SPC 1630Z Day 1 Outlook
DAY 1 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1127 AM CDT WED JUN 20 2012 VALID 201630Z - 211200Z ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF WI...MN...AND IA... ...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF SOUTHERN KS AND THE TX/OK PANHANDLES... ...MN/WI/IA... AN EXPANSIVE UPPER RIDGE IS PRESENT TODAY OVER MOST OF THE EASTERN AND SOUTHERN STATES...WHILE AN UPPER TROUGH DOMINATES THE WEATHER OVER THE NORTHERN PLAINS. THE PRIMARY SURFACE BOUNDARY ASSOCIATED WITH THE TROUGH EXTENDS FROM NORTHWEST WI INTO CENTRAL NEB...THEN SOUTHWESTWARD INTO THE OK/TX PANHANDLES. THIS BOUNDARY WILL BE THE FOCUS FOR SCATTERED THUNDERSTORMS THIS AFTERNOON AND EVENING. A FAST-MOVING CLUSTER OF STORMS NEAR DLH WILL MOVE INTO LAKE SUPERIOR SOON. HOWEVER...CONVERGENCE ALONG THE TRAILING SURFACE BOUNDARY WILL LIKELY RESULT IN SCATTERED THUNDERSTORM DEVELOPMENT OVER PARTS OF WESTERN WI...SOUTHEAST MN...AND EASTERN IA BY MID/LATE AFTERNOON. THE AIR MASS AHEAD OF THE BOUNDARY IS QUITE MOIST AND WILL BECOME MODERATELY UNSTABLE WITH MLCAPE VALUES OVER 2000 J/KG. STEERING FLOW PARALLEL WITH THE BOUNDARY WILL LIKELY RESULT IN A LONG SQUALL LINE THIS EVENING ALONG THE BOUNDARY AS IT MOVES ACROSS THE SLIGHT RISK AREA. LAPSE RATES ARE NOT PARTICULARLY STEEP...BUT THE POTENTIAL EXISTS FOR A FEW BOW/LEWP STRUCTURES ALONG THE LINE RESULTING IN CORRIDORS OF DAMAGING WINDS AND HAIL. ...KS/OK/TX... MORNING SURFACE ANALYSES SHOW A COLD FRONT SURGING SOUTHWARD ALONG THE CENTRAL HIGH PLAINS. THIS BOUNDARY WILL LIKELY EXTEND FROM NORTHEAST NM INTO SOUTH-CENTRAL KS BY LATE AFTERNOON. FULL HEATING WILL RESULT IN DEEP MIXING AND HELP WEAKEN THE CAP...RESULTING IN SCATTERED THUNDERSTORM DEVELOPMENT ALONG THE FRONT. 30+ DEGREE SURFACE T-TD SPREADS...STEEP LOW LEVEL LAPSE RATES...MLCAPE VALUES OVER 2000 J/KG...AND STRENGTHENING NORTHWESTERLY MID LEVEL WINDS WILL COMBINE TO YIELD A RISK OF ISOLATED SEVERE STORMS. LOCALLY DAMAGING WINDS WILL BE THE MAIN THREAT...ALTHOUGH HAIL IS ALSO POSSIBLE IN THE STRONGEST STORMS. ...NY/VT... MODELS DIFFER ON EXTENT OF CONVECTION THAT WILL AFFECT NY/NEW ENGLAND THIS AFTERNOON AND EVENING. THE AREA MOST LIKELY TO SEE A FEW THUNDERSTORMS WILL BE ACROSS NORTHEAST NY AND NORTHERN VT. IF STORMS CAN FORM IN THIS AREA...RATHER STRONG NORTHWESTERLY MID/UPPER LEVEL FLOW COMBINED WITH MODERATE INSTABILITY WILL POSE A RISK OF A FEW STRONG/SEVERE STORMS CAPABLE OF GUSTY WINDS AND HAIL. ..HART/MOSIER.. 06/20/2012
via SPC Forecast Products http://www.spc.noaa.gov/products/outlook/day1otlk_1630.html
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