SPC MD 706

MD 0706 CONCERNING SEVERE THUNDERSTORM WATCH 241… FOR PARTS OF CENTRAL AND ERN NEB


MESOSCALE DISCUSSION 0706
NWS STORM PREDICTION CENTER NORMAN OK
0954 PM CDT FRI MAY 04 2012

AREAS AFFECTED...PARTS OF CENTRAL AND ERN NEB

CONCERNING...SEVERE THUNDERSTORM WATCH 241...

VALID 050254Z - 050430Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 241
CONTINUES.

SUMMARY...THE SVR WEATHER THREAT THROUGH THE REST OF THE EVENING IS
EXPECTED TO BE CONFINED TO CENTRAL NEB AND POTENTIALLY INTO PARTS OF
NERN AND EAST CENTRAL NEB TO THE W OF THE NEB/IA BORDER.  HAIL AND
STRONG WIND GUSTS WILL REMAIN THE PRIMARY THREATS.

FARTHER E ALONG AND E OF THE NEB/IA BORDER...A CONVECTIVELY
STABILIZED AIR MASS SUGGESTS THE ERN EXTENT OF WW 241 COULD BE
CANCELLED EARLY.  THE REST OF WW 241 SHOULD BE MAINTAINED THROUGH
05Z AND THE WRN EXTENT OF WW 239 IN CENTRAL NEB HAS BEEN TEMPORALLY
EXTENDED UNTIL 04Z.

DISCUSSION...SURFACE ANALYSIS AND TRENDS IN REGIONAL RADAR IMAGERY
SHOWED THE TRAILING OUTFLOW BOUNDARY ATTENDANT TO THE MCS THAT MOVED
EWD ACROSS NRN-NERN IA AND ADJACENT SRN-SERN MN EXTENDED FROM
CENTRAL IA /30 N DSM/ SWWD TO 25 SSE OLU...THEN WWD TO JUST S OF
LBF...AND NWWD TO WEST CENTRAL NEB.  STREAMLINE ANALYSES OF 850 MB
FLOW PER WIND PROFILERS AND WSR-88D VWP DATA INDICATED A SLY LLJ
EXTENDING FROM CENTRAL KS INTO SOUTH CENTRAL NEB WHICH SHOULD
SUSTAIN ONGOING CENTRAL NEB CONVECTIVE COMPLEX LOCATED JUST N OF THE
E-W OUTFLOW BOUNDARY.  THE LLJ INTO THIS REGION WILL PROMOTE
ISENTROPIC ASCENT AND STRENGTHENING WAA ACROSS THE ACTIVE PORTION OF
WW 241/239...WITH ELEVATED CONVECTION EXTENDING EVEN INTO NERN NEB
AND NWRN IA.  RESIDUAL MODERATE INSTABILITY ACROSS THIS REGION
COMBINED WITH EFFECTIVE BULK SHEAR OF 40-50 KT AND STEEP MIDLEVEL
LAPSE RATES WILL CONTINUE TO SUPPORT A THREAT FOR HAIL AND STRONG
WIND GUSTS WITH THE SUSTAINED UPDRAFTS.

MEANWHILE...THE SAME 850 MB STREAMLINE ANALYSIS INDICATED DIFFLUENT
FLOW OVER NERN KS WHICH SHOULD CONTINUE TO LIMIT LOW LEVEL
CONVERGENCE AND ANY NEW CONVECTIVE DEVELOPMENT IN THE SHORT TERM
INTO SERN NEB AND FAR SWRN IA.

..PETERS.. 05/05/2012

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

ATTN...WFO...DMX...FSD...OAX...GID...LBF...

LAT...LON   41420027 42359968 42509907 42409838 42649740 43229625
            43099527 42829485 41859531 40659601 40609625 40349719
            40219888 40319968 40540019 41420027

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