NWS STORM PREDICTION CENTER NORMAN OK 1130 AM CDT SAT JUN 28 2014 VALID 281630Z - 291200Z ...THERE IS A SLGT RISK OF SVR TSTMS FROM THE SRN PLAINS ACROSS THE MIDDLE MO AND UPPER MS VALLEYS... ...SUMMARY... CONSIDERABLE THUNDERSTORM ACTIVITY APPEARS LIKELY THIS AFTERNOON AND EVENING FROM PARTS OF THE SOUTHERN PLAINS AND LOWER TO MID MISSOURI VALLEY NORTHWARD INTO THE UPPER MISSISSIPPI VALLEY. SOME OF THESE STORMS MAY BE ACCOMPANIED WITH DAMAGING WIND GUSTS AND HAIL. ...SRN PLAINS INTO LOWER MO VALLEY... CONVECTIVE COMPLEX OVER NRN OK IS PROGRESSING EWD/SEWD AND HAS MAINTAINED AN ISOLATED SEVERE RISK DURING THE MORNING. THE MCS IS LOCATED ALONG THE SRN PART OF THE NEGATIVELY TILTED UPPER TROUGH EXTENDING FROM WRN SD INTO FAR WRN OK...AND AS THIS SYSTEM BEGINS TO LIFT NEWD TOWARD THE LOWER MO VALLEY...INCREASING LARGE SCALE ASCENT WILL OVERSPREAD THE LOW LEVEL MOISTURE/INSTABILITY AXIS FROM CENTRAL OK INTO CENTRAL MO. EXTENSIVE CLOUD COVER REMAINS OVER THIS REGION WHICH WILL LIMIT THE INTENSITY OF DIABATIC HEATING ACROSS THE BROADER REGION...BUT BREAKS IN CLOUD COVER MAY PERMIT LOCALIZED POCKETS OF STRONGER INSTABILITY TO DEVELOP. VISIBLE IMAGERY/RADAR SHOW STORMS DEVELOPING ALONG THE LEADING EDGE OF THE NRN OK MCS AND EXTENDING NEWD ALONG A PRE-FRONTAL BOUNDARY FROM SERN KS INTO WEST CENTRAL MO WHERE OBJECTIVE MESOANALYSIS FIELDS INDICATE CIN IS DIMINISHING. WINDS ALOFT BACK IN THE MID-LEVELS TO A MORE SOUTHERLY COMPONENT WITH LARGELY UNIDIRECTIONAL SHEAR SUGGESTING POTENTIAL FOR SHORT LINEAR CONVECTIVE SEGMENTS TO DEVELOP. VERTICAL SHEAR OF 30-35 KT IN THE LOWEST 6 KM AND MODERATE INSTABILITY WITH MLCAPE OF 1500-2000 J/KG WILL PROMOTE STRONG/SEVERE STORMS WITH LARGE HAIL AND DAMAGING WIND GUSTS THE PRIMARY THREAT DURING THE AFTERNOON AND EVENING. OTHER MORE ISOLATED STORMS MAY DEVELOP ALONG/AHEAD OF THE NRN OK MCS AS THE OUTFLOW MOVES SEWD/SWD OVER WRN/CENTRAL OK AND THE ERN TX PANHANDLE WHERE STEEP LAPSE RATES ARE CONTRIBUTING TO AN INCREASINGLY UNSTABLE AIR MASS...WITH MLCAPE REACHING 2000-2500 J/KG THIS AFTERNOON. DYNAMIC FORCING FOR ASCENT WILL BE DIMINISHING AS THE UPPER TROUGH BEGINS TO LIFT NE OF THE AREA THIS AFTERNOON AND HEIGHTS RISE...HOWEVER CONVERGENCE ALONG THE OUTFLOW AND ZONES OF ENHANCED HEATING MAY BE SUFFICIENT FOR CURRENT STORMS TO INTENSIFY ALONG THE LEADING EDGE OF THE SYSTEM. LARGE HAIL AND DAMAGING WIND GUSTS WILL BE POSSIBLE INTO THE EVENING HOURS. ...MIDDLE MO VALLEY INTO THE UPPER MS VALLEY... A PRE-FRONTAL CONVERGENCE BOUNDARY IS EVIDENT IN VISIBLE SATELLITE IMAGERY ARCING FROM LOW OVER CENTRAL ND ACROSS ARCING SERN ND INTO SWRN MN AND WRN IA. THIS MAY PROVIDE A FOCUS FOR NEW THUNDERSTORM DEVELOPMENT THIS AFTERNOON AS HIGHER SURFACE DEW POINTS AROUND 70 ARE LOCATED ALONG/AHEAD OF THE BOUNDARY. CLOUDS AHEAD OF THE BOUNDARY WILL LIKELY INHIBIT TO SOME EXTENT THE MAGNITUDE OF DIABATIC HEATING AND DESTABILIZATION...HOWEVER...INCREASING LARGE SCALE ASCENT AHEAD OF THE APPROACHING UPPER TROUGH WILL ENHANCE CONVECTIVE POTENTIAL DURING THE AFTERNOON. A FEW STRONG/SEVERE STORMS ARE EXPECTED IN ASSOCIATION WITH SEVERAL LINEAR SEGMENTS AS THEY PROGRESS EWD/NEWD ACROSS THE REGION. ADDITIONAL STORMS ARE ALSO EXPECTED TO DEVELOP ALONG/AHEAD OF THE SURFACE FRONT AS IT MOVE EWD/NEWD ACROSS THE AREA WITH MODEL GUIDANCE INDICATING NEW STORMS FORMING OVER ERN PARTS OF SD AND NEB LATER THIS AFTERNOON. STRONGER CELLS WILL BE CAPABLE OF LARGE HAIL AND DAMAGING WIND GUSTS. ...WRN KS/SRN NEB LATE TONIGHT... A STRONG LOW LEVEL JET IS FORECAST TO DEVELOP OVER THE SRN HIGH PLAINS LATER TONIGHT WHICH WILL TRANSPORT LOW LEVEL MOISTURE NWD INTO WRN KS AND POSSIBLY SRN NEB. WARM ADVECTION AND CONVERGENCE AT THE NOSE OF THE LLJ MAY PROMOTE DEVELOPMENT OF PRIMARILY ELEVATED STORMS LATE IN THE PERIOD. MODEL GUIDANCE IS NOT CONSISTENT IN THE PREDICTION OF STRONG STORMS WITH THE OPERATIONAL AND PARALLEL NAM PARENT RUNS SHOWING A STRONGER INSTABILITY AND PRECIPITATION SIGNAL. THE 5 PER CENT HAIL AREA HAS BEEN TRENDED WWD INTO WRN KS AND SRN NEB FOR THIS LATE PERIOD POSSIBILITY AND WILL AWAIT LATER OBSERVATIONAL AND MODEL GUIDANCE TO FURTHER ASSESS THE THREAT.
samedi 28 juin 2014
Jun 28, 2014 1630 UTC Day 1 Convective Outlook
DAY 1 CONVECTIVE OUTLOOK
Inscription à :
Publier les commentaires (Atom)
Aucun commentaire:
Enregistrer un commentaire