The SPC is forecasting ...severe thunderstorms expected over parts of the northeast us this afternoon.... Please read the latest public statement about this event.
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SPC AC 102229 DAY 1 CONVECTIVE OUTLOOK AMEND 1 NWS STORM PREDICTION CENTER NORMAN OK 0529 PM CDT TUE JUN 10 2008 VALID 102225Z - 111200Z ...THERE IS A MDT RISK OF SVR TSTMS ACROSS PARTS OF VT...NH...ERN NY...ERN PA...NJ...MD AND NRN VA... ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF NEW ENGLAND...THE MID-ATLANTIC...ERN GREAT LAKES...CNTRL APPALACHIAN MTNS... ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE NRN PLAINS AND NRN HIGH PLAINS... ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE CNTRL PLAINS... AMENDED TO ADD SLIGHT RISK IN NRN AND ERN MT AND ADDED 5% TOR IN WRN KS ...NRN AND ERN MT... A LINE OF ORGANIZED THUNDERSTORMS IS ONGOING FROM NORTH OF BILLINGS TO NORTHEAST OF GREAT FALLS. THIS ACTIVITY IS IN A STRONGLY SHEARED ENVIRONMENT UPSTREAM FROM AN IMPRESSIVE UPPER-LEVEL TROUGH/LOW. STEEPENING LOW-LEVEL LAPSE RATES AND STRONG LOW-LEVEL FLOW SHOULD SUPPORT A WIND DAMAGE THREAT AS THE LINE MOVES EWD THIS EVENING. LARGE HAIL WILL ALSO BE POSSIBLE WITH THE MORE INTENSE CELLS. ...NERN STATES... COLD FRONT CURRENTLY FROM WRN NY SWWD INTO CNTRL KY WILL CONTINUE EWD THIS AFTERNOON AND TONIGHT IN ASSOCIATION WITH SHORT WAVE TROUGH LIFTING NEWD THROUGH THE LOWER GREAT LAKES. THE STRONGEST AIR MASS DESTABILIZATION HAS OCCURRED ALONG PRE-FRONTAL/LEE TROUGH FROM CNTRL NY SWD INTO THE PIEDMONT REGION WHERE DEWPOINTS IN THE 60S TO LOWER 70S IN CONJUNCTION WITH STRONG DAYTIME HEATING ARE CONTRIBUTING TO MLCAPES OF 2000-2500 J/KG. MCS WHICH INITIATED OVER WRN NY EARLIER TODAY IS IN PROGRESS ALONG THE INTERNATIONAL BORDER OVER NRN NEW ENGLAND...WELL IN ADVANCE OF MIDLEVEL AND SURFACE TROUGHS. DOWNSTREAM AIR MASS EWD INTO ME IS HOT AND MOIST WHICH SHOULD SUPPORT AN EWD CONTINUATION OF SYSTEM THIS AFTERNOON INTO EVENING. LARGE HAIL AND DAMAGING WINDS WILL REMAIN THE PRIMARY SEVERE WEATHER HAZARDS. ADDITIONAL TSTMS ARE EXPECTED TO INCREASE IN COVERAGE AND INTENSITY IN THE LEE OF THE HIGHER TERRAIN AND/OR ALONG LEE TROUGH LATE THIS AFTERNOON INTO EVENING AS LEADING EDGE OF STRONGER HEIGHT FALLS ATTENDANT TO SHORT WAVE TROUGH BEGIN TO OVERSPREAD MODERATELY UNSTABLE BOUNDARY LAYER. RUC OBJECTIVE FIELDS AND REGIONAL VWPS INDICATE THAT THE STRONGER MID AND HIGH-LEVEL WIND FIELDS /AND RESULTANT VERTICAL SHEAR/ WILL PERSIST OVER NY/PA THROUGH THE REMAINDER OF THE DIURNAL HEATING CYCLE WITH A GENERAL DECREASE IN VERTICAL SHEAR SWD ALONG LEE TROUGH. LARGELY UNIDIRECTIONAL WSWLY TROPOSPHERIC FLOW COMBINED WITH THE MODERATE INSTABILITY AND STEEP LOW-LEVEL LAPSE RATES