The SPC is forecasting ...severe thunderstorms expected over parts of the northern plains this afternoon and tonight.... Please read the latest public statement about this event.
| Categorical Graphic |
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| Probabilistic Tornado Graphic |
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| Probability of a tornado within 25 miles of a point. Hatched Area: 10% or greater probability of EF2 - EF5 tornadoes within 25 miles of a point. |
| Probabilistic Damaging Wind Graphic |
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| Probability of damaging thunderstorm winds or wind gusts of 50 knots or higher within 25 miles of a point. Hatched Area: 10% of greater probability of wind gusts 65 knots or greater within 25 miles of a point. |
| Probabilistic Large Hail Graphic |
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| Probability of hail 1" or larger within 25 miles of a point. Hatched Area: 10% or greater probability of hail 2" or larger within 25 miles of a point. |
SPC AC 261636 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1136 AM CDT TUE JUL 26 2011 VALID 261630Z - 271200Z ...THERE IS A MDT RISK OF SVR TSTMS OVER NORTH CENTRAL/NERN SD AND SOUTH CENTRAL/SERN ND... ...THERE IS A SLGT RISK OF SVR TSTMS OVER THE NRN/CENTRAL PLAINS INTO THE UPPER MS VALLEY... ...THERE IS A SLGT RISK OF SVR TSTMS OVER THE NERN STATES... ...NRN/CENTRAL PLAINS... UPPER VORTICITY MAX OVER SRN ALBERTA IS FORECAST TO MOVE EWD ACROSS THE SRN PRAIRIE PROVINCES WITH GRADUAL HEIGHT FALLS OVERSPREADING THE NRN PLAINS THROUGH TONIGHT. ASSOCIATED COLD FRONT FROM ERN MT SWWD ACROSS WY WILL MOVE EWD ACROSS PART SOD THE NRN PLAINS...REACHING A LINE FROM EXTREME ERN ND/CENTRAL SD/CENTRAL WY BY THE END OF THE PERIOD. A WARM FRONT FROM SERN SD INTO A LOW OVER SERN MT WILL LIFT NWD TODAY...ALTHOUGH ITS PROGRESS MAY BE LIMITED BY CLOUD COVER SPREADING ENEWD OVER THE NRN TWO-THIRDS OF SD. VERY STEEP MID LEVEL LAPSE RATES AND ATTENDANT EML HAVE OVERSPREAD THE REGION...INDICATING THAT SURFACE-BASED STORMS WILL BE DELAYED UNTIL LATER THIS AFTERNOON AND EVENING. CURRENT WIDELY SCATTERED ELEVATED STORMS FROM NWRN ND SEWD INTO NERN SD ARE ASSOCIATED WITH WARM ADVECTION IN THE 850-700 MB LAYER...AND ARE EXPECTED TO SLOWLY SPREAD EWD. STRONGER CELLS MAY PRODUCE ISOLATED HAIL...SEE SWOMCD 1746 FOR MORE NEAR-TERM DETAILS. AS LOW LEVEL MOISTURE CONTINUES TO SPREAD NWD THIS AFTERNOON AND HEATING OCCURS WITHIN BREAKS IN CLOUD COVER...ATMOSPHERE WILL BECOME INCREASINGLY UNSTABLE FROM SERN SD INTO CENTRAL/SERN ND...WITH MLCAPE OF 2000-3000 J/KG EXPECTED. THE CAP IS EXPECTED TO GRADUALLY WEAKEN WITH NEW STORMS INITIATING OVER PARTS OF WRN ND INTO CENTRAL SD BY MID-LATE AFTERNOON. VERTICAL WIND PROFILES ARE FORECAST TO EXHIBIT STRONG VEERING AND SPEED INCREASE IN THE LOWEST 3-4 KM...WHICH WILL PROMOTE SUPERCELL DEVELOPMENT. IF DISCRETE STORMS CAN BE MAINTAINED AFTER INITIATION...THERE WILL BE POTENTIAL FOR STRONGER CELLS TO PRODUCE VERY LARGE HAIL AND A FEW TORNADOES...SEVERAL OF WHICH COULD BE STRONG. STORMS ARE EXPECTED TO MOVE EWD THROUGH THE EVENING HOURS...WITH THE POSSIBILITY OF SOME UPSCALE GROWTH INTO ONE OR TWO MCS/S MOVING TOWARD THE UPPER MS VALLEY. OTHER STORMS ARE EXPECTED TO DEVELOP SSWWD ALONG THE SURFACE TROUGH EXTENDING OVER WRN/CENTRAL NEB AND NERN CO. STRONG DIABATIC HEATING AND STEEP LAPSE RATES COUPLED WITH SUFFICIENT VERTICAL SHEAR WILL BE FAVORABLE FOR SEVERE STORMS INCLUDING A FEW SUPERCELLS. LARGE HAIL AND DAMAGING WINDS WILL BE THE PRIMARY THREATS. STORMS WILL SPREAD ENEWD THROUGH THE EVENING HOURS BEFORE DIMINISHING AFTER 03-06Z. ...NERN STATES... STRONG/SEVERE STORMS WILL CONTINUE TO DEVELOP ALONG/AHEAD OF A COLD FRONT MOVING ACROSS THE LOWER GREAT LAKES AND ACROSS THE NERN STATES. FAVORABLE JET LEVEL FORCING FOR ASCENT AND COLDER TEMPERATURES ALOFT WILL PROVIDE SUPPORT FOR SEVERE STORMS WITH POTENTIAL TO PRODUCE LARGE HAIL AND STRONG WIND GUSTS INTO THE EVENING HOURS. ..WEISS/GARNER.. 07/26/2011 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z