP FROM THE SW TO NE AS WEDNESDAY
NIGHT PROGRESSES...WITH THE BETTER CHANCES FOR RAINFALL FROM EARLY
THURSDAY MORNING THROUGH MUCH OF THURSDAY. GIVEN THE PROGRESSIVE
NATURE OF THIS SYSTEM...THE RISK FOR HEAVY RAIN IS LIMITED.
NEVERTHELESS WITH PWS BETWEEN 1 AND 1.5 INCHES...WILL NEED TO
MONITOR HEAVY RAIN POTENTIAL TOWARD THE MO/ARK BORDER. WITH THE
REGION ON THE COOL SIDE OF THE BOUNDARY SEVERE WEATHER IS NOT
EXPECTED.

THURSDAY NIGHT...A SLOWER EXIT TO THIS SYSTEM IS POSSIBLE...BUT
CURRENT INDICATIONS ARE FOR PRECIP TO EXIT STAGE EAST BY THIS
PERIOD. HAVE KEPT A SLIGHT CHC MENTION...ESPECIALLY OVER EASTERN
ZONES...AS A HOMAGE TO A SLOWER EXIT. SOME CLEARING IS POSSIBLE AS
NW WINDS BEGIN TO ADVECT A DRIER AIRMASS INTO THE REGION. BELOW AVG
TEMPS IN THE 40S ARE EXPECTED.

GAGAN

LONG TERM (FRIDAY THROUGH TUESDAY)...

MED RANGE MODEL OUTPUT AGREES IN DEVELOPING NORTHWEST FLOW ALOFT
AS RIDGING AMPLIFIES OVER THE WESTERN CONUS AND TROUGHING DEEPENS
IN THE NORTHEASTERN CONUS. THIS PATTERN IS PROGGED TO BEGIN
BREAKING DOWN AT SOME POINT NEXT WEEK...WHICH IS WHERE MODELS
BEGIN TO WAVER A BIT. THE BOTTOM LINE FOR THE EXTENDED PERIOD IS
GENERALLY DRY WITH AT OR BELOW AVERAGE TEMPERATURES. THERE IS
OPPORTUNITY FOR A BRIEF SHOT OR TWO AT SOME LIGHT RAIN AS
SHORTWAVES ROUND THE EASTERN TROUGH...BUT TIMING SUCH FEATURES IS
A RATHER MOOT EXERCISE AT THIS JUNCTURE.

GAGAN

&&

.AVIATION...

FOR THE 0000 UTC KSGF/KJLN TAFS...A FEW BREAKS ARE DEVELOPING
IN THE MVFR CEILINGS AHEAD OF A COLD FONT OVER SOUTHEAST
KANSAS...HOWEVER...THUNDERSTORMS HAVE ALSO RECENTLY ERUPTED ALONG
THIS FRONT AS WELL...AND EXPECT THEM TO MOVE EAST INTO THE KJLN
AREA EARLY THIS EVENING...AND INTO KSGF MID/LATE EVENING. LOW END
MVFR OR IFR CONDITIONS WILL OCCUR BEHIND THE FRONT DURING THE
OVERNIGHT HOURS....ESPECIALLY IF CONSIDERABLE PRECIP CONTINUES TO
DEVELOP WITH THE FROPA. HIGH PRESSURE BUILDS INTO THE AREA WED
WITH LOWER CEILINGS EXPECTED TO SCATTER OUT. DSA

&&

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

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE SPRINGFIELD MO
357 PM CDT TUE MAY 13 2008

KSZ073-097-101-MOZ055>058-066>071-077>083-088>098-101>106-142100-
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-
357 PM CDT TUE MAY 13 2008

...SEVERE STORMS POSSIBLE TONIGHT...

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

.DAY ONE...LATE THIS AFTERNOON AND TONIGHT.

  WEATHER HAZARDS EXPECTED:

  VERY LARGE HAIL TO THE SIZE OF BASEBALLS...DAMAGING WINDS IN
  EXCESS OF 70 MPH AND ISOLATED TORNADOES.

  AREAS AFFECTED AND TIMING:

  VERY LARGE HAIL...DAMAGING STRAIGHT LINE WINDS AND ISOLATED
  TORNADOES WILL BE POSSIBLE AFTER 5 PM WEST OF HIGHWAY 65.
  DAMAGING STRAIGHT LINE WINDS AND LARGE HAIL WILL THEN BE
  POSSIBLE ACROSS MUCH OF THE MISSOURI OZARKS OVERNIGHT.
  ISOLATED TORNADOES WILL STILL BE POSSIBLE OVERNIGHT ALONG
  AND SOUTH OF HIGHWAY 60 AND WEST OF A HOUSTON TO WEST PLAINS
  LINE.

