Severe Storm Outlook Narrative (AC)
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780
ACUS11 KWNS 231841
SWOMCD
SPC MCD 231841
MNZ000-SDZ000-NDZ000-232115-

MESOSCALE DISCUSSION 1373
NWS STORM PREDICTION CENTER NORMAN OK
0141 PM CDT SAT JUL 23 2016

AREAS AFFECTED...PORTIONS OF ERN SD...SERN ND...WRN MN

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 231841Z - 232115Z

PROBABILITY OF WATCH ISSUANCE...60 PERCENT

SUMMARY...THE AREA IS BEING MONITORED FOR AN INCREASING RISK FOR SVR
TSTMS THIS AFTERNOON. WW ISSUANCE WILL BE POSSIBLE WITHIN THE NEXT
FEW HOURS.

DISCUSSION...TSTMS ARE EXPECTED TO INCREASE IN COVERAGE/INTENSITY
DURING THE NEXT FEW HOURS...ESPECIALLY IN THE 1930Z-2200Z TIME
FRAME...AS ASCENT PRECEDING A SHORTWAVE TROUGH CONTINUES TO OVERTAKE
THE DIURNALLY DESTABILIZING BOUNDARY LAYER. THE STRONGEST
INSTABILITY -- CHARACTERIZED BY 1500-2500 J/KG OF MLCAPE -- EXTENDS
ACROSS CNTRL INTO NERN SD. THIS IS WHERE THE STRONGEST SFC HEATING
HAS OCCURRED AMIDST SFC DEWPOINTS IN THE LOWER 70S. AIR-MASS
RECOVERY IS UNDERWAY ACROSS PARTS OF W-CNTRL/SWRN MN IN THE WAKE OF
EARLIER CONVECTION...AND DESTABILIZATION IN THESE AREAS MAY OCCUR
DURING THE NEXT FEW HOURS -- ESPECIALLY AS LOW-LEVEL SLYS INCREASE
AHEAD OF THE TROUGH AND PROMOTE POSITIVE THETA-E ADVECTION.

INCIPIENT CONVECTION IS ALREADY DEVELOPING NEAR/W OF THE ABERDEEN SD
AREA...AND ADDITIONAL CONVECTION SHOULD DEVELOP NWD INTO SERN ND
ATOP RESIDUAL OUTFLOW AS FORCING FOR ASCENT INCREASES. LARGE HAIL
AND DMGG WINDS MAY ACCOMPANY INITIAL ACTIVITY...AS 35-45 KT OF
EFFECTIVE SHEAR POTENTIALLY SUPPORTS INITIAL SUPERCELL TSTMS/TSTM
CLUSTERS...AND A TORNADO CANNOT BE RULED OUT GIVEN BACKED SFC WINDS
AND RELATED STREAMWISE VORTICITY.

HOWEVER...CONGEALING COLD POOLS SHOULD TEND TO YIELD UPSCALE GROWTH
INTO AN MCS SPREADING EWD/SEWD...INVOF A NW/SE EFFECTIVE BOUNDARY
ANALYZED BEHIND THE BACK EDGE OF CONVECTION LIFTING NEWD ACROSS THE
UPPER MS VALLEY. THE OVERALL SVR HAZARD SHOULD TRANSITION TOWARD
DMGG WIND GUSTS BY LATE AFTERNOON AND INTO THE EVENING IF AN MCS
WERE TO EVOLVE.

GIVEN THE RELATIVELY RECENT DIURNAL MODIFICATION OF RAIN-COOLED
BOUNDARY-LAYER AIR IN WRN MN/SERN ND/VICINITY...AND RELATED
MESOSCALE VARIABILITY IN THE RATE OF BUOYANCY GAINS...THERE IS
UNCERTAINTY REGARDING THE OVERALL EVOLUTION OF THE SVR RISK. IN
PARTICULAR...THE TIMING OF THE DEVELOPMENT OF A MORE SUBSTANTIAL SVR
RISK...AND ITS AREAL COVERAGE ARE SOMEWHAT UNCERTAIN.
HOWEVER...CONVECTIVE TRENDS WILL CONTINUE TO BE MONITORED.

..COHEN/WEISS.. 07/23/2016

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...MPX...FGF...FSD...ABR...BIS...

LAT...LON   44909842 46139863 46789793 46869664 46349545 44599456
            43899599 44039750 44909842




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