MESOSCALE DISCUSSION 1456, AREAS AFFECTED...FAR ERN ND AND ADJACENT FAR NWRN MN CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

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MESOSCALE DISCUSSION 1456 NWS STORM PREDICTION CENTER NORMAN OK 0515 PM CDT THU JUL 12 2012 AREAS AFFECTED...FAR ERN ND AND ADJACENT FAR NWRN MN CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY VALID 122215Z - 122315Z PROBABILITY OF WATCH ISSUANCE...20 PERCENT SUMMARY...THE POTENTIAL IS LOW FOR AN ISOLATED TORNADO DURING THE REMAINDER OF THE AFTERNOON INTO THE EARLY EVENING ACROSS FAR ERN ND INTO ADJACENT COUNTIES OF NWRN MN. TSTMS WILL ALSO REMAIN POSSIBLE INTO CENTRAL ND...BUT THE SEVERE WEATHER THREAT SHOULD BE QUITE LOW. DISCUSSION...ALTHOUGH REGIONAL RADAR IMAGERY/LIGHTNING DATA SHOWED AN INCREASE IN TSTM COVERAGE IN FAR ERN/NERN ND SINCE 21Z GIVEN A MOIST/MODERATELY UNSTABLE ENVIRONMENT...THE POTENTIAL FOR SEVERE STORMS...INCLUDING AN ISOLATED TORNADO THREAT...IS EXPECTED TO REMAIN LOW LATE THIS AFTERNOON AND EARLY EVENING. 21Z MESOANALYSIS SHOWED A PERSISTENT AREA OF LOW PRESSURE IN NERN ND AND A SECOND LOW OVER NERN SD...WITH THE TSTM ACTIVITY DEVELOPING ALONG A SURFACE TROUGH EXTENDING SWD THROUGH FAR ERN ND. WEAK DEEP LAYER SHEAR IS NOT CONDUCIVE FOR SUPERCELLS AND 15-20 KT WSWLY MEAN FLOW HAS RESULTED IN STORMS MOVING E/NEWD OFF THE SURFACE BOUNDARY. DESPITE FAVORABLE SURFACE VORTICITY ALONG THE N-S ORIENTED TROUGH AND SUFFICIENT SFC-3 KM CAPE FOR NON-MESOCYCLONE TORNADO DEVELOPMENT...THE FACT THAT STORMS ARE NOT REMAINING ON THE BOUNDARY IS GREATLY REDUCING THE THREAT FOR ISOLATED TORNADOES. FARTHER W/NW INTO CENTRAL PARTS OF ND...A FEW STORMS HAVE DEVELOPED INVOF ANOTHER SURFACE TROUGH TRAILING SW TO W THEN NW THROUGH CENTRAL/NORTH CENTRAL ND. WEAK INSTABILITY/SHEAR PARAMETER SPACE SUGGESTS THIS ACTIVITY WILL HAVE A DIFFICULT TIME TO BECOME SUSTAINED AND PRODUCE A SEVERE WEATHER THREAT. TSTMS WILL REMAIN POSSIBLE AS ASCENT ALONG THE SRN EXTENT OF A VORT LOBE MOVES ACROSS NORTH CENTRAL/CENTRAL ND INTO THE EVENING.