  DISCUSSION:

  LOW LEVEL MOISTURE CONTINUES INCREASE THIS AFTERNOON ACROSS
  THE REGION AHEAD OF A COLD FRONT. THE COMBINATION OF
  INCREASING LOW LEVEL MOISTURE AND COOL TEMPERATURES IN THE
  UPPER ATMOSPHERE WILL CREATE A MODERATELY UNSTABLE
  ATMOSPHERE. A LAYER OF WARM AIR AROUND 6000 FEET ABOVE THE
  GROUND WILL CONTINUE TO SUPPRESS SEVERE THUNDERSTORM
  DEVELOPMENT ACROSS EXTREME SOUTHEAST KANSAS AND WESTERN
  MISSOURI THIS AFTERNOON.

  BETWEEN 5 AND 8 PM...WEAK UPPER LEVEL ENERGY AND AN
  APPROACHING UPPER LEVEL JET WILL ALLOW FOR ISOLATED TO
  WIDELY SCATTERED THUNDERSTORMS TO DEVELOP ACROSS EASTERN
  KANSAS AND OKLAHOMA AHEAD OF AN ADVANCING COLD FRONT. ANY
  STORMS THAT DEVELOP WILL INITIALLY MOVE TO THE NORTHEAST
  AROUND 30 TO 35 MPH...ENTERING WESTERN MISSOURI LATER THIS
  EVENING. THE COMBINATION OF MODERATE INSTABILITY AND WIND
  SHEAR WILL SUPPORT VERY LARGE HAIL AND DAMAGING STRAIGHT
  LINE WINDS WITH ANY THUNDERSTORMS THAT DEVELOP THIS EVENING
  WEST OF HIGHWAY 65. LOW LEVEL WIND SHEAR WILL BE SOMEWHAT
  WEAK AHEAD OF THE FRONT...BUT WILL STILL BE SUFFICIENT FOR
  THE POSSIBILITY OF ISOLATED TORNADOES.

  ANY THUNDERSTORMS THAT DEVELOP EARLY THIS EVENING ARE
  THEN EXPECTED TO MERGE INTO A BROKEN LINE OF STORMS
  DURING THE LATE EVENING AND OVERNIGHT HOURS. THIS BROKEN
  LINE OF STORMS WILL THEN LIKELY PASS THROUGH THE REST OF
  THE MISSOURI OZARKS LATE TONIGHT. DAMAGING STRAIGHT LINE
  WINDS AND HAIL TO THE SIZE OF HALF DOLLARS WILL BE THE
  MAIN THREATS WITH THESE STORMS. ISOLATED TORNADOES WILL
  STILL BE POSSIBLE ALONG AND SOUTH OF HIGHWAY 60 AND WEST
  OF A HOUSTON TO WEST PLAINS LINE DURING THE OVERNIGHT
  HOURS.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY.

  A FRONTAL BOUNDARY WILL STALL OUT OVER NORTHERN ARKANSAS
  ON WEDNESDAY BEFORE LIFTING BACK TO THE NORTH AS AN UPPER
  LEVEL DISTURBANCE LIFTS NORTHEAST INTO THE PLAINS
  WEDNESDAY NIGHT. SHOWERS AND THUNDERSTORMS WITH LOCALLY
  HEAVY RAINFALL WILL SPREAD NORTHWARD INTO SOUTHERN
  MISSOURI WEDNESDAY NIGHT AND THURSDAY. AT THIS TIME IT
  APPEARS AS IF THE STORMS WILL REMAIN BELOW SEVERE
  LIMITS...HOWEVER HEAVY RAIN MAY LEAD TO FLOODING OVER
  EXTREME SOUTHERN MISSOURI.

.SPOTTER INFORMATION STATEMENT...

  SPOTTER ACTIVATION WILL LIKELY BE NEEDED THIS EVENING WEST
  OF HIGHWAY 65. SPOTTER ACTIVATION WILL THEN BE POSSIBLE
  OVERNIGHT ALONG AND SOUTH OF HIGHWAY 60 AND WEST OF A
  HOUSTON TO WEST PLAINS LINE.

&&

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)

SCHAUMANN/GAGAN