The SPC has issued a mesoscale discussion this morning and will upgrade the next day one convective outlook that will be issued soon from general thunderstorms to their standard slight risk for severe weather for areas just to the west of Alabama. This slight risk should encompass much of Central Mississippi and could make it into Alabama.
A MCS leftover from yesterday’s severe weather across the Plains continues to push east today. The added uplift with this system’s outflow and a very warm and unstable air mass will allow for strong and possibly severe storms to develop across the region. We will be monitoring this activity very carefully today. We are already seeing scattered showers and thunderstorms develop this morning across Alabama. With any storms that develop today torrential rain, gusty winds, hail and frequent lightning will be the main concerns.
MESOSCALE DISCUSSION 1105
NWS STORM PREDICTION CENTER NORMAN OK
1019 AM CDT MON JUN 17 2013
AREAS AFFECTED…NRN LA…SE AR…CENTRAL MS
CONCERNING…OUTLOOK UPGRADE
VALID 171519Z – 171715Z
SUMMARY…DESTABILIZATION WITH SURFACE HEATING WILL SUPPORT RENEWED
STORM DEVELOPMENT ALONG OUTFLOW BOUNDARIES BY EARLY AFTERNOON…WITH
POTENTIAL FOR A FEW DAMAGING GUSTS. A PORTION OF NRN LA…SE
AR…AND CENTRAL MS WILL BE UPGRADED TO SLIGHT RISK IN THE 1630Z
UPDATE…AND A SEVERE TSTM WATCH COULD BE NEEDED BY EARLY AFTERNOON.
DISCUSSION…AN OVERNIGHT MCS IS NOW WEAKENING ACROSS WRN AR AND NE
TX…WITH THE LEADING EDGE OF THE PRECIPITATION DEMARCATED BY AN
EXTENSIVE NE-SW ORIENTED OUTFLOW BOUNDARY. A SEPARATE/SMALLER
CLUSTER OF STORMS ACROSS NRN MS HAS ALSO PRODUCED A WEAK OUTFLOW
BOUNDARY ALONG ITS SRN-WRN FLANK. BETWEEN THESE BOUNDARIES…STRONG
SURFACE HEATING IS UNDERWAY…AND REGIONAL 12Z SOUNDINGS FROM
SHV/JAN SHOW THE POTENTIAL FOR AFTERNOON MLCAPE VALUES AOA 3000 J/KG
WITH LITTLE CONVECTIVE INHIBITION ONCE SURFACE TEMPERATURES WARM
INTO THE 87-91 F RANGE. THUS…RENEWED THUNDERSTORM DEVELOPMENT IS
EXPECTED ALONG THE REMNANT OUTFLOW BOUNDARIES BY EARLY
AFTERNOON…IN AN ENVIRONMENT SUPPORTIVE OF STRONG
UPDRAFTS/PRECIPITATION LOADING…AS WELL AS DOWNBURSTS CAPABLE OF
PRODUCING DAMAGING GUSTS. THOUGH THE CONVECTION WILL REMAIN
MULTICELLULAR IN THE RELATIVELY WEAK VERTICAL SHEAR
ENVIRONMENT…THE OUTFLOW BOUNDARIES AND AN UPSTREAM MCV IN OK WILL
HELP PROVIDE SOME DEGREE OF ORGANIZATION TO THE CONVECTIVE CLUSTERS.
