Epic Outbreak of Tornadoes Across the Southeast on 27-28 April 2011 Impacts Northeast Georgia and Western North Carolina

Strong to Severe Storms in the Upper Midwest; Bering Sea Low Continues to Impact Southwest Alaska

Scattered severe thunderstorms are possible Thursday across central and eastern Minnesota, Iowa, and western Wisconsin. A few tornadoes, isolated very large hail, and damaging winds may occur. In southwest Alaska, a Bering Sea low continues to cause strong winds, significant rainfall, and high seas, with further impacts expected Friday into the weekend from a North Pacific storm. Read More >

ZCZC SPCSWOD48 ALL ACUS48 KWNS 230850 SPC AC 230850 DAY 4-8 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 0350 AM CDT SAT APR 23 2011 VALID 261200Z - 011200Z ...DISCUSSION... SUBSTANTIAL SEVERE WEATHER POTENTIAL IS EXPECTED TO SHIFT SLOWLY EWD ACROSS THE ERN U.S. DAYS 4-6 /TUE. 4-26 THROUGH THU. 4-28/...AS A LARGE UPPER TROUGH PROGRESSES FROM THE CENTRAL U.S. DAY 4 ACROSS THE MS VALLEY DAY 5...AND THEN ON EWD THROUGH DAYS 6/7. MODEL DIFFERENCES WITH RESPECT TO TIMING OF THIS FEATURE BEGIN TO EMERGE DAY 5...BUT BECOME INCREASINGLY PRONOUNCED THROUGH DAYS 6 AND 7 AS THE TROUGH APPROACHES THE E COAST STATES/ERN ATLANTIC. THE PRIMARY SEVERE THREAT DAY 4 IS PROGGED FROM E TX NEWD ACROSS THE ARKLATEX INTO THE MID MS VALLEY...AS A SHORT-WAVE TROUGH DIGS ESEWD INTO THIS REGION...WITHIN THE LARGER-SCALE TROUGH. UNSTABLE AIRMASS COMBINED WITH THE ENERGETIC SHORT-WAVE FEATURE AND ASSOCIATED/STRONG FLOW FIELD SUGGESTS WIDESPREAD SEVERE WEATHER POTENTIAL -- INCLUDING RISKS FOR LARGE HAIL...DAMAGING WINDS...AND ISOLATED TORNADOES. THE THREAT SHOULD SHIFT E OF THE MS VALLEY INTO THE MID SOUTH/SOUTHEAST DAY 5...AS THE SHORT-WAVE FEATURE TAKES ON A NEUTRAL TO EVEN NEGATIVE TILT AS IT CROSSES THIS REGION. AGAIN -- AMPLY UNSTABLE AIRMASS COMBINED WITH THE STRENGTH OF THE UPPER SYSTEM AND ASSOCIATED FLOW FIELD SUGGESTS WIDESPREAD SEVERE WEATHER CAN BE EXPECTED...INCLUDING THE POTENTIAL FOR TORNADOES. AS MODELS BEGIN DIVERGING SOMEWHAT WITH RESPECT TO TIMING AND SMALLER-SCALE DETAILS...DEGREE OF THREAT SHIFTING ACROSS THE APPALACHIANS LATE DAY 5 AND INTO DAY 6 BECOMES LESS CERTAIN. WHILE SEVERE WEATHER WILL BE LIKELY WITH THE FRONT EXPECTED TO REACH THE ATLANTIC COAST BY THE END OF THE PERIOD...WILL REFRAIN FROM HIGHLIGHTING A THREAT AREA THIS FORECAST. WITH THE FRONT LIKELY OFFSHORE BY THE START OF DAY 7... SEVERE WEATHER POTENTIAL ACROSS THE U.S. APPEARS LESS WIDESPREAD/SIGNIFICANT AND MUCH MORE UNCERTAIN THROUGH THE END OF THE PERIOD. ..GOSS.. 04/23/2011 CLICK TO GET WUUS48 PTSD48 PRODUCT