The SPC is forecasting ...severe thunderstorms expected over parts of the central plains this afternoon and tonight.... Please read the latest public statement about this event.
| Categorical Graphic |
|---|
|
| Probabilistic Tornado Graphic |
 |
 |
| Probabilistic Damaging Wind Graphic |
 |
 |
| Probabilistic Large Hail Graphic |
 |
 |
SPC AC 051243 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0743 AM CDT SAT MAY 05 2007 VALID 051300Z - 061200Z ...THERE IS A HIGH RISK OF SVR TSTMS TODAY THROUGH THIS EVENING ACROSS PARTS OF CENTRAL KS AND CENTRAL NEB... ...THERE IS A MDT RISK OF SVR TSTMS OVER PARTS OF SOUTHERN SD...WESTERN AND CENTRAL NEB...CENTRAL KS...AND NORTHWEST OK... ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS MUCH OF THE PLAINS STATES FROM ND TO TX... ...REGIONAL OUTBREAK OF SEVERE THUNDERSTORMS AND TORNADOES IS FORECAST THIS AFTERNOON ACROSS PARTS OF CENTRAL KS AND CENTRAL NEB... ...CENTRAL PLAINS... MORNING WATER VAPOR IMAGERY SHOWS LARGE UPPER TROUGH OVER THE NORTHERN ROCKIES. THIS FEATURE IS EXPECTED TO REMAIN NEARLY STATIONARY THROUGH TODAY...AS 80-90 KNOT MID LEVEL SPEED MAX ROTATES INTO THE CENTRAL PLAINS. SURFACE LOW NOW OVER SOUTHEAST CO WILL LIFT SLOWLY NORTHWARD INTO WESTERN NEB BY THIS AFTERNOON...WITH DRYLINE EXTENDING SOUTHWARD ACROSS CENTRAL KS AND INTO EXTREME WESTERN OK. POCKETS OF LOW CLOUDS AND POSSIBLY SHOWERS WILL PERSIST THROUGH THE MORNING ALONG AND EAST OF THE DRYLINE...SOMEWHAT LIMITING DAYTIME HEATING. HOWEVER...12Z DDC SOUNDING SHOWS THAT ENVIRONMENT IS EXTREMELY MOIST AND UNSTABLE...AND ONLY WEAKLY CAPPED. COMBINATION OF WEAK HEATING AND LARGE SCALE ASCENT SHOULD REMOVE CAP AND ALLOW SCATTERED THUNDERSTORM DEVELOPMENT RELATIVELY EARLY TODAY. ...CENTRAL NEB/KS... PRESENT INDICATIONS ARE THAT CONVECTION WILL INTENSIFY BY EARLY AFTERNOON ALONG DRYLINE FROM WESTERN NEB INTO CENTRAL KS. ACTIVITY MAY BE ISOLATED...BUT POTENTIAL EXISTS FOR REPEAT INITIATION AS STORMS MOVE QUICKLY NORTH-NORTHEASTWARD OFF THE DRYLINE. FORECAST SOUNDINGS THROUGHOUT THIS REGION SHOW VERTICAL SHEAR PROFILES VERY FAVORABLE FOR SUPERCELLS CAPABLE OF VERY LARGE HAIL. COMBINATION OF EXTREME INSTABILITY /MLCAPE VALUES OF 2500-4000 J/KG/...LOW LCL HEIGHTS...HIGH SURFACE DEWPOINTS...AND STRONG LOW LEVEL SHEAR /EFFECTIVE HELICITY VALUES OF 200-300 M2/S2/ ALSO FAVOR THE POTENTIAL FOR LONG-LIVED...STRONG TORNADOES. ACTIVITY IS EXPECTED TO LIFT NORTH-NORTHEASTWARD ACROSS MUCH OF NEB/KS OVERNIGHT WITH A CONTINUED RISK OF TORNADOES...LARGE HAIL...AND DAMAGING WINDS. ...OK/TX... LARGE SCALE FORCING FOR VERTICAL MOTION WILL INCREASE ALONG SURFACE DRYLINE AFTER DARK FROM WESTERN OK INTO WEST TX. SCATTERED THUNDERSTORMS ARE LIKELY TO DEVELOP ALONG THIS AXIS...WHERE HIGH CAPE VALUES AND SUFFICIENT VERTICAL SHEAR WILL PROMOTE A RISK OF SEVERE/SUPERCELL STORMS. LARGE HAIL WILL BE THE MAIN THREAT...ISOLATED TORNADOES COULD ALSO OCCUR OVER WESTERN OK/NORTHWEST TX THIS EVENING. ...NEB/SD... FARTHER NORTH...SIGNIFICANT UPPER FORCING WILL OVERSPREAD NORTHERN NEB AND SOUTHERN SD LATE THIS AFTERNOON AND EVENING. WARM SECTOR AIR MASS MAY NOT DEVELOP THIS FAR NORTHWARD. HOWEVER...FORECAST SOUNDINGS INDICATE SUBSTANTIAL ELEVATED CAPE AND STRONG SHEAR PROFILES. ORGANIZED MULTICELL OR SUPERCELL STORMS CAPABLE OF LARGE HAIL WILL BE LIKELY OVER THIS REGION. ..HART/GRAMS.. 05/05/2007 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z