MESO: Mesoscale Discussion 1851

ACUS11 KWNS 072024
SWOMCD
SPC MCD 072024
SDZ000-NDZ000-MTZ000-WYZ000-072230-

MESOSCALE DISCUSSION 1851
NWS STORM PREDICTION CENTER NORMAN OK
0324 PM CDT SAT SEP 07 2013

AREAS AFFECTED...MT...SD...ND

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 072024Z - 072230Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...THE CHANCE FOR A FEW SEVERE TSTMS WITH LARGE HAIL AND HIGH
WINDS WILL INCREASE THROUGH THE REST OF THE AFTERNOON FROM SOUTHEAST
MT ACROSS ADJACENT PORTIONS OF SW ND AND NW SD. A WATCH IS POSSIBLE
IN THE NEXT 1-2 HOURS.

DISCUSSION...A CORRIDOR OF MODERATE INSTABILITY HAS DEVELOPED ALONG
A STALLED FRONTAL SEGMENT THAT STRETCHES FROM CNTRL SD NWWD TO ERN
MT. STRONG HEATING ALONG AND SOUTH OF THIS ZONE SHOULD CONTINUE TO
AID IN THE EROSION OF ANY REMAINING CONVECTIVE INHIBITION AND
SUPPORT AT LEAST ISOLATED SFC-BASED STORM DEVELOPMENT OVER THE NEXT
FEW HOURS. WHILE LARGE SCALE CONTRIBUTION TO ASCENT IS SUBTLE...LOW
LEVEL FEATURES IN ADDITION TO THE STALLED FRONTAL SEGMENT INCLUDE
RAIN-COOLED/DIFFERENTIAL HEATING BOUNDARY EXTENDING FROM SERN MT
ACROSS WRN ND...AS WELL AS A WEAK LEE/THERMAL TROUGH EXTENDING SOUTH
ACROSS SERN MT. ENHANCED CONVERGENCE/LIFT NEAR THE TRIPLE POINT OF
THESE ANALYZED MESOSCALE FEATURES MAY BE AIDING MORE ROBUST TSTM
DEVELOPMENT ACROSS NRN CUSTER COUNTY ATTM.

ADDITIONAL CONVECTIVE DEVELOPMENT IS EXPECTED TO OCCUR AS A
MID-LEVEL SWLY WIND MAX OF 30-35KT CRESTS THE UPPER RIDGE AXIS FROM
NRN WY TO ERN MT OVER THE NEXT FEW HOURS. RESULTING DEEP-LAYER SPEED
AND DIRECTIONAL SHEAR WILL NOMINALLY SUPPORT UPDRAFT
ORGANIZATION/INTENSIFICATION. A NARROW NW-SE ORIENTED CORRIDOR OF
ENHANCED LOW LEVEL SHEAR WILL BE SITUATED ALONG AND NORTH OF THE
REMNANT FRONTAL ZONE. ANY DISCRETE CELLS THAT CAN INTERACT WITH THIS
BOUNDARY MAY HAVE AN OPPORTUNITY AT DEVELOPING STRONGER LOW-LEVEL
MESOCYCLONES. SEVERE WEATHER POTENTIAL IN THE FORM OF HAIL AND WIND
MAY INCREASE THROUGH EARLY EVENING WITH THE POSSIBILITY OF A SMALL
MCS EVOLVING IF STORM COVERAGE BECOMES GREAT ENOUGH.

THE REGION WILL CONTINUE TO BE MONITORED FOR A POSSIBLE WATCH IN THE
NEXT COUPLE OF HOURS.

..CARBIN/MEAD.. 09/07/2013

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

ATTN...WFO...BIS...UNR...BYZ...GGW...

LAT...LON 44510305 44850421 45380660 45770733 46820731 47350594
46500290 46060220 45250202 44510305

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