SPC 1730Z Day 2 Outlook
DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1230 PM CDT FRI JUN 21 2013 VALID 221200Z - 231200Z ...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE NORTH-CENTRAL PLAINS TO THE UPPER MS VALLEY/GREAT LAKES... ...SYNOPSIS... WITHIN A RIBBON OF MODERATELY STRONG SUMMERTIME SOUTHWESTERLY MID-LEVEL FLOW FROM THE GREAT BASIN TO THE NORTHERN PLAINS/UPPER MIDWEST...AN UPPER TROUGH CURRENTLY OVER THE NORTHERN INTERMOUNTAIN REGION IS EXPECTED TO BECOME MORE PROGRESSIVE AS IT SHIFTS EAST-NORTHEASTWARD TOWARD THE NORTHERN HIGH-PLAINS BY SATURDAY NIGHT. IN ASSOCIATION WITH A RELATIVELY MOIST AIRMASS AND SEMI-STATIONARY FRONTAL ZONE...ALBEIT MODIFIED BY MCS ACTIVITY/OUTFLOW...YET ANOTHER DAY OF SEVERE TSTMS CAN BE EXPECTED IN THE SAME GENERAL PORTIONS /AS TODAY/ OF THE NORTH-CENTRAL HIGH PLAINS INTO PARTS OF THE UPPER MIDWEST/PERHAPS GREAT LAKES REGION. ...NORTH-CENTRAL HIGH PLAINS TO THE UPPER MS VALLEY/GREAT LAKES... INITIALLY...CLUSTERS OF TSTMS ARE LIKELY TO BE ONGOING ACROSS THE UPPER MS VALLEY/GREAT LAKES VICINITY INCLUDING PORTIONS OF WI/MI. A FEW EARLY DAY SEVERE TSTMS /HAIL AND PERHAPS WIND/ CANNOT BE RULED OUT...BUT SUBSEQUENT SURFACE BASED SEVERE POTENTIAL IS UNCERTAIN/LOW PROBABILITY FOR AREAS SUCH AS MI/LOWER GREAT LAKES REGION GIVEN A LIKELY SEPARATION FROM THE PRIMARY INSTABILITY AXIS AND INFLUENCES OF PRIOR MCS/S ACROSS THE REGION. A MORE CERTAIN/CONSEQUENTIAL SEVERE RISK SEEMS LIKELY TO EVOLVE ACROSS PORTIONS OF THE NORTH-CENTRAL HIGH PLAINS...POTENTIALLY RELATIVELY EARLY IN THE DAY...AND ALMOST CERTAINLY BY EARLY/MID AFTERNOON AS HEIGHT FALLS/APPRECIABLE FORCING FOR ASCENT BEGINS TO INFLUENCE THE REGION VIA THE APPROACHING NORTHERN ROCKIES UPPER TROUGH. WITH A RELATIVELY PERSISTENT SURFACE LOW ACROSS THE CENTRAL HIGH PLAINS...SUCH DEVELOPMENT IS LIKELY TO BE FOCUSED ALONG/NORTH OF A SOUTHWEST-NORTHEAST ORIENTED FRONTAL ZONE...AS MOIST LOW-LEVEL UPSLOPE TRAJECTORIES PERSIST TO ITS NORTH. SUCH DEVELOPMENT...LIKELY BECOMING INCREASINGLY SURFACE BASED DURING AFTERNOON...SHOULD OCCUR WITHIN A CORRIDOR FROM CENTRAL/EASTERN WY AND FAR SOUTHEAST MT INTO SD AND FAR WESTERN/NORTHERN PORTIONS OF NEB. STRONG VERTICAL SHEAR /40-50 KT/ AND MODERATE TO STRONG INSTABILITY /MOST CERTAIN AND PROBABLE NEB INTO EASTERN SD WHERE 3500+ J PER KG MLCAPE IS LIKELY/ WILL SUPPORT A COMBINATION OF SUPERCELLS AND SUSTAINED MULTICELLS CAPABLE OF LARGE HAIL AND A COUPLE OF TORNADOES. BUT GIVEN THE DEGREE OF FORCING FOR ASCENT AND RELATIVELY WEAK HIGH-LEVEL FLOW...IT SEEMS PROBABLE THAT RELATIVELY QUICK MCS DEVELOPMENT COULD OCCUR DURING THE AFTERNOON AND CERTAINLY BY SATURDAY EVENING. ACCORDINGLY...ONE OR MORE ORGANIZED CLUSTERS/MCS WITH A DAMAGING WIND THREAT SEEMS PROBABLE ACROSS PARTS OF THE MIDDLE MO VALLEY VICINITY POTENTIALLY INCLUDING PORTIONS OF NEB AND SOUTHERN/EASTERN SD INTO SOUTHERN MN/NORTHWEST IA. ...SOUTHERN HIGH PLAINS... STRONG HEATING IS AGAIN ANTICIPATED SATURDAY AFTERNOON IN VICINITY OF THE DRYLINE FROM SOUTHWEST KS INTO FAR WEST TX. WHILE VERTICAL SHEAR THROUGH A DEEP LAYER WILL REMAIN MODEST...STEEP LOW LEVEL LAPSE RATES/SUFFICIENT INSTABILITY WILL EXIST FOR LOCALLY STRONG/INTENSE UPDRAFTS CAPABLE OF ISOLATED BOUTS OF SEVERE HAIL AND WIND...PRIMARILY DURING THE LATE AFTERNOON/EARLY EVENING HOURS OF SATURDAY. PENDING SUBSEQUENT GUIDANCE INTO THE DAY 1 PERIOD...AREAS SUCH AS THE TX PANHANDLE COULD WARRANT A SLIGHT RISK UPGRADE. ..GUYER.. 06/21/2013
via SPC Forecast Products http://www.spc.noaa.gov/products/outlook/day2otlk_1730.html
Be First to Comment