WILL BE SUPPORTIVE OF BOWING LINE SEGMENTS CAPABLE OF MAINLY DAMAGING WINDS AND LARGE HAIL THROUGH THIS EVENING. ...SERN MT INTO SWRN MN... DEEPENING LEE CYCLONE OVER E-CNTRL WY WILL SLOWLY DEVELOP SEWD THIS EVENING BEFORE TURNING MORE NEWD INTO N-CNTRL NEB LATE TONIGHT INTO WEDNESDAY MORNING. ASSOCIATED WARM FRONT INTENSIFYING FROM THIS LOW EWD ACROSS SRN SD/NRN NEB INTO CNTRL IA WILL CONCURRENTLY LIFT NWD THROUGH THE REMAINDER OF THE PERIOD. LATEST SURFACE OBSERVATIONS INDICATE AN AXIS OF MODEST BOUNDARY LAYER MOISTURE /DEWPOINTS IN THE MID 40S TO LOWER 50S/ WRAPPING NWD/NWWD AROUND SURFACE LOW THROUGH WRN SD INTO NERN WY. THIS AREA IS ON THE SRN FRINGE OF MORE PERSISTENT MID AND HIGH CLOUDS WHICH SHOULD ALLOW BOUNDARY LAYER TO BECOME SLIGHTLY TO MODERATELY UNSTABLE WITH SBCAPES APPROACHING 500-1000 J/KG. CUMULUS FIELD DEVELOPING IN DEEPER-MIXED BOUNDARY LAYER OVER CNTRL/ERN WY SUGGESTS THAT AIR MASS IS BECOMING INCREASINGLY SUPPORTIVE OF DEEP...MOIST CONVECTION. FURTHER HEATING/MOISTENING ALONG PRIMARY INSTABILITY AXIS SHOULD EVENTUALLY SUPPORT ISOLATED/SCATTERED TSTM DEVELOPMENT OVER PORTIONS OF NERN WY INTO WRN SD. CURRENT RAP VWP INDICATES STRONGLY VEERING WIND FIELDS THROUGH THE LOWEST 3-4 KM AGL WITH MORE THAN SUFFICIENT VERTICAL SHEAR FOR SUPERCELLS. LARGE HAIL AND DAMAGING WINDS APPEAR TO BE THE PRIMARY SEVERE WEATHER HAZARDS. FARTHER E...A STRONGER CAP WILL LIKELY PRECLUDE DIURNAL TSTM DEVELOPMENT ALONG WARM FRONT OVER SD. HOWEVER...INCREASING WAA/ISENTROPIC ASCENT ALONG NOSE OF 60+ LLJ SHOULD FOSTER ELEVATED TSTM DEVELOPMENT NEAR AND N OF SURFACE BOUNDARY. THE PRESENCE OF STEEP MIDLEVEL LAPSE RATES AND INCREASING LOW-LEVEL MOISTURE WILL CONTRIBUTE TO MODERATE ELEVATED INSTABILITY WITH MUCAPES OF 2000 J/KG. THIS INSTABILITY COMBINED WITH RATHER STRONG CLOUD-BEARING SHEAR SUGGESTS THE POTENTIAL FOR SUPERCELLS CAPABLE OF LARGE HAIL AND PERHAPS ISOLATED...DAMAGING WIND GUSTS. ...WRN KS... VISIBLE SATELLITE IMAGERY INDICATES A GROWING CUMULUS FIELD OVER THE TX PNHDL NWD INTO FAR WRN KS ALONG WRN EDGE OF A MORE MOIST BOUNDARY LAYER SURGING NWD THROUGH THE HIGH PLAINS. LATEST SHORT TERM MODEL GUIDANCE REMAINS CONSISTENT IN SUGGESTING THAT ISOLATED...DIURNAL TSTM DEVELOPMENT IS POSSIBLE ALONG DRYLINE LATER THIS AFTERNOON INTO EVENING. SHOULD INITIATION OCCUR...KINEMATIC ENVIRONMENT WILL BE SUPPORTIVE OF SUPERCELLS CAPABLE OF LARGE HAIL AND LOCALLY DAMAGING WINDS. FARTHER E...AN ISOLATED STORM OVER S-CNTRL KS APPEARS TO BE ASSOCIATED WITH THE SRN EXTENSION OF A WEAK SHORT WAVE TROUGH MOVING ACROSS KS. THIS STORM WILL BE CAPABLE OF SOME HAIL AS IT CONTINUES EWD. ..BROYLES.. 06/10/2008 CLICK TO GET WUUS01 PTSDY1 PRODUCT NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z