SWOMCD
SPC MCD 190042
MNZ000-NDZ000-MTZ000-190245-
MESOSCALE DISCUSSION 0833
NWS STORM PREDICTION CENTER NORMAN OK
0742 PM CDT FRI MAY 18 2007
AREAS AFFECTED...MUCH OF ND EWD INTO NWRN MN
CONCERNING...SEVERE THUNDERSTORM WATCH 279...
VALID 190042Z - 190245Z
THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 279
CONTINUES.
THROUGH 02-04Z...GREATEST SEVERE WEATHER THREAT IS EXPECTED TO EXIST
ACROSS CNTRL AND SRN PORTIONS OF WW 279 AREA.
LATEST MESOANALYSIS INDICATED COLD FRONT/OUTFLOW COMPOSITE BOUNDARY
SURGING SWD AT AROUND 25 KT THROUGH CNTRL ND...WITH THIS FEATURE
EXTENDING ALONG A LINE FROM 30 E ISN TO N60 TO 10 SE GFK AS OF
0020Z. SCATTERED TSTMS ARE IN PROGRESS TO THE N OF THIS BOUNDARY
OVER ERN MOUNTRAIL...WARD...MCHENRY AND PIERCE COUNTIES WITH MORE
WIDELY SCATTERED DEVELOPMENT TO THE S FROM DUNN AND MERCER COUNTIES
SEWD TO MORTON AND GRANT COUNTIES. 00Z BIS SOUNDING SHOWED THE
PRESENCE OF QUITE STEEP LAPSE RATES AND A DEEP MIXED BOUNDARY LAYER
AHEAD OF THIS COMPOSITE BOUNDARY WITH MLCAPES OF AROUND 1000 J/KG.
VERTICAL SHEAR WAS MARGINAL...THOUGH STILL SUFFICIENT FOR SOME STORM
ORGANIZATION.
EXPECT THE SEVERE THREAT TO DIMINISH WITH ONGOING STORMS TO THE N OF
THIS SURGING FRONTAL BOUNDARY OWING TO STRENGTHENING LOW-LEVEL
STABILITY DUE TO WET BULB COOLING AND/OR COLD ADVECTION. THE BETTER
POTENTIAL FOR A FEW SEVERE STORMS WILL EXIST WITHIN PRE-FRONTAL AIR
MASS NEAR AND E OF BIS SHOULD ONGOING STORMS W OF BIS BECOME BETTER
ORGANIZED.
FARTHER TO THE E...A SUPERCELL WHICH DEVELOPED OVER GRIGGS COUNTY
HAS WEAKENED AS WELL APPARENTLY DUE TO THE INGESTION OF CONSIDERABLE
OUTFLOW FROM IT/S SURGING REAR FLANK DOWNDRAFT. 00Z ABR SOUNDING
WAS QUITE SIMILAR TO THAT OF BIS...SUGGESTING THAT SOME SEVERE
THREAT WILL CONTINUE WITH THIS STORM IF IT CAN RE-ORGANIZE ALONG THE
LEADING EDGE OF THIS STORM-SCALE OUTFLOW BOUNDARY.
.MEAD.. 05/19/2007
..PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...FGF...BIS...GGW...
49210423 49089489 48479506 48319544 47039540 46949609
46529611 46510087 46900127 46860314 47190329 47250417
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