The SPC is forecasting ...severe thunderstorms expected over parts of the central and northern plains...and over the lower missouri and mid mississippi valleys...this afternoon through early monday.... Please read the latest public statement about this event.
| Categorical Graphic |
|---|
|
| Probabilistic Tornado Graphic |
 |
 |
| Probabilistic Damaging Wind Graphic |
 |
 |
| Probabilistic Large Hail Graphic |
 |
 |
SPC AC 201613 DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1113 AM CDT SUN JUN 20 2010 VALID 201630Z - 211200Z ...THERE IS A MDT RISK OF SVR TSTMS FROM NERN WY/SERN MT ACROSS SRN AND WRN SD/MUCH OF NEB INTO WRN IA/FAR NRN MO... ...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK AREA...FROM THE NRN AND CNTRL HI PLNS TO THE MID MS VLY... ...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF NEW ENGLAND AND THE MID ATLANTIC CST... ...SYNOPSIS... UPPER LOW OVER OREGON TO MOVE TO SWRN MT BY 12Z MON. OF MORE IMPORTANCE TO SEVERE DEVELOPMENT TODAY IS THE MID LEVEL TROUGH/WIND MAX ROTATING NEWD FROM UT/NV ACROSS CO/WY THIS AFTERNOON THEN EWD INTO PLAINS TONIGHT. OUTFLOW FROM OVERNIGHT CONVECTION HAS PUSHED LOW LEVEL MOISTURE WWD TO FRONT RANGE NRN CO AND AS FAR W AS E SLOPES OF WIND RIVER AND BIG HORN MTNS IN WY. SFC LOW WRN KS WILL DEEPEN THIS AFTERNOON SUPPORTING THE VERY MOIST/UNSTABLE BOUNDARY LAYER IN CENTRAL PLAINS TO DEVELOP NWD INTO SRN NEB. ...NRN/CENTRAL HIGH PLAINS... MDT RISK HAS BEEN EXTENDED WWD TO E SLOPES OF NERN WY INTO SERN MT AS THE MOIST UPSLOPE EXPECTED TO HOLD UNTIL STORM INITIATION BY MID AFTERNOON. WITH MLCAPES AOA 2000 J/KG...40-50KT OF SHEAR AND VERY STEEP MID LEVEL LAPSE RATES...CONDITIONS SUPPORT SUPERCELLS AND VERY LARGE HAIL. IN ADDITION TORNADOES WILL BE POSSIBLE WITH ANY SUPERCELL. HAVE EXTENDED THE SLIGHT SWD TO DEN METRO GIVEN THE CURRENT AVAILABLE LOW LEVEL MOISTURE AND POTENTIAL OF THE CAP ERODING. IF CONVECTION IS ABLE TO INITIATE THE AMOUNT OF CAPE AND SHEAR WILL SUPPORT SUPERCELLS INCLUDING LARGE HAIL. SEVERE THUNDERSTORMS WILL MOVE/PROPAGATE EWD INTO NRN HIGH PLAINS BY THIS EVENING...LIKELY DEVELOPING UPSCALE INTO ONE OR MORE MCS/S ACCOMPANIED BY DAMAGING WINDS ALONG WITH THE LARGE HAIL AND ISOLATED TORNADO POTENTIAL. ...SD/NEB/WRN IA... BY LATER THIS AFTERNOON/EVENING SEVERE THUNDERSTORM DEVELOPMENT WILL RESPOND TO THE VERY UNSTABLE WARM SECTOR SURGING NWD THRU CENTRAL PLAINS WITH MLCAPES AOA 4000 J/KG BY MID AFTERNOON AND BEING LIFTED BY RETREATING E/W SURFACE BOUNDARY VICINITY KS/NEB BORDER. VEERING SHEAR PROFILES COUPLED WITH THE HIGH INSTABILITY...SUPPORT SUPERCELLS INCLUDING TORNADO AND VERY LARGE HAIL THREAT. AGAIN SOON AFTER INITIATION STORMS WILL DEVELOP UPSCALE TO FORWARD PROPAGATING MCS/S AND AN INCREASING CONCERN FOR DAMAGING WINDS. OVERNIGHT THERE IS CERTAINLY A POTENTIAL FOR A DERECHO TYPE WIND EVENT TRACKING FROM NEB INTO IA...WITH DETAILS YET TO BE DETERMINED. HAVE SHIFTED MDT RISK S AND W OUT OF PORTIONS OF SD AND IA GIVEN THAT THE FOCUS OF CONVERGENCE WITH THE LOW LEVEL JET THIS EVENING IS ACROSS NEB INTO WRN IA. ...NEW ENGLAND AND SERN NY/NJ TODAY... COLD FRONT EXTENDS FROM WRN NY INTO SERN QUEBEC WITH A PRE-FRONTAL TROUGH FROM SERN NY NEWD INTO THE NEW ENGLAND STATES. DIABATIC WARMING OF THE MOIST BOUNDARY LAYER IS DESTABILIZING THE WARM SECTOR...BUT MLCAPE SHOULD REMAIN BELOW 2000 J/KG DUE TO MODEST /6 C/KM 700-500 MB/ LAPSE RATES. WEAK CAP AND DEEPER FORCING FOR ASCENT ASSOCIATED VORTICITY MAXIMUM MOVING THROUGH SRN QUEBEC IS CONTRIBUTING TO THE DEVELOPMENT OF STORMS ACROSS NRN ME AS WELL AS FARTHER SOUTHWEST ALONG THE FRONT AND IN PRE-FRONTAL WARM SECTOR. A BELT OF 35-40 KT FLOW ALOFT ALONG SRN PERIPHERY OF UPPER TROUGH IS CONTRIBUTING TO 30-35 KT UNIDIRECTIONAL WLY BULK SHEAR. THIS ENVIRONMENT WILL SUPPORT MIXED CONVECTIVE MODES WITH MULTICELL LINE SEGMENTS...A FEW SMALL CLUSTERS AS WELL AS SOME DISCRETE CELLS WITH MODEST UPDRAFT ROTATION. ..HALES/STOPPKOTTE.. 06/20/2010 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z