SPC MD 1772

MD 1772 CONCERNING SEVERE POTENTIAL…WATCH POSSIBLE FOR S-CNTRL AND SERN NEB / N-CNTRL AND NERN KS / FAR SWRN IA AND NWRN MO

MESOSCALE DISCUSSION 1772
NWS STORM PREDICTION CENTER NORMAN OK
0218 PM CDT MON SEP 07 2015

AREAS AFFECTED...S-CNTRL AND SERN NEB / N-CNTRL AND NERN KS / FAR
SWRN IA AND NWRN MO

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

VALID 071918Z - 072045Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...THE THREAT FOR A FEW SEVERE STORMS IS EXPECTED TO INCREASE
THROUGH MID TO LATE AFTERNOON AND CONVECTIVE TRENDS ARE BEING
MONITORED FOR A POSSIBLE WATCH.

DISCUSSION...LATEST TRENDS IN VOLUMETRIC RADAR DATA INDICATE THAT A
SMALL CLUSTER OF TSTMS OVER WEBSTER...NUCKOLLS...CLAY AND HAMILTON
COUNTIES IN S-CNTRL NEB HAS AT LEAST TEMPORARILY INTENSIFIED AS OF
19Z.  MESOANALYSIS INDICATES THAT THIS ACTIVITY IS LOCATED NEAR OR
JUST NW OF A QUASI-STATIONARY BOUNDARY STRETCHING FROM A SURFACE LOW
LOCATED N OF RSL NEWD THROUGH E-CNTRL NEB AND INTO CNTRL IA.  

MODIFICATION OF RAP-BASED FORECAST SOUNDINGS FOR CURRENT SURFACE
CONDITIONS SUGGESTS THAT A NARROW AXIS FROM NEAR THE NEB-KS BORDER N
OF CNK SWD INTO CNTRL KS IS NOW NEARLY UNCAPPED FOR SURFACE-BASED
PARCELS.  HOWEVER...A COMPLICATING FACTOR TO THE FORECAST IS A
COOLER AND LIKELY MORE STABLE BOUNDARY LAYER PRESENT OVER SERN
NEB...NERN KS...SWRN IA AND NWRN MO OWING TO THE NWWD ADVECTION OF
CONVECTIVELY-PROCESSED AIR BEING EMITTED BY A DECAYING MCS OVER ERN
KS / WRN MO.  AS A RESULT IT REMAINS UNCLEAR WHETHER THE CURRENT
STORMS WILL CONTINUE TO INTENSIFY AS THEY PROGRESS FROM THE MORE
FAVORABLE THERMODYNAMIC ENVIRONMENT INTO ONE THAT AT LEAST CURRENTLY
APPEARS MORE HOSTILE TO SURFACE-BASED STORM DEVELOPMENT/SUSTENANCE.

SHOULD STORMS EFFECTIVELY BECOME ROOTED IN THE BOUNDARY LAYER...THE
PRESENCE OF A VERTICALLY VEERING WIND PROFILE AND 45-55 KT OF
EFFECTIVE BULK SHEAR WILL BE SUPPORTIVE OF SUPERCELL STORM MODES
WITH A RISK FOR LARGE HAIL...DAMAGING OUTFLOW WINDS AND PERHAPS A
BRIEF TORNADO OR TWO.

CONVECTIVE TRENDS WILL CONTINUE TO BE MONITORED AND IF IT BECOMES
APPARENT THAT A SUSTAINED SEVERE WEATHER THREAT IS DEVELOPING...A
WATCH MAY NEED TO BE CONSIDERED.

..MEAD/HART.. 09/07/2015

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

ATTN...WFO...EAX...OAX...TOP...GID...

LAT...LON   39739865 40289838 40639766 41209583 41069524 40509507
            40049516 39769545 39459633 39369764 39399830 39739865 

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from SPC Mesoscale Discussions http://1.usa.gov/1Ne6DYs