Categorical Graphic
Probabilistic Tornado Graphic
Probabilistic Damaging Wind Graphic
Probabilistic Large Hail Graphic

   SPC AC 181239
   
   DAY 1 CONVECTIVE OUTLOOK  
   NWS STORM PREDICTION CENTER NORMAN OK
   0739 AM CDT THU JUN 18 2009
   
   VALID 181300Z - 191200Z
   
   ...THERE IS A MDT RISK OF SVR TSTMS THIS AFTERNOON AND TONIGHT
   ACROSS PARTS OF EASTERN SD...SOUTHERN MN...MUCH OF IA...SOUTHERN
   WI...NORTHERN IL...AND NORTHERN IND...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE CENTRAL/NORTHERN
   PLAINS INTO THE MID ATLANTIC AND SOUTHEAST STATES...
   
   ...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE SOUTHERN HIGH
   PLAINS...
   
   ANOTHER VERY ACTIVE SEVERE WEATHER DAY IS EXPECTED TODAY AROUND THE
   PERIPHERY OF AN UPPER RIDGE.  SEVERAL CLUSTERS OF SEVERE STORMS ARE
   LIKELY ACROSS THE COUNTRY AFFECTING AREAS FROM THE PLAINS STATES TO
   THE MID ATLANTIC AND SOUTHEAST.
   
   ...OH VALLEY INTO SOUTHEAST TODAY...
   A MATURE AND FAST-MOVING BOW ECHO IS CURRENTLY AFFECTING EASTERN IL
   AND WILL TRACK INTO IND SHORTLY.  THIS ACTIVITY WILL TRACK
   SOUTHEASTWARD ALONG THE NORTH EDGE OF A VERY MOIST AND UNSTABLE
   AIRMASS INTO KY/TN THIS AFTERNOON.  GIVEN THE LONGEVITY OF THIS
   SYSTEM AND SUFFICIENT VERTICAL SHEAR...IT IS LIKELY THAT THE MCS
   WILL MAINTAIN A RISK OF SEVERE STORMS TO THE CREST OF APPALACHIANS
   AND POSSIBLY INTO NC/SC/GA THIS EVENING.  DAMAGING WINDS APPEAR TO
   BE THE MAIN THREAT.
   
   ...MIDWEST INTO UPPER MS VALLEY...
   A LARGE RESERVOIR OF HIGH INSTABILITY RESIDES ACROSS THE CENTRAL
   PLAINS AND MID MS VALLEY THIS MORNING.  WIDESPREAD MUCAPE VALUES OF
   3000-5000 J/KG WILL DEVELOP BY AFTERNOON WITH A RELATIVELY WEAK CAP
   AROUND THE EDGES FROM NEB/SD INTO IA/MN/WI/IL.  SEVERAL ROUNDS OF
   SEVERE STORMS WILL LIKELY AFFECT THIS AREA...BEGINNING WITH THE
   ONGOING BOW ECHO OVER NORTHWEST IA.  THIS MCS WILL TRACK EASTWARD
   AND WILL LIKELY WEAKEN AS IT MOVES INTO WI/IL LATER THIS MORNING.
   
   BY MID AFTERNOON...THE OUTFLOW BOUNDARY ASSOCIATED WITH THE MORNING
   CONVECTION IS EXPECTED TO EXTEND ACROSS CENTRAL IA.  BACKED LOW
   LEVEL WINDS ALONG AND NORTH OF THE BOUNDARY...COUPLED WITH STRONG
   DAYTIME HEATING AND DEWPOINTS IN THE MID 70S WILL YIELD EXTREME
   INSTABILITY WITH MLCAPE VALUES APPROACHING 5000 J/KG AND LITTLE CAP.
   FORECAST SOUNDINGS OVER SOUTHERN MN AND NORTHERN IA INDICATE THE
   RISK OF INTENSE SUPERCELLS FORMING OVER THIS AREA CAPABLE OF VERY
   LARGE HAIL...DAMAGING WINDS...AND PERHAPS SIGNIFICANT TORNADOES. 
   THESE STORMS WILL TRACK EASTWARD INTO SOUTHWEST WI AND NORTHERN
   IL...WITH CONSOLIDATION INTO A LARGE MCS EXPECTED.  BOW ECHO
   FORMATION IS POSSIBLE DURING THE EVENING ACROSS NORTHERN IL/IND WITH
   THE THREAT OF WIDESPREAD DAMAGING WINDS.  STORMS MAY TRACK AS FAR
   EAST AS CENTRAL OH OVERNIGHT.
   
   ...MID ATLANTIC REGION...
   MORNING WATER VAPOR IMAGERY SHOWS AN UPPER TROUGH ROTATING EASTWARD
   ACROSS THE UPPER OH VALLEY.  THIS TROUGH WILL PASS ACROSS THE MID
   ATLANTIC COASTAL REGION TODAY AND HELP TO INITIATE SCATTERED
   THUNDERSTORMS FROM NYC SOUTHWARD INTO VA/NC.  SURFACE DEWPOINTS IN
   THE 70S ARE PRESENT THIS MORNING ACROSS PARTS OF VA/NC WHERE STRONG
   INSTABILITY WILL LIKELY DEVELOP BY EARLY AFTERNOON.  ALL MODELS ARE
   IN GENERAL AGREEMENT THAT SCATTERED THUNDERSTORMS WILL DEVELOP OVER
   THIS AREA.  VERTICAL SHEAR PROFILES APPEAR SUFFICIENT FOR THE
   DEVELOPMENT OF A FEW SUPERCELLS OVER THIS AREA CAPABLE OF DAMAGING
   WINDS...HAIL...AND ISOLATED TORNADOES.
   
   ...WEST TX...
   SIMILAR TO YESTERDAY...MODEL GUIDANCE IS IN STRONG AGREEMENT THAT A
   BAND OF HIGH-BASED THUNDERSTORMS WILL DEVELOP THIS AFTERNOON FROM
   EASTERN NM INTO WEST TX INCLUDING THE PANHANDLE.  40-50F T-TD
   SPREADS COUPLED WITH 25-30 KNOT EFFECTIVE SHEAR WILL SUPPORT
   ORGANIZED MULTICELL STORMS CAPABLE OF DAMAGING WINDS AND HAIL.
   
   ..HART/JEWELL.. 06/18/2009
   
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   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1630Z