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| Probabilistic Graphic |
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| Probability of severe weather within 25 miles of a point. Hatched Area: 10% or greater probability of significant severe within 25 miles of a point. |
SPC AC 011729 DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1229 PM CDT WED JUN 01 2011 VALID 021200Z - 031200Z ...THERE IS A SLGT RISK OF SVR TSTMS THU/THU NIGHT ACROSS PARTS OF THE NRN PLAINS... ...THERE IS A SLGT RISK OF SVR TSTMS THU ACROSS PARTS OF THE SOUTHERN APPALACHIANS AND ADJACENT PIEDMONT... ...SYNOPSIS... MODELS SUGGEST THAT SOME FURTHER AMPLIFICATION OF THE UPPER FLOW MAY OCCUR ACROSS THE U.S. DURING THIS FORECAST PERIOD. A VIGOROUS SHORT WAVE IMPULSE...NOW TO THE SOUTHEAST OF THE ALEUTIANS...IS PROGGED TO DIG TOWARD THE PACIFIC COAST AND CONTRIBUTE TO THE NORTHEASTWARD ACCELERATION OF ANOTHER STRONG IMPULSE OUT OF BROADER WESTERN U.S. UPPER TROUGHING. AS THIS OCCURS...RIDGING NORTH OF A LINGERING SUBTROPICAL HIGH CENTER OVER THE SOUTH CENTRAL U.S. APPEARS LIKELY TO BUILD TOWARD HUDSON BAY...WITH DOWNSTREAM TROUGHING DIGGING OFF THE NORTH ATLANTIC COAST. WHILE DRY STABLE CONDITIONS PREVAIL ACROSS MUCH OF THE NORTHEASTERN STATES IN THE WAKE OF A SIGNIFICANT COLD FRONT...MUCH OF THE SOUTHEAST WILL REMAIN SEASONABLY MOIST. AND SIGNIFICANT MOISTURE RETURN WILL CONTINUE NORTHWARD AND EASTWARD OUT OF THE PLAINS THROUGH THE UPPER MISSISSIPPI VALLEY AND GREAT LAKES REGION BY 12Z FRIDAY. ...NORTHERN PLAINS... UNCERTAINTIES LINGER CONCERNING THE EXTENT OF THE CONVECTIVE POTENTIAL ACROSS THE REGION THURSDAY. THIS INCLUDES THE DETAILS OF SURFACE CYCLONE EVOLUTION FROM THE LEE OF THE NORTHERN ROCKIES INTO THE CANADIAN PRAIRIES AND NORTHERN U.S. PLAINS...AND THE STRENGTH OF MID-LEVEL CAPPING ASSOCIATED WITH VERY WARM ELEVATED MIXED LAYER AIR ADVECTING OFF THE PLATEAU AND ROCKIES. STRONG MID-LEVEL HEIGHT FALLS ARE PROGGED TO DEVELOP NORTHEASTWARD ACROSS THE NORTHERN ROCKIES INTO SASKATCHEWAN/MANITOBA...ASSOCIATED WITH THE STRONG SHORT WAVE IMPULSE EMERGING FROM THE INTERMOUNTAIN WEST. BUT THIS MAY REMAIN MOSTLY TO THE NORTHWEST OF THE WARM SECTOR OF THE SURFACE CYCLONE. DAYTIME HEATING IS EXPECTED TO CONTRIBUTE TO MODERATELY LARGE CAPE IN THE WARM SECTOR BY LATE AFTERNOON...AS HIGH AS 3000+ J/KG ALONG AND EAST OF THE DRY LINE ACROSS PARTS OF WESTERN NORTH DAKOTA INTO CENTRAL SOUTH DAKOTA...WHERE LOW-LEVEL CONVERGENCE SEEMS LIKELY TO BECOME SUPPORTIVE OF AT LEAST ISOLATED TO SCATTERED STORM DEVELOPMENT. VERTICAL SHEAR...NEAR THE PERIPHERY OF A 70-90 KT SOUTHWESTERLY 500 MB JET ACCOMPANYING THE UPPER IMPULSE...WILL BE SUFFICIENT FOR SUPERCELLS...WHICH LIKELY WILL PERSIST AND GRADUALLY SPREAD EASTWARD THROUGH THE EVENING HOURS. UPSCALE CONVECTIVE GROWTH INTO AN ORGANIZED SEVERE MESOSCALE CONVECTIVE SYSTEM ACROSS THE CENTRAL/EASTERN DAKOTAS THURSDAY EVENING DOES NOT APPEAR OUT OF THE QUESTION. THIS COULD POSE A BROADER SCALE DAMAGING WIND AND HAIL THREAT WHICH MAY CONTINUE INTO PARTS OF MINNESOTA OVERNIGHT. ...SOUTHERN APPALACHIANS AND ADJACENT PIEDMONT... UPPER RIDGING APPEARS LIKELY TO REMAIN STRONG ACROSS THE REGION ...WITH NEGLIGIBLE HEIGHT FALLS EXPECTED IN ASSOCIATION WITH THE TROUGH DIGGING OFF THE NORTH ATLANTIC COAST. HOWEVER...MODELS ARE SUGGESTIVE THAT AN AREA OF BROADER SCALE UPWARD VERTICAL MOTION MAY DEVELOP IN ASSOCIATION WITH LOWER/MID-LEVEL WARM ADVECTION. THIS MAY AID OROGRAPHIC FORCING OF CONVECTIVE DEVELOPMENT IN THE PRESENCE OF A VERY WARM AND MOIST... MODERATELY UNSTABLE AIR MASS...CHARACTERIZED BY STEEP LOW-LEVEL LAPSE RATES AND CAPE OF 2000-3000+ J/KG. IT APPEARS THAT STRONGER PULSING STORMS COULD BECOME RELATIVELY NUMEROUS AS LIGHT NORTHERLY FLOW CONTRIBUTES TO PROPAGATION OFF THE HIGHER TERRAIN INTO THE PIEDMONT AND PERHAPS PORTIONS OF THE UPPER TENNESSEE VALLEY LATE THURSDAY AFTERNOON. ..KERR.. 06/01/2011 CLICK TO GET WUUS02 PTSDY2 PRODUCT NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 0600Z