MESOSCALE DISCUSSION 2109
NWS STORM PREDICTION CENTER NORMAN OK
0153 PM CST SAT NOV 10 2012

AREAS AFFECTED...ERN NEB...CNTRL KS

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY

VALID 101953Z - 102200Z

PROBABILITY OF WATCH ISSUANCE...80 PERCENT

SUMMARY...DISCRETE TSTMS ARE EXPECTED TO DEVELOP ALONG A
COLD/QUASI-STATIONARY FRONT AND DRYLINE BETWEEN 21-23Z. THIS
ACTIVITY SHOULD BECOME SUPERCELLULAR WITH PRIMARY INITIAL THREATS OF
SEVERE HAIL/WIND ALONG WITH A FEW TORNADOES...WITH UPSCALE GROWTH
PROBABLE DURING THE EVENING.

DISCUSSION...19Z SURFACE ANALYSIS PLACED A SERIES OF CYCLONES ALONG
A FRONTAL ZONE FROM E-CNTRL CO E/NEWD INTO NERN NEB. A DRYLINE
INTERSECTED THE FRONT NEAR GRI...EXTENDING S/SWWD INTO THE ERN TX
PANHANDLE. ASCENT ASSOCIATED WITH THE VIGOROUS SHORT WAVE TROUGH IN
THE LEE OF THE ROCKIES APPEARS TO BE STRENGTHENING IN THE HIGH
PLAINS...INFERRED BY DEEPENING CU DEVELOPMENT W OF THE DRYLINE. THIS
LOBE OF ASCENT INVOF CO/NEB/KS BORDER WILL OVERSPREAD THE
DRYLINE/FRONT INTERSECTION AROUND 22Z...WHERE SURFACE PRESSURE FALLS
ARE CURRENTLY MAXIMIZED. INITIAL TSTM DEVELOPMENT IS PROBABLE HERE
WITH ACTIVITY RIDING ALONG AND N OF THE FRONT. ADDITIONAL STORMS
WILL FIRE SOUTH ALONG THE DRYLINE BY 00Z.

AIR MASS AHEAD OF THE DRYLINE IS CHARACTERIZED BY 20-30 F SURFACE
TEMPERATURE/DEW POINT SPREADS...AS MODEST BOUNDARY LAYER MOISTURE
REMAINS THE PRIMARY LIMITING FACTOR TO A MORE ROBUST SEVERE THREAT.
EVEN WITH MODEST BUOYANCY...STEEP MID-LEVEL LAPSE RATES AND
STRENGTHENING DEEP-LAYER SHEAR WILL PROMOTE UPDRAFT ROTATION WITH
WIDELY SCATTERED SWATHS OF SEVERE HAIL/WIND PROBABLE. AS A PLUME OF
56-58 F SURFACE DEW POINTS IN S-CNTRL KS TO W-CNTRL OK IS DRAWN
NWD...A FEW TORNADOES MAY DEVELOP. OTHERWISE...ACTIVITY SHOULD
EVOLVE INTO BOWING STRUCTURES/SHORT-LINE SEGMENTS WITH A PRIMARY
RISK OF DAMAGING WIND.

..GRAMS/WEISS.. 11/10/2012