000
ACUS11 KWNS 260149
SWOMCD
SPC MCD 260148
SDZ000-NDZ000-MTZ000-WYZ000-260315-

MESOSCALE DISCUSSION 0800
NWS STORM PREDICTION CENTER NORMAN OK
0848 PM CDT SAT MAY 25 2013

AREAS AFFECTED...EASTERN MT/SOUTHERN ND/WESTERN AND CENTRAL SD

CONCERNING...TORNADO WATCH 217...

VALID 260148Z - 260315Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 217 CONTINUES.

SUMMARY...TORNADO WATCH 217 CONTINUES UNTIL 04Z...WITH DAMAGING
WINDS/LARGE HAIL AND A TORNADO OR TWO REMAINING POSSIBLE ACROSS
EASTERN MT AND WESTERN/NORTHERN SD INTO SOUTHERN ND. EARLY
INDICATIONS ARE THAT AN ADDITIONAL WATCH /OR EXTENSION/ MIGHT BE
WARRANTED BEYOND 04Z ESPECIALLY ACROSS PORTIONS OF SD.

DISCUSSION...ALONG AN ANGLING ROUGHLY NORTHWEST-SOUTHEAST ORIENTED
FRONTAL ZONE...SCATTERED SEMI-DISCRETE STORMS/SOME SUPERCELLS
CONTINUE ACROSS EASTERN MT INTO NORTHWEST SD...IN ADDITION TO NEAR
THE RAPID CITY AREA ON A MORE ISOLATED BASIS AS OF 0130Z. BASED ON
00Z OBSERVED SOUNDINGS FROM GLASGOW MT/RAPID CITY SD AND
SUPPLEMENTAL SPC MESOANALYSIS DATA...MLCAPE GENERALLY RANGES FROM
1000-1750 J/KG WITHIN THIS CORRIDOR COINCIDENT WITH 45-50 KT OF
EFFECTIVE BULK SHEAR. SCENARIO WILL REMAIN FAVORABLE FOR CONTINUED
SEVERE STORMS/SUPERCELLS CAPABLE OF SEVERE HAIL AND LOCALLY DAMAGING
WINDS. SOME TORNADO POTENTIAL WILL ALSO CONTINUE OVER THE NEXT HOUR
OR TWO /ROUGHLY THROUGH 03Z/ ESPECIALLY WITHIN A CORRIDOR FROM
EXTREME SOUTHEAST MT/NORTHWEST ND SOUTHEASTWARD TOWARD THE RAPID
CITY AREA/EASTWARD ALONG THE I-90 VICINITY. IN THIS
CORRIDOR...FACTORS SUCH AS NOCTURNALLY INCREASING BOUNDARY LAYER
CINH WILL BE OFFSET BY LOWERING TEMP-DEWPOINT SPREADS AND INCREASING
SOUTHEASTERLY WINDS WITHIN THE LOWEST 1-2 KM...WITH A
BACKING/STRENGTHENING TREND WELL NOTED IN RECENT RAPID CITY WSR-88D
VWP DATA /30 KT AROUND 1 KM/.

MEANWHILE...A WELL-ORGANIZED QUASI-LINEAR COMPLEX WITH EMBEDDED
SMALL BOWING STRUCTURES CONTINUES TO MAKE A MODEST EASTWARD MOTION
ACROSS FAR SOUTHERN ND /NEARING THE MISSOURI RIVER AND BISMARCK AREA
AT 0130Z/ AND NORTHERN SD. DAMAGING WINDS/SOME SEVERE HAIL WILL
REMAIN A POSSIBILITY IN THE SHORT-TERM AND/OR ESPECIALLY ALONG THE
MCS SOUTHERN FLANK ACROSS NORTHERN ND...WITH A MORE STABLE AIRMASS
LOCATED PROGRESSIVELY EAST OF THE MISSOURI RIVER.

..GUYER.. 05/26/2013

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

ATTN...WFO...FSD...ABR...BIS...UNR...BYZ...GGW...

LAT...LON   46000676 48030635 48330471 46800368 46660199 46920021
            43939900 43120065 43800275 45070439 46000676