MESO: Mesoscale Discussion 1867

ACUS11 KWNS 092210
SWOMCD
SPC MCD 092209
NEZ000-KSZ000-COZ000-WYZ000-100045-

MESOSCALE DISCUSSION 1867
NWS STORM PREDICTION CENTER NORMAN OK
0509 PM CDT MON SEP 09 2013

AREAS AFFECTED...PORTIONS OF NERN CO...FAR NWRN KS...WRN NEB...FAR
SERN WY

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 092209Z - 100045Z

PROBABILITY OF WATCH ISSUANCE...5 PERCENT

SUMMARY...ISOLATED SVR STORMS MAY OCCUR INTO THE EVENING HOURS...BUT
THE COVERAGE/INTENSITY OF SUCH ACTIVITY IS EXPECTED TO BE TOO
MARGINAL FOR WW ISSUANCE.

DISCUSSION...ASCENT ACCOMPANYING TERRAIN-DRIVEN CIRCULATIONS INVOF
THE ROCKY MOUNTAIN FRONT RANGE IS BEING AUGMENTED BY MODEST UPSLOPE
FLOW ON THE COOLER SIDE OF A WAVY...QUASI-STATIONARY FRONT ANALYZED
FROM CNTRL NEB INTO FAR ERN/S-CNTRL CO. AN ISOLATED STORM COULD ALSO
EVOLVE WITHIN MORE CONCENTRATED CUMULUS CONGESTUS FOCUSED ON THE
WARMER SIDE OF THE BOUNDARY FROM NERN CO INTO FAR SWRN NEB.

THROUGH THE EVENING...ANY CONVECTION WILL HAVE A TENDENCY TO SPREAD
NEWD OVER THE HIGH PLAINS WITH ENHANCED MID-LEVEL SWLY/WSWLY FLOW.
GREATER CONVECTIVE COVERAGE SHOULD BE CONCENTRATED NEAR AND N OF THE
LATITUDE OF DENVER...WHERE WATER VAPOR IMAGERY INDICATES A RIBBON OF
ENHANCED MID-LEVEL MOISTURE SERVING TO AID UPDRAFT SHELTERING. THE
COMBINATION OF SFC TEMPERATURES IN THE 80S/LOWER 90S AMIDST
DEWPOINTS IN THE UPPER 40S/LOWER 50S IS CONTRIBUTING TO AROUND
500-1000 J/KG OF MLCAPE. THIS COULD COMBINE WITH MODERATE DEEP SHEAR
OFFERED BY 25-40 KT OF MID-LEVEL FLOW PER CYS/FTG VWP DATA FOR A FEW
ORGANIZED CONVECTIVE CLUSTERS...WITH THE POTENTIAL FOR SPORADIC SVR
WIND/HAIL. STRONG WIND GUSTS WILL BE AIDED BY SIZABLE SFC
TEMP-DEWPOINT SPREADS OVER 30F.

HOWEVER...VIS IMAGERY SUGGESTS AN AREA OF BILLOW CLOUD FORMATIONS
FROM NERN CO INTO SWRN NEB ON THE COOLER SIDE OF THE
BOUNDARY...PERHAPS INDICATIVE OF HIGHER BOUNDARY-LAYER STATIC
STABILITY THAT COULD BE DELETERIOUS FOR SUSTAINED/INTENSE UPDRAFTS.
DEEP FORCING FOR ASCENT IS ALSO LIMITED PER WATER VAPOR IMAGERY...IN
THE ABSENCE OF MORE SALIENT MID-LEVEL PERTURBATIONS. AND...WITHOUT A
MOISTER/MORE UNSTABLE BOUNDARY LAYER...ANY INSTANCES OF SVR STORMS
SHOULD BE QUITE ISOLATED.

..COHEN/EDWARDS.. 09/09/2013

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

ATTN...WFO...LBF...GLD...BOU...CYS...

LAT...LON 39480495 41310475 42410173 41660053 39950137 38970362
39480495

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