SWODY1
SPC AC 030558
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1258 AM CDT SUN APR 03 2011
VALID 031200Z - 041200Z
...THERE IS A MDT RISK OF SVR TSTMS ACROSS PARTS OF ERN KS AND NW
MO...
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE MID-MO
VALLEY...CNTRL PLAINS...SRN PLAINS...WRN OZARKS AND WRN GREAT
LAKES...
...SEVERE WEATHER EVENT EXPECTED FROM ERN KS NEWD ACROSS NRN MO INTO
WRN AND NRN IL THIS AFTERNOON AND EVENING...
...MID-MO VALLEY/CNTRL PLAINS/MID-MS VALLEY/WRN GREAT LAKES...
AN UPPER-LEVEL TROUGH WILL MOVE INTO THE NRN PLAINS AND CNTRL
ROCKIES TODAY. WELL AHEAD OF THE SYSTEM...A POWERFUL 65 TO 80 KT
LOW-LEVEL JET WILL BE IN PLACE ACROSS THE MID-MO VALLEY AND LOWER OH
VALLEY THIS AFTERNOON. THE LOW-LEVEL JET WILL RAPIDLY TRANSPORT
MOISTURE NEWD INTO THE SLIGHT RISK AREA BY MID-AFTERNOON WITH SFC
DEWPOINTS LIKELY REACHING INTO THE MID 60S F FROM ERN KS NEWD TO WRN
IL. THE MOIST AIRMASS SHOULD ALLOW MODERATE INSTABILITY TO DEVELOP
ACROSS A BROAD AREA AHEAD OF A FAST-MOVING COLD FRONT. AS THE
CAPPING INVERSION WEAKENS AND LOW-LEVEL CONVERGENCE INCREASES ALONG
THE FRONT...NUMEROUS STRONG TO SEVERE THUNDERSTORMS SHOULD INITIATE
WITH A BROKEN LINE DEVELOPING DURING THE LATE AFTERNOON.
FORECAST SOUNDINGS AT 21Z SUGGEST THE STRONGEST INSTABILITY WILL BE
LOCATED IN ERN KS AND WRN MO WHERE MLCAPE VALUES ARE FORECAST TO
REACH THE 2500 TO 3500 J/KG RANGE. IN ADDITION...A PLUME OF STEEP
MID-LEVEL LAPSE RATES IS FORECAST TO NOSE INTO ERN KS AND NW MO
WHERE DEEP LAYER SHEAR SHOULD BE QUITE STRONG. THIS ENVIRONMENT WILL
LIKELY SUPPORT SUPERCELL DEVELOPMENT WITH A WIDESPREAD THREAT FOR
LARGE HAIL ESPECIALLY ACROSS ERN KS AND NW MO WHERE A MODERATE RISK
AREA HAS BEEN OUTLOOKED. VERY LARGE HAIL WILL BE POSSIBLE WITH THE
MORE DOMINATE SUPERCELLS THAT REMAIN DISCRETE. TORNADOES WILL ALSO
BE POSSIBLE WITH THE BETTER-ORGANIZED SUPERCELLS. THE TORNADO THREAT
MAY BE GREATEST NEWD ACROSS NRN MO INTO WRN AND NRN IL WHERE THE
STORMS WILL HAVE ACCESS TO GREATER LOW-LEVEL SHEAR. IF DISCRETE
ROTATING STORMS CAN PERSIST INTO THE EARLY EVENING WHEN THE
LOW-LEVEL JET IS FORECAST TO STRENGTHEN...THEN AN ISOLATED STRONG
TORNADO WILL BE POSSIBLE. DUE TO THE STRONG LOW-LEVEL FLOW OF 60 TO
70 KT AND BECAUSE OF THE AMOUNT OF INSTABILITY FORECAST...WIND
DAMAGE COULD BE WIDESPREAD FROM ERN KS NEWD ACROSS NRN MO INTO NW IL
ESPECIALLY IF A NEARLY CONTINUOUS LINE OF INTENSE STORMS DEVELOPS
DURING THE EARLY EVENING.
...SRN PLAINS/WRN OZARKS...
MOISTENING OF THE AIRMASS ACROSS THE SRN PLAINS WILL CONTINUE TODAY
AS THE SRN END OF A WELL-DEFINED LOW-LEVEL JET MOVES EWD ACROSS THE
REGION. MODERATE INSTABILITY IS FORECAST BY MID TO LATE AFTERNOON
FROM CNTRL AND NORTH TX EXTENDING NWD INTO CNTRL AND ERN OK WHERE
FORECAST SOUNDINGS SHOW MLCAPE VALUES AROUND 2500 J/KG. IN SPITE OF
THE INSTABILITY...A CAPPING INVERSION WILL LIKELY REMAIN IN PLACE
FOR MUCH OF THE AFTERNOON AND EVENING SUPPRESSING CONVECTIVE
DEVELOPMENT. SEVERAL MODEL FORECASTS INITIATE STORMS IN NE OK AND NW
AR DURING THE LATE EVENING WITH STORMS EXPANDING SWWD ALONG A COLD
FRONT DURING THE OVERNIGHT PERIOD. THE MODERATE INSTABILITY...STEEP
MID-LEVEL LAPSE RATES AND STRONG DEEP LAYER SHEAR SHOULD BE
SUFFICIENT FOR A LARGE HAIL AND WIND DAMAGE THREAT. AFTER
MIDNIGHT...ISOLATED THUNDERSTORM DEVELOPMENT COULD OCCUR SWWD ACROSS
CNTRL AND NORTH TX AS THE COLD FRONT MOVES INTO THE REGION FROM THE
NORTHWEST. FORECAST SOUNDINGS IN CNTRL AND NORTH TX AT 09Z TO 12Z
SUGGEST DEEP LAYER SHEAR MAY BE STRONG ENOUGH FOR A MARGINAL WIND
DAMAGE AND HAIL THREAT.
..BROYLES/GARNER.. 04/03/2011
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