MESO: Mesoscale Discussion 1901

ACUS11 KWNS 170013
SWOMCD
SPC MCD 170012
NEZ000-KSZ000-COZ000-WYZ000-170145-

MESOSCALE DISCUSSION 1901
NWS STORM PREDICTION CENTER NORMAN OK
0712 PM CDT SUN AUG 16 2009

AREAS AFFECTED...ERN CO...WRN KS...SWRN NEB

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 170012Z - 170145Z

ISOLATED HIGH-BASED TSTMS WILL POSE A THREAT FOR SEVERE HAIL AND
MICROBURSTS THIS EVENING. ALTHOUGH DEEP-LAYER SHEAR IS FAVORABLE FOR
UPDRAFT ROTATION AND SPLITTING CELLS...WEAK BUOYANCY AND
SURFACE-BASED INHIBITION THAT INCREASES WITH ERN EXTENT SUGGEST ANY
SEVERE EVENTS SHOULD INITIALLY BE SPORADIC AND MARGINAL. A WW IS NOT
ANTICIPATED IN THE SHORT-TERM...BUT OBSERVATIONAL TRENDS WILL
CONTINUE TO BE CLOSELY MONITORED FOR A POSSIBLE WW LATER THIS
EVENING.

RECENT RADAR/SATELLITE IMAGERY DEPICTED ISOLATED TSTMS FORMING OFF
THE HIGHER TERRAIN AND SPREADING EWD MAINLY ALONG AND N OF THE
PALMER DIVIDE. SPLITTING CELLS HAVE ALREADY OCCURRED WITH TSTMS IN
MORGAN AND ERN WELD COUNTY CO...WHICH PLATTEVILLE CO PROFILER
SUPPORTS WITH STRONG SPEED SHEAR AND UNIDIRECTIONAL SWLYS SAMPLED
FROM 2-8 KM AGL. NEVERTHELESS...ACTIVITY APPEARS TO BE STRUGGLING
GIVEN THE PRESENCE OF MIDDLE 30S TO MIDDLE 40S SURFACE DEW POINTS
CONTRIBUTING TO A WEAKLY UNSTABLE AIR MASS WITH MLCAPE AROUND 500
J/KG PER 00Z DEN RAOB...AND SURFACE-BASED INHIBITION THAT INCREASES
WITH EXTENT E OF THE HIGHER TERRAIN. NEVERTHELESS...ASCENT
ASSOCIATED WITH CNTRL ROCKIES MID/UPPER-LEVEL IMPULSE EVIDENT IN
WATER VAPOR IMAGERY SHOULD MAINTAIN ISOLATED TSTM ACTIVITY THROUGH
THE EVENING. AN INCREASE IN ELEVATED TSTM COVERAGE AND INTENSITY MAY
OCCUR TOWARDS LATE EVENING ACROSS WRN KS/SWRN NEB AS A SELY LLJ
STRENGTHENS WITH ROBUST POSITIVE THETA-E ADVECTION.

..GRAMS.. 08/17/2009

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

ATTN...WFO...LBF...DDC...GLD...PUB...BOU...CYS...

LAT...LON 39860502 40590475 41290361 41490227 41310124 40660063
39690054 39020059 37940087 37500156 37390261 37560394
37860434 38260478 39860502

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