SPC MD 1719

MD 1719 CONCERNING SEVERE POTENTIAL…WATCH POSSIBLE FOR EAST CENTRAL-SERN NEB/WEST CENTRAL-SWRN IA/NERN KS/NWRN MO


MESOSCALE DISCUSSION 1719
NWS STORM PREDICTION CENTER NORMAN OK
1228 PM CDT WED AUG 08 2012

AREAS AFFECTED...EAST CENTRAL-SERN NEB/WEST CENTRAL-SWRN IA/NERN
KS/NWRN MO

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 081728Z - 081830Z

PROBABILITY OF WATCH ISSUANCE...60 PERCENT

SUMMARY...TSTMS ARE EXPECTED TO INCREASE IN COVERAGE...GENERALLY IN
A LINEAR MODE...ACROSS NERN NEB AND NWRN IA EARLY THIS AFTERNOON
WITH A SUBSEQUENT INCREASE IN STORM INTENSITIES AND SVR WEATHER
THREAT FOR DAMAGING WINDS AND LARGE HAIL.  WW MAY BE NEEDED THIS
AFTERNOON ACROSS THE DISCUSSION AREA.

DISCUSSION...AT 17Z...REGIONAL RADAR IMAGERY SHOWED AN INTENSIFYING
BROKEN LINE OF STORMS LOCATED OVER NERN NEB /CUMING AND THURSTON
COUNTIES NEB/ INTO ADJACENT WOODBURY COUNTY IA.  THIS ACTIVITY WAS
MOVING SEWD ALONG THE RELATIVELY COOLER EAST SIDE OF A WARM FRONT
WHICH EXTENDED SEWD FROM A SURFACE LOW N OF OFK THROUGH FAR ERN AND
SERN NEB INTO FAR NERN KS.  MEANWHILE...A PERSISTENT MESO-HIGH
REMAINED OVER NERN MO AS A RESULT OF EARLIER CONVECTION...WITH AN
ATTENDANT CONVECTIVE OUTFLOW BOUNDARY ARCING FROM NORTH CENTRAL IL
SWWD THROUGH NERN MO AT 30 NW STL...AND THEN EXTENDED WWD INVOF OF
COU...SZL...AND OJC.

STRONG SURFACE HEATING ALONG AND W OF THE WARM FRONT IN ERN NEB AND
BENEATH A PLUME OF STEEP MIDLEVEL LAPSE RATES EXTENDING FROM NEB
INTO WRN IA IS AIDING IN INCREASING DESTABILIZATION /MLCAPE
1500-2000 J PER KG/.  MODIFIED 12Z OMAHA SOUNDING SUGGESTED SURFACE
TEMPERATURES IN THE LOWER 90S WILL BE NEEDED TO REDUCE INHIBITION
FOR SURFACE BASED STORMS.  GIVEN CLEAR SKIES DOWNSTREAM OF THE
ONGOING NERN NEB STORMS...CONVECTIVE TEMPERATURES WILL BE MET EARLY
THIS AFTERNOON ALLOWING STORMS TO BECOME SURFACE BASED SUPPORTING AN
INCREASING POTENTIAL FOR DAMAGING WINDS.  STRENGTHENING EFFECTIVE
BULK SHEAR OF 30-40 KT WITH VECTORS ORIENTED PARALLEL TO THE WARM
FRONT SHOULD MAINTAIN PRIMARILY A LINEAR MODE THAT WOULD SUPPORT A
DAMAGING WIND THREAT.  IN ADDITION...THE SHEAR/INSTABILITY PARAMETER
SPACE WILL ALSO SUPPORT A HAIL THREAT.

..PETERS/THOMPSON.. 08/08/2012

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

ATTN...WFO...DMX...EAX...FSD...OAX...TOP...

LAT...LON   40269666 41919702 42459600 42689500 42659460 42349429
            40639383 39669357 39089503 39069591 39339644 40269666

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