MESO: Mesoscale Discussion 0708

ACUS11 KWNS 100657
SWOMCD
SPC MCD 100656
MNZ000-SDZ000-NDZ000-100830-

MESOSCALE DISCUSSION 0708
NWS STORM PREDICTION CENTER NORMAN OK
0156 AM CDT TUE MAY 10 2011

AREAS AFFECTED...NWRN SD AND PARTS OF SRN/CENTRAL AND ERN ND

CONCERNING...SEVERE THUNDERSTORM WATCH 267...

VALID 100656Z - 100830Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 267
CONTINUES.

GIVEN CURRENT CONVECTIVE TRENDS ACROSS NWRN SD SHOWING A LOWER
NUMBER OF STRONGER STORMS...WW 267 WILL BE ALLOWED TO EXPIRE AS
SCHEDULED AT 08Z. UNTIL THEN...AND ALSO THROUGH THE OVERNIGHT
ACROSS SRN/CENTRAL AND ERN ND...ISOLATED SEVERE STORMS REMAIN
POSSIBLE WITH HAIL BEING THE PRIMARY THREAT FROM THE ELEVATED
ACTIVITY.

RECENT WATER VAPOR IMAGERY SHOWED A SHORTWAVE TROUGH LOCATED OVER
ERN WY...WITH THIS FEATURE EXPECTED TO MOVE INTO THE WRN DAKOTAS BY
12Z RESULTING IN THE STRONGEST FORCING ALOFT TO AFFECT THE WRN
DAKOTAS. ALTHOUGH EFFECTIVE BULK SHEAR REMAINS STRONG /AROUND 50
KT/ ACROSS THE VALID PART OF WW 267 TO SUPPORT ORGANIZED
STORMS...WEAKENING AVAILABLE INSTABILITY IN THIS AREA SUGGESTS THE
OBSERVED DECREASE IN STRONGER UPDRAFTS SHOULD PERSIST.

MEANWHILE...A 50 KT SSELY LLJ EXTENDS ACROSS ERN SD WITH STRONG LOW
LEVEL WAA EXPECTED TO DEVELOP NWD INTO ND OVERNIGHT/EARLY THIS
MORNING AS THE ABOVE MENTIONED TROUGH AND EWD EXTENDING WARM FRONT
SPREAD NWD. THE LLJ WILL MAINTAIN A FEED OF MODERATE INSTABILITY
INTO CENTRAL/ERN ND. THIS COMBINED WITH THE LOW LEVEL WAA WILL
SUPPORT TSTMS DEVELOPING/MOVING NWD...BUT GIVEN STRONGER FORCING
ALOFT REMAINING WEST OVER THE WRN DAKOTAS...THE OVERALL COVERAGE OF
STRONGER STORMS IS NOT EXPECTED TO BE SUFFICIENT TO WARRANT A NEW
WATCH.

..PETERS.. 05/10/2011

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

ATTN...WFO...FGF...ABR...BIS...UNR...

LAT...LON 44290097 44360256 44940367 45930326 47600037 47719841
47599706 46269641 45879640 46069758 46369902 45860011
44690047 44440040 44290097

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