July 15 Severe Weather Discussion

There is a slight risk of severe weather in Montana, Eastern Dakotas, Northeast Nebraska, Minnesota, North Iowa.

STRONG-SEVERE ELEVATED TSTMS ARE IN PROGRESS THIS MORNING ACROSS
   PORTIONS OF WRN/CNTRL MN WHERE LOW-LEVEL WAA/ISENTROPIC ASCENT IS
   BEING ENHANCED BY VEERING NOCTURNAL LLJ.  12Z ABR SOUNDING SHOWS
   THAT THIS ACTIVITY IS BEING FUELED BY A THERMODYNAMIC ENVIRONMENT
   CHARACTERIZED BY VERY MOIST BOUNDARY LAYER AND STEEP MIDLEVEL LAPSE
   RATES WITH MUCAPE OF 3000-3500+ J/KG.  THOUGH THE LLJ WILL DIMINISH
   THROUGH THE REMAINDER OF THE MORNING...WEAK WAA WILL
   PERSIST...LIKELY SUSTAINING ONGOING ACTIVITY WITH A CONTINUED THREAT
   FOR MAINLY LARGE HAIL.
   
   BY AFTERNOON...CONSIDERABLE UNCERTAINTY EXISTS WITH REGARD TO SEVERE
   WEATHER POTENTIAL DUE TO THE TENDENCY FOR MIDLEVEL HEIGHT RISES IN
   THE WAKE OF SHORT WAVE TROUGH CURRENTLY LIFTING NEWD THROUGH
   ND...AND THE LINGERING EFFECTS OF ONGOING STORMS ACROSS MN.  ONE
   AREA OF ENHANCED TSTM POTENTIAL WILL LIKELY BE ALONG THE LEADING
   EDGE OF CLOUD SHIELD ASSOCIATED WITH A CONVECTIVELY INDUCED
   VORTICITY MAXIMUM OVER CNTRL NEB WHICH WILL CONTINUE NEWD THROUGH
   THE MID MO VALLEY TODAY.  HERE...DAYTIME HEATING COMBINED WITH
   BOUNDARY LAYER DEWPOINTS IN THE 70S WILL YIELD A STRONGLY UNSTABLE
   AIR MASS WITH MLCAPE APPROACHING 3000-3500 J/KG.  STRONGER
   DEEP-LAYER SHEAR WILL REMAIN FARTHER TO THE N/NW OF MCV TRACK WITH
   ENVIRONMENT SUPPORTIVE OF MULTICELL AND MARGINAL SUPERCELL STORM
   MODES.  HAIL AND LOCALLY DAMAGING WINDS WILL BE THE MAIN THREATS.
   
   ELSEWHERE...ISOLATED TO WIDELY SCATTERED SEVERE TSTMS WILL BE
   POSSIBLE ALONG SURFACE FRONT WHICH WILL STALL THIS AFTERNOON FROM
   THE RED RIVER VALLEY INTO CNTRL NEB.  LARGE HAIL AND DAMAGING WINDS
   ARE POSSIBLE WITH THE GREATEST POTENTIAL FOR A TORNADO OR TWO
   EXISTING ALONG OUTFLOW-REINFORCED WARM FRONT LIFTING NWD/NEWD
   THROUGH FAR ERN ND AND NWRN MN.
   
   ...NRN HIGH PLAINS...
   
   MIDLEVEL HEIGHT GRADIENT WILL TIGHTEN TODAY BETWEEN STRONG VORTICITY
   MAXIMUM TRANSLATING ACROSS CNTRL SASKATCHEWAN AND BUILDING RIDGE
   AXIS OVER THE NRN PLAINS INTO UPPER MS VALLEY.  AND WHILE
   LARGE-SCALE FORCING WILL REMAIN NEGLIGIBLE THROUGH THE DIURNAL
   HEATING CYCLE...CONVERGENCE ALONG WEAK SURFACE FRONT AND OROGRAPHIC
   INFLUENCES WILL LIKELY FOSTER WIDELY SCATTERED TSTM DEVELOPMENT THIS
   AFTERNOON INTO EVENING.  RESIDUAL BOUNDARY LAYER DEWPOINTS IN THE
   50S BENEATH STEEP MIDLEVEL LAPSE RATES WILL YIELD MODERATE
   INSTABILITY LATER TODAY WITH MLCAPE OF 1000-1500 J/KG.  WHEN COUPLED
   WITH VERTICALLY VEERING WIND PROFILES AND 35-50 KT OF DEEP-LAYER
   SHEAR...SETUP WILL FAVOR SUPERCELL STORM MODES WITH THE PRIMARY
   HAZARDS BEING LARGE HAIL AND DAMAGING WIND GUSTS.
   
   ...GULF COAST STATES...
   
   FORCING ASSOCIATED WITH QUASI-STATIONARY MIDLEVEL VORTICITY MAXIMUM
   AND RESIDUAL SYNOPTIC- AND MESO-SCALE BOUNDARIES WILL SERVE AS THE
   FOCI FOR WIDESPREAD TSTM ACTIVITY THROUGH THE DIURNAL HEATING CYCLE.
   GIVEN THE PRESENCE OF A VERY MOIST AIR MASS /I.E. PW VALUES IN
   EXCESS OF TWO INCHES/ AND STEEPENING LOW-LEVEL LAPSE
   RATES...ENVIRONMENT WILL BECOME SUPPORTIVE OF STRONG WET MICROBURSTS
   CAPABLE OF LOCALLY DAMAGING WIND GUSTS.